C. elegans HSP-12.3 is a 12.3 kDa member of the small heat shock protein (sHSP/HSP20) family. It contains an alpha-crystallin domain (SHSP domain) but has an unusually short N-terminal region and lacks a C-terminal tail, making it one of the smallest known sHSPs. Recombinant HSP-12.3 forms tetramers rather than the large oligomeric complexes typical of other sHSPs, and critically, it lacks detectable in vitro chaperone-like activity (PMID:9744800). This distinguishes it from canonical sHSPs that function as holdase chaperones. HSP-12.3 physically interacts with HSP-12.2 (PMID:9744800). The protein is associated with reproductive tissues including vulva and spermatheca (PMID:11001875). Despite lacking chaperone activity in vitro, C. elegans 12 kDa sHSPs play roles in dauer formation, longevity, and reproduction in vivo. The PMID:9744800 study concludes that tetramers are the building blocks of sHSP complexes and that higher multimer formation, mediated through the N-terminal domains, is a prerequisite for chaperone-like activity. Consistent with this atypical profile, an evolutionary survey of sHSP-mediated sequestration classified HSP-12.3 as sequestrase-negative, arguing against a major role in inclusion-forming sequestration. Rather than acting as a canonical holdase, hsp-12.3 behaves as a stress-response/longevity effector gene: it is regulated by insulin/IGF-1 signaling via DAF-16/FOXO (upregulated when daf-2/IIS is reduced, downregulated when daf-16 activity is reduced), reduced in hpk-1 loss-of-function animals, and listed among HIF-1-positively-regulated stress-response genes under short-term hypoxia. Its protein abundance increases with age and rises further in long-lived daf-2 mutants. hsp-12.3(RNAi) has not been shown to alter lifespan, but this is inconclusive given unverified RNAi specificity and potential redundancy/heterotetramerization with HSP-12.2.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
|
GO:0005737
cytoplasm
|
IBA
GO_REF:0000033 |
ACCEPT |
Summary: IBA annotation for cytoplasmic localization, inferred phylogenetically from a large set of sHSP orthologs across fly, worm, mouse, rat, human, and zebrafish species. The inference is phylogenetically well-supported. sHSPs are generally cytoplasmic proteins, and immunohistochemical data in C. elegans shows HSP12 proteins in vulva and spermatheca tissue (PMID:11001875).
Reason: Cytoplasmic localization is well-established for sHSP family proteins. The IBA inference from multiple orthologs is phylogenetically sound and consistent with immunohistochemical localization data in C. elegans (PMID:11001875). Falcon deep research concurs that, in the absence of gene-specific reporter data, the most defensible statement is that HSP-12.3 is a small cytosolic sHSP-family protein.
Supporting Evidence:
file:worm/hsp-12.3/hsp-12.3-deep-research-falcon.md
the most defensible current statement is that **Hsp-12.3 is a small cytosolic sHSP-family protein**, but its precise subcellular compartment(s) and tissue specificity require confirmation with gene-specific reporters or specific antibodies.
|
|
GO:0005634
nucleus
|
IBA
GO_REF:0000033 |
KEEP AS NON CORE |
Summary: IBA annotation for nuclear localization based on phylogenetic inference from mammalian sHSP orthologs including CRYAA, CRYAB, HSP27/HSPB1 that have been reported to translocate to the nucleus under stress conditions. Nuclear localization is not the primary compartment for sHSPs and has not been specifically demonstrated for C. elegans HSP-12.3.
Reason: Nuclear localization has been reported for some mammalian sHSP orthologs. The IBA inference is phylogenetically supported but represents a secondary or stress-dependent localization. Not the primary compartment for sHSP function. Retained as non-core.
|
|
GO:0009408
response to heat
|
IBA
GO_REF:0000033 |
ACCEPT |
Summary: IBA annotation for involvement in heat stress response, inferred phylogenetically from a large set of sHSP orthologs across fly, worm, and zebrafish. HSP-12.3 is classified as a heat shock protein (HSP20 family), and while its in vivo response to heat has not been specifically characterized, its classification as an sHSP and the IBA inference from well-characterized orthologs support this annotation.
Reason: HSP-12.3 is a member of the sHSP/HSP20 family which is fundamentally involved
in heat stress response. The IBA inference from multiple well-characterized
sHSP orthologs is phylogenetically well-supported, and this inference alone is
sufficient to ACCEPT "response to heat" as a core sHSP-family function (even
though the mechanism likely differs from canonical chaperone activity and is
probably partner-dependent rather than canonical holdase activity).
Note: the falcon deep research evidence on hsp-12.3 regulation
(DAF-16/FOXO insulin-signaling targeting, reduced expression in hpk-1
loss-of-function animals, HIF-1-positive regulation under short-term hypoxia,
and increased protein abundance with age and in long-lived daf-2 mutants)
demonstrates general stress-pathway/longevity regulation, NOT heat-specific
induction. No heat-specific induction data (e.g. heat-shock fold-change values)
for hsp-12.3 were available in that report, so those general-stress entries
were not anchored here as heat-specific evidence; the ACCEPT rests on the IBA
inference.
|
|
GO:0042026
protein refolding
|
IBA
GO_REF:0000033 |
REMOVE |
Summary: IBA annotation for protein refolding, inferred phylogenetically primarily from Drosophila sHSP orthologs. However, HSP-12.3 has been experimentally demonstrated to lack chaperone-like activity in vitro (PMID:9744800). Kokke et al. showed that recombinant HSP-12.3 forms tetramers and is devoid of in vitro chaperone-like abilities. The authors concluded that higher multimer formation, mediated through the N-terminal domains that HSP-12.3 lacks, is a prerequisite for chaperone-like activity. This annotation is therefore incorrect for HSP-12.3.
Reason: HSP-12.3 has been directly demonstrated to lack chaperone-like activity in vitro (PMID:9744800). It forms tetramers rather than the large oligomeric complexes required for chaperone function. The IBA inference from Drosophila sHSP orthologs does not apply because HSP-12.3 has divergent structural properties (very short N-terminal region, no C-terminal tail) that preclude holdase/chaperone activity. There is also a NOT annotation for GO:0051082 (unfolded protein binding) from the same publication confirming this.
Supporting Evidence:
PMID:9744800
both appear devoid of in vitro chaperone-like abilities. This supports the notion that tetramers are the building blocks of sHSP complexes, and that higher multimer formation, mediated through the N-terminal domains, is a prerequisite for chaperone-like activity.
file:worm/hsp-12.3/hsp-12.3-deep-research-falcon.md
Recombinant **HSP-12.3 did not prevent citrate synthase aggregation** in a thermal unfolding assay, indicating **no detectable classical holdase activity under those conditions**.
file:worm/hsp-12.3/hsp-12.3-deep-research-falcon.md
HSP-12.3 was classified as sequestrase-negative and lacked sequence features associated with sequestrase-positive sHSPs, arguing against a major role in inclusion-forming sequestration.
|
|
GO:0031072
heat shock protein binding
|
IPI
PMID:9744800 Caenorhabditis elegans small heat-shock proteins Hsp12.2 and... |
ACCEPT |
Summary: IPI annotation for heat shock protein binding based on Kokke et al. 1998 (PMID:9744800). The study demonstrated physical interaction between HSP-12.3 and HSP-12.2 (WB:WBGene00002011), both of which are 12 kDa sHSPs that form tetramers. This represents homotypic interaction within the sHSP family.
Reason: The physical interaction between HSP-12.3 and HSP-12.2 is directly demonstrated by experimental evidence (PMID:9744800). Heat shock protein binding accurately captures this interaction between sHSP family members. This is a core molecular function for HSP-12.3.
Supporting Evidence:
PMID:9744800
they are the first sHSPs shown to occur as tetramers, rather than forming the usual large multimeric complexes
file:worm/hsp-12.3/hsp-12.3-deep-research-falcon.md
Unlike many sHSPs that form larger multimeric assemblies, HSP-12.3 is reported to assemble as a **tetramer**, and is additionally reported to form **heterotetramers with HSP-12.2**.
|
|
GO:0051082
unfolded protein binding
|
IDA
NOT
PMID:9744800 Caenorhabditis elegans small heat-shock proteins Hsp12.2 and... |
ACCEPT |
Summary: NOT annotation (negated IDA) for unfolded protein binding based on Kokke et al. 1998 (PMID:9744800). The study directly tested recombinant HSP-12.3 for chaperone-like activity and found it devoid of the ability to prevent aggregation of denaturing substrate proteins. This negative result is consistent with the structural analysis showing that HSP-12.3 forms tetramers rather than the large oligomeric complexes required for chaperone function. GO:0051082 is proposed for obsoletion, but the negation is still informative as it indicates this protein does not have holdase activity.
Reason: This NOT annotation is an important negative result directly demonstrated by experimental evidence (PMID:9744800). HSP-12.3 lacks chaperone-like activity and does not bind unfolded proteins in the functional sense despite being an sHSP family member. The negation correctly documents this experimentally determined absence of function.
Supporting Evidence:
PMID:9744800
[Both HSP-12.2 and HSP-12.3 are] devoid of in vitro chaperone-like abilities.
file:worm/hsp-12.3/hsp-12.3-deep-research-falcon.md
Recombinant **HSP-12.3 did not prevent citrate synthase aggregation** in a thermal unfolding assay, indicating **no detectable classical holdase activity under those conditions**.
|
The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.
You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.
We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.
We are interested in where in or outside the cell the gene product carries out its function.
We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.
Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.
The literature retrieved here explicitly refers to hsp-12.3 as the C. elegans small heat shock protein encoded by ORF F38E11.1 (also referred to as Ce12.3), placing it in the Hsp12 / small heat shock protein (sHSP) group with an α-crystallin domain and a strongly reduced overall architecture compared with larger sHSPs. This matches the UniProt-provided identity for Q20164 (SHSP domain-containing protein; HSP20 family; α-crystallin/sHSP domain). (krause2013structuralandfunctional pages 29-32, ramsay2012investigatingtherolea pages 37-42)
sHSPs are ATP-independent chaperone-like proteins classically associated with buffering proteotoxic stress. In C. elegans, Hsp-12 family proteins are described as very small (~12 kDa) proteins that retain the conserved α-crystallin domain but have markedly shortened N-termini and little to no C-terminal tail, i.e., a “minimal” sHSP architecture. (krause2013structuralandfunctional pages 29-32, ramsay2012investigatingtherolea pages 37-42)
Unlike many sHSPs that form larger multimeric assemblies, HSP-12.3 is reported to assemble as a tetramer, and is additionally reported to form heterotetramers with HSP-12.2. This suggests that HSP-12.3’s primary functional unit in vivo could involve partner-dependent assembly rather than the large polydisperse oligomers seen in many other sHSPs. (ramsay2012investigatingtherole pages 82-86, krause2013structuralandfunctional pages 29-32)
A recurring theme in the Hsp-12 family is that standard in vitro aggregation-suppression assays may not detect robust activity for some members. Recombinant HSP-12.3 did not prevent citrate synthase aggregation in a thermal unfolding assay, indicating no detectable classical holdase activity under those conditions. This negative result has been interpreted as consistent with the highly truncated termini (important for substrate binding/solubility in many sHSPs) and/or with specialized in vivo contexts not captured by the assay. (ramsay2012investigatingtherole pages 42-46, ramsay2012investigatingtherolea pages 42-46)
Multiple sources treat hsp-12.3 as an IIS/DAF-16-associated stress gene: it is reported as upregulated when daf-2/IIS is reduced and downregulated when daf-16 activity is reduced, consistent with hsp-12.3 being among downstream DAF-16-linked stress/longevity effector genes (often cited alongside canonical targets such as sod-3 in the broader literature). (ramsay2012investigatingtherolea pages 82-86, ramsay2012investigatingtherolea pages 31-37)
In a peer-reviewed study of HPK-1 in stress responses and aging, hsp-12.3 (F38E11.1) is specifically noted among genes with reduced expression in hpk-1 loss-of-function animals (microarray Table S1 referenced in the paper). Although the excerpt available here does not provide a gene-specific fold change for hsp-12.3, the same study reports that loss of HPK-1 reduces survival after acute heat stress by ~25%, and that HPK-1 and DAF-16 act in the same genetic pathway for lifespan regulation (no additive effect in daf-16; hpk-1). (berber2016homeodomaininteractingproteinkinase pages 9-10)
A 2024 genome-wide study of short-term hypoxia responses and HIF-1 binding reports hsp-12.3 among stress-response genes positively regulated by HIF-1 under short-term hypoxia (listed in Table 1 category “Stress response”). In the excerpt available, the authors provide a category-level enrichment statistic (Bonferroni/FDR reported for that group) but not a gene-specific hsp-12.3 fold-change value, and the excerpt does not provide direct locus-level ChIP-seq binding evidence for hsp-12.3 (so “direct HIF-1 target” status cannot be confirmed from the provided text). (feng2024wholegenomeprofiling pages 4-6)
Direct, hsp-12.3-specific subcellular localization evidence was limited in the retrieved text excerpts. A structural/functional characterization of C. elegans Hsp12-family proteins reports immunostaining and developmental expression patterns primarily for Hsp12.6, with adult staining restricted to vulval cells and the spermatheca; the authors note antibody cross-reactivity suggesting similar localization for other family members such as Hsp12.3, but this remains inferred rather than definitively demonstrated for Hsp-12.3. (krause2013structuralandfunctional pages 29-32)
Given the lack of direct localization data for Hsp-12.3 in the extracted material, the most defensible current statement is that Hsp-12.3 is a small cytosolic sHSP-family protein, but its precise subcellular compartment(s) and tissue specificity require confirmation with gene-specific reporters or specific antibodies.
In the retrieved lifespan/RNAi testing described in a thesis focused on the paralog hsp-12.6, hsp-12.3(RNAi) did not measurably alter lifespan across several tested genetic backgrounds (including wild type and stress/longevity pathway mutant backgrounds). Importantly, the authors caution that RNAi specificity was not confirmed and propose that redundancy (including potential dependence on HSP-12.2/HSP-12.3 heterotetramer formation) could mask phenotypes; therefore these negative data should be considered inconclusive rather than definitive evidence of no function. (ramsay2012investigatingtherolea pages 82-86, ramsay2012investigatingtherole pages 82-86)
A high-quality mechanistic study of conserved sHSP-mediated sequestration of misfolded proteins classifies Hsp-12.3 as “sequestrase-negative” in their assay framework (i.e., no complementation/sequestration activity detected in that system). The same work links sequestrase activity to specific sequence features in terminal extensions (including differences in average N- and C-terminal extension lengths between positive vs negative sHSPs), and notes that Hsp-12.3 lacks motifs/sequence features associated with sequestrase-positive behavior in their analyses. Functionally, this suggests Hsp-12.3 is unlikely to be a major driver of inclusion-forming sequestration, and instead may act via other sHSP mechanisms (or in specialized contexts not captured by that assay). (shrivastava2022thecytoprotectivesequestration pages 24-28, shrivastava2022thecytoprotectivesequestration pages 6-8)
Deep quantitative proteomics identified HSP-12.3 among proteins that increase with age. Specifically, the study reported 55 proteins that increased with age; 25% (14/55) increased to a greater extent in long-lived daf-2(e1370) mutants, and HSP-12.3 is explicitly listed among this subset. This supports the interpretation that HSP-12.3 is part of the proteostasis/stress-protective remodeling associated with aging and IIS modulation at the protein abundance level, not only transcriptionally. (narayan2016deepproteomeanalysis pages 10-12)
The inclusion of hsp-12.3 in a 2024 HIF-1 hypoxia-responsive gene set expands its functional annotation beyond IIS/DAF-16-associated stress response, implicating it in the cross-talk between hypoxia and proteostasis/stress programs. However, the available excerpt does not specify whether HIF-1 regulation is direct (via ChIP peak at the locus) or indirect. (feng2024wholegenomeprofiling pages 4-6)
A 2024 npj Science of Food study in an Aβ-transgenic worm model (CL4176) emphasizes that transcriptomic changes under a neuroprotective intervention involve stress/detox and metabolism programs controlled by transcription factors including DAF-16, SKN-1, PMK-1, and others. While this paper’s excerpted pages do not provide a direct hsp-12.3 quantitative value, it provides current context for why hsp-family genes are frequently used as pathway readouts in real-world worm intervention experiments. (valdes2024invivoneuroprotective pages 10-11)
The most consistent, evidence-backed annotation is that HSP-12.3 is a minimal α-crystallin-domain sHSP that forms tetramers/heterotetramers, is regulated in major stress/longevity transcriptional programs (DAF-16-linked and HIF-1-linked), and shows age- and daf-2-dependent abundance changes, but has unclear direct substrate specificity and unclear localization based on currently retrieved text excerpts. (ramsay2012investigatingtherole pages 82-86, krause2013structuralandfunctional pages 29-32, feng2024wholegenomeprofiling pages 4-6, narayan2016deepproteomeanalysis pages 10-12)
Mechanistically, the evidence argues against classifying HSP-12.3 as a major “sequestrase” (inclusion-forming sequestration factor) in the framework of Shrivastava et al. 2022, and against strong generic holdase activity in the standard citrate synthase assay; this combination supports a model where HSP-12.3 has context-specific or partner-dependent functions (e.g., specific client proteins, specific tissues, or specific stress combinations) that remain to be precisely defined experimentally. (ramsay2012investigatingtherolea pages 42-46, shrivastava2022thecytoprotectivesequestration pages 24-28)
The table below consolidates the main annotation-relevant findings by evidence type, with citation IDs and DOIs/URLs where available.
| Aspect | Key finding | Evidence type | Study (author, year, journal) | Quantitative/statistical detail (if any) | URL/DOI (if present in paper metadata) | Citation ID to use |
|---|---|---|---|---|---|---|
| identity/domain | HSP-12.3 is the C. elegans small heat shock protein encoded by F38E11.1 (Ce12.3), belonging to the Hsp12/sHSP family and retaining the conserved α-crystallin domain with very short N-terminus and little or no C-terminal tail. | Sequence/structural annotation; comparative family analysis | Krause, 2013, unknown journal; Ramsay, 2012, unknown journal | Family proteins are ~12.2–12.6 kDa; α-crystallin core described as ~80–100 aa. | N/A | (krause2013structuralandfunctional pages 29-32, ramsay2012investigatingtherolea pages 37-42) |
| oligomerization | Unlike many sHSPs that form large multimers, HSP-12.3 is reported to assemble as a tetramer, and HSP-12.2/HSP-12.3 can form heterotetramers. | In vitro biochemistry / oligomerization analysis | Krause, 2013, unknown journal; Ramsay, 2012, unknown journal | Tetrameric organization reported for Hsp12 members except Hsp12.6 in recombinant preparations. | N/A | (krause2013structuralandfunctional pages 29-32, ramsay2012investigatingtherole pages 82-86) |
| in vitro chaperone activity | Recombinant HSP-12.3 did not prevent aggregation of thermally unfolding citrate synthase in standard assays, so no conventional in vitro chaperone activity was detected. | In vitro chaperone assay | Ramsay, 2012, unknown journal | Negative assay reported at 43°C with citrate synthase aggregation assay. | N/A | (ramsay2012investigatingtherole pages 42-46, ramsay2012investigatingtherolea pages 42-46) |
| regulation/pathways | hsp-12.3 is repeatedly described as a DAF-16/FOXO-associated insulin-signaling target, being upregulated when daf-2/IIS is reduced and downregulated when daf-16 activity is reduced; hpk-1 loss also reduces hsp-12.3 expression. | Transcriptomics / genetics | Ramsay, 2012, unknown journal; Berber et al., 2016, Scientific Reports | No gene-specific fold-change reported in extracted text; HPK-1 loss reduced post-stress survival by ~25% overall, while hsp-12.3 was among genes reduced in hpk-1(-). | https://doi.org/10.1038/srep19582 | (ramsay2012investigatingtherolea pages 82-86, berber2016homeodomaininteractingproteinkinase pages 9-10, ramsay2012investigatingtherolea pages 31-37) |
| hypoxia/HIF-1 | In 2024 whole-genome hypoxia profiling, hsp-12.3 was listed among stress-response genes positively regulated by HIF-1 under short-term hypoxia, but the supplied excerpt did not give an hsp-12.3-specific fold change or direct-target ChIP evidence. | RNA-seq / hypoxia transcriptomics | Feng, Qu & Powell-Coffman, 2024, PLOS ONE | Stress-response category significance Bonferroni/FDR = 7.88E-03; no per-gene hsp-12.3 value in provided text. | https://doi.org/10.1371/journal.pone.0295094 | (feng2024wholegenomeprofiling pages 4-6) |
| proteostasis/sequestration | In the evolutionary sequestration study, HSP-12.3 was classified as sequestrase-negative and lacked sequence features associated with sequestrase-positive sHSPs, arguing against a major role in inclusion-forming sequestration. | Comparative functional assay / sequence-feature analysis | Shrivastava et al., 2022, Journal of Cell Biology | Sequestrase-positive sHSPs had longer NTEs on average (39 vs 25 aa) and longer CTEs (21 vs 6 aa); Hsp-12.3 was in the “none” group for sequestrase activity. | https://doi.org/10.1083/jcb.202202149 | (shrivastava2022thecytoprotectivesequestration pages 24-28, shrivastava2022thecytoprotectivesequestration pages 6-8) |
| expression with age | HSP-12.3 protein abundance increases with age and is among age-increasing proteins that rise even more strongly in long-lived daf-2 mutants. | Deep quantitative proteomics | Narayan et al., 2016, Cell Systems | 55 proteins increased with age; 25% (14/55) increased to a much greater extent in daf-2(e1370), including HSP-12.3; >9,300 proteins were reproducibly identified per replicate. | https://doi.org/10.1016/j.cels.2016.06.011 | (narayan2016deepproteomeanalysis pages 10-12) |
| localization/tissue expression | Direct HSP-12.3 localization evidence is limited; cross-reactive antibody data suggest expression patterns similar to Hsp12-family proteins, while Hsp12.6 family staining in adults is restricted to vulval cells and spermatheca, so localization for HSP-12.3 remains inferred rather than definitive. | Immunostaining / family-level expression analysis | Krause, 2013, unknown journal | Hsp12.6 peaks in L1 and in adults localizes to vulval cells and spermatheca; explicit HSP-12.3 localization was not shown in the excerpt. | N/A | (krause2013structuralandfunctional pages 29-32, krause2013structuralandfunctional pages 1-8) |
| phenotypes/functional tests | hsp-12.3 RNAi did not measurably alter lifespan in several tested genetic backgrounds, but the result is considered inconclusive because RNAi specificity was not verified and redundancy with hsp-12.2/heterotetramerization could mask function. | Genetics / RNAi lifespan testing | Ramsay, 2012, unknown journal | No lifespan effect seen in N2, phsp-12.6::HSP-12.6::DSRED2, hsf-1(sy441), or daf-16(mu86) backgrounds in the reported experiments. | N/A | (ramsay2012investigatingtherolea pages 82-86, ramsay2012investigatingtherole pages 82-86) |
Table: This table compiles the most relevant evidence found for C. elegans hsp-12.3/F38E11.1, organized by annotation-relevant aspects such as domain identity, regulation, localization, and functional testing. It is useful as a quick evidence map distinguishing direct findings from family-level inference and highlighting where data remain limited.
Note: Some sources retrieved as theses/unknown-journal texts (e.g., Ramsay 2012; Krause 2013) contained relevant Hsp-12.3 family characterization but did not include stable DOI metadata in the extracted segments. (ramsay2012investigatingtherolea pages 82-86, krause2013structuralandfunctional pages 29-32)
References
(krause2013structuralandfunctional pages 29-32): M Krause. Structural and functional characterization of small heat shock proteins of the nematode caenorhabditis elegans. Unknown journal, 2013.
(ramsay2012investigatingtherolea pages 37-42): LF Ramsay. Investigating the role of the small heat shock protein, hsp-12.6, in longevity in caenorhabditis elegans. Unknown journal, 2012.
(ramsay2012investigatingtherole pages 82-86): LF Ramsay. Investigating the role of the small heat shock protein, hsp-12.6, in longevity in caenorhabditis elegans. Unknown journal, 2012.
(ramsay2012investigatingtherole pages 42-46): LF Ramsay. Investigating the role of the small heat shock protein, hsp-12.6, in longevity in caenorhabditis elegans. Unknown journal, 2012.
(ramsay2012investigatingtherolea pages 42-46): LF Ramsay. Investigating the role of the small heat shock protein, hsp-12.6, in longevity in caenorhabditis elegans. Unknown journal, 2012.
(ramsay2012investigatingtherolea pages 82-86): LF Ramsay. Investigating the role of the small heat shock protein, hsp-12.6, in longevity in caenorhabditis elegans. Unknown journal, 2012.
(ramsay2012investigatingtherolea pages 31-37): LF Ramsay. Investigating the role of the small heat shock protein, hsp-12.6, in longevity in caenorhabditis elegans. Unknown journal, 2012.
(berber2016homeodomaininteractingproteinkinase pages 9-10): Slavica Berber, Mallory Wood, Estelle Llamosas, Priya Thaivalappil, Karen Lee, Bing Mana Liao, Yee Lian Chew, Aaron Rhodes, Duygu Yucel, Merlin Crossley, and Hannah R Nicholas. Homeodomain-interacting protein kinase (hpk-1) regulates stress responses and ageing in c. elegans. Scientific Reports, Jan 2016. URL: https://doi.org/10.1038/srep19582, doi:10.1038/srep19582. This article has 27 citations and is from a peer-reviewed journal.
(feng2024wholegenomeprofiling pages 4-6): Dingxia Feng, Long Qu, and Jo Anne Powell-Coffman. Whole genome profiling of short-term hypoxia induced genes and identification of hif-1 binding sites provide insights into hif-1 function in caenorhabditis elegans. PLOS ONE, 19:e0295094, May 2024. URL: https://doi.org/10.1371/journal.pone.0295094, doi:10.1371/journal.pone.0295094. This article has 8 citations and is from a peer-reviewed journal.
(shrivastava2022thecytoprotectivesequestration pages 24-28): Aseem Shrivastava, Carl Alexander Sandhof, Kevin Reinle, Areeb Jawed, Carmen Ruger-Herreros, Dominic Schwarz, Declan Creamer, Carmen Nussbaum-Krammer, Axel Mogk, and Bernd Bukau. The cytoprotective sequestration activity of small heat shock proteins is evolutionarily conserved. Sep 2022. URL: https://doi.org/10.1083/jcb.202202149, doi:10.1083/jcb.202202149. This article has 20 citations and is from a highest quality peer-reviewed journal.
(shrivastava2022thecytoprotectivesequestration pages 6-8): Aseem Shrivastava, Carl Alexander Sandhof, Kevin Reinle, Areeb Jawed, Carmen Ruger-Herreros, Dominic Schwarz, Declan Creamer, Carmen Nussbaum-Krammer, Axel Mogk, and Bernd Bukau. The cytoprotective sequestration activity of small heat shock proteins is evolutionarily conserved. Sep 2022. URL: https://doi.org/10.1083/jcb.202202149, doi:10.1083/jcb.202202149. This article has 20 citations and is from a highest quality peer-reviewed journal.
(narayan2016deepproteomeanalysis pages 10-12): Vikram Narayan, Tony Ly, Ehsan Pourkarimi, Alejandro Brenes Murillo, Anton Gartner, Angus I. Lamond, and Cynthia Kenyon. Deep proteome analysis identifies age-related processes in c. elegans. Cell Systems, 3:144-159, Aug 2016. URL: https://doi.org/10.1016/j.cels.2016.06.011, doi:10.1016/j.cels.2016.06.011. This article has 141 citations and is from a domain leading peer-reviewed journal.
(valdes2024invivoneuroprotective pages 10-11): Alberto Valdés, José David Sánchez-Martínez, Rocío Gallego, Elena Ibáñez, Miguel Herrero, and Alejandro Cifuentes. In vivo neuroprotective capacity of a dunaliella salina extract - comprehensive transcriptomics and metabolomics study. NPJ Science of Food, Jan 2024. URL: https://doi.org/10.1038/s41538-023-00246-7, doi:10.1038/s41538-023-00246-7. This article has 12 citations and is from a domain leading peer-reviewed journal.
(krause2013structuralandfunctional pages 1-8): M Krause. Structural and functional characterization of small heat shock proteins of the nematode caenorhabditis elegans. Unknown journal, 2013.
id: Q20164
gene_symbol: hsp-12.3
product_type: PROTEIN
status: IN_PROGRESS
taxon:
id: NCBITaxon:6239
label: Caenorhabditis elegans
description: >-
C. elegans HSP-12.3 is a 12.3 kDa member of the small heat shock protein (sHSP/HSP20)
family. It contains an alpha-crystallin domain (SHSP domain) but has an unusually
short N-terminal region and lacks a C-terminal tail, making it one of the smallest
known sHSPs. Recombinant HSP-12.3 forms tetramers rather than the large oligomeric
complexes typical of other sHSPs, and critically, it lacks detectable in vitro
chaperone-like activity (PMID:9744800). This distinguishes it from canonical sHSPs
that function as holdase chaperones. HSP-12.3 physically interacts with HSP-12.2
(PMID:9744800). The protein is associated with reproductive tissues including vulva
and spermatheca (PMID:11001875). Despite lacking chaperone activity in vitro, C.
elegans 12 kDa sHSPs play roles in dauer formation, longevity, and reproduction
in vivo. The PMID:9744800 study concludes that tetramers are the building blocks
of sHSP complexes and that higher multimer formation, mediated through the N-terminal
domains, is a prerequisite for chaperone-like activity. Consistent with this atypical
profile, an evolutionary survey of sHSP-mediated sequestration classified HSP-12.3
as sequestrase-negative, arguing against a major role in inclusion-forming
sequestration. Rather than acting as a canonical holdase, hsp-12.3 behaves as a
stress-response/longevity effector gene: it is regulated by insulin/IGF-1 signaling
via DAF-16/FOXO (upregulated when daf-2/IIS is reduced, downregulated when daf-16
activity is reduced), reduced in hpk-1 loss-of-function animals, and listed among
HIF-1-positively-regulated stress-response genes under short-term hypoxia. Its
protein abundance increases with age and rises further in long-lived daf-2 mutants.
hsp-12.3(RNAi) has not been shown to alter lifespan, but this is inconclusive given
unverified RNAi specificity and potential redundancy/heterotetramerization with
HSP-12.2.
existing_annotations:
- term:
id: GO:0005737
label: cytoplasm
evidence_type: IBA
original_reference_id: GO_REF:0000033
review:
summary: >-
IBA annotation for cytoplasmic localization, inferred phylogenetically from
a large set of sHSP orthologs across fly, worm, mouse, rat, human, and
zebrafish species. The inference is phylogenetically well-supported. sHSPs
are generally cytoplasmic proteins, and immunohistochemical data in C. elegans
shows HSP12 proteins in vulva and spermatheca tissue (PMID:11001875).
action: ACCEPT
reason: >-
Cytoplasmic localization is well-established for sHSP family proteins. The
IBA inference from multiple orthologs is phylogenetically sound and consistent
with immunohistochemical localization data in C. elegans (PMID:11001875).
Falcon deep research concurs that, in the absence of gene-specific reporter
data, the most defensible statement is that HSP-12.3 is a small cytosolic
sHSP-family protein.
supported_by:
- reference_id: file:worm/hsp-12.3/hsp-12.3-deep-research-falcon.md
supporting_text: |-
the most defensible current statement is that **Hsp-12.3 is a small cytosolic sHSP-family protein**, but its precise subcellular compartment(s) and tissue specificity require confirmation with gene-specific reporters or specific antibodies.
- term:
id: GO:0005634
label: nucleus
evidence_type: IBA
original_reference_id: GO_REF:0000033
review:
summary: >-
IBA annotation for nuclear localization based on phylogenetic inference from
mammalian sHSP orthologs including CRYAA, CRYAB, HSP27/HSPB1 that have been
reported to translocate to the nucleus under stress conditions. Nuclear
localization is not the primary compartment for sHSPs and has not been
specifically demonstrated for C. elegans HSP-12.3.
action: KEEP_AS_NON_CORE
reason: >-
Nuclear localization has been reported for some mammalian sHSP orthologs. The
IBA inference is phylogenetically supported but represents a secondary or
stress-dependent localization. Not the primary compartment for sHSP function.
Retained as non-core.
- term:
id: GO:0009408
label: response to heat
evidence_type: IBA
original_reference_id: GO_REF:0000033
review:
summary: >-
IBA annotation for involvement in heat stress response, inferred
phylogenetically from a large set of sHSP orthologs across fly, worm, and
zebrafish. HSP-12.3 is classified as a heat shock protein (HSP20 family),
and while its in vivo response to heat has not been specifically characterized,
its classification as an sHSP and the IBA inference from well-characterized
orthologs support this annotation.
action: ACCEPT
reason: |-
HSP-12.3 is a member of the sHSP/HSP20 family which is fundamentally involved
in heat stress response. The IBA inference from multiple well-characterized
sHSP orthologs is phylogenetically well-supported, and this inference alone is
sufficient to ACCEPT "response to heat" as a core sHSP-family function (even
though the mechanism likely differs from canonical chaperone activity and is
probably partner-dependent rather than canonical holdase activity).
Note: the falcon deep research evidence on hsp-12.3 regulation
(DAF-16/FOXO insulin-signaling targeting, reduced expression in hpk-1
loss-of-function animals, HIF-1-positive regulation under short-term hypoxia,
and increased protein abundance with age and in long-lived daf-2 mutants)
demonstrates general stress-pathway/longevity regulation, NOT heat-specific
induction. No heat-specific induction data (e.g. heat-shock fold-change values)
for hsp-12.3 were available in that report, so those general-stress entries
were not anchored here as heat-specific evidence; the ACCEPT rests on the IBA
inference.
- term:
id: GO:0042026
label: protein refolding
evidence_type: IBA
original_reference_id: GO_REF:0000033
review:
summary: >-
IBA annotation for protein refolding, inferred phylogenetically primarily from
Drosophila sHSP orthologs. However, HSP-12.3 has been experimentally demonstrated
to lack chaperone-like activity in vitro (PMID:9744800). Kokke et al. showed
that
recombinant HSP-12.3 forms tetramers and is devoid of in vitro chaperone-like
abilities. The authors concluded that higher multimer formation, mediated through
the N-terminal domains that HSP-12.3 lacks, is a prerequisite for chaperone-like
activity. This annotation is therefore incorrect for HSP-12.3.
action: REMOVE
reason: >-
HSP-12.3 has been directly demonstrated to lack chaperone-like activity in vitro
(PMID:9744800). It forms tetramers rather than the large oligomeric complexes
required for chaperone function. The IBA inference from Drosophila sHSP orthologs
does not apply because HSP-12.3 has divergent structural properties (very short
N-terminal region, no C-terminal tail) that preclude holdase/chaperone activity.
There is also a NOT annotation for GO:0051082 (unfolded protein binding) from
the
same publication confirming this.
supported_by:
- reference_id: PMID:9744800
supporting_text: >-
both appear devoid of in vitro chaperone-like abilities. This supports the
notion that tetramers are the building blocks of sHSP complexes, and that
higher multimer formation, mediated through the N-terminal domains, is a
prerequisite for chaperone-like activity.
- reference_id: file:worm/hsp-12.3/hsp-12.3-deep-research-falcon.md
supporting_text: |-
Recombinant **HSP-12.3 did not prevent citrate synthase aggregation** in a thermal unfolding assay, indicating **no detectable classical holdase activity under those conditions**.
- reference_id: file:worm/hsp-12.3/hsp-12.3-deep-research-falcon.md
supporting_text: |-
HSP-12.3 was classified as sequestrase-negative and lacked sequence features associated with sequestrase-positive sHSPs, arguing against a major role in inclusion-forming sequestration.
- term:
id: GO:0031072
label: heat shock protein binding
evidence_type: IPI
original_reference_id: PMID:9744800
review:
summary: >-
IPI annotation for heat shock protein binding based on Kokke et al. 1998
(PMID:9744800). The study demonstrated physical interaction between HSP-12.3
and HSP-12.2 (WB:WBGene00002011), both of which are 12 kDa sHSPs that form
tetramers. This represents homotypic interaction within the sHSP family.
action: ACCEPT
reason: >-
The physical interaction between HSP-12.3 and HSP-12.2 is directly demonstrated
by experimental evidence (PMID:9744800). Heat shock protein binding accurately
captures this interaction between sHSP family members. This is a core molecular
function for HSP-12.3.
supported_by:
- reference_id: PMID:9744800
supporting_text: >-
they are the first sHSPs shown to occur as tetramers, rather than forming
the usual large multimeric complexes
- reference_id: file:worm/hsp-12.3/hsp-12.3-deep-research-falcon.md
supporting_text: |-
Unlike many sHSPs that form larger multimeric assemblies, HSP-12.3 is reported to assemble as a **tetramer**, and is additionally reported to form **heterotetramers with HSP-12.2**.
- term:
id: GO:0051082
label: unfolded protein binding
evidence_type: IDA
original_reference_id: PMID:9744800
negated: true
review:
summary: >-
NOT annotation (negated IDA) for unfolded protein binding based on Kokke et
al.
1998 (PMID:9744800). The study directly tested recombinant HSP-12.3 for
chaperone-like activity and found it devoid of the ability to prevent aggregation
of denaturing substrate proteins. This negative result is consistent with the
structural analysis showing that HSP-12.3 forms tetramers rather than the large
oligomeric complexes required for chaperone function. GO:0051082 is proposed
for
obsoletion, but the negation is still informative as it indicates this protein
does not have holdase activity.
action: ACCEPT
reason: >-
This NOT annotation is an important negative result directly demonstrated by
experimental evidence (PMID:9744800). HSP-12.3 lacks chaperone-like activity
and does not bind unfolded proteins in the functional sense despite being an
sHSP family member. The negation correctly documents this experimentally
determined absence of function.
supported_by:
- reference_id: PMID:9744800
supporting_text: >-
[Both HSP-12.2 and HSP-12.3 are] devoid of in vitro chaperone-like abilities.
full_text_unavailable: true
- reference_id: file:worm/hsp-12.3/hsp-12.3-deep-research-falcon.md
supporting_text: |-
Recombinant **HSP-12.3 did not prevent citrate synthase aggregation** in a thermal unfolding assay, indicating **no detectable classical holdase activity under those conditions**.
references:
- id: GO_REF:0000033
title: Annotation inferences using phylogenetic trees
findings: []
- id: PMID:9744800
title: Caenorhabditis elegans small heat-shock proteins Hsp12.2 and Hsp12.3
form tetramers and have no chaperone-like activity.
findings:
- statement: >-
Recombinant C. elegans HSP-12.2 and HSP-12.3 form tetramers, making them
the first sHSPs shown to occur as tetramers. Both are devoid of in vitro
chaperone-like abilities. These proteins have very short N-terminal regions
and lack C-terminal tails. The authors conclude that higher multimer
formation, mediated through N-terminal domains, is a prerequisite for
chaperone-like activity.
supporting_text: >-
both appear devoid of in vitro chaperone-like abilities. This supports the
notion that tetramers are the building blocks of sHSP complexes, and that
higher multimer formation, mediated through the N-terminal domains, is a
prerequisite for chaperone-like activity.
- id: PMID:11001875
title: Association of several small heat-shock proteins with reproductive
tissues in the nematode Caenorhabditis elegans.
findings:
- statement: >-
Immunohistochemical analysis shows that HSP12 proteins are expressed in
vulva and spermatheca of C. elegans.
supporting_text: >-
the tissues expressing the greatest number of smHSPs are vulva (HSP12s,
HSP43 and, under stress, HSP16s) and spermatheca (HSP12s, HSP25, HSP43
and, under stress, HSP16s).
- id: file:worm/hsp-12.3/hsp-12.3-deep-research-falcon.md
title: Falcon deep research report on hsp-12.3
findings:
- statement: |
HSP-12.3 is a minimal alpha-crystallin-domain sHSP encoded by ORF F38E11.1
(Ce12.3) with a markedly shortened N-terminus and little to no C-terminal
tail, placing it in the Hsp12/sHSP group of the smallest known sHSPs.
supporting_text: |-
In *C. elegans*, Hsp-12 family proteins are described as **very small (~12 kDa)** proteins that retain the conserved **α-crystallin domain** but have **markedly shortened N-termini** and **little to no C-terminal tail**, i.e., a “minimal” sHSP architecture.
- statement: |
HSP-12.3 assembles as a tetramer and forms heterotetramers with HSP-12.2,
consistent with partner-dependent assembly rather than the large
polydisperse oligomers of canonical sHSPs.
supporting_text: |-
Unlike many sHSPs that form larger multimeric assemblies, HSP-12.3 is reported to assemble as a **tetramer**, and is additionally reported to form **heterotetramers with HSP-12.2**.
- statement: |
Recombinant HSP-12.3 did not prevent citrate synthase aggregation in a
thermal unfolding assay, indicating no detectable classical holdase
activity under those conditions, consistent with its highly truncated
termini.
supporting_text: |-
Recombinant **HSP-12.3 did not prevent citrate synthase aggregation** in a thermal unfolding assay, indicating **no detectable classical holdase activity under those conditions**.
- statement: |
In an evolutionary study of sHSP-mediated sequestration, HSP-12.3 was
classified as sequestrase-negative and lacked sequence features associated
with sequestrase-positive sHSPs, arguing against a major role in
inclusion-forming sequestration.
supporting_text: |-
HSP-12.3 was classified as sequestrase-negative and lacked sequence features associated with sequestrase-positive sHSPs, arguing against a major role in inclusion-forming sequestration.
- statement: |
hsp-12.3 is repeatedly described as a DAF-16/FOXO-associated insulin-signaling
target, upregulated when daf-2/IIS is reduced and downregulated when daf-16
activity is reduced.
supporting_text: |-
it is reported as **upregulated when daf-2/IIS is reduced** and **downregulated when daf-16 activity is reduced**, consistent with hsp-12.3 being among downstream DAF-16-linked stress/longevity effector genes
- statement: |
hsp-12.3 (F38E11.1) shows reduced expression in hpk-1 loss-of-function
animals, linking it to HPK-1/DAF-16-dependent stress and aging regulation.
supporting_text: |-
**hsp-12.3 (F38E11.1)** is specifically noted among genes with **reduced expression** in **hpk-1 loss-of-function** animals (microarray Table S1 referenced in the paper).
- statement: |
A 2024 whole-genome hypoxia study lists hsp-12.3 among stress-response genes
positively regulated by HIF-1 under short-term hypoxia, though direct
locus-level HIF-1 binding evidence was not confirmed in the excerpt.
supporting_text: |-
A 2024 genome-wide study of short-term hypoxia responses and HIF-1 binding reports **hsp-12.3** among **stress-response genes positively regulated by HIF-1 under short-term hypoxia**
- statement: |
Deep quantitative proteomics identified HSP-12.3 among proteins that increase
with age, with a greater increase in long-lived daf-2(e1370) mutants,
indicating IIS-dependent proteostasis remodeling at the protein level.
supporting_text: |-
Deep quantitative proteomics identified **HSP-12.3 among proteins that increase with age**.
- statement: |
The most defensible current localization statement is that HSP-12.3 is a
small cytosolic sHSP-family protein; precise compartment and tissue
specificity remain to be confirmed with gene-specific reporters.
supporting_text: |-
the most defensible current statement is that **Hsp-12.3 is a small cytosolic sHSP-family protein**, but its precise subcellular compartment(s) and tissue specificity require confirmation with gene-specific reporters or specific antibodies.
core_functions:
- molecular_function:
id: GO:0031072
label: heat shock protein binding
directly_involved_in:
- id: GO:0009408
label: response to heat
locations:
- id: GO:0005737
label: cytoplasm
description: >-
HSP-12.3 is an atypical sHSP that forms tetramers and physically interacts
with HSP-12.2 (PMID:9744800). Unlike canonical sHSPs, it lacks chaperone-like
activity in vitro due to its very short N-terminal region and absence of
C-terminal tail, which prevents higher-order oligomerization required for
holdase function (PMID:9744800). Its role in the heat stress response may
involve protein-protein interactions with other sHSP family members rather
than direct substrate holdase activity.