Adipogenic Histone Mark Regulation by Matrix Metalloproteinase 14 in Collagen-Rich Microenvironments

Abstract

Adipogenesis is directed by both transcriptional network and posttranslational modification of chromatin structure. Although adipogenesis in vivo proceeds in collagen-rich extracellular matrix (ECM) environments, the impact of ECM proteins and their modifying enzymes on the epigenetic regulation of adipogenesis has been largely unknown. We aimed to define the role of fibrillar type I collagen and its modifying enzymes in regulating adipogenic chromatin signatures and gene regulation in the in vivo-like settings. Adipogenic cocktail induces a robust increase in the level of protranscriptional acetylated histone H3 at lysine 9 (H3K9ac) within 24 h. When cultured atop fibrillar type I collagen gel, however, H3K9ac levels in differentiating 3T3-L1 cells are substantially reduced. The suppression of adipogenic histone mark in differentiating 3T3-L1 cells is type I collagen density dependent and released by heat denaturing of the subjacent collagen substratum, pointing to the critical role played by the triple-helical structure of type I collagen. By probing adipogenic collagenolysis with a series of proteinase inhibitors, matrix metalloproteinase (MMP) family members are found to be responsible for adipogenic collagenolysis. At the same time, MMP inhibitor specifically blocked the adipogenic induction of H3K9ac. By targeting individual MMP using small interfering RNA oligos, MMP14 was identified as the major adipogenic MMP critical for H3K9 acetylation. Consistently, MMP14-null adipose tissues display diminished protranscriptional histone mark H3K9ac while maintaining repressive histone mark tri-methylated histone H3 at lysine 9 (H3K9me3). Taken together, MMP14-dependent collagenolysis plays the major role in regulating adipogenic histone marks by releasing the epigenetic constraints imposed by fibrillar type I collagen.

Fat depot-specific gene signature and ECM remodeling of Sca1high adipose-derived stem cells

“…The lobules of adipocytes are enwrapped by a dense network of collagen fibers, particularly in subcutaneous adipose tissues (Chun et al, 2006). Type I collagen fibers are suppressive to adipogenic histone modifications, which precede adipocyte gene expression (Sato-Kusubata et al, 2011). Therefore, the collagen-rich environment may restrain the full adipogenic potential of ASCs in subcutaneous adipose tissues in vivo .…”

“…Adipogenesis was induced by adding 10 μg/ml porcine insulin, 0.5 mM 3-Isobutyl-1-Methyxathine, and 0.25 μM dexamethasone (all from Sigma) as described before (Sato-Kusubata et al, 2011). The lipid droplets were visualized using BODIPY 493/503 (Molecular Probe) (Listenberger and Brown, 2001).…”

“…Fluoresceinated collagen degradation assay was performed as described previously (Chun and Inoue, 2014; Sato-Kusubata et al, 2011). Type I collagen was extracted from aged rat tails and lyophilized.…”

“…While subcutaneous Sca1 high cells exerted slow and focused collagenolysis mediated by membrane-bound collagenases (MMP14-MMP2 axis), visceral Sca1 high cells displayed rapid, bulk collagenolysis, which is partly mediated by secreted collagenases, i.e., MMP8 or MMP13. (Sabeh et al, 2009; Sato-Kusubata et al, 2011) and a MMP-independent mechanism.…”

Longitudinal muscle gene expression patterns associated with differential intramuscular fat in cattle

“…One is that during adipogenesis the ECM develops from a fibrillar to laminar structure as cells move from commitment to growth and triglyceride storage (Mariman and Wang, 2010). In addition, adipogenesis tends to proceed in a collagen-rich ECM environment (Sato-Kusubata et al, 2011). Further, mature adipocytes invest a substantial amount of energy on ECM maintenance (Mariman and Wang, 2010).…”