Human Cre-GFP adenoviral particles

REV-ERB agonists have demonstrated anti-fibrotic effects in the heart and other organs. The role of REV-ERB in cardiac fibroblasts remains unstudied. Here, researchers used genetic deletion of REV-ERBα and β in vitro to characterize differences in the function of REV-ERB in mouse embryonic fibroblasts and cardiac fibroblasts. Researchers found that cardiac fibroblasts with double deletion of REV-ERB α/β had reduced viability and proliferation, but increased migration and myofibroblast activation. Thus, REV-ERB α/β has an important cell-autonomous role in cardiac fibroblasts to maintain them in a healthy, quiescent state. Furthermore, the study showed that an existing REV-ERB agonist, SR9009, strongly inhibited cardiac fibroblast activation, but in a REV-ERB-independent manner, highlighting the need for the development of novel REV-ERB agonists for the treatment of cardiac fibrosis.

Here, researchers isolated primary cardiac fibroblasts (CFs) from Nr1d1/2 fl/fl mice and infected them with adenovirus expressing Cre (Ad-Cre-GFP) or control (Ad-GFP). Infection efficiency was close to 100%, and they found that adenovirus-induced Cre expression resulted in a 94% reduction in Nr1d1 and an 87% reduction in Nr1d2 in Ad-Cre-GFP infected CFs (Figure 1A, B). Cardiac fibroblast activation was stimulated by treatment with TGFβ-1, and immunostaining for αSMA and qRT-PCR for myofibroblast markers were performed. Interestingly, while there were no differences at baseline, DKO CFs showed higher cells positive for αSMA signaling compared to controls with TGFβ-1 activation (Figure 1C, D). Consistent with this finding, TGFβ-1 treatment induced higher expression of myofibroblast markers Acta2 and Col1a1 in DKO CFs but did not induce the expression of Fn1 (Figure 1E).

Figure 1. REV-ERB deletion leads to exaggerated activation of CFs. (Luo X, et al., 2022)