Secreted Frizzled-related protein 2 (sFRP2) plays a key role in chronic fibrosis after myocardial infarction and in heart failure. The study was aimed at elucidating the mechanisms through which sFRP2 may regulate the growth and extracellular matrix (ECM) remodeling of adult mouse cardiac fibroblasts (CFs). We found that sFRP2 activates CFs in part through canonical Wnt/β-catenin signaling as evidenced by increased expression of Axin2 and Wnt3a, but not Wnt5a, as well as accumulation of nuclear β-catenin. CFs in response to sFRP2 exhibited robust cell proliferation associated with increased glucose consumption and lactate production, a phenomenon termed "the Warburg effect" in oncology. The coupling between CF expansion and anaerobic glycolysis is marked by upregulation of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and tissue-nonspecific alkaline phosphatase (TNAP). In conjunction with these phenotypic changes, the CFs accelerated ECM remodeling through upregulating expression of the matrix metalloproteinase 1 (MMP1) and MMP13 genes, two members of the Collagenase subfamily, and enzyme activities of MMP2 and MMP9, two members of the Gelatinase subfamily. Consistent with the induction of multiple MMPs possessing collagenolytic activities, the steady-state level of collagen type I present in CF spent medium was reduced by sFRP2. Analysis of non-CF cell types revealed that the observed multifaceted effects of sFRP2 in growth control, glucose metabolism and ECM regulation are largely restricted to CFs and highly sensitive to Wnt signaling perturbation. The study provides a molecular framework upon which the functional versatility and signaling complexity of sFRP2 in cardiac fibrosis may be better defined.
- cardiac fibroblast
- Copyright © 2016, American Journal of Physiology-Cell Physiology