| 2002 |
SSBP3/SSDP1 (Ssdp family) proteins interact specifically with the LIM-domain-binding protein Ldb1 as components of Ldb1-associated nuclear complexes in HeLa cells; this interaction does not depend on nucleic acids. In Xenopus, Ssdp1 mRNA enhances axis induction by Ldb1 in conjunction with Xlim1, demonstrating functional conservation as a cofactor of Ldb1. |
Co-immunoprecipitation from HeLa nuclear extracts, DNase/RNase treatment controls, Xenopus axis induction assay, Drosophila genetic interaction |
Proceedings of the National Academy of Sciences of the United States of America |
High |
12381786
|
| 2003 |
Ssdp proteins bind to a highly conserved N-terminal domain of Ldb1/Chip that is distinct from the LIM-binding domain and the self-dimerization domain. In Drosophila, Ssdp modifies the in vivo activity of Chip–Apterous LIM-homeodomain complexes; null ssdp clones are cell-lethal, while hypomorphic clones phenocopy Chip/apterous loss-of-function. |
Domain mapping by deletion constructs and binding assays, Drosophila mosaic clone analysis with null and hypomorphic alleles |
Development (Cambridge, England) |
High |
12642495
|
| 2005 |
Ssdp1 contains a transcriptional activation domain; the C-terminal region of SSDP1 is sufficient for transcriptional activity in both yeast and mammalian cells. Importantly, this transcriptional function of SSDP1 is not required for its interaction with Ldb1. |
Yeast two-hybrid transcription assays, mammalian reporter assays with C-terminal deletion constructs, Co-IP for Ldb1 interaction |
Biochemical and biophysical research communications |
Medium |
16325762
|
| 2005 |
Ssdp1 functions as an essential activator component of the Lim1–Ldb1 transcriptional complex in vivo; Ssdp1(hsk/hsk) mutant mice have reduced Ssdp1 expression and display anterior head defects phenocopying Lim1 mutants. Ssdp1 genetically interacts with both Lim1 and Ldb1 in head development and body growth, and enhances transcriptional activation through a Lim1–Ldb1 complex in transfected cells. |
Mouse loss-of-function (headshrinker mutant), transfection-based transcriptional activation assay, genetic interaction analysis |
Development (Cambridge, England) |
High |
15857913
|
| 2006 |
The proline-rich domain of Ssdp1 is critical for embryonic head development. Gene-trapped mice expressing Ssdp1 truncated before the proline-rich sequence exhibit a lethal abnormal head-development phenotype resembling Lim1, Ssdp1, or Otx2 knockouts, while mice retaining most of the proline-rich domain develop normally. |
Gene-trap mouse lines encoding defined Ssdp1 truncations, embryo phenotypic analysis |
Proceedings of the National Academy of Sciences of the United States of America |
High |
16864769
|
| 2008 |
Ssdp1 is predominantly cytoplasmic in 293T cells but undergoes nuclear translocation upon co-expression with Lck (a Src-family tyrosine kinase). Lck induces tyrosine phosphorylation of Ssdp1, and mutation of N-terminal tyrosine residues 23 and 25 markedly reduces both phosphorylation and nuclear localization. Lck also enhances Ssdp1 transcriptional activity within a LIM-HD/cofactor complex. |
Fluorescence microscopy for localization, co-transfection and Western blot for phosphorylation, Src kinase inhibitor (PP2) treatment, site-directed mutagenesis (Y23/Y25), reporter assay |
Journal of cellular biochemistry |
Medium |
18080319
|
| 2010 |
SSDP1 interacts with CLIM (LDB/NLI) cofactors in zebrafish neurons; overexpression of the N-terminal CLIM-interaction domain of SSDP1 (N-SSDP1) increases endogenous CLIM protein levels in vivo, impairing eye and midbrain-hindbrain boundary formation and sensory axon growth. N-SSDP1 partially rescues axon-growth inhibition caused by dominant-negative CLIM, indicating SSDP1 stabilizes LIM-HD/CLIM complexes. |
Zebrafish overexpression and morpholino knockdown, immunohistochemistry for CLIM levels, axon growth assay, dominant-negative rescue epistasis |
Developmental biology |
Medium |
21056553
|
| 2015 |
The Chip/LDB-SSDP (ChiLS) complex is the specific binding ligand for NPFxD motifs in Pygo proteins (and other nuclear factors including Runt/RUNX2 and ARID1). ChiLS also binds Groucho/TLE. ChiLS forms the core module of the Wnt enhanceosome, priming developmental control genes for Wnt responses and conferring context-dependence on TCF/LEF enhancers. |
Proteomics (mass spectrometry pulldown), in vitro binding assays, Drosophila embryonic midgut enhancer studies, genetic interaction |
eLife |
High |
26312500
|
| 2015 |
SSBP3 interacts with Ldb1 and Isl1 in pancreatic β-cell lines and in mouse and human islets, as determined by cross-linked immunoprecipitation and mass spectrometry. SSBP3 knockdown in β-cell lines causes mRNA deficiencies similar to Ldb1 reduction, and SSBP3 occupies known Ldb1–Isl1 target promoters (MafA and Glp1r). |
Cross-linked immunoprecipitation + mass spectrometry, Co-IP in β-cell lines and primary islets, shRNA knockdown, ChIP for promoter occupancy, qRT-PCR |
Molecular endocrinology (Baltimore, Md.) |
High |
26495868
|
| 2016 |
Forced expression of Ssbp3 in mouse embryonic stem cells upregulates trophoblast lineage marker genes (Cdx2), activates MAPK/Erk1/2 and TGF-β pathways, reduces methylation of the Elf5 promoter, and promotes trophoblast-like differentiation. Conversely, depletion of Ssbp3 attenuates trophoblast marker gene expression induced by Oct4 downregulation or BMP4/bFGF treatment. |
Gain- and loss-of-function in mouse ESCs, Affymetrix microarray, qRT-PCR, Western blot, bisulfite sequencing, teratoma and embryo injection assays |
Stem cell research & therapy |
Medium |
27236334
|
| 2019 |
Crystal structures of the dimerization domains of Chip/LDB and SSDP were solved. Systematic surface-scanning mutagenesis combined with in vitro and in vivo binding assays identified conserved surface residues required for Chip/LDB–SSDP and Chip/LDB–Pygo-NPFxD interactions. ChiLS adopts a rotationally symmetrical SSDP2–LDB2–SSDP2 (4:2) architecture; integrity of ChiLS is essential for Pygo binding, with NPFxD pockets flanking the Chip/LDB dimer. |
X-ray crystallography (DARPin-chaperone aided), structure-designed surface-scanning mutagenesis, in vitro binding assays, in vivo functional assays |
Proceedings of the National Academy of Sciences of the United States of America |
High |
31570581
|
| 2023 |
Pancreas-specific and islet-specific deletion of SSBP3 in mice causes neonatal hyperglycemia and glucose intolerance with loss of β-cell maturity markers (MafA, Pdx1, UCN3) and disrupted islet architecture (increased α- and ε-cells). Inducible adult β-cell-specific SSBP3 deletion impairs glucose-stimulated insulin secretion. RNA-seq of SSBP3Δβ-cell islets reveals decreased β-cell function genes and increased dedifferentiation markers, overlapping with Ldb1 and Isl1 knockout gene sets. |
Conditional knockout mouse (LoxP allele × Pdx1-Cre, Pax6-Cre, inducible β-cell Cre), glucose tolerance tests, GSIS (in vivo and in vitro), immunofluorescence, RNA-seq |
Molecular metabolism |
High |
37536498
|
| 2023 |
In Drosophila, Ssdp (the SSBP3 ortholog) overexpression decreases levels of armadillo (β-catenin) and wingless in larval wing discs, implicating canonical Wnt signaling in Ssdp functionality. Ssdp manipulations alter neuropil brain volume, glial cell number, synaptic density, and neuronal mitochondrial morphology, and perturb oxidative stress pathways. |
Drosophila overexpression/knockdown, immunostaining, confocal imaging, RNA sequencing, ROS measurement |
PLoS biology |
Medium |
37486945
|
| 2025 |
SSBP3 (but not SSBP2 or SSBP4) is essential for erythroid cell viability. LDB1 (not single-stranded DNA) is the predominant chromatin tether for SSBP3 genome-wide. SSBP3 depletion (under one hour in SSBP2/4 knockout cells) globally weakens LDB1-dependent chromatin loops and reduces nascent transcription without affecting LDB1 chromatin binding. SSBP3 stabilizes LDB1 homodimers in solution, providing a mechanistic basis for its role in LDB1-mediated enhancer–promoter looping. |
Rapid depletion (acute SSBP3 degradation), ChIP-seq, Hi-C/chromatin conformation capture, nascent transcription assay, SSBP2/4 double knockout cells, solution biochemistry for LDB1 dimerization |
bioRxivpreprint |
Medium |
bio_10.1101_2025.06.05.658047
|