CSRP1

CSRP1 is a LIM/double zinc-finger domain protein that functions as a transcriptional co-activator and signaling adaptor in cardiovascular development, differentiation, and cancer biology. Its LIM domains mediate zinc-dependent homodimerization and physical interactions with transcription factors SRF, GATA4, TBX5, and TRPS1 to co-activate cardiac gene programs such as the NPPA promoter, while interaction with Dishevelled 2 and Diversin couples CSRP1 to noncanonical Wnt/PCP signaling required for convergent extension and cardiac mesoderm migration (PMID:7938009, PMID:29326753, PMID:17592114). CSRP1 mRNA stability is controlled by METTL3/YTHDF1-mediated m6A modification, and CSRP1 promotes glycolysis and cell survival in acute myeloid leukemia, while in neuroblastoma it drives differentiation, neurite extension, and apoptotic sensitivity through both intrinsic (caspase-9, mitochondrial DNA-dependent) and extrinsic (caspase-8) pathways (PMID:39565517, PMID:40198006). In renal cell carcinoma, CSRP1 overexpression suppresses PD-L1, inhibits proliferation, and enhances responses to anti-PD-L1 immunotherapy in vivo (PMID:41351404).

1. 1992 Medium

   Identification of CSRP1 as a serum-responsive LIM-domain gene mapped to human chromosome 1q24-1q32 established it as a widely expressed, immediate-early gene belonging to a developmentally important protein superfamily.

   Evidence Northern blotting of serum-stimulated fibroblasts; somatic cell hybrid and in situ hybridization chromosome mapping

   PMID:1374386 PMID:1385304

   Open questions at the time

   • Functional role beyond expression induction unknown
   • No protein-level interaction data at this stage
   • Tissue-specific function not addressed
2. 1994 High

   Demonstrating that the LIM domain is both necessary and sufficient for zinc-dependent homodimerization resolved how CSRP1 self-associates and established the LIM domain as an autonomous protein–protein interaction module.

   Evidence In vitro binding assays with domain deletions and fusions; zinc chelation experiments; cell-based dimerization

   PMID:7938009

   Open questions at the time

   • Heteromeric binding partners not yet identified
   • Functional consequence of dimerization unclear
   • No structural model of the dimer
3. 2007 High

   Placing CSRP1 within the noncanonical Wnt/PCP pathway through physical interactions with Dishevelled 2 and Diversin, and showing that its loss causes convergent extension and cardiac migration defects, answered how CSRP1 contributes to tissue morphogenesis in vivo.

   Evidence Reciprocal Co-IP of Csrp1 with Dvl2 and Diversin; morpholino knockdown in zebrafish with phenotypic analysis

   PMID:17592114

   Open questions at the time

   • Mammalian in vivo validation of PCP role missing
   • Domain mapping of Dvl2/Diversin interaction not reported
   • Downstream signaling effectors not identified
4. 2008 Medium

   Identification of a 5.0 kb Csrp1 enhancer that drives arterial smooth muscle–restricted expression from E10.0 onward defined the spatial and temporal context for CSRP1 function during cardiovascular development.

   Evidence Transgenic Cre/ROSA26R lineage tracing in mouse with Csrp1 enhancer

   PMID:18327771

   Open questions at the time

   • Endogenous Csrp1 protein expression pattern not independently confirmed by immunohistochemistry
   • Functional requirement in smooth muscle not tested by enhancer deletion
5. 2017 Medium

   Demonstrating that CSRP1 physically interacts with SRF, GATA4, TBX5, and TRPS1 and co-activates cardiac promoters — and that a human frameshift mutation disrupts these interactions — established CSRP1 as a transcriptional co-activator for cardiac gene programs.

   Evidence Co-immunoprecipitation with wild-type and mutant CSRP1; luciferase reporter assays over NPPA promoter; targeted exome sequencing

   PMID:29326753

   Open questions at the time

   • No chromatin-level evidence (ChIP) for CSRP1 occupancy at target promoters
   • Pathogenicity of the frameshift variant not confirmed in family segregation or animal model
   • Genome-wide transcriptional targets unknown
6. 2024 Medium

   Revealing that METTL3-mediated m6A modification of CSRP1 mRNA is read by YTHDF1 to stabilize the transcript, and that CSRP1 sustains glycolysis and proliferation in AML, uncovered an epitranscriptomic layer of CSRP1 regulation and a pro-survival role in leukemia.

   Evidence RNA immunoprecipitation; RNA stability assays; CSRP1 knockdown/overexpression with glycolysis and viability readouts in AML cells

   PMID:39565517

   Open questions at the time

   • Direct m6A site on CSRP1 mRNA not mapped at single-nucleotide resolution
   • Glycolytic targets downstream of CSRP1 not identified
   • Findings limited to AML cell lines
7. 2025 Medium

   Showing that CSRP1 promotes neuroblastoma differentiation and apoptosis through mitochondrial DNA-dependent caspase-9 activation alongside caspase-8 engagement, and separately suppresses PD-L1 to enhance anti-tumor immunity in renal cell carcinoma, broadened CSRP1's role to differentiation, apoptosis, and immune checkpoint regulation in cancer.

   Evidence Ectopic expression in neuroblastoma with ρ0 cell controls and caspase assays; overexpression in RCC cells with PD-L1 qRT-PCR, flow cytometry, and mouse xenograft anti-PD-L1 treatment

   PMID:40198006 PMID:41351404

   Open questions at the time

   • Mechanism by which CSRP1 regulates PD-L1 transcription is unknown
   • RIG-I upregulation pathway not delineated
   • Cancer phenotypes rely on overexpression without genetic loss-of-function confirmation

• The direct transcriptional targets of CSRP1, its chromatin-level occupancy, and the structural basis of its interactions with SRF/GATA4/TBX5 remain uncharacterized; how CSRP1 simultaneously participates in Wnt/PCP signaling and transcriptional co-activation, and whether these represent context-dependent or simultaneous functions, is unresolved.
• No ChIP-seq or genome-wide binding data
• No crystal or cryo-EM structure of CSRP1 in complex with any partner
• Dual signaling-adaptor vs. transcriptional co-activator roles not mechanistically reconciled