SMAD3
GeneName
SMAD3
Summary
SMAD3, also known as Smad 3 or Mad3, is a 48kDa intracellular protein that plays a pivotal role in the transforming growth factor-beta (TGF-β) signalling pathway. It is primarily localised in the nucleus and cytoplasm, where it functions as a transcription factor that regulates gene expression in response to TGF-β and activin signals. SMAD3 interacts with various proteins, including beta-catenin and nuclear receptors, facilitating its role in diverse biological processes such as cell differentiation, morphogenesis, and immune response. It is involved in the formation of heteromeric SMAD complexes and is essential for the transcriptional regulation of genes associated with development and cellular responses to stimuli.
Importance
SMAD3 is relevant to: - TGF-β signalling and its implications in fibrosis and cancer progression through its regulation of cell growth and differentiation. - Developmental biology, particularly in processes like heart looping and embryonic morphogenesis, where it influences tissue patterning and organ development. - Immune system regulation, as it modulates immune responses and inflammation, impacting conditions such as autoimmune diseases. - Cellular responses to stress and injury, contributing to wound healing and tissue repair mechanisms.
Top Products
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Abcam Product Citation Summary
The data indicates a significant focus on the role of SMAD3 in various cancer contexts, particularly in human breast cancer and pancreatic ductal adenocarcinoma (PDAC). The use of multiple antibodies in Western blotting and ChIP suggests a robust investigation into the molecular mechanisms involving SMAD3, especially in relation to TGF-β signaling pathways and cancer progression. Additionally, studies involving mouse models highlight the relevance of SMAD3 in understanding fibrotic responses and other physiological processes.
Abcam Product Citation Table
Domain
The MH1 domain is required for DNA binding. Also binds zinc ions which are necessary for the DNA binding.
The MH2 domain is required for both homomeric and heteromeric interactions and for transcriptional regulation. Sufficient for nuclear import.
The linker region is required for the TGFbeta-mediated transcriptional activity and acts synergistically with the MH2 domain.
Function
Receptor-regulated SMAD (R-SMAD) that is an intracellular signal transducer and transcriptional modulator activated by TGF-beta (transforming growth factor) and activin type 1 receptor kinases. Binds the TRE element in the promoter region of many genes that are regulated by TGF-beta and, on formation of the SMAD3/SMAD4 complex, activates transcription. Also can form a SMAD3/SMAD4/JUN/FOS complex at the AP-1/SMAD site to regulate TGF-beta-mediated transcription. Has an inhibitory effect on wound healing probably by modulating both growth and migration of primary keratinocytes and by altering the TGF-mediated chemotaxis of monocytes. This effect on wound healing appears to be hormone-sensitive. Regulator of chondrogenesis and osteogenesis and inhibits early healing of bone fractures. Positively regulates PDPK1 kinase activity by stimulating its dissociation from the 14-3-3 protein YWHAQ which acts as a negative regulator.
Involvement in disease
Colorectal cancer
CRC
A complex disease characterized by malignant lesions arising from the inner wall of the large intestine (the colon) and the rectum. Genetic alterations are often associated with progression from premalignant lesion (adenoma) to invasive adenocarcinoma. Risk factors for cancer of the colon and rectum include colon polyps, long-standing ulcerative colitis, and genetic family history.
None
The disease may be caused by variants affecting the gene represented in this entry.
Loeys-Dietz syndrome 3
LDS3
An aortic aneurysm syndrome with widespread systemic involvement. The disorder is characterized by the triad of arterial tortuosity and aneurysms, hypertelorism, and bifid uvula or cleft palate. Patients with LDS3 also manifest early-onset osteoarthritis. They lack craniosynostosis and intellectual disability.
None
The disease is caused by variants affecting the gene represented in this entry. SMAD3 mutations have been reported to be also associated with thoracic aortic aneurysms and dissection (TAAD) (PubMed:21778426). This phenotype is distinguised from LDS3 by having aneurysms restricted to thoracic aorta. As individuals carrying these mutations also exhibit aneurysms of other arteries, including abdominal aorta, iliac, and/or intracranial arteries (PubMed:21778426), they have been classified as LDS3 by the OMIM resource.
Post-translational modifications
Phosphorylated on serine and threonine residues. Enhanced phosphorylation in the linker region on Thr-179, Ser-204 and Ser-208 on EGF and TGF-beta treatment. Ser-208 is the main site of MAPK-mediated phosphorylation. CDK-mediated phosphorylation occurs in a cell-cycle dependent manner and inhibits both the transcriptional activity and antiproliferative functions of SMAD3. This phosphorylation is inhibited by flavopiridol. Maximum phosphorylation at the G(1)/S junction. Also phosphorylated on serine residues in the C-terminal SXS motif by TGFBR1 and ACVR1. TGFBR1-mediated phosphorylation at these C-terminal sites is required for interaction with SMAD4, nuclear location and transactivational activity, and appears to be a prerequisite for the TGF-beta mediated phosphorylation in the linker region. Dephosphorylated in the C-terminal SXS motif by PPM1A. This dephosphorylation disrupts the interaction with SMAD4, promotes nuclear export and terminates TGF-beta-mediated signaling. Phosphorylation at Ser-418 by CSNK1G2/CK1 promotes ligand-dependent ubiquitination and subsequent proteasome degradation, thus inhibiting SMAD3-mediated TGF-beta responses. Phosphorylated by PDPK1.
Acetylation in the nucleus by EP300 in the MH2 domain regulates positively its transcriptional activity and is enhanced by TGF-beta.
Poly-ADP-ribosylated by PARP1 and PARP2. ADP-ribosylation negatively regulates SMAD3 transcriptional responses during the course of TGF-beta signaling.
Ubiquitinated. Monoubiquitinated, leading to prevent DNA-binding (PubMed:21947082). Deubiquitination by USP15 alleviates inhibition and promotes activation of TGF-beta target genes (PubMed:21947082). Ubiquitinated by RNF111, leading to its degradation: only SMAD3 proteins that are 'in use' are targeted by RNF111, RNF111 playing a key role in activating SMAD3 and regulating its turnover (By similarity). Undergoes STUB1-mediated ubiquitination and degradation (PubMed:24613385).
Sequence Similarities
Belongs to the dwarfin/SMAD family.
Cellular localization
- Cytoplasm
- Nucleus
- Cytoplasmic and nuclear in the absence of TGF-beta. On TGF-beta stimulation, migrates to the nucleus when complexed with SMAD4 (PubMed:15799969, PubMed:21145499). Through the action of the phosphatase PPM1A, released from the SMAD2/SMAD4 complex, and exported out of the nucleus by interaction with RANBP1 (PubMed:16751101, PubMed:19289081). Co-localizes with LEMD3 at the nucleus inner membrane (PubMed:15601644). MAPK-mediated phosphorylation appears to have no effect on nuclear import (PubMed:19218245). PDPK1 prevents its nuclear translocation in response to TGF-beta (PubMed:17327236). Localized mainly to the nucleus in the early stages of embryo development with expression becoming evident in the cytoplasm of the inner cell mass at the blastocyst stage (By similarity).
Alternative names
MADH3, SMAD3, SMAD family member 3, SMAD 3, hSMAD3, JV15-2, Mothers against decapentaplegic homolog 3, MAD homolog 3, Mad3, Mothers against DPP homolog 3, hMAD-3
Database links
swissprot:P84022 entrezGene:4088 omim:603109
Other research areas
- Immuno-oncology
- Oncology