SHLD2

UniProt ID: Q86V20
Organism: Homo sapiens
Review Status: IN PROGRESS
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Gene Description

SHLD2 is the DNA-binding scaffold of the shieldin complex. It connects the SHLD3–REV7 module to SHLD1 and helps protect DNA ends from excessive resection, favoring non-homologous end joining over homologous recombination. Shieldin accumulates at nuclear DNA breaks and supports immunoglobulin class switching and end joining at damaged telomeres.

Existing Annotations Review

GO Term Evidence Action Reason
GO:0000785 chromatin
NAS
PMID:29656893
DNA Repair Network Analysis Reveals Shieldin as a Key Regula...
ACCEPT
Summary: SHLD2 is recruited to damaged chromatin.
Reason: The shieldin complex acts at chromosomal DNA breaks. Chromatin/chromosome localization agrees with the recruitment experiments and does not imply a constitutive chromosome-wide distribution.
Supporting Evidence:
PMID:29656893
Recruitment of shieldin to DSBs, via the ATM-RNF8-RNF168-53BP1-RIF1 axis, promotes NHEJ-dependent repair of intrachromosomal breaks, immunoglobulin class-switch recombination (CSR), and fusion of unprotected telomeres.
GO:0002208 somatic diversification of immunoglobulins involved in immune response
NAS
PMID:29656893
DNA Repair Network Analysis Reveals Shieldin as a Key Regula...
KEEP AS NON CORE
Summary: Shieldin supports immunoglobulin diversification by class switching.
Reason: The experimentally supported mechanism is end joining of class-switch breaks. The broad diversification term is retained as a specialized immune context of the DNA-repair machinery, rather than implying every form of antibody diversification.
Supporting Evidence:
PMID:29656893
Recruitment of shieldin to DSBs, via the ATM-RNF8-RNF168-53BP1-RIF1 axis, promotes NHEJ-dependent repair of intrachromosomal breaks, immunoglobulin class-switch recombination (CSR), and fusion of unprotected telomeres.
GO:0005515 protein binding
IPI
PMID:29656893
DNA Repair Network Analysis Reveals Shieldin as a Key Regula...
KEEP AS NON CORE
Summary: The interaction is part of shieldin complex assembly.
Reason: PMID:29656893 identifies the shieldin subunits and their interactions. Retain this partner-specific experimental interaction, while the generic protein-binding term adds little functional specificity beyond the DNA-binding scaffold activity.
Supporting Evidence:
file:human/SHLD2/SHLD2-uniprot.txt
SHLD2 forms a scaffold which interacts with a SHLD3-MAD2L2 CC subcomplex via its N-terminus, and with SHLD1 via its C-terminus
GO:0005515 protein binding
IPI
PMID:29656893
DNA Repair Network Analysis Reveals Shieldin as a Key Regula...
KEEP AS NON CORE
Summary: The interaction is part of shieldin complex assembly.
Reason: PMID:29656893 identifies the shieldin subunits and their interactions. Retain this partner-specific experimental interaction, while the generic protein-binding term adds little functional specificity beyond the DNA-binding scaffold activity.
Supporting Evidence:
file:human/SHLD2/SHLD2-uniprot.txt
SHLD2 forms a scaffold which interacts with a SHLD3-MAD2L2 CC subcomplex via its N-terminus, and with SHLD1 via its C-terminus
GO:0005515 protein binding
IPI
PMID:29656893
DNA Repair Network Analysis Reveals Shieldin as a Key Regula...
KEEP AS NON CORE
Summary: The interaction is part of shieldin complex assembly.
Reason: PMID:29656893 identifies the shieldin subunits and their interactions. Retain this partner-specific experimental interaction, while the generic protein-binding term adds little functional specificity beyond the DNA-binding scaffold activity.
Supporting Evidence:
file:human/SHLD2/SHLD2-uniprot.txt
SHLD2 forms a scaffold which interacts with a SHLD3-MAD2L2 CC subcomplex via its N-terminus, and with SHLD1 via its C-terminus
GO:0005515 protein binding
IPI
PMID:29789392
FAM35A associates with REV7 and modulates DNA damage respons...
KEEP AS NON CORE
Summary: FAM35A associates with REV7, RIF1 and 53BP1 in the DNA-repair pathway.
Reason: The full-text reciprocal immunoprecipitation experiments support the recorded interaction. Association alone does not establish a separate core molecular activity or direct contact for every recovered partner.
Supporting Evidence:
PMID:29789392
DNA repair proteins associating with FAM35A included REV7, RIF1, BLM, and TOP3A
GO:0005515 protein binding
IPI
PMID:29789392
FAM35A associates with REV7 and modulates DNA damage respons...
KEEP AS NON CORE
Summary: FAM35A associates with REV7, RIF1 and 53BP1 in the DNA-repair pathway.
Reason: The full-text reciprocal immunoprecipitation experiments support the recorded interaction. Association alone does not establish a separate core molecular activity or direct contact for every recovered partner.
Supporting Evidence:
PMID:29789392
DNA repair proteins associating with FAM35A included REV7, RIF1, BLM, and TOP3A
GO:0005515 protein binding
IPI
PMID:29789392
FAM35A associates with REV7 and modulates DNA damage respons...
KEEP AS NON CORE
Summary: FAM35A associates with REV7, RIF1 and 53BP1 in the DNA-repair pathway.
Reason: The full-text reciprocal immunoprecipitation experiments support the recorded interaction. Association alone does not establish a separate core molecular activity or direct contact for every recovered partner.
Supporting Evidence:
PMID:29789392
DNA repair proteins associating with FAM35A included REV7, RIF1, BLM, and TOP3A
GO:0005515 protein binding
IPI
PMID:34354233
ASTE1 promotes shieldin-complex-mediated DNA repair by atten...
KEEP AS NON CORE
Summary: ASTE1 is a shieldin-associated DNA-repair factor.
Reason: The original study places ASTE1 downstream of shieldin. Retain the curated physical interaction without treating generic binding as a separate core function; the cached abstract does not by itself establish the detailed contact geometry.
Supporting Evidence:
PMID:34354233
The SHLD2 subunit binds to single-stranded DNA ends and blocks end resection through OB-fold domains.
GO:0005634 nucleus
EXP
PMID:29656893
DNA Repair Network Analysis Reveals Shieldin as a Key Regula...
ACCEPT
Summary: SHLD2 functions in the nucleus during DNA repair.
Reason: Nuclear localization is supported by FAM35A imaging and the independently characterized shieldin recruitment mechanism. The IBA and vocabulary-derived rows agree with this experimentally grounded function.
Supporting Evidence:
PMID:29789392
FAM35A re-localized in damaged cell nuclei
PMID:29656893
Recruitment of shieldin to DSBs, via the ATM-RNF8-RNF168-53BP1-RIF1 axis, promotes NHEJ-dependent repair of intrachromosomal breaks, immunoglobulin class-switch recombination (CSR), and fusion of unprotected telomeres.
GO:0005634 nucleus
IBA
GO_REF:0000033
ACCEPT
Summary: SHLD2 functions in the nucleus during DNA repair.
Reason: Nuclear localization is supported by FAM35A imaging and the independently characterized shieldin recruitment mechanism. The IBA and vocabulary-derived rows agree with this experimentally grounded function.
Supporting Evidence:
PMID:29789392
FAM35A re-localized in damaged cell nuclei
PMID:29656893
Recruitment of shieldin to DSBs, via the ATM-RNF8-RNF168-53BP1-RIF1 axis, promotes NHEJ-dependent repair of intrachromosomal breaks, immunoglobulin class-switch recombination (CSR), and fusion of unprotected telomeres.
GO:0005634 nucleus
IDA
PMID:29789392
FAM35A associates with REV7 and modulates DNA damage respons...
ACCEPT
Summary: SHLD2 functions in the nucleus during DNA repair.
Reason: Nuclear localization is supported by FAM35A imaging and the independently characterized shieldin recruitment mechanism. The IBA and vocabulary-derived rows agree with this experimentally grounded function.
Supporting Evidence:
PMID:29789392
FAM35A re-localized in damaged cell nuclei
PMID:29656893
Recruitment of shieldin to DSBs, via the ATM-RNF8-RNF168-53BP1-RIF1 axis, promotes NHEJ-dependent repair of intrachromosomal breaks, immunoglobulin class-switch recombination (CSR), and fusion of unprotected telomeres.
GO:0005634 nucleus
IEA
GO_REF:0000044
ACCEPT
Summary: SHLD2 functions in the nucleus during DNA repair.
Reason: Nuclear localization is supported by FAM35A imaging and the independently characterized shieldin recruitment mechanism. The IBA and vocabulary-derived rows agree with this experimentally grounded function.
Supporting Evidence:
PMID:29789392
FAM35A re-localized in damaged cell nuclei
PMID:29656893
Recruitment of shieldin to DSBs, via the ATM-RNF8-RNF168-53BP1-RIF1 axis, promotes NHEJ-dependent repair of intrachromosomal breaks, immunoglobulin class-switch recombination (CSR), and fusion of unprotected telomeres.
GO:0005654 nucleoplasm
IDA
GO_REF:0000052
ACCEPT
Summary: Nucleoplasmic localization agrees with nuclear SHLD2 function.
Reason: The HPA immunofluorescence record lists nucleoplasm as the main location with supported reliability, consistent with the DNA-damage localization studies.
Supporting Evidence:
file:human/SHLD2/SHLD2-hpa.xml
Mainly localized to the nucleoplasm. In addition localized to the actin filaments.
PMID:29789392
FAM35A re-localized in damaged cell nuclei
GO:0005694 chromosome
IDA
PMID:29656893
DNA Repair Network Analysis Reveals Shieldin as a Key Regula...
ACCEPT
Summary: SHLD2 is recruited to damaged chromatin.
Reason: The shieldin complex acts at chromosomal DNA breaks. Chromatin/chromosome localization agrees with the recruitment experiments and does not imply a constitutive chromosome-wide distribution.
Supporting Evidence:
PMID:29656893
Recruitment of shieldin to DSBs, via the ATM-RNF8-RNF168-53BP1-RIF1 axis, promotes NHEJ-dependent repair of intrachromosomal breaks, immunoglobulin class-switch recombination (CSR), and fusion of unprotected telomeres.
GO:0005694 chromosome
IEA
GO_REF:0000044
ACCEPT
Summary: SHLD2 is recruited to damaged chromatin.
Reason: The shieldin complex acts at chromosomal DNA breaks. Chromatin/chromosome localization agrees with the recruitment experiments and does not imply a constitutive chromosome-wide distribution.
Supporting Evidence:
PMID:29656893
Recruitment of shieldin to DSBs, via the ATM-RNF8-RNF168-53BP1-RIF1 axis, promotes NHEJ-dependent repair of intrachromosomal breaks, immunoglobulin class-switch recombination (CSR), and fusion of unprotected telomeres.
GO:0010569 regulation of double-strand break repair via homologous recombination
IBA
GO_REF:0000033
MODIFY
Summary: SHLD2 restrains homologous recombination through end protection.
Reason: The broad regulation term is correct but the loss-of-function evidence establishes negative regulation: depletion permits resection and RAD51 focus formation in BRCA1-deficient cells. The gene-level judgment does not assert equivalent activity of all isoforms: PMID:30022168 reports an OB-fold-disrupting short splice form that retains recruitment but fails to suppress HR.
Supporting Evidence:
PMID:29789392
However, the BRCA1‐mutant cells formed damage‐dependent nuclear RAD51 foci following FAM35A depletion, suggesting that 5′ end resection was more active in the absence of FAM35A (Fig 5B).
PMID:30022168
Importantly, both mutants localized to DSB sites (ED Fig 10cd) and interacted with the other members of the Shieldin complex (ED Fig 10e). Therefore, the SHLD2-m1 and SHLD2S mutants are defective in suppressing HR.
GO:0035861 site of double-strand break
IBA
GO_REF:0000033
ACCEPT
Summary: SHLD2 is recruited to DNA double-strand breaks.
Reason: Shieldin recruitment downstream of the ATM–53BP1–RIF1 pathway directly supports this location. This is the site at which the complex protects DNA ends.
Supporting Evidence:
PMID:29656893
Recruitment of shieldin to DSBs, via the ATM-RNF8-RNF168-53BP1-RIF1 axis, promotes NHEJ-dependent repair of intrachromosomal breaks, immunoglobulin class-switch recombination (CSR), and fusion of unprotected telomeres.
GO:0035861 site of double-strand break
IDA
PMID:29656893
DNA Repair Network Analysis Reveals Shieldin as a Key Regula...
ACCEPT
Summary: SHLD2 is recruited to DNA double-strand breaks.
Reason: Shieldin recruitment downstream of the ATM–53BP1–RIF1 pathway directly supports this location. This is the site at which the complex protects DNA ends.
Supporting Evidence:
PMID:29656893
Recruitment of shieldin to DSBs, via the ATM-RNF8-RNF168-53BP1-RIF1 axis, promotes NHEJ-dependent repair of intrachromosomal breaks, immunoglobulin class-switch recombination (CSR), and fusion of unprotected telomeres.
GO:0035861 site of double-strand break
NAS
PMID:29656893
DNA Repair Network Analysis Reveals Shieldin as a Key Regula...
ACCEPT
Summary: SHLD2 is recruited to DNA double-strand breaks.
Reason: Shieldin recruitment downstream of the ATM–53BP1–RIF1 pathway directly supports this location. This is the site at which the complex protects DNA ends.
Supporting Evidence:
PMID:29656893
Recruitment of shieldin to DSBs, via the ATM-RNF8-RNF168-53BP1-RIF1 axis, promotes NHEJ-dependent repair of intrachromosomal breaks, immunoglobulin class-switch recombination (CSR), and fusion of unprotected telomeres.
GO:0043247 telomere maintenance in response to DNA damage
NAS
PMID:29656893
DNA Repair Network Analysis Reveals Shieldin as a Key Regula...
KEEP AS NON CORE
Summary: Shieldin promotes joining of deprotected telomeres.
Reason: The reported telomere phenotype concerns end joining of unprotected chromosome ends. Retain this specialized damage-response context without implying routine telomerase-mediated telomere lengthening.
Supporting Evidence:
PMID:29656893
Recruitment of shieldin to DSBs, via the ATM-RNF8-RNF168-53BP1-RIF1 axis, promotes NHEJ-dependent repair of intrachromosomal breaks, immunoglobulin class-switch recombination (CSR), and fusion of unprotected telomeres.
GO:0045830 positive regulation of isotype switching
IDA
PMID:29656893
DNA Repair Network Analysis Reveals Shieldin as a Key Regula...
KEEP AS NON CORE
Summary: Shieldin promotes immunoglobulin class-switch recombination.
Reason: Class switching is a specific physiological use of shieldin-mediated end joining. The underlying work includes mammalian B-cell experiments; this is distinct from a constitutive immune-specific identity for SHLD2.
Supporting Evidence:
PMID:29656893
Recruitment of shieldin to DSBs, via the ATM-RNF8-RNF168-53BP1-RIF1 axis, promotes NHEJ-dependent repair of intrachromosomal breaks, immunoglobulin class-switch recombination (CSR), and fusion of unprotected telomeres.
GO:2000042 negative regulation of double-strand break repair via homologous recombination
IDA
PMID:29656893
DNA Repair Network Analysis Reveals Shieldin as a Key Regula...
ACCEPT
Summary: SHLD2 suppresses resection-dependent homologous recombination.
Reason: Loss of FAM35A restores damage-induced RAD51 foci in BRCA1-deficient cells, consistent with shieldin restricting resection and homologous repair. The gene-level judgment does not assert equivalent activity of all isoforms: PMID:30022168 reports an OB-fold-disrupting short splice form that retains recruitment but fails to suppress HR.
Supporting Evidence:
PMID:29789392
However, the BRCA1‐mutant cells formed damage‐dependent nuclear RAD51 foci following FAM35A depletion, suggesting that 5′ end resection was more active in the absence of FAM35A (Fig 5B).
PMID:30022168
Importantly, both mutants localized to DSB sites (ED Fig 10cd) and interacted with the other members of the Shieldin complex (ED Fig 10e). Therefore, the SHLD2-m1 and SHLD2S mutants are defective in suppressing HR.
GO:2001034 positive regulation of double-strand break repair via nonhomologous end joining
IDA
PMID:29656893
DNA Repair Network Analysis Reveals Shieldin as a Key Regula...
ACCEPT
Summary: SHLD2 promotes non-homologous end joining.
Reason: Independent shieldin identification and FAM35A depletion/rescue studies establish the direction of repair-pathway regulation. The gene supports end joining as a scaffold and DNA-end protector, rather than catalyzing ligation. The gene-level judgment does not assert equivalent activity of all isoforms: PMID:30022168 reports an OB-fold-disrupting short splice form that retains recruitment but fails to suppress HR.
Supporting Evidence:
PMID:29656893
We propose that 53BP1-RIF1 act upstream to facilitate the recruitment of the shieldin complex, which we postulate shields DSBs against resection and thereby promotes NHEJ.
PMID:29789392
Expression of FAM35A isoform 1 in 293T cells (Fig 4D) restored NHEJ to normal levels (Fig 4E).
PMID:30022168
Importantly, both mutants localized to DSB sites (ED Fig 10cd) and interacted with the other members of the Shieldin complex (ED Fig 10e). Therefore, the SHLD2-m1 and SHLD2S mutants are defective in suppressing HR.
PMID:30022168
Importantly, both mutants localized to DSB sites (ED Fig 10cd) and interacted with the other members of the Shieldin complex (ED Fig 10e). Therefore, the SHLD2-m1 and SHLD2S mutants are defective in suppressing HR.
PMID:30022168
Importantly, both mutants localized to DSB sites (ED Fig 10cd) and interacted with the other members of the Shieldin complex (ED Fig 10e). Therefore, the SHLD2-m1 and SHLD2S mutants are defective in suppressing HR.
GO:2001034 positive regulation of double-strand break repair via nonhomologous end joining
IDA
PMID:29789392
FAM35A associates with REV7 and modulates DNA damage respons...
ACCEPT
Summary: SHLD2 promotes non-homologous end joining.
Reason: Independent shieldin identification and FAM35A depletion/rescue studies establish the direction of repair-pathway regulation. The gene supports end joining as a scaffold and DNA-end protector, rather than catalyzing ligation. The gene-level judgment does not assert equivalent activity of all isoforms: PMID:30022168 reports an OB-fold-disrupting short splice form that retains recruitment but fails to suppress HR.
Supporting Evidence:
PMID:29656893
We propose that 53BP1-RIF1 act upstream to facilitate the recruitment of the shieldin complex, which we postulate shields DSBs against resection and thereby promotes NHEJ.
PMID:29789392
Expression of FAM35A isoform 1 in 293T cells (Fig 4D) restored NHEJ to normal levels (Fig 4E).
PMID:30022168
Importantly, both mutants localized to DSB sites (ED Fig 10cd) and interacted with the other members of the Shieldin complex (ED Fig 10e). Therefore, the SHLD2-m1 and SHLD2S mutants are defective in suppressing HR.
PMID:30022168
Importantly, both mutants localized to DSB sites (ED Fig 10cd) and interacted with the other members of the Shieldin complex (ED Fig 10e). Therefore, the SHLD2-m1 and SHLD2S mutants are defective in suppressing HR.
PMID:30022168
Importantly, both mutants localized to DSB sites (ED Fig 10cd) and interacted with the other members of the Shieldin complex (ED Fig 10e). Therefore, the SHLD2-m1 and SHLD2S mutants are defective in suppressing HR.
GO:2001034 positive regulation of double-strand break repair via nonhomologous end joining
NAS
PMID:29656893
DNA Repair Network Analysis Reveals Shieldin as a Key Regula...
ACCEPT
Summary: SHLD2 promotes non-homologous end joining.
Reason: Independent shieldin identification and FAM35A depletion/rescue studies establish the direction of repair-pathway regulation. The gene supports end joining as a scaffold and DNA-end protector, rather than catalyzing ligation. The gene-level judgment does not assert equivalent activity of all isoforms: PMID:30022168 reports an OB-fold-disrupting short splice form that retains recruitment but fails to suppress HR.
Supporting Evidence:
PMID:29656893
We propose that 53BP1-RIF1 act upstream to facilitate the recruitment of the shieldin complex, which we postulate shields DSBs against resection and thereby promotes NHEJ.
PMID:29789392
Expression of FAM35A isoform 1 in 293T cells (Fig 4D) restored NHEJ to normal levels (Fig 4E).
PMID:30022168
Importantly, both mutants localized to DSB sites (ED Fig 10cd) and interacted with the other members of the Shieldin complex (ED Fig 10e). Therefore, the SHLD2-m1 and SHLD2S mutants are defective in suppressing HR.
PMID:30022168
Importantly, both mutants localized to DSB sites (ED Fig 10cd) and interacted with the other members of the Shieldin complex (ED Fig 10e). Therefore, the SHLD2-m1 and SHLD2S mutants are defective in suppressing HR.
PMID:30022168
Importantly, both mutants localized to DSB sites (ED Fig 10cd) and interacted with the other members of the Shieldin complex (ED Fig 10e). Therefore, the SHLD2-m1 and SHLD2S mutants are defective in suppressing HR.

Core Functions

Scaffolds the shieldin complex at DNA breaks to protect DNA ends and favor non-homologous end joining. DNA-end protection is isoform dependent; an OB-fold-disrupting short form retains recruitment but is defective in homologous-recombination suppression.

Supporting Evidence:
  • file:human/SHLD2/SHLD2-uniprot.txt
    SHLD2 forms a scaffold which interacts with a SHLD3-MAD2L2 CC subcomplex via its N-terminus, and with SHLD1 via its C-terminus
  • PMID:34354233
    The SHLD2 subunit binds to single-stranded DNA ends and blocks end resection through OB-fold domains.

References

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Deep Research

Falcon

(SHLD2-deep-research-falcon.md)

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📚 Additional Documentation

Notes

(SHLD2-notes.md)

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📄 View Raw YAML

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