Animal-Free Activin B Protein, Human (His)

Activin B, a TGFβ superfamily cytokine, is a homodimer of activin βB subunits. Activin B binds to type II transmembrane serine-threonine kinase receptors (ACTRIIA or ACTRIIB) which, in turn, activate type I receptors (ACTRI) that phosphorylate and activate canonical SMAD signaling pathways^[1][2]. Animal-Free Activin B Protein, Human (His), a recombinant animal-free protein, is produced in E. coli with a C-Terminal His-tag. It consists of 115 amino acids (G293-407A).

Activins, members of the TGF-β superfamily, are first isolated from porcine ovarian follicular fluid and identified as activating factors for the release of follicle stimulating hormone. Activin B found in most tissues including placenta, reproductive organs, bone marrow, and brain. Activin B is a regulator of inflammation and immunity, and also involved in cancer or wound healing processes^[1][2][3][4].
Activin B is highly conserved across species, with mouse, rat and human Activin B demonstrating >97% sequence homology.
Activins exist in three basic molecular forms composed of two inhibin β subunits: activin A (βAβA), activin B (βBβB), and activin AB (βAβB), and their receptors are ActRIA, ActRIB, ActRII A, and ActRIIB.  Different additional roles have since been identified for these proteins, including broad and complex effects on cell growth and differentiation, regulation of embryogenesis, development of the reproductive system, wound healing, stem cell differentiation and regulation of immune response. Activins exert their biological functions through the serine/threonine protein kinase (MAPKs) signaling pathways. Activin B might also signal through the type IC activin receptors (ACVR1C (ALK7)). The type I receptor initiates a signaling cascade by activating a phosphorylation cascade through SMAD2/3 that complexes with SMAD4 and translocates to the cell nucleus to modulate gene transcription. The effects of activin are antagonized by inhibin, which acts by blocking activin binding to its receptors and by follistatin^[1][2][3].
Activin B stimulates cell proliferation at the site of skin injury and promotes wound healing through the RhoA-Rock-JNK-cJun signaling pathway. Activin B production is increased in some cell types in response to inflammatory stimuli, most notably hepatic stellate cells, pituitary cells, and microglial cells. Activin B regulates cellular migration by inducing actin stress fiber formation. In addition, Activin B treatment can promote the adhesion, migration and invasion of type II endometrial cancer cells by up-regulating integrin β3 in a SMAD-dependent manner^[1][3][4].

Recombinant human Activin B (1  ng/mL; 48 hours) protein incubation with the normal fibroblasts (NFBs), the results show  increase expressions of Activin B, Smad2/3, TGF-β1, and endothelin-1 (ET-1) compared with the untreated NFBs. In addition, the levels of thrombospondin-1 (Tsp-1) and Oncostatin M (OSM) are significantly lower than those of the control group^[1]. Recombinant human Activin B (5  ng/mL; 24 hours) significantly decreases E-cadherin expression in both a time- and concentration-dependent manner in KLE and HEC-5 cell lines. The suppressive effects of Activin B on E-cadherin are mediated by MEK-ERK1/2-induced production of the transcription factor SNAIL^[3].

Recombinant human Activin B (5, 1 or 5  ng/mL; dorsal skin; 3 times a day for 17 days) efficiently induces the initiation of hair follicles in the skin of both cultured and neonatal mice and to promote the development of hair follicles in neonatal mouse skin. Moreover, activin-B-treated hair follicles were observed to enter the anagen stage from the telogen stage and to remain in the anagen stage^[5].

Measure by its ability to induce hemoglobin expression in K562 cells. The ED₅₀ for this effect is <0.7 ng/mL. The specific activity of recombinant human Activin B is > 1.5 x 10⁶IU/mg

Human

E. coli

C-His

P09529 (G293-407A)

3625  [NCBI]

MGLECDGRTNLCCRQQFFIDFRLIGWNDWIIAPTGYYGNYCEGSCPAYLAGVPGSASSFHTAVVNQYRMRGLNPGTVNSCCIPTKLSTMSMLYFDDEYNIVKRDVPNMIVEECGCA

Approximately 13.75 kDa

Greater than 95% as determined by reducing SDS-PAGE.

Lyophilized powder.

Lyophilized from a solution containing 1X PBS, pH 8.0.

<0.1 EU per 1 μg of the protein by the LAL method.

It is not recommended to reconstitute to a concentration less than 100 μg/mL and not higher than 500 μg/mL in ddH₂O.

Stored at -20°C for 2 years. After reconstitution, it is stable at 4°C for 1 week or -20°C for longer (with carrier protein). It is recommended to freeze aliquots at -20°C or -80°C for extended storage.

Room temperature in continental US; may vary elsewhere.

• [1]. Shi-Kang Deng, et al. Activin B signaling may promote the conversion of normal fibroblasts to scar fibroblasts. Medicine (Baltimore). 2020 Jun 12;99(24):e20253.  [Content Brief]

  [2]. Qin Jia, et al. Activin B promotes initiation and development of hair follicles in mice. Cells Tissues Organs. 2013;198(4):318-26.  [Content Brief]

  [3]. J M Young, et al. Activin B is produced early in antral follicular development and suppresses thecal androgen production. Reproduction. 2012 May;143(5):637-50.  [Content Brief]

  [4]. Siyuan Xiong, et al. Activin B promotes endometrial cancer cell migration by down-regulating E-cadherin via SMAD-independent MEK-ERK1/2-SNAIL signaling. Oncotarget. 2016 Jun 28;7(26):40060-40072.  [Content Brief]

  [5]. Sabine Gravelsina, et al. Potential of Activin B as a Clinical Biomarker in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). Biomolecules. 2021 Aug 11;11(8):1189.  [Content Brief]