Krüppel-like Factor-9 and Krüppel-like Factor-13: Highly Related, Multi-Functional, Transcriptional Repressors and Activators of Oncogenesis

KLF9 aggravates the cardiomyocyte hypertrophy in hypertrophic obstructive cardiomyopathy through the lncRNA UCA1/p27 axis

Cardiac hypertrophy refers to an abnormal increase in the thickness of the heart muscle. Our study explores the role of Krüppel-like factor 9 (KLF9) in hypertrophic obstructive cardiomyopathy (HOCM)-induced cardiomyocyte hypertrophy, providing new targets for the treatment of HOCM. Cardiomyocytes were treated with isoproterenol (ISO). The levels of natriuretic peptide B (BNP)/natriuretic peptide A (ANP)/KLF9/long non-coding RNA urothelial carcinoma-associated 1 (lncRNA UCA1)/p27 were measured. Cell surface area and protein/DNA ratio were tested. The binding between KLF9 and the lncRNA UCA1 promoter and between zeste homologue 2 (EZH2) and lncRNA UCA1 was verified. The enrichment of histone H3 lysine 27 tri-methylation (H3K27me3) and EZH2 on the p27 promoter was analysed. ISO treatment increased KLF9 and lncRNA UCA1 expression and decreased p27 expression in cardiomyocytes. KLF9 knockdown inhibited ISO-induced cardiomyocyte hypertrophy, reduced ANP and BNP expression, and alleviated cardiomyocyte damage. KLF9 activated lncRNA UCA1 expression. LncRNA UCA1 recruited EZH2 to the p27 promoter region, increasing the enrichment of H3K27me3, thereby epigenetically suppressing p27 expression. LncRNA UCA1 overexpression or p27 downregulation reduced the protective effect of KLF9 downregulation on cardiomyocyte hypertrophy. In conclusion, KLF9 activates lncRNA UCA1 expression, and lncRNA UCA1 epigenetically suppresses p27 expression, thereby exacerbating cardiomyocyte hypertrophy in HOCM.

Transcriptomic Insights into Dual Temperature-Salinity Stress Response in "Shuike No. 1", a Pioneering Rainbow Trout Strain Bred in China

Global warming poses a significant threat to aquaculture, particularly for cold-water species like rainbow trout (Oncorhynchus mykiss). Understanding the molecular mechanisms underlying stress responses is crucial for developing resilient strains. This study investigates the dual stress of salinity and temperature response of "Shuike No. 1" (SK), a pioneering commercially bred rainbow trout strain in China, using RNA-sequencing of gill, intestine, and liver tissues from fish exposed to four treatment combinations: freshwater at 16 °C, freshwater at 25 °C, saltwater (30‱) at 16 °C, and saltwater at 25 °C. Differential gene expression analysis identified a substantial number of DEGs, with the liver showing the most pronounced response and a clear synergistic effect observed under combined high-temperature and salinity stress. Weighted gene co-expression network analysis (WGCNA) revealed stress-responsive gene modules and identified hub genes, primarily associated with gene expression, endoplasmic reticulum (ER) function, disease immunity, energy metabolism, and substance transport. Key hub genes included klf9, fkbp5a, fkbp5b, ef2, cirbp, atp1b1, atp1b2, foxi3b, smoc1, and arf1. Functional enrichment analysis confirmed the prominent role of ER stress, particularly the pathway "protein processing in the endoplasmic reticulum." Our results reveal complex, tissue-specific responses to dual stress, with high temperature exerting a stronger influence than salinity. These findings provide valuable insights into the molecular mechanisms underpinning dual stress responses in SK, informing future breeding programs for enhanced resilience in the face of climate change.

Krüpple-like factors in cardiomyopathy: emerging player and therapeutic opportunities

Cardiomyopathy, a heterogeneous pathological condition characterized by changes in cardiac structure or function, represents a significant risk factor for the prevalence and mortality of cardiovascular disease (CVD). Research conducted over the years has led to the modification of definition and classification of cardiomyopathy. Herein, we reviewed seven of the most common types of cardiomyopathies, including Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC), diabetic cardiomyopathy, Dilated Cardiomyopathy (DCM), desmin-associated cardiomyopathy, Hypertrophic Cardiomyopathy (HCM), Ischemic Cardiomyopathy (ICM), and obesity cardiomyopathy, focusing on their definitions, epidemiology, and influencing factors. Cardiomyopathies manifest in various ways ranging from microscopic alterations in cardiomyocytes, to tissue hypoperfusion, cardiac failure, and arrhythmias caused by electrical conduction abnormalities. As pleiotropic Transcription Factors (TFs), the Krüppel-Like Factors (KLFs), a family of zinc finger proteins, are involved in regulating the setting and development of cardiomyopathies, and play critical roles in associated biological processes, including Oxidative Stress (OS), inflammatory reactions, myocardial hypertrophy and fibrosis, and cellular autophagy and apoptosis, particularly in diabetic cardiomyopathy. However, research into KLFs in cardiomyopathy is still in its early stages, and the pathophysiologic mechanisms of some KLF members in various types of cardiomyopathies remain unclear. This article reviews the roles and recent research advances in KLFs, specifically those targeting and regulating several cardiomyopathy-associated processes.