Aherrahrou, R. | bioRxiv Science

bioRxiv2021

Deficiency of ZC3HC1 increases vascular smooth muscle cell migration, proliferation and neointima formation following injury

RationaleThe ZC3HC1 gene has been linked to various cardiovascular traits. One variant, rs11556924-T, has been found to lower the risk of coronary artery disease (CAD) and blood pressure but increases carotid intima-media thickness (IMT). ObjectiveThis study aimed to determine how ZC3HC1 affects IMT using in vitro and in vivo models. We analyzed the effect of the rs11556924-T allele on ZC3HC1 expression in vascular smooth muscle cells (SMCs) from 151 multi-ethnic heart transplant donors. The results showed that rs11556924-T was associated with lower ZC3HC1 expression and faster SMC migration. ZC3HC1 knockdown (KD) experiments supported these findings, showing increased migration and proliferation. Mechanistically ZC3HC1 KD led to decreased expression of contractile marker genes and the accumulation of cyclin B1, a key cell cycle protein. Pathway analysis of differentially expressed genes between ZC3HC1 KD and controls SMCs showed decreased expression of genes in the cell division and cytoskeleton organization pathways, as well as higher expression of genes involved in extracellular matrix organization and cytokine-mediated signaling. To validate these findings in vivo, we generated and characterized knockout (Zc3hc1-/-) mice. These mice had enhanced neointima formation in response to arterial injury and faster SMCs migration ability. However, complete loss of Zc3hc1 led to a significant reduction in SMC proliferation and lower cyclin B1 protein level. In addition, immunostaining and confocal microscopy demonstrated, for the first time, that ZC3HC1 and Cyclin B1 were located at the cleavage furrow during mitotic progression of SMCs. ConclusionsCollectively, our study suggests that lower ZC3HC1/NIPA level leads to increased SMC migration and neointima formation. Moreover, we proposed a biphasic role of NIPA in proliferation. Lower levels of NIPA promote SMC proliferation, while complete loss of NIPA hampers cell division and abrogates proliferation.

genetics↗

bioRxiv2021

Adipocyte-specific modulation of KLF14 expression in mice leads to sex-dependent impacts in adiposity and lipid metabolism

Genome-wide association studies identified single nucleotide polymorphisms on chromosome 7 upstream of KLF14 to be associated with metabolic syndrome traits and increased risk for Type 2 Diabetes (T2D). The associations were more significant in women than in men. The risk allele carriers expressed lower levels of the transcription factor KLF14 in adipose tissues than non-risk allele carriers. To investigate how adipocyte KLF14 regulates metabolic traits in a sex-dependent manner, we characterized high-fat diet fed male and female mice with adipocyte-specific Klf14 deletion or overexpression. Klf14 deletion resulted in increased fat mass in female mice and decreased fat mass in male mice. Female Klf14-deficient mice had overall smaller adipocytes in subcutaneous fat depots but larger adipocytes in parametrial depots, indicating a shift in lipid storage from subcutaneous to visceral fat depots. They had reduced metabolic rates and increased respiratory exchange ratios consistent with increased utilization of carbohydrates as an energy source. Fasting and isoproterenol-induced adipocyte lipolysis was defective in female Klf14-deficient mice and concomitantly adipocyte triglycerides lipase mRNA levels were downregulated. Female Klf14-deficient mice cleared blood triglyceride and NEFA less efficiently than wild type. Finally, adipocyte-specific overexpression of Klf14 resulted in lower total body fat in female but not male mice. Taken together, consistent with human studies, adipocyte KLF14 deficiency in female but not in male mice causes increased adiposity and redistribution of lipid storage from subcutaneous to visceral adipose tissues. Increasing KLF14 abundance in adipocytes of females with obesity and T2D may provide a novel treatment option to alleviate metabolic abnormalities.

physiology↗