Role of the matrixin MMP-2 in multicellular organization of adipocytes cultured in basement membrane components

Abstract

Primary rat adipocytes cultured in basement membrane component gels migrated and organized into large, three-dimensional, multicellular clusters. Gross morphological changes seen during this reorganization are described. The rate of cluster formation decreased with age of the rats and was stimulated by insulin in older, but not in younger rats. Echistatin, a disintegrin, partially inhibited the formation of multicellular clusters in a concentration-dependent fashion (50% inhibitory concentration approximately 10 nM). The original extracellular matrix was initially remodeled and eventually destroyed by the time large multicellular clusters were observed. This implied that one or more matrix-degrading protease(s) were being secreted. Adipocyte-conditioned medium was found to contain a divalent cation-sensitive gelatinase activity at approximately 72 and/or approximately 62 kDa. The elution profile of this activity from gelatin-Sepharose 4B was similar to matrix metalloproteinase 2 (MMP-2, a 72-kDa matrixin with a 62-kDa mature form), and the dimethyl sulfoxide eluant from these columns contained MMP-2 immunoreactivity. MMP-2 concentration and activity were greater in conditioned medium from young than from older animals; however, insulin did not affect the amount of MMP-2 in adipocyte-conditioned media. The matrixin inhibitor 1,10-phenanthroline not only blocked gelatinase activity in zymograms but also prevented extracellular matrix remodeling and destruction, as well as adipocyte migration and the formation of cell-cell contacts in adipocyte cultures. These observations are consistent with the hypothesis that the matrixin MMP-2 is secreted by adipocytes. Whereas matrixin activity alone may not be sufficient for the formation of multicellular clusters, the data indicate that it may have a requisite role in this process.

Matrix Metalloproteinases Are Differentially Expressed in Adipose Tissue during Obesity and Modulate Adipocyte Differentiation

“…Recent studies have documented the change of MMP gene expression and activities during adipocyte differentiation (11,12,14). Consistent with these data, we showed that MMP-2 and TIMP-1 are differentially regulated during adipocyte differentiation.…”

“…It has been proposed that serine proteases of the plasminogen system positively regulated adipocyte differentiation in vitro, as well as in vivo during mammary gland involution (10). Other studies have demonstrated that mature fat cells and cultured adipocytes secreted gelatinases A and B (MMP-2 and MMP-9, respectively), and that their proteolytic activities were induced during adipocyte differentiation (11,12). Further, elevated expression of MMP-2 was reported in adipose tissue of obese mice (13).…”

Gender-specific genetic associations of polymorphisms in ACE, AKR1C2, FTO and MMP2 with weight gain over a 10-year period

“…MMP2 is an endopeptidase that degrades the basement membrane surrounding adipocytes and thus may facilitate hypertrophic development of adipocytes and formation of adipocyte clusters (Brown et al 1997). An induction of the MMP2 transcription in adipose tissue of obese mice and during human adipocyte differentiation has been reported (Chavey et al 2003;Dubois et al 2008).…”

Potential role of increased matrix metalloproteinase-2 (MMP2) transcription in impaired adipogenesis in type 2 diabetes mellitus

“…An induction of the MMP2 transcription in the adipose tissue of genetically obese mice has also been reported [10] but our finding of higher expression in T2DM, compared to obese non-diabetic subjects, is novel. MMP2 is an endopeptidase that degrades the basement membrane surrounding adipocytes and thus may facilitate hypertrophic development of adipocytes and formation of adipocyte clusters [11]. Recent studies demonstrate a direct but inconsistent effect of MMP2 on early phases of murine preadipocyte differentiation [4,12].…”