👤 Yasuhito Shirai

Ectopic fat deposition refers to lipid accumulation that affects metabolic function and tissue characteristics. Japanese Black cattle are distinguished by their high intramuscular fat content, which contributes to their distinctive character. However, the genetic mechanisms underlying these traits remain unclear. This study compared gene expression patterns in different muscle regions to identify genes associated with intramuscular fat accumulation. First, we conducted RNA sequencing to analyze differences in gene expression profiles among the sternocleidomastoid, pectoralis minor, and pectoralis major muscles. In addition, single-cell nuclear RNA sequencing was conducted to investigate the cellular composition of these muscle tissues. Distinct gene expression patterns were observed among the different muscles. In the pectoralis, which contains a high proportion of intramuscular fat, adipocyte-related genes such as This study provides novel insight into the genetic regulation of intramuscular fat accumulation. It improves our understanding of the molecular mechanisms underlying their distinctive meat characteristics. Show less

Megacystis microcolon intestinal hypoperistalsis syndrome (MMIHS) is defined as a congenital visceral myopathy with genetic mutations. However, the etiology and pathophysiology are not fully understood. We aimed to generate a gene leiomodin-1a (lmod1a) modification technique to establish a zebrafish model of MMIHS. We targeted lmod1a in zebrafish using CRISPR/Cas9. After confirming the genotype, we measured the expression levels of the target gene and protein associated with MMIHS. A gut transit assay and spatiotemporal mapping were conducted to analyze the intestinal function. Genetic confirmation showed a 5-base-pair deletion in exon 1 of lmod1a, which caused a premature stop codon. We observed significant mRNA downregulation of lmod1a, myh11, myod1, and acta2 and the protein expression of Lmod1 and Acta2 in the mutant group. A functional analysis of the lmod1a mutant zebrafish showed that its intestinal peristalsis was fewer, slower, and shorter in comparison to the wild type. This study showed that targeted deletion of lmod1a in zebrafish resulted in depletion of MMIHS-related genes and proteins, resulting in intestinal hypoperistalsis. This model may have the potential to be utilized in future therapeutic approaches, such as drug discovery screening and gene repair therapy for MMIHS. Show less

Cardio-ankle vascular index (CAVI) is an arterial stiffness index that correlates inversely with body mass index (BMI) and subcutaneous fat area. Lipoprotein lipase (LPL) that catalyzes the hydrolysis of serum triglycerides is produced mainly in adipocytes. Serum LPL mass reflects LPL expression in adipose tissue, and its changes correlate inversely with changes in CAVI. We hypothesized that LPL derived from subcutaneous adipose tissue (SAT) suppresses the progression of arteriosclerosis and examined the relationship of LPL gene expression in different adipose tissues and serum LPL mass with CAVI in Japanese patients with severe obesity undergoing laparoscopic sleeve gastrectomy (LSG). This study was a single-center retrospective database analysis. Fifty Japanese patients who underwent LSG and had 1-year postoperative follow-up data were enrolled (mean age 47.5 years, baseline BMI 46.6 kg/m2, baseline HbA1c 6.7%). SAT and visceral adipose tissue (VAT) samples were obtained during LSG surgery. LPL gene expression was analyzed by real-time PCR. Serum LPL mass was measured by ELISA using a specific monoclonal antibody against LPL. At baseline, LPL mRNA expression in SAT correlated positively with serum LPL mass, but LPL mRNA expression in VAT did not. LPL mRNA expression in SAT was correlated, and serum LPL mass tended to correlate inversely with the number of metabolic syndrome symptoms, but LPL mRNA expression in VAT did not. LPL mRNA expression in SAT and CAVI tended to correlate inversely in the group with visceral-to-subcutaneous fat ratio of 0.4 or higher, which is considered metabolically severe. Serum LPL mass increased 1 year after LSG. Change in serum LPL mass at 1 year after LSG tended to be an independent factor inversely associated with change in CAVI. Serum LPL mass reflected LPL mRNA expression in SAT in Japanese patients with severe obesity, and LPL mRNA expression in SAT was associated with CAVI in patients with visceral obesity. The change in serum LPL mass after LSG tended to independently contribute inversely to the change in CAVI. This study suggests that LPL derived from SAT may suppress the progression of arteriosclerosis. Show less

A basic helix-loop-helix transcription factor Hey2 is expressed in the ventricular myocardium and endocardium of mouse embryos, and Hey2 null mice die perinatally showing ventricular septal defect, dysplastic tricuspid valve and hypoplastic right ventricle. In order to understand region-specific roles of Hey2 during cardiac morphogenesis, we generated Hey2 conditional knockout (cKO) mice using Mef2c-AHF-Cre, which was active in the anterior part of the second heart field and the right ventricle and outflow tract of the heart. Hey2 cKO neonates reproduced three anomalies commonly observed in Hey2 null mice. An earliest morphological defect was the lack of right ventricular extension along the apico-basal axis at midgestational stages. Underdevelopment of the right ventricle was present in all cKO neonates including those without apparent atresia of right-sided atrioventricular connection. RNA sequencing analysis of cKO embryos identified that the gene expression of a non-chamber T-box factor Tbx2 was ectopically induced in the chamber myocardium of the right ventricle. Consistently, mRNA expression of the Mycn transcription factor, which was a cell cycle regulator transcriptionally repressed by Tbx2, was down regulated, and the number of S-phase cells was significantly decreased in the right ventricle of cKO heart. These results suggest that Hey2 plays an important role in right ventricle development during cardiac morphogenesis, at least in part, through mitigating Tbx2-dependent inhibition of Mycn expression. Show less