Regulation of transforming growth factor-beta1 (TGF-β1)-induced pro-fibrotic activities by circadian clock gene BMAL1

Abstract

BackgroundBMAL1 is a transcriptional activator of the molecular clock feedback network. Besides its role in generating circadian rhythms, it has also been shown to be involved in the modulation of cell proliferation, autophagy and cancer cell invasion. However, the role of BMAL1 in pulmonary fibrogenesis is still largely unknown. In this study, we investigated the crosstalk between BMAL1 and the signaling transduction and cellular activities of TGF-β1, a key player in lung fibrogenesis.MethodsLungs from wild type and TGF-β1-adenovirus-infected mice were harvested and homogenized for isolation of RNA and protein. RT-PCR and Western Blotting were employed to measure the expression level of clock genes and TGF-β1-induced downstream target genes. siRNA against human BMAL1 gene was transfected by using lipofectamine RNAiMAX to knockdown the endogenous BMAL1 in both lung epithelial cells and fibroblasts.ResultsOur results showed that TGF-β1 is able to up-regulate BMAL1 expression in both lung epithelial cells and normal lung fibroblasts. In animal models of pulmonary fibrosis, BMAL1 expression was also significantly higher in adenovirus-TGF-β1-infected mice than in the control group. Interestingly, BMAL1 was mostly found in a deacetylated form in the presence of TGF-β1. Importantly, siRNA–mediated knockdown of BMAL1 significantly attenuated the canonical TGF-β1 signaling pathway and altered TGF-β1-induced epithelial-mesenchymal transition and MMP9 production in lung epithelial cells. In addition, BMAL1 knockdown inhibited the fibroblast to myofibroblast differentiation of normal human lung fibroblasts.ConclusionsOur results indicate that activation of TGF-β1 promotes the transcriptional induction of BMAL1. Furthermore, BMAL1 is required for the TGF-β1-induced signaling transduction and pro-fibrotic activities in the lung.

Thalidomide Prevented and Ameliorated Pathogenesis of Crohn’s Disease in Mice via Regulation of Inflammatory Response and Fibrosis

“…Frontiers in Pharmacology | www.frontiersin.org December 2019 | Volume 10 | Article 1486 at the same time (Scheibe et al, 2019). TGF-β is the key cytokine of fibrosis in most tissues and closely related to the development of fibrosis and the synthesis of ECM (Dong et al, 2016). TGF-β exhibits crucial effects on the regulation of fibrosis and wound healing, which directly or indirectly promotes fibrosis, including the migration and activation of ECM-producing cells and synthesis of ECM proteins (Levine et al, 1993).…”

Role of Non-Coding RNAs in Lung Circadian Clock Related Diseases

“…For instance, TGF-β has been shown to suppress the expression of PER1, PER2 and REV-ERBα [90]. TGF-β1 itself has been shown to upregulate BMAL1 in lung epithelial cells as well as fibroblasts [91]. TGF-β itself is subject to circadian control by BMAL1 and CLOCK genes [91,92].…”

Musashi‐2 and related stem cell proteins in the mouse suprachiasmatic nucleus and their potential role in circadian rhythms

“…Another notable result from studies manipulating MSI2 levels is that MSI2 targets TGFβ receptor expression ( Table 3). Expression of the core clock protein BMAL1 is increased by TGFβ in epithelial cells and fibroblasts of lung (Dong et al, 2016), whereas it suppresses Per1 and Per2 expression in NIH 3T3 fibroblasts (Gast et al, 2012). Interestingly, Rentas et al also identified significant MSI2 targeting of PER1, PER2, NR1D2, and ARNTL2, suggesting effects on clock protein expression that should be examined further in the SCN.…”