Versican proteolysis mediates myocardial regression during outflow tract development

Abstract

An important phase of cardiac outflow tract (OFT) formation is the remodeling of the distal region of the common outlet in which the myocardial sleeve is replaced by with smooth muscle. Here we demonstrate that expression of the proteoglycan versican is reduced before the loss of myocardium from the distal cardiac outlet concomitant with an increase in production of the N-terminal cleavage fragment of versican. To test whether versican proteolysis plays a role in OFT remodeling, we determined the effects of adenoviral-mediated expression of a versican isoform devoid of known matrix metalloproteinase cleavage sites (V3) and an N-terminal fragment of versican (G1). V3 expression promoted an increase in thickness of the proximal OFT myocardial layer independent of proliferation. In contrast, the G1 domain caused thinning and interruptions of the OFT myocardium. These in vivo findings were consistent with findings using cultured primary cardiomyocytes showing that the V3 promoted myocardial cell-cell association while the G1 domain caused a loss of myocardial cell-cell association. Taken together, we conclude that intact versican and G1-containing versican cleavage products have opposing effects on myocardial cells and that versican proteolysis may facilitate the loss of distal myocardium during OFT remodeling. Developmental Dynamics 236:671-683, 2007.

Caveolin-1 deletion exacerbates cardiac interstitial fibrosis by promoting M2 macrophage activation in mice after myocardial infarction

“…Protein samples of 30 µg from individual hearts were electrophoresed on a 4–15% SDS-PAGE gel, as previously described [16,17]. Briefly, separated proteins were transferred to nitrocellulose membranes, blocked for non-specific protein binding using 5% BSA in 50 mM Tris, pH7.2/150 mM NaCl/0.5% Tween 20 (TBST), and probed for selected proteins with a specific primary antibody followed by a secondary peroxidase labeled antibody for detection.…”

Lumican deficiency results in cardiomyocyte hypertrophy with altered collagen assembly

“…Standard histological procedures were used [19]. The lumican antibodies used included a gift from Dr. A. Oldberg, Lund University and a lumican anibody against mouse from R & D Systems™ (AF2846); Laminin antibody was purchased from Abcam (ab11575).…”

Versican and the regulation of cell phenotype in disease

“…Furthermore, injection of an adenovirus that contained the V3 gene into a developing mouse heart led to an increase in the outflow track myocardium and at least a two-fold increase in the compact layer of the ventricular myocardium. Notably, this study found that when only the G1 domain of versican was expressed, opposite effects were seen [36]. Given that V3 may resist degradation, these findings suggest that V3 may have dominant effects on phenotype when compared to degraded forms of versican.…”

“…For example, forced expression of V3 in a chondrogenic cell line disrupts the deposition and organization of V0/V1 isoforms and inhibits mesenchymal condensation and chondrogenesis [35]. Kern and colleagues [36] transduced mouse embryonic cardiomyocytes with V3 and noticed a marked reduction in proliferation of the cardiomyocytes and a significant increase in myocardial cell-cell association. Furthermore, injection of an adenovirus that contained the V3 gene into a developing mouse heart led to an increase in the outflow track myocardium and at least a two-fold increase in the compact layer of the ventricular myocardium.…”