KLF13 Attenuates Lipopolysaccharide-Induced Alveolar Epithelial Cell Damage by Regulating Mitochondrial Quality Control via Binding PGC-1α.

Sepsis is a clinically life-threatening syndrome, and acute lung injury is the earliest and most serious complication. We aimed to assess the role of kruppel-like factor 13 (KLF13) in lipopolysaccharide (LPS)-induced human alveolar type II epithelial cell damage and to reveal the possible mechanism related to peroxisome proliferator-activated receptor-γ co-activator 1-α (PGC-1α). In LPS-treated A549 cells with or without KLF13 overexpression or PGC-1α knockdown, cell viability was measured by a cell counting kit-8 assay. Enzyme-linked immunosorbent assay kits detected the levels of inflammatory factors, and terminal deoxynucleotidyl transferase dUTP nick-end labeling staining measured cell apoptosis. Besides, mitochondrial reactive oxygen species (MitoSOX) and mitochondrial membrane potential were detected using MitoSOX red- and JC-1 staining. Expression of proteins related to mitochondrial quality control (MQC) was evaluated by western blot. Co-immunoprecipitation (Co-IP) assay was used to analyze the interaction between KLF13 and PGC-1α. Results indicated that KLF13 was highly expressed in LPS-treated A549 cells. KLF13 upregulation elevated the viability and reduced the levels of inflammatory factors in A549 cells exposed to LPS. Moreover, KLF13 gain-of-function inhibited LPS-induced apoptosis of A549 cells, accompanied by upregulated BCL2 expression and downregulated Bax and cleaved caspase3 expression. Furthermore, MQC was improved by KLF13 overexpression, as evidenced by decreased MitoSOX, JC-1 monomers and increased JC-1 aggregates, coupled with the changes of proteins related to MQC. In addition, Co-IP assay confirmed the interaction between KLF13 and PGC-1α. PGC-1α deficiency restored the impacts of KLF13 upregulation on the inflammation, apoptosis, and MQC in LPS-treated A549 cells. In conclusion, KLF13 attenuated LPS-induced alveolar epithelial cell inflammation and apoptosis by regulating MQC via binding PGC-1α.

KLF13 restrains Dll4-muscular Notch2 axis to improve the muscle atrophy.

BACKGROUND: Muscle atrophy can cause muscle dysfunction and weakness. Krüppel-like factor 13 (KLF13), a central regulator of cellular energy metabolism, is highly expressed in skeletal muscles and implicated in the pathogenesis of several diseases. This study investigated the role of KLF13 in muscle atrophy, which could be a novel therapeutic target. METHODS: The effects of gene knockdown and pharmacological targeting of KLF13 on skeletal muscle atrophy were investigated using cell-based and animal models. Clofoctol, an antibiotic and KLF13 agonist, was also investigated as a candidate for repurposing. The mechanisms related to skeletal muscle atrophy were assessed by measuring the expression levels and activation statuses of key regulatory pathways and validated using gene knockdown and RNA sequencing. RESULTS: In a dexamethasone-induced muscle atrophy mouse model, the KLF13 knockout group had decreased muscle strength (N) (1.77 ± 0.10 vs. 1.48 ± 0.16, P < 0.01), muscle weight (%) [gastrocnemius (Gas): 76.0 ± 5.69 vs. 60.7 ± 7.23, P < 0.001; tibialis anterior (TA): 75.8 ± 6.21 vs. 67.5 ± 5.01, P < 0.05], and exhaustive running distance (m) (495.5 ± 64.8 vs. 315.5 ± 60.9, P < 0.05) compared with the control group. KLF13 overexpression preserved muscle mass (Gas: 100 ± 6.38 vs. 120 ± 14.4, P < 0.01) and the exhaustive running distance (423.8 ± 59.04 vs. 530.2 ± 77.45, P < 0.05) in an in vivo diabetes-induced skeletal muscle atrophy model. Clofoctol treatment protected against dexamethasone-induced muscle atrophy. Myotubes treated with dexamethasone, an atrophy-inducing glucocorticoid, were aggravated by KLF13 knockout, but anti-atrophic effects were achieved by inducing KLF13 overexpression. We performed a transcriptome analysis and luciferase reporter assays to further explore this mechanism, finding that delta-like 4 (Dll4) was a novel target gene of KLF13. The KLF13 transcript repressed Dll4, inhibiting the Dll4-Notch2 axis and preventing muscle atrophy. Dexamethasone inhibited KLF13 expression by inhibiting myogenic differentiation 1 (i.e., MYOD1)-mediated KLF13 transcriptional activation and promoting F-Box and WD repeat domain containing 7 (i.e., FBXW7)-mediated KLF13 ubiquitination. CONCLUSIONS: This study sheds new light on the mechanisms underlying skeletal muscle atrophy and potential drug targets. KLF13 regulates muscle atrophy and is a potential therapeutic target. Clofoctol is an attractive compound for repurposing studies to treat skeletal muscle atrophy.

Human Genetics of Tricuspid Atresia and Univentricular Heart.

Tricuspid atresia (TA) is a rare congenital heart condition that presents with a complete absence of the right atrioventricular valve. Because of the rarity of familial and/or isolated cases of TA, little is known about the potential genetic abnormalities contributing to this condition. Potential responsible chromosomal abnormalities were identified in exploratory studies and include deletions in 22q11, 4q31, 8p23, and 3p as well as trisomies 13 and 18. In parallel, potential culprit genes include the ZFPM2, HEY2, NFATC1, NKX2-5, MYH6, and KLF13 genes. The aim of this chapter is to expose the genetic components that are potentially involved in the pathogenesis of TA in humans. The large variability in phenotypes and genotypes among cases of TA suggests a genetic network that involves many components yet to be unraveled.

miR-135b Aggravates Fusobacterium nucleatum-Induced Cisplatin Resistance in Colorectal Cancer by Targeting KLF13.

Cisplatin resistance is the main cause of colorectal cancer (CRC) treatment failure, and the cause has been reported to be related to Fusobacterium nucleatum (Fn) infection. In this study, we explored the role of Fn in regulating cisplatin resistance of CRC cells and its underlying mechanism involved. The mRNA and protein expressions were examined by qRT-PCR and western blot. Cell proliferation and cell apoptosis were assessed using CCK8 and flow cytometry assays, respectively. Dual-luciferase reporter gene assay was adopted to analyze the molecular interactions. Herein, our results revealed that Fn abundance and miR-135b expression were markedly elevated in CRC tissues, with a favorable association between the two. Moreover, Fn infection could increase miR-135b expression via a concentration-dependent manner, and it also enhanced cell proliferation but reduced apoptosis and cisplatin sensitivity by upregulating miR-135b. Moreover, KLF13 was proved as a downstream target of miR-135b, of which overexpression greatly diminished the promoting effect of miR-135b or Fn-mediated cisplatin resistance in CRC cells. In addition, it was observed that upstream 2.5 kb fragment of miR-135b promoter could be interacted by ß-catenin/TCF4 complex, which was proved as an effector signaling of Fn. LF3, a blocker of ß-catenin/TCF4 complex, was confirmed to diminish the promoting role of Fn on miR-135b expression. Thus, it could be concluded that Fn activated miR-135b expression through TCF4/ß-catenin complex, thereby inhibiting KLF13 expression and promoting cisplatin resistance in CRC.

TET3-mediated novel regulatory mechanism affecting trophoblast invasion and migration: Implications for preeclampsia development.

INTRODUCTION: Aberrant expression of genes has been demonstrated to be related to the abnormal function of trophoblasts and lead to the occurrence and progression of Preeclampsia (PE). However, the underlying mechanism of PE has not been elucidated. METHODS: We performed PCR analysis to investigate TET3 expression in PE placental tissues. Cell assays were performed in HTR-8/SVneo and JAR. Cell invasion and migration events were investigated by transwell assays in vitro. ChIP-PCR and Targeted bisulfite sequencing were conducted to detect the demethylation of related CpG sites in the KLF13 promoter after inhibition of TET3. In conjunction with bioinformatics analysis, luciferase reporter assays were performed to elucidate the mechanism by which miR-544 binds to TET3/KLF13 mRNA. RESULTS: In this study, we identified genes associated with human extravillous trophoblasts by conducting sc-seq analysis from the GEO. Then, we measured the expression of TET3 in a larger clinical sample. The results showed that TET3, a DNA demethylase, was found to be expressed at much higher levels in the preeclamptic placenta compared to the control. Then, the inhibition of TET3 significantly promoted trophoblast cell migration and invasion. Conversely, TET3 overexpression suppressed cell migration and invasion in vitro. Further RNA sequencing and mechanism analysis indicated that the inhibition of TET3 suppressed the activation of KLF13 by reducing the demethylation of related CpG sites in the KLF13 promoter, thereby transcriptionally inactivating KLF13 expression. Moreover, luciferase reporter assay indicate that TET3 and KLF13 were direct targets of miR-544. DISCUSSION: This study uncovers a TET3-mediated regulatory mechanism in PE progression and suggests that targeting the placental miR-544-TET3-KLF13-axis might provide new diagnostic and therapeutic strategies for PE.