👤 Kazushi Sawamura

Adiponectin is an anti-diabetic and anti-atherogenic protein secreted primarily from adipose tissue. Adiponectin and modified LDL (mLDL) form a complex to modulate their biological activity. To elucidate the significance of the complex formation, we analyzed its effects on vascular tissue and developed and verified novel quantifying methods for adiponectin. To study the significance of the mLDL-adiponectin complex (MAC) formation, we used the wire-myography method on rat mesenteric artery. We developed a method to measure MAC by using LOX-1 as the capture protein and anti-adiponectin antibody for detection. We compared serum MAC levels between hemodialysis patients and control subjects. Administering mLDL alone to rat mesenteric artery impaired endothelium-dependent vasorelaxation, whereas simultaneously administering adiponectin with mLDL protected rat mesenteric artery from the mLDL-induced impairment of vasorelaxation. This finding indicates MAC formation prevents endothelium from mLDL-induced dysfunction in tissue. Using our novel ELISA for MAC, we found that MAC was increasingly detectable depending on the doses of mLDL and adiponectin in vitro. In serum, hemodialysis patients showed a significantly higher ratio of MAC-high patients (higher than the median level of MAC) than did healthy controls. Furthermore, the MAC-high hemodialysis group had lower mLDL activity measured as LOX-1 ligand containing apoB. Using our ELISA, we detected MAC in human serum that protected blood vessels from the deleterious effects of oxidized LDL. Show less

Atherosclerotic cardiovascular disease (ASCVD), including coronary heart disease and cerebrovascular disease, is caused by the accumulation of plaque on artery walls. Elevated levels of low-density lipoprotein (LDL) cholesterol significantly contribute to the development and progression of ASCVD. Multiple studies have provided evidence of a correlation between individual LDL subpopulations and the development of atherosclerosis (AS); among these, small, dense low-density lipoprotein (sdLDL) and lipoprotein(a) [Lp(a)] have been particularly implicated. There are multiple considerations of why sdLDL may cause AS including their low affinity for the LDL receptor, their ability to diffuse into the artery wall and remain there for a long time, and their tendency to become excessively oxidized. Oxidized LDL (oxLDL), generated under oxidative stress, drives AS by impairing endothelial function, promoting foam cell formation, and triggering vascular inflammation. Lp(a) contributes to the development and progression of AS by causing inflammation of the arterial wall. Studies conducted in recent years have found that electronegative LDL [L5/LDL(-)] may also be an important factor in the development and progression of AS. L5/LDL(-) causes atherosclerotic changes in the vascular wall by triggering apoptosis in endothelial cells via the lectin-like oxLDL receptor-1. This article offers an updated overview of ASCVD and briefly examines the classifications of atherogenic LDL subfractions and their roles in atherogenesis. Show less

Lipid metabolic disorders play critical roles in atherogenesis. Traditionally, it has been suggested that reduced high density lipoprotein (HDL) levels might be an important morbidity indicator for cardiovascular diseases. Therefore, it has been argued that therapeutically raising HDL levels may reduce atherogenesis in patients with dyslipidemia. However, recent clinical trials to elevate serum HDL levels by pharmacologic approaches failed to demonstrate clinical efficacy. Thus, to investigate the functionality of HDL and to explore the possible clinical relevance as well as to define an effective indicator that can represent HDL function may provide another key and reference to disclose the clinical treatment of dyslipidemia. We analyzed the association between the data of dichlorofluorescein assay (assay the functionality of HDL), the effect of HDL on oxidized low density lipoprotein (oxLDL)-stimulated endothelial progenitor cells (EPCs) in vitro, levels of circulating EPCs, and ex vitro EPC colony forming units of each case, we defined the indicator (relative HDL index (RHDL index) = dichlorofluorescein assay result of each subject/dichlorofluorescein assay reading of our young healthy controls) that may represent functionality of HDL. HDL from healthy adults protected oxLDL-treated EPCs by modulating p38 mitogen-activated protein kinase and Rho activation and by promoting nitric oxide production. HDL from subject with RHDL index ≧2 also failed to restore the functionality of oxLDL-treated EPCs via cell-signaling pathways in vitro. The RHDL index significantly correlated with patients' circulating EPC number or EPC colony forming units ex vivo. In conclusions, we explored the RHDL index as a score to predict a patient's EPC functions in vivo and ex vitro. Show less

Association between gastric inhibitory polypeptide receptor polymorphism, rs10423928, and body mass index in olanzapine-treated schizophrenia was examined. Body mass index change for the A/T+A/A genotypes was significantly higher than that for the T/T genotype. rs10423928 may predict weight gain in schizophrenia. Show less

In interspecific hybrids between Drosophila melanogaster and Drosophila simulans, the D. simulans nucleoporin-encoding Nup96(sim) and Nup160(sim) can cause recessive lethality if the hybrid does not also inherit the D. simulans X chromosome. In addition, Nup160(sim) leads to recessive female sterility in the D. melanogaster genetic background. Here, we conducted carefully controlled crosses to better understandthe relationship between Nup96(sim) and Nup160(sim). Nup96(sim) did not lead to female sterility in the D. melanogaster genetic background, and double introgression of Nup96(sim) and Nup160(sim) did not generally lead to lethality when one was heterozygous and the other homozygous (hemizygous). It appears that introgression of additional autosomal D. simulans genes is necessary to cause lethality and that the effect of the introgression is dominant to D. melanogaster alleles. Interestingly, the genetic background affected dominance of Nup96(sim), and double introgression carrying homozygous Nup96(sim) and hemizygous Nup160(sim) resulted in lethality. Thus, Nup96(sim) and Nup160(sim) seem to be two components of the same incompatibility. Show less

Previous reports have suggested that the Nucleoporin 160 (Nup160) gene of Drosophila simulans (Nup160(sim)) causes the hybrid inviability, female sterility, and morphological anomalies that are observed in crosses with D. melanogaster. Here we have confirmed this observation by transposon excision from the P{EP}Nup160(EP372) insertion mutation of D. melanogaster. Null mutations of the Nup160 gene resulted in the three phenotypes caused by Nup160(sim), but revertants of the gene did not. Interestingly, several mutations produced by excision partially complemented hybrid inviability, female sterility, or morphological anomalies. In the future, these mutations will be useful to further our understanding of the developmental mechanisms of reproductive isolation. Based on our analyses with the Nup160(sim) introgression line, the lethal phase of hybrid inviability was determined to be during the early pupal stage. Our analysis also suggested that homozygous Nup160(sim) in D. melanogaster leads to slow development. Thus, Nup160(sim) is involved in multiple aspects of reproductive isolation between these two species. Show less

We have been analyzing genes for reproductive isolation by replacing Drosophila melanogaster genes with homologs from Drosophila simulans by interspecific backcrossing. Among the introgressions established, we found that a segment of the left arm of chromosome 2, Int(2L)S, carried recessive genes for hybrid sterility and inviability. That nuclear pore protein 160 (Nup160) in the introgression region is involved in hybrid inviability, as suggested by others, was confirmed by the present analysis. Male hybrids carrying an X chromosome of D. melanogaster were not rescued by the Lethal hybrid rescue (Lhr) mutation when the D. simulans Nup160 allele was made homozygous or hemizygous. Furthermore, we uniquely found that Nup160 is also responsible for hybrid sterility. Females were sterile when D. simulans Nup160 was made homozygous or hemizygous in the D. melanogaster genetic background. Genetic analyses indicated that the D. simulans Nup160 introgression into D. melanogaster was sufficient to cause female sterility but that other autosomal genes of D. simulans were also necessary to cause lethality. The involvement of Nup160 in hybrid inviability and female sterility was confirmed by transgene experiment. Show less