👤 Shiko Okabe

Chronic low-grade inflammation underlies many microvascular complications of diabetes, including diabetic kidney disease (DKD). Lipoxins (LXs), an endogenously produced family of lipid mediators, resolve inflammation and protect against renal scarring as occurs in DKD. This study examined the mechanism by which LXs protect against DKD, focusing on the regulation of VCAM-1 and the recruitment of macrophages to the diabetic glomerulus. LXA4 and two fourth-generation mimetics were assessed in diabetic ApoE knockout mice, followed by in vitro studies in the main renal cell populations, including podocytes, proximal tubular, mesangial, and glomerular endothelial cells. LXs attenuated albuminuria, mesangial expansion, and collagen and fibronectin deposition as both a preventive and delayed intervention in experimental DKD. LXs also consistently attenuated the TNF-α-induced expression of VCAM-1 in all the human and mouse renal cell populations examined. Further analysis identified that the renoprotection was in part mediated by an epigenetic modification of the VCAM-1 gene through H3K4 monomethylation, which did not appear to be dependent on NF-κB activation in human glomerular endothelial cells. LXs protect against DKD by modulating glomerular endothelial cell inflammation and via a novel LX-mediated epigenetic mechanism regulating the VCAM-1 promoter in these cells. Lipoxins (LXs) protect against diabetic kidney disease (DKD) by resolving chronic low-grade inflammation, but the exact mechanism by which this occurs is not known. We investigated the effect of LXs on inflammatory markers and the recruitment of macrophages to the diabetic glomerulus by using LXs as both a preventive and delayed interventional treatment in streptozotocin-induced diabetic ApoE knockout mice. Protection against DKD was associated with reduced glomerular macrophage accumulation. LXs also attenuated the expression of VCAM1 in glomerular endothelial cells. LXs protect against DKD in part by a mechanism that reduces VCAM1 gene expression via H3K4 monomethylation on the VCAM1 gene. Show less

Endothelial to mesenchymal transition (EndMT), the transformation of endothelial cells into a mesenchymal-like state, is regulated by various factors, including transcription factors such as activator protein 1 (AP-1). While recent studies have confirmed the role of EndMT in atherosclerosis, the involvement of AP-1 in EndMT, particularly in the context of human diabetes, remains unclear. This study aimed to elucidate the role of the AP-1 transcription factor complex in EndMT associated with atherosclerosis in diabetes, utilising both an in vivo preclinical model and an ex vivo model using patient-derived serum for translational relevance. Additionally, it sought to profile gene expression changes following AP-1 inhibition in an EndMT model under high glucose conditions. Serum from patients with and without type 2 diabetes mellitus (T2DM) was used to assess EndMT in primary human aortic endothelial cells (HAECs) in the presence and absence of the AP-1 inhibitor T-5224. EndMT was evaluated through immunofluorescent staining of these cells and of aortic sections from a murine model of diabetes-associated atherosclerosis in a preclinical early intervention study. Furthermore, HAECs were used to explore the effects of AP-1 inhibition on the transcriptional signature of EndMT. Patient-derived serum induced EndMT in HAECs, which T-5224 effectively prevented, as confirmed by immunofluorescent staining. Immunofluorescent analysis of the aortic sinus also revealed that T-5224 treatment inhibited EndMT, leading to reduced atherosclerosis in Apoe This study identifies AP-1 inhibition with T-5224 as a potential therapeutic approach for EndMT resulting in reduced atherosclerosis in diabetes. The use of human serum underscores the translational relevance of these findings. Show less

Age-related macular degeneration (AMD) is the most common cause of vision loss in elderly individuals throughout the developed world. Inhibitors of vascular endothelial growth factor have been successfully used to treat choroidal neovascularization in late-stage AMD. The pathogenesis of early-stage AMD, however, remains largely unknown, impairing efforts to develop effective therapies that prevent progression to late-stage AMD. To address this, we performed comparative transcriptomics of macular and extramacular retinal pigmented epithelium-choroid (RPE-choroid) tissue from early-stage AMD patients. We found that expression of fatty acid desaturase 1 ( Show less

We have previously shown that expression of SIAH1 is frequently down-regulated in HCCs and associated with their advanced stages. It has been shown that SIAH1 functions in the phosphorylation-independent degradation of beta-catenin and induces apoptosis and growth arrest. To examine if the effects of SIAH1 overexpression depend on the altered beta-catenin signaling pathway, we transferred the SIAH1 gene into three hepatoma cell lines with different genetic backgrounds: HepG2 (mutant beta-catenin), SNU475 (mutant AXIN1), and Huh7 cells (wild type beta-catenin and AXIN1). SIAH1 significantly decreased aberrant beta-catenin signal in HepG2 and SNU475 cells and induced growth arrest and apoptosis. However, SIAH1 also induced apoptosis in Huh7 cells, which retained a normal membranous distribution pattern of beta-catenin. Immunoblotting study demonstrated that SIAH1 also reduces the amount of PEG10 protein, which is known to be frequently overexpressed in HCC and to promote cell proliferation. These data suggest that PEG10 is another target protein of SIAH1 to induce apoptosis in hepatoma cells. Our results should lead to a better understanding of the relationship between deregulation of beta-catenin signals and hepatocarcinogenesis. Further investigations into the mechanisms by which SIAH1 promotes apoptosis and suppresses cell growth should also allow for the discovery of new therapeutic strategies. Show less

We previously demonstrated that metastasis-related tumor suppressor gene(s) may exist on chromosome 8p21-22 on allelotype analysis of early colorectal carcinomas (CRC) with lymph node metastasis. Here, we searched for target gene(s) in this chromosomal region in the UniGene database. The EXTL3 (also called EXTR1) gene was selected as a candidate because of its homology to EXT1 and EXT2, putative tumor suppressor genes. We screened 12 CRC cell lines for mutations by means of polymerase chain reaction (PCR)-single strand conformation polymorphism. Three cell lines showed EXTL3 mutations, all of which were located within exon 3 and caused amino acid substitutions. Reverse transcription-PCR analysis showed that the EXTL3 expression was lacking in 1 of the 12 colorectal cancer cell lines. Although there is still no definitive evidence that EXTL3 is a tumor suppressor gene for CRC, these data suggest that inactivation of the EXTL3 gene may at least offer a selective growth advantage for some CRC cell lines. Show less