KLF5 silence attenuates proliferation and epithelial-mesenchymal transition induction in Hep-2 cells through NF-κB signaling pathway

Krüppel-like factors in tumors: Key regulators and therapeutic avenues

Krüppel-like factors (KLFs) are a group of DNA-binding transcriptional regulators with multiple essential functions in various cellular processes, including proliferation, migration, inflammation, and angiogenesis. The aberrant expression of KLFs is often found in tumor tissues and is essential for tumor development. At the molecular level, KLFs regulate multiple signaling pathways and mediate crosstalk among them. Some KLFs may also be molecular switches for specific biological signals, driving their transition from tumor suppressors to promoters. At the histological level, the abnormal expression of KLFs is closely associated with tumor cell stemness, proliferation, apoptosis, and alterations in the tumor microenvironment. Notably, the role of each KLF in tumors varies according to tumor type and different stages of tumor development rather than being invariant. In this review, we focus on the advances in the molecular biology of KLFs, particularly the regulations of several classical signaling pathways by these factors, and the critical role of KLFs in tumor development. We also highlight their strong potential as molecular targets in tumor therapy and suggest potential directions for clinical translational research.

HDAC4 induces the development of asthma by increasing Slug-upregulated CXCL12 expression through KLF5 deacetylation

Background

Asthma is a frequently occurring respiratory disease with an increasing incidence around the world. Airway inflammation and remodeling are important contributors to the occurrence of asthma. We conducted this study aiming at exploring the effect of Histone deacetylase 4 (HDAC4)-mediated Kruppel-like factor 5 (KLF5)/Slug/CXC chemokine ligand-12 (CXCL12) axis on the development of asthma in regulation of airway inflammation and remodeling.

Methods

An asthmatic rat model was induced by ovalbumin (OVA) irrigation, and determined HDAC4, KLF5, Slug, and CXCL12 expression in the lung tissues by RT-qPCR and Western blot assay. OVA was also used to induce a cell model of asthma in human BEAS-2B and HBE135-E6E7bronchial epithelial cells. The airway hyperresponsiveness (AHR), and expression of inflammatory cytokines in model mice were examined using methacholine challenge test and ELISA. The biological behaviors were measured in asthma model bronchial smooth muscle cells (BSMCs) following loss- and gain- function approaches. The interactions between HDAC4, KLF5, Slug, and CXCL12 were also detected by IP assay, dual luciferase gene reporter assay, and ChIP.

Results

HDAC4 was upregulated in lung tissues of OVA-induced asthmatic mice, and inhibition of HDAC4 alleviated the airway inflammation and remodeling. HDAC4 increased KLF5 transcriptional activity through deacetylation; deacetylated KLF5 bound to the promoter of Slug and transcriptionally upregulated Slug expression, which in turn increased the expression of CXCL12 to promote the inflammation in bronchial epithelial cells and thus induce the proliferation and migration of BSMCs.

Conclusion

Collectively, HDAC4 deacetylates KLF5 to upregulate Slug and CXCL12, thereby causing airway remodeling and facilitating progression of asthma.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-02812-7.

The roles and regulation of the KLF5 transcription factor in cancers

Krüppel‐like factor 5 (KLF5) is a member of the KLF family. Recent studies have suggested that KLF5 regulates the expression of a large number of new target genes and participates in diverse cellular functions, such as stemness, proliferation, apoptosis, autophagy, and migration. In response to multiple signaling pathways, various transcriptional modulation and posttranslational modifications affect the expression level and activity of KLF5. Several transgenic mouse models have revealed the physiological and pathological functions of KLF5 in different cancers. Studies of KLF5 will provide prognostic biomarkers, therapeutic targets, and potential drugs for cancers.

Interfering microRNA-410 attenuates atherosclerosis via the HDAC1/KLF5/IKBα/NF-κB axis

MicroRNA (miR)-410 plays a potential role in the pathogenesis of atherosclerosis. The current study mainly focuses on the underlying mechanism of miR-410/histone deacetylase 1 (HDAC1)/KLF5/nuclear factor κB (NF-κB) inhibitor α (IKBα)/NF-κB axis in atherosclerosis. miR-410 expression was determined using quantitative real-time PCR in both mouse models of atherosclerosis and human umbilical endothelial cells (HUVECs) treated with oxidized low-density lipoprotein (ox-LDL). The study subsequently predicted regulators associated with miR-410 through bioinformatics, and their binding relation was further verified through dual luciferase reporter gene and RNA immunoprecipitation (RIP) assays, and how HDAC1 regulated KLF5 was tested through coimmunoprecipitation (coIP). In HUVECs, miR-410 and HDAC1 mRNA expression; HDAC1, KLF5, IKBα, p65, p-p65, VCAM-1, ICAM-1, and MCP-1 protein expression; and inflammatory cytokine expressions were detected using quantitative real-time PCR, western blot, and ELISA. The present study further tested cell functions by Cell Counting Kit-8 (CCK-8), flow cytometry, and the colony-formation assay. It was revealed that miR-410 could target HDAC1, whereas HDAC1 could target transcription factor KLF5, increasing IKBα expression, thus suppressing NF-κB in atherosclerosis. Furthermore, silencing miR-410 or overexpressing HDAC1 increased cell viability and suppressed apoptosis and an inflammatory reaction in HUVECs in atherosclerosis. Blocking miR-410 promotes HDAC1 expression and increases IKBα levels through KLF5 to suppress NF-κB, thus preventing development of atherosclerosis.