Krüppel-like factor 5 transcription factor is a positive regulator of NRG-1 in human coronary artery smooth muscle cells

Peidong Cao, Xiaotong Qin, Wenze Fu, Chun Gui

Abstract

Background: Structural remodelling of the heart and blood vessels is an important basis for the development of cardiovascular disease. Krüppel-like factor 5 (KLF5), an important regulator of cardiovascular remodelling, promotes vascular smooth muscle cell (VSMC) proliferation and inflammatory responses. Neuregulin 1 (NRGI) is a positive regulator of angiogenesis, and its receptors are human epidermal growth factor receptors ErbB2, ErbB3, and ErbB4, which constitute the NRG1/ErbB signalling system. However, the relationship between the mechanism by which KLF5 promotes smooth muscle cell proliferation and the role of NRGI has not been elucidated
Materials and methods: Human coronary artery smooth muscle cells (HCASMCs) were cultured, and DNA fragments specifically enriched for binding to KLF5 proteins in HCASMCs. These were sequenced and analysed by chromatin immunoprecipitation sequencing (ChIP-seq), and downstream proteins NRG1 that could be regulated by KLF5 were identified. Dual luciferase assay was performed to verify whether KLF5 regulated the expression of NRGI, and HCASMC was transfected using KLF5 lentivirus, which was further verified by reverse transcription-polymerase chain reaction (RT-PCR) and western blot. To examine the function of the KLF5/NRG1/ErbB pathway in VSMC proliferation, we performed VSMC proliferation assays utilising ErbB2/3/4 receptor blockers
Results: NRG is a direct transcriptional target gene of KLF5. KLF5 was able to promote the mRNA and protein expression of NRG1 in HCASMC, blocking ErbB2/3/4 receptors, and the role of KLF5 in promoting smooth muscle cell proliferation was attenuated.
Conclusion: KLF5 may be one of the mechanisms by which VSMC proliferation may be promoted by upregulating the NRG1/ErbB pathway.