Advances in the relationship between Kruppel-like factor 15 and cardiovascular disease research

Effects of Halloysite Nanotubes and Multi-walled Carbon Nanotubes on Kruppel-like Factor 15-Mediated Downstream Events in Mouse Hearts After Intravenous Injection

Halloysite nanotubes (HNTs) are nanomaterials (NMs) derived from natural clays and have been considered as biocompatible NMs for biomedical uses. However, the cardiovascular toxicity of HNTs has not been thoroughly investigated. In this study, we compared the cardiotoxicity of HNTs and multi-walled carbon nanotubes (MWCNTs), focusing on the changes in Kruppel-like factor (KLF)-mediated signaling pathways. Mice were intravenously injected with 50 µg NMs, once a day, for 5 days, and then mouse hearts were removed for experiments. While HNTs or MWCNTs did not induce obvious pathological changes, RNA-sequencing data suggested the alterations of KLF gene expression. We further confirmed an increase of Klf15 positive cells, accompanied by changes in Klf15-related gene ontology (GO) terms. We noticed that most of the changed GO terms are related with the regulation of gene expression, and we confirmed that the NMs increased myoneurin (Mynn) but decreased snail family transcriptional repressor 1 (Snai1), two transcription factors (TFs) related with Klf15. Besides, the changed GO terms also include metal ion binding and positive regulation of glucose import, and we verified an increase of phosphoenolpyruvate carboxykinase 1 (Pck1) and insulin receptor (Insr). However, HNTs and MWCNTs only showed minimal impact on cell death signaling pathways, and no increase in apoptotic sites was observed after NM treatment. We concluded that intravenous administration of HNTs and MWCNTs activated a protective TF, namely Klf15 in mouse aortas, to alter gene expression and signaling pathways related with metal ion binding and glucose import.

Molecular Pathways and Animal Models of Cardiomyopathies

Cardiomyopathies are a heterogeneous group of disorders of the heart muscle that ultimately result in congestive heart failure. Rapid progress in genetics, molecular and cellular biology with breakthrough innovative genetic-engineering techniques, such as next-generation sequencing and multiomics platforms, stem cell reprogramming, as well as novel groundbreaking gene-editing systems over the past 25 years has greatly improved the understanding of pathogenic signaling pathways in inherited cardiomyopathies. This chapter will focus on intracellular and intercellular molecular signaling pathways that are activated by a genetic insult in cardiomyocytes to maintain tissue and organ level regulation and resultant cardiac remodeling in certain forms of cardiomyopathies. In addition, animal models of different clinical forms of human cardiomyopathies with their summaries of triggered key molecules and signaling pathways will be described.

Transcriptome analysis of Klf15‑mediated inhibitory functions in a mouse deep venous thrombosis model

Krüppel-like family (KLF) members are important regulators of proinflammatory activation in the vasculature. A transcriptome study involving RNA sequencing (RNA-seq) and quantitative PCR (qPCR) was performed to investigate Klf15 and Klf15-regulated gene levels in C57BL/6 mice with inferior vena cava thrombi and in control (Blank) mice. A total of 2,206 differentially expressed genes (DEGs), including 1,330 upregulated and 876 downregulated genes, were identified between the deep venous thrombosis (DVT) group and the Blank group. Additionally, 1,041 DEGs (235 upregulated and 806 downregulated) were identified between the Klf15-small interfering RNA (siRNA) and Klf15-negative control (NC) groups. The DEGs were subjected to Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses, and qPCR was conducted to validate the results. A total of seven significant DEGs were selected from the RNA-seq results. Matrix metalloproteinases (Mmp)12, Mmp13, Mmp19, Arg1, Ccl2, heme oxygenase-1 and Fmo3 levels were significantly higher, while Klf15 levels were lower, in the DVT group than in the Blank group. Fmo3 and Mmp19 have not been previously identified as DVT-associated DEGs. Klf15, Mmp12 and Mmp13 levels were compared between the Klf15-siRNA and Klf15-NC groups. Mmp12 and Mmp13 expression was significantly higher, while that of Klf15 was lower, in the Klf15-siRNA group than in the Klf15-NC group. Critical roles of Klf15, Mmp12 and Mmp13 have been identified, which have not previously been shown to help regulate DVT initiation and progression. Moreover, Klf15-mediated regulation of DVT may be modulated by downregulation of various genes, such as Mmp12 and Mmp13, potentially providing a theoretical foundation and diagnostic criteria for DVT treatment.