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this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.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.
Identity is verified. The requested target is human CCNB1, encoding cyclin B1 (UniProt P14635), not a similarly named protein from another organism. Human-cell studies consistently identify cyclin B1 as a B-type mitotic cyclin whose cyclin-box region supports CDK1 association and localization, while its less-structured N terminus contains trafficking, chromosome-binding, and destruction determinants. These observations agree with the supplied UniProt assignment to the cyclin family, Cyclin A/B subfamily, and the listed cyclin-like domains. No conflicting gene identity was encountered. (bentley2007distinctsequenceelements pages 1-2, pfaff2013determinantsofhuman pages 1-2)
Cyclin B1 is not itself an enzyme. Its primary function is to bind and activate the catalytic serine/threonine kinase CDK1, forming the cyclin-B1–CDK1 complex, historically termed maturation- or M-phase-promoting factor. Cyclin B1 controls when, where, and toward which substrates CDK1 acts. Rising complex activity drives mitotic entry and progression; rapid APC/C-dependent cyclin-B1 destruction extinguishes CDK1 activity and initiates mitotic exit. (lindqvist2007cyclinb1–cdk1activation pages 1-2, holder2020ordereddephosphorylationinitiated pages 2-3)
The most important recent mechanistic advance is a 2024 human-cell study showing that cyclin B1 and APC/C are spatially co-concentrated on mitotic chromosomes. An N-terminal arginine anchor binds the nucleosome acidic patch, accelerating APC/C recognition and cyclin-B1 destruction; disrupting this interaction delayed degradation and produced aneuploidy and polyploidy. (cirillo2024spatialcontrolof pages 13-14)
| Annotation topic | Current conclusion | Strongest evidence/model and method | Quantitative detail | Evidence strength / limitation |
|---|---|---|---|---|
| Identity and domain fit | CCNB1 denotes human cyclin B1, represented by UniProt P14635. Its cyclin-box-dependent CDK binding and regulatory N-terminal region agree with assignment to the cyclin family, Cyclin A/B subfamily. | Human cyclin-B1–GFP deletion/mutagenesis and live-cell imaging mapped centrosomal targeting to cyclin-box sequences and chromosome targeting to the unstructured N terminus. (bentley2007distinctsequenceelements pages 1-2, pfaff2013determinantsofhuman pages 1-2) | The cyclin box supports major partner and localization functions; the N-terminal region contains separable localization and destruction determinants. | High confidence. Multiple human-cell studies match the supplied UniProt identity, although they do not independently define every InterPro boundary. |
| Primary molecular function | Cyclin B1 is a nonenzymatic regulatory cyclin, not a kinase. It binds and activates the catalytic serine/threonine kinase CDK1, forming cyclin-B1–CDK1/MPF and conferring temporal, spatial, and substrate-selection information. | Single-cell analysis quantified CDK1 dephosphorylation and APC3 phosphorylation during human mitotic entry; imaging and kinetic modeling showed continuing activation after centrosome separation. (lindqvist2007cyclinb1–cdk1activation pages 1-2) | Supporting extract studies summarized in the paper found cyclin-B1-associated CDK1 activity at about 30% of maximum near the end of G2 before feedback-driven activation. | High confidence for the regulatory-partner function. Catalysis belongs to CDK1; the reported percentage is not a universal human-cell threshold. |
| Substrate specificity | The complex preferentially phosphorylates Ser/Thr-Pro motifs: minimal S/T-P and optimal S/T-P-X-K/R. Cyclin-mediated docking, CKS1-dependent priming, localization, and noncanonical sites broaden physiological specificity. | Human cyclin-B1 work describes the canonical motif; a 2023 expert perspective integrated phosphoproteomic and biochemical evidence for noncanonical sites and distal docking. (bentley2007distinctsequenceelements pages 1-2, valk2023cdksignalingvia pages 1-2) | CDKs collectively phosphorylate thousands of Ser/Thr sites; no single motif defines the complete cyclin-B1–CDK1 substrate set. | High confidence for canonical motifs; evolving evidence for noncanonical sites. Some docking principles derive from CDK systems other than human CCNB1. |
| Activation and checkpoint regulation | Cyclin B1 accumulates in G2, while WEE1 and PKMYT1/MYT1 inhibit associated CDK1 through Thr14/Tyr15 phosphorylation. CDC25 removes these phosphates; reciprocal CDK1–CDC25 activation and WEE1 inhibition generate positive feedback. DNA-damage signaling through ATR/ATM–CHK1/CHK2 and p53 restrains activation. | Human single-cell activation measurements and modeling, supported by a systematic mechanistic review of CDC25C and checkpoint pathways. (liu2020theroleof pages 2-3, lindqvist2007cyclinb1–cdk1activation pages 1-2) | CDC25-mediated dephosphorylation proceeds with Thr14 before Tyr15; different cyclin-B1–CDK1 activity levels are required for mitotic entry and later progression. | High mechanistic confidence. Exact thresholds vary by model, cell type, and assay; part of the checkpoint synthesis comes from review evidence. |
| Subcellular localization | Cyclin B1 is predominantly cytoplasmic during interphase but shuttles through the nucleus. At prophase it accumulates in the nucleus and localizes to centrosomes, spindle microtubules, condensed chromosomes, and unattached kinetochores. | Live spinning-disk confocal microscopy of full-length and mutant human cyclin-B1–GFP, HEC1/MAD2 perturbation, and chromosome-targeting mutagenesis. (bentley2007distinctsequenceelements pages 1-2, pfaff2013determinantsofhuman pages 1-2) | Bentley et al. imaged at least 50 full-length-expressing cells and at least 30 cells for several major mutants at 15–45-second intervals. | High confidence in cultured human cells. Fluorescent-fusion expression can alter abundance or localization, although the findings agree with endogenous-protein studies. |
| Mitotic processes | Spatially organized cyclin-B1–CDK1 phosphorylation promotes centrosome separation, chromosome condensation, nuclear-envelope breakdown, spindle assembly, and maintenance of the mitotic state. | Human single-cell activity measurements and localization-mutant studies position cyclin-B1–CDK1 near substrates involved in chromosome and spindle remodeling. (lindqvist2007cyclinb1–cdk1activation pages 1-2, pfaff2013determinantsofhuman pages 1-2) | Cyclin-B1–CDK1 activation continues after centrosome separation rather than occurring as one instantaneous pulse. | High confidence for the overall mitotic role. Individual downstream substrates differ in how directly their dependence on CCNB1, rather than another cyclin-B complex, has been demonstrated. |
| Spindle-assembly checkpoint | Cyclin-B1–CDK1 establishes a checkpoint-permissive state by phosphorylating human MPS1 at Ser281, enabling MPS1 recruitment to unattached kinetochores. PP2A-B55 reverses this state as cyclin B1 declines. | Human-cell mutation and kinetochore-tethering experiments showed that MPS1-S281A failed to localize or recruit downstream checkpoint proteins, whereas direct Mis12 tethering bypassed the requirement. (hayward2019cdk1ccnb1createsa pages 1-2) | The checkpoint remains responsive until CCNB1 falls below a characteristic functional threshold; no universal molar threshold was reported. | High confidence from a direct human-cell mechanism. This is one component of a larger network involving MPS1, BUB proteins, MAD1/MAD2, CDC20, Aurora B, and phosphatases. |
| APC/C destruction and mitotic exit | Once the spindle checkpoint is satisfied, APC/C–CDC20 recognizes cyclin B1, polyubiquitylates it, and promotes proteasomal destruction. CDK1 inactivation releases PP1 and PP2A-B55, driving ordered dephosphorylation and mitotic exit. | Human-cell temporal proteomics and phosphoproteomics with APC/C perturbation identified cyclin-B proteolysis as an initiating event for global mitotic dephosphorylation. (holder2020ordereddephosphorylationinitiated pages 27-28, holder2020ordereddephosphorylationinitiated pages 2-3) | Cyclin B, securin, and geminin showed an approximately 5-minute half-life, whereas several later mitotic regulators had half-lives exceeding 60 minutes. | High confidence. Some analyses report cyclin B at the family level, although CCNB1 is the principal mitotic cyclin-B substrate discussed. |
| 2024 spatial-degradation advance | An N-terminal arginine anchor binds the nucleosome acidic patch, concentrating cyclin B1 with APC/C on mitotic chromosomes and accelerating degradation. Disrupting this interaction delays degradation and compromises chromosome-number stability. | CRISPR editing, live-cell imaging, fluorescence cross-correlation spectroscopy, biochemical reconstitution, mutagenesis, and cryo-EM in human hTERT RPE-1 cells. (cirillo2024spatialcontrolof pages 13-14, cirillo2024spatialcontrolof pages 19-20) | Apparent cyclin-B1–APC/C dissociation constant was about 80 nM at chromosomes versus 180 nM in cytoplasm; arginine-anchor mutants produced aneuploidy and polyploidy. | Strong recent mechanistic evidence. This remains a cultured-cell study; conservation and tissue-level relevance require further testing. |
| 2023 substrate-specificity advance | Current expert interpretation rejects a motif-only model: important CDK phosphorylation can occur at sites lacking the conventional +1 proline when cyclin-specific or CKS1-mediated docking supplies specificity. | A 2023 perspective synthesized fixed-cell phosphoproteomics, in-vitro kinase assays, and prior biochemical studies. (valk2023cdksignalingvia pages 1-2) | Noncanonical sites are often enriched for basic residues, including Lys at +3 and sometimes +2, +4, or +5. | Moderate-to-high conceptual support. The source spans CDK biology; not every proposed site has been validated specifically with human cyclin-B1–CDK1 in vivo. |
| Cancer association | Elevated CCNB1 often reflects a high mitotic fraction and can experimentally contribute to chromosome instability and tumor initiation. It is a candidate proliferation or prognostic marker, but association does not establish tumor-specific dependence. | Cyclin-B1-overexpressing mice showed increased tumorigenesis and aneuploidy; human lung-tumor measurements found marked overexpression not fully explained by Ki-67/BUB1 controls. (nam2014cyclinb2and pages 6-7) | CCNB1 transcript was more than 10-fold elevated in 43% of lung adenocarcinomas and 37% of squamous-cell carcinomas in that study. | Moderate translational evidence. The human result is older and cohort-specific; overexpression is not a validated companion diagnostic or proof of direct targetability. |
| 2024 preclinical application example | In bladder-cancer cell lines, puerarin altered a CENPA/PLK1/CCNB1-associated network and inhibited proliferation. CCNB1 served mainly as an inferred downstream pathway readout rather than a demonstrated direct target. | CCK-8 assays, flow cytometry, TMT proteomics, network analysis, docking, and western blotting in human T24 and 5637 cells. (xu2024puerarinmodulationof pages 1-2) | Puerarin IC50 was 218 µM in T24 and 198 µM in 5637 cells; 1,385 differentially expressed proteins were detected; modeled CENPA binding energy was −6.3 kcal/mol. | Low-to-moderate, hypothesis-generating evidence. Limitations include high-micromolar exposure, computational target inference, no direct CCNB1 binding, and no patient efficacy data. |
| Translational and clinical status | CCNB1 is used in research as a G2/M or proliferation marker and pharmacodynamic pathway readout. Strategies more often target CDK1 regulators, spindle machinery, or APC/C/checkpoint pathways. No approved direct CCNB1 drug, established standalone clinical assay, or CCNB1-selected treatment standard was identified. | Recent HCC and bladder-cancer studies measured CCNB1 after experimental compounds; available evidence is from cell lines or disease models rather than interventional clinical validation. (xu2024puerarinmodulationof pages 10-10, andrade2024antiproliferativeactivityof pages 13-14, andrade2024antiproliferativeactivityof pages 2-4) | The HCC expression study used four independent experiments and compound concentrations of 10–40 µM, depending on cell line, but reported no CCNB1-specific clinical effect size. | Preclinical only. Clinical utility remains unproven, and CCNB1 measurements can be confounded by proliferation rate, tumor composition, and cell-cycle distribution. |
Table: Evidence matrix summarizing the verified identity, molecular function, regulation, localization, degradation, recent mechanistic advances, and translational status of human CCNB1 (UniProt P14635). It distinguishes established human-cell mechanisms from emerging or preclinical findings.
The literature uses CCNB1 for the human gene and cyclin B1 for its protein product. The reported biological behavior—CDK1 activation, mitotic accumulation, cyclin-box-dependent functions, and APC/C-regulated destruction—is fully consistent with UniProt P14635, “G2/mitotic-specific cyclin-B1.” The organism is Homo sapiens throughout the human mechanistic evidence summarized here. Studies from mouse oocytes or other species are used only as comparative background and are labeled as such. (kim2023meioticcellcycle pages 3-5, bentley2007distinctsequenceelements pages 1-2)
The domain architecture also aligns with the supplied InterPro annotations. The cyclin-box/cyclin-like region provides the folded interface through which cyclin B1 regulates CDK1 and contributes to centrosomal targeting. In contrast, the N-terminal region is relatively unstructured and contains separable determinants for chromosome association, cytoplasmic retention/nuclear export, and APC/C-dependent degradation. Live-cell deletion and mutagenesis experiments showed that the N terminus is necessary and sufficient for chromatin association, whereas centrosome recruitment depends substantially on sequences in the cyclin box. (bentley2007distinctsequenceelements pages 1-2, pfaff2013determinantsofhuman pages 1-2)
Cyclin B1 binds CDK1 and induces an active kinase conformation while contributing substrate selection and intracellular targeting. Therefore, it is misleading to assign an independently catalyzed reaction or substrate to cyclin B1 alone. The relevant catalytic reaction is performed by the cyclin-B1–CDK1 complex:
protein-OH + ATP → protein-O-phosphate + ADP, principally on serine or threonine residues.
In human cells, cyclin-B1–CDK1 activation initiates mitotic entry, and continued activation after centrosome separation is required for later mitotic progression. Single-cell measurements of CDK1 inhibitory-site dephosphorylation and phosphorylation of the CDK1 substrate APC3 supported a gradual, thresholded activation process resembling a bistable switch rather than one instantaneous pulse. (lindqvist2007cyclinb1–cdk1activation pages 1-2)
The conventional minimal CDK recognition motif is S/T-P, and the optimal motif is S/T-P-X-K/R. However, motif occurrence alone does not establish a physiological substrate. Specificity also depends on cyclin-mediated docking, CKS-family phosphoadaptor interactions, prior phosphorylation, accessibility, and spatial colocalization. (bentley2007distinctsequenceelements pages 1-2, valk2023cdksignalingvia pages 1-2)
A 2023 expert perspective emphasized that important CDK phosphorylation events can occur at noncanonical sites lacking the usual +1 proline. In such cases, specificity can be restored through cyclin-specific short linear motifs or CKS1 binding to primed phosphosites. Noncanonical sites are often enriched for basic residues, including lysine at +3 and sometimes +2, +4, or +5. Thus, present understanding has moved from a motif-only model to a multivalent recognition model. This conclusion is strong at the level of general CDK biology, although not every proposed noncanonical site has been validated specifically with human cyclin-B1–CDK1 in vivo. The perspective was published November 1, 2023; DOI: https://doi.org/10.1091/mbc.e22-06-0196. (valk2023cdksignalingvia pages 1-2)
Cyclin B1 accumulates during G2 and forms complexes with CDK1. The associated kinase is initially restrained by inhibitory phosphorylation of CDK1 at Thr14 and Tyr15, imposed by WEE1- and MYT1/PKMYT1-family kinases. CDC25 phosphatases activate the complex by removing these phosphates; evidence summarized in human-cell work indicates that Thr14 is removed before Tyr15. Cyclin-B1–CDK1 then reinforces its own activation by stimulating CDC25 and inhibiting WEE1, creating positive feedback. (liu2020theroleof pages 2-3, lindqvist2007cyclinb1–cdk1activation pages 1-2)
Earlier extract measurements summarized by Lindqvist et al. placed cyclin-B1-associated CDK1 activity at approximately 30% of maximum near the end of G2, before feedback-driven full activation. This is useful evidence for threshold behavior, but it should not be treated as a universal human-cell concentration or clinical cutoff. Different activity levels appear sufficient for mitotic entry versus continued mitotic progression. Lindqvist et al. was published May 1, 2007; DOI: https://doi.org/10.1371/journal.pbio.0050123. (lindqvist2007cyclinb1–cdk1activation pages 1-2)
ATR–CHK1 and ATM–CHK2 signaling, together with p53-dependent pathways, restrains cyclin-B1–CDK1 activation after DNA damage, in part by inhibiting CDC25 and sustaining WEE1/MYT1-mediated CDK1 inhibition. This prevents premature mitotic entry with damaged or incompletely replicated DNA. A 2020 systematic review also documents reciprocal CDK1 phosphorylation of CDC25C, including Thr48, Thr67, Thr138, Ser205, and Ser285, illustrating the positive-feedback architecture. Published June 2020; DOI: https://doi.org/10.1186/s12935-020-01304-w. (liu2020theroleof pages 2-3)
Cyclin B1 has no single static location; its movement is integral to its function.
During interphase it is concentrated mainly in the cytoplasm, although it shuttles through the nucleus. At prophase, phosphorylation within its cytoplasmic-retention/nuclear-export region favors nuclear accumulation. Cyclin-B1–CDK1 then acts in both cytoplasmic and nuclear compartments to coordinate centrosome separation, chromosome condensation, nuclear-envelope breakdown, Golgi remodeling, and spindle assembly. Cytoplasmic kinase activity can persist even while much of cyclin B1 translocates into the nucleus. (bentley2007distinctsequenceelements pages 1-2, lindqvist2007cyclinb1–cdk1activation pages 1-2)
During mitosis, human cyclin B1 localizes to:
Distinct sequence elements mediate these locations. Chromatin localization depends primarily on the N-terminal region and does not require CDK1 binding; centrosomal localization relies more strongly on cyclin-box sequences. Kinetochore recruitment includes both CDK1-dependent and CDK1-independent mechanisms. Bentley et al. used spinning-disk confocal microscopy of human cyclin-B1–GFP constructs, imaging at least 50 cells expressing full-length protein and at least 30 cells for several major mutants at 15–45-second intervals. Published December 2007; DOI: https://doi.org/10.1091/mbc.e06-06-0539. (bentley2007distinctsequenceelements pages 1-2)
Pfaff and King subsequently mapped chromosome association to a short conserved N-terminal motif and basic residues within or adjacent to the destruction box. Their live-cell mutagenesis results supported electrostatic interaction with DNA or chromatin as a localization mechanism. Published March 11, 2013; DOI: https://doi.org/10.1371/journal.pone.0059169. (pfaff2013determinantsofhuman pages 1-2)
Cyclin-B1–CDK1 phosphorylation drives the characteristic transitions of early mitosis: centrosome separation, chromosome condensation, nuclear-lamina disassembly and nuclear-envelope breakdown, spindle assembly, and suppression or reorganization of interphase processes. Localization of the complex near centrosomes, chromatin, kinetochores, and spindle structures increases access to distinct substrate pools. (bentley2007distinctsequenceelements pages 1-2, lindqvist2007cyclinb1–cdk1activation pages 1-2)
Cyclin-B1–CDK1 is not merely held upstream of the spindle checkpoint; it helps construct the checkpoint-responsive state. In human cells, the complex regulates phosphorylation of MPS1 Ser281, enabling MPS1 recruitment to unattached kinetochores. An MPS1-S281A mutant failed to localize properly or support recruitment of downstream checkpoint proteins, whereas direct tethering of the mutant to the kinetochore protein Mis12 bypassed the requirement. (hayward2019cdk1ccnb1createsa pages 1-2)
As cyclin B1 falls at metaphase–anaphase, PP2A-B55 increasingly opposes CDK1, MPS1 is dephosphorylated, and the period during which kinetochores can regenerate a checkpoint signal closes. This mechanism integrates CCNB1 with MPS1, KNL1, BUB proteins, MAD1/MAD2, CDC20, the mitotic checkpoint complex, APC/C, and PP2A-B55. Hayward et al. was published online January 23, 2019; DOI: https://doi.org/10.1083/jcb.201808014. (hayward2019cdk1ccnb1createsa pages 1-2)
Once all chromosomes achieve appropriate spindle attachment, spindle-checkpoint inhibition of APC/C–CDC20 is relieved. APC/C recognizes cyclin B1 through degron-dependent and spatial mechanisms, polyubiquitylates it, and directs proteasomal destruction. Loss of cyclin B1 inactivates CDK1; this releases PP1 and PP2A-B55 from CDK1-dependent inhibition and triggers ordered dephosphorylation of mitotic substrates. (holder2020ordereddephosphorylationinitiated pages 2-3)
High-temporal-resolution proteomics showed that cyclin B, securin, and geminin undergo highly selective rapid degradation with an approximately 5-minute half-life at the metaphase–anaphase transition, whereas several later mitotic regulators had half-lives exceeding 60 minutes. Cyclin-B destruction was required for the bulk of subsequent protein dephosphorylation and therefore acts as a causal switch for mitotic exit, rather than simply accompanying it. Holder et al. was published June 2020; DOI: https://doi.org/10.7554/eLife.59885. (holder2020ordereddephosphorylationinitiated pages 27-28, holder2020ordereddephosphorylationinitiated pages 2-3)
Cirillo et al. combined CRISPR editing, live-cell imaging, fluorescence cross-correlation spectroscopy, biochemical reconstitution, mutagenesis, and cryo-electron microscopy in human hTERT RPE-1 cells. They found that an N-terminal arginine anchor binds the nucleosome acidic patch and promotes cyclin-B1 interaction with APC/C on mitotic chromosomes. The apparent cyclin-B1–APC/C dissociation constant was approximately 80 nM at chromosomes, compared with 180 nM in cytoplasm. (cirillo2024spatialcontrolof pages 13-14, cirillo2024spatialcontrolof pages 19-20)
Mutating the arginine anchor reduced APC/C association, delayed cyclin-B1 degradation throughout the cell, and caused aneuploidy and polyploidy. The work explains why cyclin B1 can be destroyed rapidly immediately after checkpoint satisfaction: mitotic chromosomes function as a reaction platform that increases local enzyme–substrate concentration and productive rebinding. Published August 2024; DOI: https://doi.org/10.1038/s44318-024-00194-2. This is strong mechanistic evidence in cultured human cells, but tissue-level consequences and evolutionary generality remain to be established. (cirillo2024spatialcontrolof pages 13-14)
The 2023 analysis by Valk et al. argues that conventional S/T-P-X-K/R motifs explain only part of physiologically important CDK signaling. Cyclin docking, CKS1-mediated processive phosphorylation, and noncanonical sites may generate a broad spectrum of phosphorylation rates and activity thresholds. For CCNB1 annotation, this means substrate inference should not rely solely on scanning proteins for canonical motifs; direct biochemical or perturbational evidence remains necessary. (valk2023cdksignalingvia pages 1-2)
Because CCNB1 abundance closely tracks G2/M activity, high expression is frequently observed in proliferative tumors. This makes it useful as a research marker, but it also creates a major interpretive confounder: association with poor prognosis may reflect mitotic fraction rather than a unique tumor-driving dependency.
Experimental overexpression nevertheless can be functional. In transgenic mouse models, elevated cyclin B1 increased aneuploidy and tumor development, including greater colon-tumor incidence, multiplicity, size, and invasion in an APC-mutant background. In one human lung-tumor analysis, CCNB1 transcript was elevated more than tenfold in 43% of adenocarcinomas and 37% of squamous-cell carcinomas; comparisons with BUB1 and Ki-67 argued that this was not explained solely by a larger cycling-cell fraction. Published April 2014; DOI: https://doi.org/10.1038/ncb2952. These results support biological relevance but do not constitute a validated clinical assay. (nam2014cyclinb2and pages 6-7)
Recent translational studies generally treat CCNB1 as a pathway readout or candidate biomarker, not a directly bound drug target. In bladder-cancer T24 and 5637 cells, puerarin produced IC50 values of 218 µM and 198 µM, respectively; TMT proteomics identified 1,385 differentially expressed proteins, and network analysis nominated CDK1, CCNB1, and PLK1 downstream of CENPA. Modeled puerarin–CENPA binding energy was −6.3 kcal/mol, and CENPA protein decreased after treatment. The authors hypothesized downstream regulation of PLK1 and CCNB1, but did not demonstrate direct puerarin binding to cyclin B1. Received February 9, accepted April 26, and available online April 29, 2024; DOI: https://doi.org/10.53388/TMR20240209001. (xu2024puerarinmodulationof pages 1-2)
That study is hypothesis-generating rather than clinically actionable: it used cancer cell lines, required high-micromolar compound concentrations, relied partly on network inference and docking, and supplied no patient efficacy data. (xu2024puerarinmodulationof pages 10-10, xu2024puerarinmodulationof pages 1-2)
A separate April 2024 hepatocellular-carcinoma study measured CCNB1 among G2/M genes after treatment with the N-acylhydrazone LASSBio-2052. Experiments used HepG2 and Hep3B cells, four independent gene-expression experiments, and 10–40 µM treatment depending on the cell line. Again, CCNB1 was a downstream transcriptional readout, not the demonstrated molecular binding target. DOI: https://doi.org/10.3390/biomedicines12040892. (andrade2024antiproliferativeactivityof pages 13-14, andrade2024antiproliferativeactivityof pages 2-4)
No approved drug that directly and selectively targets cyclin B1, no established standalone CCNB1 clinical diagnostic, and no CCNB1-selected standard therapy were identified in the reviewed evidence. Therapeutic development more commonly targets CDK1 regulators, WEE1/PKMYT1, spindle machinery, or APC/C/checkpoint pathways. CCNB1 expression or protein abundance is currently most defensible as:
The most precise annotation is: CCNB1 encodes the spatially and temporally regulated cyclin subunit of the principal mitotic CDK complex. Its essential role is not a broad generic effect on proliferation but the activation, targeting, and eventual shutdown of CDK1 across the G2/M transition. Cyclin B1 accumulation and localization establish mitotic kinase activity; its destruction converts the cell from a high-CDK mitotic state to a phosphatase-dominated exit state. (lindqvist2007cyclinb1–cdk1activation pages 1-2, holder2020ordereddephosphorylationinitiated pages 2-3)
Several points deserve caution:
Human CCNB1/P14635 is an unambiguous, well-supported mitotic cyclin. Through its cyclin-box interaction with CDK1 and its N-terminal localization and destruction signals, cyclin B1 coordinates mitotic entry, chromosome and spindle remodeling, checkpoint competence, and mitotic exit. Its function is executed dynamically in the cytoplasm, nucleus, centrosomes, spindle, kinetochores, and mitotic chromatin. The 2024 discovery that nucleosome binding spatially accelerates APC/C-mediated destruction substantially refines the canonical model by showing that mitotic chromosomes actively organize cyclin-B1 turnover. Translationally, CCNB1 remains a valuable proliferation/G2-M marker and mechanistic pathway readout, but direct clinical drugging or standalone biomarker use is not yet established.
References
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