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. Author manuscript; available in PMC: 2016 Apr 21.
Published in final edited form as: J Cell Physiol. 2015 May;230(5):1075–1085. doi: 10.1002/jcp.24839

FIGURE 7. Proposed mechanism of action of MATα2 and MATβ during human HSC trans-differentiation.

FIGURE 7

Transition of quiescent HSCs to activated state leads to increased phosphorylation and stabilization of MATα2 and MATβ proteins. Phosphorylation of MATα2 involves a MEK-mediated mechanism whereas MATβ is phosphorylated via an ERK/MEK-Raf loop. Increased phosphorylation at certain sites facilitates enhanced interaction between MATα2 and MATβ subunits. The enhanced phospho-stabilization of MAT proteins may promote human HSCs trans-differentiation by causing altered recruitment of MAT-interacting target proteins previously identified such as ERK and PI3-K kinases in human HSCs (Ramani et al, 2010; Peng et al, 2013) or MAT-interacting kinase-anchor proteins ( Ramani. unpublished observations). These interactions might lead to de-regulated HSC signaling thereby promoting HSC activation and cell growth.