| 1989 |
The INHBB gene encodes a 407-amino acid precursor with a prepro region of 292 amino acids followed by the mature 115-amino acid C-terminal domain. Mammalian cells transfected with a βB-subunit expression plasmid secreted an activin B homodimer (~22 kDa). Co-expression of βA and βB subunits produced all three activin isoforms (A, AB, and B). Purified activin B stimulated FSH release in vitro and induced hemoglobin accumulation in K562 cells with potency (ED50 ~2 ng/ml) indistinguishable from activin A. |
cDNA/genomic cloning, transfection and secretion assay, in vitro pituitary FSH assay, K562 cell differentiation assay |
Molecular endocrinology |
High |
2575216
|
| 1986 |
Human ovarian inhibin consists of two forms sharing a common alpha subunit covalently linked to one of two distinct beta subunits (βA or βB). The βB subunit sequence (INHBB) is highly conserved with its porcine equivalent, differing at only one of 232 positions. |
cDNA cloning and nucleotide sequencing |
Biochemical and biophysical research communications |
High |
3754442
|
| 1991 |
Activin B (the INHBB homodimer) binds to the cloned activin receptor (a predicted transmembrane serine/threonine kinase) expressed in COS cells with an affinity of 180 pM, and can compete with activin A for receptor binding. |
Expression cloning, 125I-activin A binding competition assay in COS cell transfectants |
Cell |
High |
1646080
|
| 2000 |
Replacement of the mature protein-coding region of Inhba with Inhbb (creating the InhbaBK knock-in allele) rescued Inhba-null craniofacial phenotypes (whisker, palate, tooth defects), demonstrating functional compensation between activin A and activin B within the TGF-β superfamily when expressed from the same locus. However, novel somatic, testicular, genital, and hair growth phenotypes emerged, indicating distinct dosage and bioactivity differences between the two ligands. |
Gene targeting (knock-in), mouse genetics, phenotypic analysis |
Nature genetics |
High |
10932194
|
| 2000 |
Activin βC subunit (encoded by a related gene) can form heterodimers with activin βA and βB subunits in vitro (activin AC and BC), but cannot dimerize with the inhibin alpha subunit. This establishes that INHBB (βB) is capable of forming novel heterodimeric activin complexes beyond the canonical activin B homodimer. |
In vitro dimerization assay, antibody localization, co-immunoprecipitation |
The Journal of clinical endocrinology and metabolism |
Medium |
11134153
|
| 2004 |
Activin B (INHBB homodimer) and activin AB signal through the type I receptor serine/threonine kinase ALK7, in combination with ActRIIA, to mediate insulin secretion from pancreatic β-cells. This receptor preference distinguishes activin B from activin A (which preferentially uses ALK4). The differential signaling depends on the homo- or heterodimeric assembly of activin isoforms. |
Receptor binding assay, reporter gene assay, pancreatic β-cell (MIN6) insulin secretion assay, receptor co-expression experiments |
Molecular and cellular endocrinology |
High |
15196700
|
| 2008 |
Activin B (INHBB homodimer) was identified in human and mouse serum by affinity purification using soluble ActRII and ActRIIB, confirming it circulates as an endocrine factor. Activin B bound both ActRII and ActRIIB and, like myostatin, inhibited myoblast-to-myotube differentiation in vitro. |
Affinity purification from serum, mass spectrometry proteomics, in vitro binding assay, myoblast differentiation assay |
Molecular endocrinology |
High |
18927237
|
| 2012 |
Activin B (encoded by Inhbb) induces phosphorylation of Smad1/5/8 in human hepatoma-derived cells and, synergistically with IL-6/STAT-3 signaling, up-regulates hepcidin expression. The effect on hepcidin is mediated through BMP signaling, most likely via activin receptor-like kinase 3 (ALK3). Inhbb mRNA is dramatically induced in mouse liver after LPS challenge, preceding Smad1/5/8 phosphorylation and hepcidin (Hamp) mRNA increases. |
In vivo LPS challenge, Smad1/5/8 phosphorylation assay, qPCR, ALK3 inhibitor treatment, primary hepatocyte assay |
Blood |
High |
22611157
|
| 2013 |
Elevated activin B (among other activins) reduces skeletal muscle mass and function by stimulating the ActRIIB pathway, leading to increased transcription of atrophy-related ubiquitin ligases and decreased Akt/mTOR-mediated protein synthesis. Activin B was identified as one of the most potent negative regulators of muscle mass, and the resulting muscle wasting is fully reversible. |
rAAV6-mediated overexpression in mice, ActRIIB signaling assays, ubiquitin ligase expression assays, Akt/mTOR pathway analysis |
FASEB journal |
High |
24378873
|
| 2015 |
RNAi-mediated knockdown of INHBB in mouse granulosa cells arrests cells in G1 phase, increases apoptosis, and decreases estradiol and progesterone production. Mechanistically, INHBB knockdown downregulated Cyclin D1, Cyclin E, and Bcl2 protein expression while upregulating Bax, and reduced mRNA levels of CYP19A1 and CYP11A1, placing INHBB as a regulator of cell cycle progression and steroidogenesis in granulosa cells. |
RNAi knockdown, flow cytometry, Western blot, ELISA, qRT-PCR |
The Journal of reproduction and development |
Medium |
26063610
|
| 2017 |
Menin represses Inhbb expression by facilitating recruitment of Ezh2 to the Inhbb promoter via an indirect mechanism involving Akt phosphorylation, resulting in H3K27me3 repressive marks at the Inhbb locus. Loss of Menin leads to reduced H3K27me3 at the Inhbb locus and increased activin B expression both in vitro and in vivo in insulinoma models. |
ChIP assay, H3K27me3 chromatin immunoprecipitation, Menin knockout cell lines and animal models, Akt inhibitor experiments |
Biochimica et biophysica acta. Gene regulatory mechanisms |
Medium |
28215965
|
| 2020 |
Sox9 directly binds to the INHBB enhancer and induces INHBB expression in hepatoma cells, promoting secretion of activin B. Secreted activin B in turn activates surrounding hepatic stellate cells through activin B/Smad signaling, promoting liver fibrosis and HCC metastasis. Inhibition of activin B/Smad signaling attenuated peri-tumoral fibrosis and metastasis. |
Gain- and loss-of-function experiments, ChIP assay (Sox9 binding to INHBB enhancer), orthotopic HCC tumor model, Smad signaling inhibition |
Cancer letters |
Medium |
33246092
|
| 2021 |
Tubular epithelial cell-derived INHBB (activin B) promotes renal fibrosis by activating surrounding interstitial fibroblasts in a paracrine manner through activin B/Smad signaling. Ectopic expression of INHBB in tubular cells initiates interstitial fibrosis in vivo, while INHBB inhibition blocks fibroblast activation and ameliorates fibrosis from ureteral obstruction or ischemia-reperfusion injury. Upregulation of INHBB in injured tubular cells depends on transcription factor Sox9. |
In vivo INHBB inhibition and ectopic overexpression in mouse fibrosis models, in vitro overexpression in tubular cells, Smad signaling assays |
The Journal of pathology |
Medium |
34543458
|
| 2022 |
A missense variant in INHBB (p.Met360Thr/p.Met364Thr in mice) disrupts activin B biosynthesis in vitro without affecting inhibin B production, reducing circulating activin B levels. In knock-in mice, this variant increased testis size, Sertoli cell number, and round spermatid number without affecting fertility, demonstrating that activin B specifically regulates testis cell composition independent of FSH. |
CRISPR/Cas9 knock-in mouse model, in vitro biosynthesis assay, serum hormone analysis, histomorphometry |
Endocrinology |
Medium |
35022746
|
| 2023 |
INHBB knockdown in human endometrial stromal cells suppresses ADCY1-mediated cAMP production and downstream cAMP signaling, thereby attenuating decidualization. RNA-seq identified INHBB-ADCY1 as a mechanistic axis, and a positive correlation between INHBB and ADCY1 expression was confirmed in endometria from recurrent implantation failure patients. |
siRNA knockdown, RNA-seq, cAMP analogue rescue experiment, qRT-PCR, Pearson correlation analysis |
Journal of assisted reproduction and genetics |
Medium |
36913138
|
| 2025 |
INHBB knockdown in colorectal cancer cells reduces migration, invasion, and hepatic metastasis in vivo by attenuating TGF-β/Smad2/3/Smad4 signaling (decreased Smad2/3 phosphorylation), reversing EMT (E-cadherin upregulation, N-cadherin and vimentin downregulation), and sensitizing cells to anoikis. |
siRNA knockdown in HCT116/Caco-2 cells, Western blot for Smad phosphorylation, EMT markers and anoikis assay, in vivo spleen injection xenograft model |
Tissue & cell |
Medium |
41380489
|