| 1997 |
SMAD9 (Smad8) is phosphorylated by constitutively active ALK-2 but not ALK-4, and upon ALK-2 signaling associates with Smad4, leading to synergistic transcriptional activation of mesoderm target genes; Smad8 can rescue expression of mesoderm genes blocked by truncated ALK-2 in Xenopus embryos. |
Xenopus embryo injection, receptor-specific phosphorylation assay, co-immunoprecipitation, transcriptional reporter assay, epistasis rescue experiment |
Proceedings of the National Academy of Sciences of the United States of America |
High |
9371779
|
| 1998 |
Xenopus Smad8 lacks the C-terminal SSXS phosphorylation motif present in other receptor-Smads and functions in a negative feedback loop downstream of BMP-4: BMP signaling induces Smad8 expression, and Smad8 overexpression blocks BMP-4-mediated ventral mesoderm induction and partially blocks activin signaling, indicating Smad8 negatively modulates BMP and possibly other TGF-β family signals. |
Xenopus embryo overexpression, ectodermal explant assays, gene expression analysis, epistasis via dominant-negative and ligand-blocking experiments |
Development (Cambridge, England) |
High |
9449668
|
| 1999 |
A splice variant of Smad8 (Smad8B) lacking 47 amino acids including the SSXS phosphorylation site forms specific complexes with Smad8 or Smad4 in mammalian cells, remains cytoplasmic upon ALK-2 activation (unlike full-length Smad8 which translocates to the nucleus), and acts as a dominant inhibitor of BMP signaling. |
Molecular cloning, co-immunoprecipitation in mammalian cells, subcellular localization assay, dominant-negative functional assay |
Genes to cells : devoted to molecular & cellular mechanisms |
Medium |
10583507
|
| 2000 |
Mouse Smad8 is phosphorylated by constitutively active BMP type I receptors ALK-3 and ALK-6 (as well as ALK-2), inducing Smad8 interaction with Smad4 and nuclear translocation; ALK-5 (TGF-β type I receptor) does not act on Smad8. Smad8 and Smad4 cooperatively activate the Xvent2 promoter. Dominant-negative Smad8 inhibits BMP-2-induced alkaline phosphatase activity in mesenchymal and myoblastic cell lines. |
Phosphorylation assay with constitutively active receptors, co-immunoprecipitation, nuclear translocation assay, promoter-reporter assay, dominant-negative overexpression with ALP activity assay |
Biochemical and biophysical research communications |
High |
10814522
|
| 2006 |
A constitutively active Smad8 variant (lacking the MH1 domain) transfected into MSCs coexpressing BMP2 drives differentiation toward tendon-like cells both in vitro and in vivo, while inhibiting the osteogenic pathway normally induced by BMP2. |
Transfection of engineered MSC line, in vitro morphological and gene expression profiling, in vivo implantation in Achilles tendon defect, double quantum filtered MRI |
The Journal of clinical investigation |
Medium |
16585960
|
| 2006 |
Genetic epistasis in mouse embryos demonstrates that Smad8 homozygous null animals are viable and fertile, and loss of Smad8 does not exacerbate phenotypes of Smad1 or Smad5 single nulls, indicating functional redundancy among BMP R-Smads in early mouse development. |
Gene targeting (Smad8 null and conditional alleles), compound mutant genetic analysis, LacZ reporter for expression domain mapping |
Developmental biology |
High |
16765933
|
| 2009 |
A nonsense mutation in SMAD9 (c.606C>A, p.C202X) produces a truncated protein that is not phosphorylated by constitutively active ALK3 or ALK1, cannot interact with SMAD4, and shows inefficient transcriptional activation compared to wild-type SMAD8, establishing loss-of-function of SMAD9 as causally linked to pulmonary arterial hypertension. |
Phosphorylation assay, co-immunoprecipitation, promoter-reporter transcriptional assay with SMAD4 and ca-ALK3 |
Journal of medical genetics |
Medium |
19211612
|
| 2009 |
Smad8 loss-of-function in adult mice causes medial thickening and smooth muscle hyperplasia in distal pulmonary arteries characteristic of PAH, with upregulated Activin/TGF-β signaling and aberrant Prx1 and Tenascin-C expression; a subset of mutants also developed pulmonary adenomas, revealing a role for Smad8 in growth control. |
Gene targeting in mice (loss-of-function), histopathology, immunostaining for downstream signaling components |
Human molecular genetics |
Medium |
19419974
|
| 2011 |
SMAD9 mutation completely abrogates BMP-induced processing of microRNAs (miR-21, miR-27a, miR-100) in pulmonary artery endothelial and smooth muscle cells, whereas canonical BMP-Smad signaling is only partially reduced, identifying a non-redundant non-canonical role for Smad8 in miRNA biogenesis; overexpression of SMAD9 corrects miRNA processing and reverses the hyperproliferative phenotype. |
Patient-derived cell lines (PAEC/PASMC), miRNA expression profiling, SMAD9 overexpression rescue experiment, antiproliferative assay |
American journal of respiratory and critical care medicine |
Medium |
21920918
|
| 2012 |
CREBZF, a bZIP transcription factor, was identified as a novel Smad8-binding protein via yeast two-hybrid screening using the MH2 domain of Smad8 as bait; the interaction was confirmed by co-immunoprecipitation with Smads 1, 5, and 8 in a prostate cancer cell line. CREBZF overexpression inhibits BMP response element promoter activity and abolishes BMP-6-induced cell growth inhibition. |
Yeast two-hybrid screen, co-immunoprecipitation, promoter-reporter assay, cell growth assay |
Molecular and cellular biochemistry |
Medium |
22707059
|
| 2014 |
Constitutively active Smad9(DVD) has lower transcriptional activity than Smad1(DVD) or Smad5(DVD) despite all three associating with Smad4 and binding target DNA; the linker region of Smad9 is sufficient to reduce transcriptional activity. Smad9 expression is induced by BMP signaling (similar to inhibitory Smads), and Smad9 forms complexes with Smad1 and binds DNA while suppressing target gene transcription, without inhibiting the type I receptor kinase (unlike I-Smads). |
Constitutively active Smad constructs (DVD mutants), transcriptional reporter assay, co-immunoprecipitation, DNA binding assay, gene expression analysis, domain-swap (linker region transfer) |
Scientific reports |
High |
25534700
|
| 2014 |
In zebrafish, zygotic smad9 acts redundantly with smad1 downstream of smad5 to mediate dorso-ventral patterning; double knockdown of smad1 and smad9 strongly dorsalizes embryos and cannot be rescued by smad5 overexpression, whereas smad5 knockdown can be fully rescued by smad1 or smad9 overexpression. Smad1 and smad9 transcription initiations are repressed by each other, and both are direct transcriptional targets of Smad5. Smad9 is also required for myelopoiesis. |
Morpholino knockdown, mRNA overexpression rescue, genetic epistasis, transcriptional target validation |
The Journal of biological chemistry |
High |
24488494
|
| 2016 |
BMP4 transcriptionally upregulates Smad8/9 expression in multiple cell lines through BMP-responsive elements (BREs) spanning nt -121 to nt -44 of the Smad8/9 promoter; phosphorylated Smad1/5/8/9 specifically binds these BREs, and BMP4-induced expression is cycloheximide-insensitive (direct) and blocked by LDN-193189 (BMP type I receptor inhibitor). |
Promoter-reporter assay, chromatin immunoprecipitation (phospho-Smad binding to BREs), cycloheximide chase, pharmacological inhibition |
Journal of cellular biochemistry |
Medium |
26748560
|
| 2019 |
Hepatocyte-specific knockout of Smad1/5/8 (triple knockout) causes greater iron overload than Smad1/5 double knockout, demonstrating a redundant but critical role for SMAD8 in hepcidin production and iron homeostasis; Smad1/5/8 are required for hepcidin regulation by testosterone and EGF but not inflammation. Smad8 single knockout mice show no iron phenotype. |
Hepatocyte-specific conditional knockout mice (Cre/loxP), iron loading assays, hepcidin mRNA/protein measurement, pathway inhibitor treatments, dietary iron manipulation |
Hepatology (Baltimore, Md.) |
High |
31127639
|
| 2019 |
A missense mutation in SMAD9 (c.65T>C, p.Leu22Pro) segregates with high bone mass in an autosomal dominant pedigree; in silico modeling predicts severe disruption of the MH1 DNA-binding domain, suggesting this is a loss-of-function mutation that reduces BMP inhibition and increases osteoblast activity. |
Whole exome sequencing, in silico protein structure modeling, genetic segregation analysis, pQCT bone measurement |
Journal of bone and mineral research |
Low |
31525280
|
| 2021 |
ASB2 is the specific E3 ubiquitin ligase for SMAD9: ASB2 ubiquitylates SMAD9 (but not SMAD1 or SMAD5) and targets it for proteasomal degradation. In zebrafish, Asb2 knockdown causes thinned ventricular wall and dilated ventricle, phenotypes rescued by simultaneous Smad9 knockdown, establishing the ASB2-SMAD9 axis as essential for cardiogenesis. |
Ubiquitylation assay, proteasome inhibitor treatment, co-immunoprecipitation, zebrafish knockdown (morpholino), genetic epistasis rescue experiment, cardiac phenotype quantification |
Scientific reports |
High |
34845242
|
| 2022 |
In DMD patient muscle and mdx mouse muscle, Smad8 mRNA is elevated 48-fold (whereas Smad1, 2, 3, 5 are minimally changed). Smad8 silencing in C2C12 myoblasts derepresses miR-1, miR-133a, and miR-133b, promotes myoblast differentiation, upregulates myogenic regulatory factors, and suppresses IL-6, identifying Smad8 as a negative regulator of muscle miRNAs downstream of BMP4 in dystrophic muscle. |
shRNA gene silencing in C2C12 myoblasts, BMP4 stimulation, western blot, RT-qPCR for miRNAs and myogenic markers, cytokine measurement |
International journal of molecular sciences |
Medium |
35886863
|
| 2022 |
SMAD9 binds directly to the MYCN promoter and transcriptionally activates MYCN expression in neuroblastoma cells; reciprocally, MYCN binds the SMAD9 enhancer and transactivates SMAD9, forming a positive feedback loop. SMAD9 genetic suppression inhibits MYCN-amplified neuroblastoma cell proliferation and tumorigenicity in vitro and in vivo. |
ChIP-seq, CRISPRi, dual-luciferase reporter assay, gene knockdown, subcutaneous xenograft model, RNA-seq |
Journal of experimental & clinical cancer research : CR |
Medium |
36539767
|
| 2024 |
SMAD9 undergoes N-glycosylation mediated by MGAT1; exosomal circZNF638 from osteoclasts recruits EWSR1 to upregulate MGAT1, which mediates N-glycosylation of SMAD9 and thereby inhibits osteoblast differentiation and mineralization. |
Co-immunoprecipitation/protein interaction assay, N-glycosylation measurement, ALP activity, alizarin red staining, western blot, exosome isolation |
Connective tissue research |
Low |
41744136
|
| 2026 |
SMAD9 knockdown in hPSC-derived pancreatic differentiation impairs human β cell identity and insulin secretion function, establishing a role for SMAD9 in directing pancreatic β cell fate. |
RNA-seq transcriptomic profiling during hPSC differentiation, gene knockdown (loss-of-function), insulin secretion functional assay |
Cell death & disease |
Low |
41807373
|
| 2015 |
A germline SMAD9 variant (V90M) predicted to be activating reduces PTEN (phosphatase and tensin homolog) expression when expressed in HEK cells, an effect also observed in patient polyp tissue, linking SMAD9 gain-of-function to hamartomatous polyposis. |
Transfection of SMAD9 V90M in HEK cells, western blot for PTEN expression, patient tissue analysis |
Gastroenterology |
Low |
26122142
|
| 2021 |
Smad8 (phosphorylated) is expressed in the anterior necrotic zone of chick limb in a pattern correlating with programmed cell death areas; BMP and retinoic acid induce Smad8 expression before cell death onset, while sonic hedgehog inhibits Smad8 expression in the ANZ. However, phospho-SMAD1/5/8 and TUNEL staining do not co-localize in dying cells, indicating Smad8-mediated BMP signaling activates a molecular cascade leading to cell death rather than directly executing it. |
In situ hybridization, immunostaining (phospho-Smad1/5/8 and TUNEL), BMP/RA/SHH treatment of chick limb explants |
Development, growth & differentiation |
Low |
21711459
|