αII-spectrin and βII-spectrin do not affect TGFβ1-induced myofibroblast differentiation

MiR-210-5p regulates STAT3 activation by targeting STAT5A in the differentiation of dermal fibroblasts

Elucidating the molecular mechanism of the microRNAs in skin fibrosis is critical for identifying a novel therapeutic strategy for hypertrophic scar (HS). In this study, it was shown that miR-210-5p is induced by TGFβ, and that overexpression of miR-210-5p promoted the differentiation of human dermal fibroblasts (HDFs) into myofibroblasts. STAT5A is required for TGFβ-induced STAT3 activity. Here, we show that miR-210-5p attenuated TGFβ-induced STAT3 signaling pathway by suppressing the expression of STAT5A. Taken together, the present study suggests that TGFβ-induced miR-210-5p reduced STAT5A expression, leading to aberrant activation of STAT3, and facilitate skin fibrosis in HDFs.

Emerging therapeutic targets for cardiac arrhythmias: role of STAT3 in regulating cardiac fibroblast function

Introduction : Cardiac fibrosis contributes to the development of cardiovascular disease (CVD) and arrhythmia. Cardiac fibroblasts (CFs) are collagen-producing cells that regulate extracellular matrix (ECM) homeostasis. A complex signaling network has been defined linking environmental stress to changes in CF function and fibrosis. Signal Transducer and Activator of Transcription 3 (STAT3) has emerged as a critical integrator of pro-fibrotic signals in CFs downstream of several established signaling networks. Areas covered : This article provides an overview of STAT3 function in CFs and its involvement in coordinating a vast web of intracellular pro-fibrotic signaling molecules and transcription factors. We highlight recent work elucidating a critical role for the fibroblast cytoskeleton in maintaining spatial and temporal control of STAT3-related signaling . Finally, we discuss potential opportunities and obstacles for therapeutic targeting of STAT3 to modulate cardiac fibrosis and arrhythmias. Relevant publications on the topic were identified through Pubmed. Expert opinion : Therapeutic targeting of STAT3 for CVD and arrhythmias presents unique challenges and opportunities. Thus, it is critical to consider the multimodal and dynamic nature of STAT3 signaling. Going forward, it will be beneficial to consider ways to maintain balanced STAT3 function, rather than large-scale perturbations in STAT3 function.

βIV-Spectrin/STAT3 complex regulates fibroblast phenotype, fibrosis, and cardiac function

Increased fibrosis is a characteristic remodeling response to biomechanical and neurohumoral stress and a determinant of cardiac mechanical and electrical dysfunction in disease. Stress-induced activation of cardiac fibroblasts (CFs) is a critical step in the fibrotic response, although the precise sequence of events underlying activation of these critical cells in vivo remain unclear. Here, we tested the hypothesis that a βIV-spectrin/STAT3 complex is essential for maintenance of a quiescent phenotype (basal nonactivated state) in CFs. We reported increased fibrosis, decreased cardiac function, and electrical impulse conduction defects in genetic and acquired mouse models of βIV-spectrin deficiency. Loss of βIV-spectrin function promoted STAT3 nuclear accumulation and transcriptional activity, and it altered gene expression and CF activation. Furthermore, we demonstrate that a quiescent phenotype may be restored in βIV-spectrin-deficient fibroblasts by expressing a βIV-spectrin fragment including the STAT3-binding domain or through pharmacological STAT3 inhibition. We found that in vivo STAT3 inhibition abrogates fibrosis and cardiac dysfunction in the setting of global βIV-spectrin deficiency. Finally, we demonstrate that fibroblast-specific deletion of βIV-spectrin is sufficient to induce fibrosis and decreased cardiac function. We propose that the βIV-spectrin/STAT3 complex is a determinant of fibroblast phenotype and fibrosis, with implications for remodeling response in cardiovascular disease (CVD).