Affinage

SNRPD1

Small nuclear ribonucleoprotein Sm D2 · UniProt P62316

Length
118 aa
Mass
13.5 kDa
Annotated
2026-06-10
8 papers in source corpus 8 papers cited in narrative 8 extracted findings
Cross-family judge vs UniProt: UniProt preferred faithfulness: 6/6 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

SNRPD1 (Sm-D1) is a core Sm protein of canonical snRNPs whose assembly into spliceosomal particles underlies its role in pre-mRNA splicing across diverse cellular contexts (PMID:11574479, PMID:28595116). It is encoded by the single functional gene of a multigene family, two other members being processed pseudogenes (PMID:9168134). SNRPD1 is incorporated into canonical snRNPs but is specifically excluded from U7 snRNPs, where the special Sm-binding site of U7 snRNA dictates that its position is instead occupied by the Sm-like protein Lsm10 (PMID:11574479). In human pluripotent stem cells SNRPD1 physically associates with SNRPA1 and PNN to support a pluripotency-specific spliceosome, and its depletion causes loss of pluripotency and blocks reprogramming (PMID:28595116). Its C-terminal GR-repeat region, bearing dimethylarginine modifications, forms the major SLE autoantibody epitope recognized by anti-Sm sera and also mediates a direct interaction with the HCV nonstructural protein NS3 that redistributes NS3 to the nucleus (PMID:9175921, PMID:14524621). In cancer cells SNRPD1 promotes proliferation and G1/S cell cycle progression and suppresses autophagy through the PI3K/AKT/mTOR/4EBP1 pathway, and its mRNA is stabilized post-transcriptionally by the m6A reader IGF2BP2 (PMID:33879154, PMID:37268273, PMID:39411513).

Mechanistic history

Synthesis pass · year-by-year structured walk · 8 steps
  1. 1997 Medium

    Establishing that SNRPD1 is the sole functional gene of its family clarified that a single locus produces the Sm-D1 protein, distinguishing it from non-coding processed pseudogenes.

    Evidence Southern blotting, sequencing and CAT reporter promoter mapping in transfected cells

    PMID:9168134

    Open questions at the time
    • Promoter regulation in physiological contexts not defined
    • No link to protein function established here
  2. 1997 Medium

    Identifying the C-terminal GR-repeat region with dimethylarginine modifications as the immunoreactive determinant explained why Sm-D1 is a dominant SLE autoantigen.

    Evidence Baculovirus-expressed recombinant Sm-D1 tested by ELISA against patient anti-Sm sera and monoclonal antibodies

    PMID:9175921

    Open questions at the time
    • Does not establish the role of this modification in normal snRNP function
    • Mechanism of autoantibody generation not addressed
  3. 2001 High

    Showing that SNRPD1 is specifically excluded from U7 snRNPs and replaced by Lsm10 demonstrated that the RNA Sm-binding site selects which Sm proteins are incorporated, distinguishing canonical from specialized snRNPs.

    Evidence Affinity purification of U7 snRNPs with microsequencing and Sm-site functional mapping

    PMID:11574479

    Open questions at the time
    • Structural basis of D1 exclusion not resolved at atomic level
    • Functional consequence of substitution for histone mRNA processing not detailed here
  4. 2003 Medium

    Identifying a direct HCV NS3–Sm-D1 interaction via the GR-repeat region linked the autoantigenic domain to a viral protein and to altered NS3 subcellular localization.

    Evidence Yeast two-hybrid, deletion mapping and immunostaining co-localization

    PMID:14524621

    Open questions at the time
    • No in vitro reconstitution of the interaction
    • Functional consequence for splicing or viral replication not established
  5. 2017 Medium

    Demonstrating that SNRPD1 associates with SNRPA1 and PNN and is required for pluripotency placed it within a pluripotency-specific spliceosome rather than only housekeeping splicing.

    Evidence Reciprocal Co-IP, co-localization with hPS spliceosomes, and siRNA knockdown with reprogramming/pluripotency assays

    PMID:28595116

    Open questions at the time
    • Specific splicing targets supporting pluripotency not defined
    • Single lab, no in vivo validation
  6. 2021 Medium

    Knockdown causing G0/G1 arrest in breast cancer linked SNRPD1 to cell cycle progression and chemosensitivity beyond its housekeeping splicing role.

    Evidence siRNA knockdown with flow cytometry, qPCR, western blot and doxorubicin response assays

    PMID:33879154

    Open questions at the time
    • Molecular link between splicing function and cell cycle control not defined
    • Mechanism of altered drug sensitivity unresolved
  7. 2023 Medium

    Showing that SNRPD1 knockdown induces autophagy and blocks PI3K/AKT/mTOR/4EBP1 signaling defined a signaling pathway through which it supports tumor growth.

    Evidence siRNA knockdown in vitro and xenograft in vivo with pathway western blots, autophagy markers and Ki67 staining

    PMID:37268273

    Open questions at the time
    • Direct molecular connection between SNRPD1 and PI3K/AKT/mTOR not established
    • Whether effect depends on splicing activity unknown
  8. 2024 Medium

    Identifying IGF2BP2 as an m6A reader that stabilizes SNRPD1 mRNA established a post-transcriptional mechanism controlling SNRPD1 protein levels in cancer.

    Evidence RIP and MeRIP assays, mRNA stability qRT-PCR, and functional rescue by co-transfection in TNBC cells

    PMID:39411513

    Open questions at the time
    • Specific m6A sites on SNRPD1 mRNA not mapped
    • Upstream regulation of IGF2BP2 in this context unknown

Open questions

Synthesis pass · forward-looking unresolved questions
  • How SNRPD1's core spliceosomal function mechanistically connects to its cancer-associated cell cycle, autophagy, and signaling phenotypes remains unresolved.
  • No identified splicing targets bridging spliceosome assembly and proliferation/autophagy
  • Whether oncogenic effects require splicing activity is untested

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0003723 RNA binding 2 GO:0005198 structural molecule activity 2
Localization
GO:0005634 nucleus 1
Pathway
R-HSA-8953854 Metabolism of RNA 2
Partners
IGF2BP2NS3PNNSNRPA1
Complex memberships
spliceosomal snRNP

Evidence

Reading pass · 8 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2001 Purified U7 snRNPs from HeLa cells specifically lack Sm proteins D1 (SNRPD1) and D2, despite containing other conventional Sm proteins; this absence is largely dictated by the special Sm binding site of U7 snRNA, and the vacant D1 position is instead occupied by a novel Sm-like protein Lsm10. Biochemical fractionation and affinity purification of U7 snRNPs with biotinylated oligonucleotide, followed by microsequencing of associated polypeptides; functional mapping via U7 snRNA Sm-site analysis The EMBO journal High 11574479
1997 The SNRPD1 gene (encoding Sm-D1) is the single functional gene among a multigene family; it contains three introns and its promoter activity was localized to a 0.38 kb PstI fragment by CAT reporter gene fusion assays. Two other family members are processed pseudogenes. Southern blotting, DNA sequencing, CAT reporter gene fusion assays in cell transfection Gene Medium 9168134
1997 Recombinant Sm-D1 (SNRPD1) expressed in a baculovirus eukaryotic system retains antigenicity equivalent to native Sm-D1, demonstrating that the C-terminal GR-repeat region (containing dimethylarginine post-translational modifications) constitutes immunoreactive determinants recognized by SLE patient anti-Sm sera and anti-Sm monoclonal antibodies. Baculovirus expression and purification of recombinant Sm-D1; direct antibody-binding ELISA comparing recombinant vs. native protein; testing with patient sera and monoclonal antibodies Clinical immunology and immunopathology Medium 9175921
2003 HCV nonstructural protein NS3 physically binds to SNRPD1 (Sm-D1) via the C-terminal GR-repeat region of Sm-D1; co-expression of NS3 alters the subcellular localization of NS3 from cytoplasm to nucleus, and changes the expression pattern of Sm-D1. Yeast two-hybrid assay to identify interaction; deletion mutant mapping of the binding region; immunostaining to assess co-localization and subcellular redistribution Microbiology and immunology Medium 14524621
2017 SNRPD1 physically interacts with SNRPA1 and PNN within human pluripotent stem cell spliceosomes; depletion of SNRPD1 causes loss of pluripotency, blocks hiPS generation, and reduces hPS spliceosome abundance, placing SNRPD1 as a required component for pluripotency-specific spliceosome assembly. Co-immunoprecipitation (physical interaction); co-localization with hPS spliceosomes; siRNA knockdown with pluripotency marker loss and reprogramming efficiency assays Stem cell research Medium 28595116
2021 SNRPD1 knockdown in breast cancer cells causes cell cycle arrest at G0/G1 phase and halted tumor cell growth; reduced SNRPD1 expression also reduces sensitivity to doxorubicin specifically in triple-negative breast cancer cells. siRNA knockdown, flow cytometry cell cycle analysis, qPCR, western blotting, drug response assay Cancer cell international Medium 33879154
2023 SNRPD1 knockdown in hepatocellular carcinoma cells induces autophagy (increased autophagic vacuoles, upregulation of ATG5, ATG7, ATG12) and blocks the PI3K/AKT/mTOR/4EBP1 signaling pathway; SNRPD1 inhibition also suppresses tumor growth in vivo. siRNA knockdown in vitro and xenograft in vivo; western blotting for PI3K/AKT/mTOR/4EBP1 pathway proteins; autophagy gene expression and vacuole detection; Ki67 immunostaining in vivo Archives of biochemistry and biophysics Medium 37268273
2024 IGF2BP2, an m6A reader RNA-binding protein, binds SNRPD1 mRNA and enhances its stability through m6A-dependent mechanisms, thereby increasing SNRPD1 protein expression; IGF2BP2 overexpression reverses the anti-tumor effects of SNRPD1 knockdown in TNBC cells. RIP (RNA immunoprecipitation) assay to detect IGF2BP2-SNRPD1 mRNA interaction; methylated RNA immunoprecipitation (MeRIP) for m6A; qRT-PCR for RNA stability; functional rescue by co-transfection Breast cancer (Dove Medical Press) Medium 39411513

Source papers

Stage 0 corpus · 8 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2001 Purified U7 snRNPs lack the Sm proteins D1 and D2 but contain Lsm10, a new 14 kDa Sm D1-like protein. The EMBO journal 138 11574479
2017 The unique spliceosome signature of human pluripotent stem cells is mediated by SNRPA1, SNRPD1, and PNN. Stem cell research 26 28595116
2021 SNRPD1 confers diagnostic and therapeutic values on breast cancers through cell cycle regulation. Cancer cell international 19 33879154
1997 Screening of SLE sera using purified recombinant Sm-D1 protein from a baculovirus expression system. Clinical immunology and immunopathology 17 9175921
2003 Hepatitis C virus nonstructural protein NS3 binds to Sm-D1, a small nuclear ribonucleoprotein associated with autoimmune disease. Microbiology and immunology 11 14524621
2023 SNRPD1 inhibition suppresses the proliferation of hepatocellular carcinoma and promotes autophagy through the PI3K/AKT/mTOR/4EBP1 pathway. Archives of biochemistry and biophysics 10 37268273
2024 The Potential Role of SNRPD1 Stabilized by IGF2BP2 in the Progression of Triple-Negative Breast Cancer. Breast cancer (Dove Medical Press) 1 39411513
1997 Analysis of genes for human snRNP Sm-D1 protein and identification of the promoter sequence which shows segmental homology to the promoters of Sm-E and U1 snRNA genes. Gene 1 9168134

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