Wnt1-Inducible Signaling Pathway Protein-1 (WISP1) Modulation of Cardiac Fibroblasts Activity

Abstract ID 98908 Poster Board 269 Our lab has previously published that Human antigen R (HuR) is necessary for myofibroblast (MF) activation of cultured primary cardiac fibroblasts (CFs) and identified Wnt1-inducible signaling pathway protein-1 (WISP1; Ccn4) as a downstream HuR target gene. The objective of this work was to identify the functional and mechanistic role of WISP1 on the initiation and resolution of MF activity. Wisp1 has been shown to be involved in several cellular processes, including adhesion, migration, and proliferation, but its role in cardiac fibroblasts remain largely unknown. Our working hypothesis is that HuR-dependent expression of WISP1 is both necessary and sufficient for initial and sustained MF activation and promotes pathological remodeling of the heart. Data from our lab revealed that HuR and WISP1 are significantly co-expressed as strong markers of MF activation and HuR directly regulates WISP1 expression in a TGFβ-dependent manner. To delineate the function of WISP1, we utilized a gain- and loss-of-function approach in cultured primary cardiac fibroblasts. Prior to pro-fibrotic stimulation with TGFβ, we treated CFs with either recombinant WISP1 or WISP1 siRNA. Expression and knockdown of WISP1 was confirmed by qPCR and western blot. MF function was determined at 48 hours post-transfection via scratch wound healing assay. In a gain-of-function study, treatment with recombinant Wisp1 induced scratch assay wound closure to the same extent as TGFβ alone. In a loss-of-function study, CFs treated with WISP1 siRNA and TGFβ fully closed after 24 hours, whereas those treated with WISP1 siRNA alone did not. In CFs treated with TGFβ, the expression of MF marker aSMA and type 1 collagen (Col1a1), which was quantified by immunofluorescence, revealed decreased stress fibers and collagen synthesis in the absence of WISP1. Surprisingly, treatment with recombinant WISP1 induced aSMA expression and collagen synthesis beyond that of treatment with TGFβ alone. In summary, our data demonstrates that WISP1 activity is necessary and sufficient for the functional activation of primary cardiac fibroblasts and potentially mediates MF activation through a TGFβ-independent pathway. Sharon Parkins: NIH F31HL170636, AHA 23PRE1029875, T32 HL125204 Mike Tranter; NIH R01 HL132111, NIH R01 HL166326