👤 T Fujisawa

Dipeptidyl peptidase-4 (DPP-4) inhibitors enhance circulating levels of biologically intact incretins, yet the relative contribution of glucose-dependent insulinotropic polypeptide (GIP) to their metabolic effects remains incompletely understood. While glucagon-like peptide-1 (GLP-1) has long been emphasized in incretin biology, emerging evidence suggests important physiological roles for GIP. This study investigated whether endogenous GIP signaling is indispensable for the glucose-lowering and anti-obesity effects of DPP-4 inhibition. Male Gipr DPP-4 inhibition significantly improved glucose tolerance and attenuated body-weight gain in HFD-fed Gipr Endogenous GIP signaling is essential for both glucose-lowering and anti-obesity actions of DPP-4 inhibitors in mice. GLP-1 elevation alone is insufficient to compensate for GIP receptor deficiency. These findings refined the mechanistic understanding of DPP-4 inhibitors, highlighted the physiological importance of GIP, and suggested context-dependent metabolic actions of incretins. Show less

Advanced esophageal squamous cell carcinoma (ESCC) has a poor prognosis, and current treatments provide limited survival benefits. This study aimed to identify prognostic biomarkers and therapeutic targets by genomic profiling of advanced ESCC using circulating tumor DNA (ctDNA). The SCRUM-MONSTAR GOZILA study is a nationwide, plasma-based molecular profiling project using Guardant360, involving 31 core cancer institutions in Japan. We evaluated the genomic landscape of advanced ESCC and investigated associations between specific alterations and overall survival (OS). The correlation between blood tumor mutation burden (bTMB) and clinical outcomes in patients with PD-1 inhibitors was also assessed using multiple cutoff values (2, 4, 6, 8, and 10 mutations/Mb). Among 313 patients, alterations predominantly consisted of single nucleotide variants (SNVs, 68.9%) and copy number alterations (20.7%). ctDNA analysis identified key genomic alterations linked to poor outcomes in advanced ESCC, revealing potential prognostic biomarkers and therapeutic targets. In contrast, bTMB did not show predictive value for the efficacy of PD-1 inhibitors in this study. Show less

Congenital hypogonadotropic hypogonadism (CHH) is a genetically heterogeneous disorder, with multiple causative and candidate genes identified to date. To clarify underlying genetic factors involved in the development of CHH. We examined 88 Japanese patients with CHH using gene panel analysis (GPA) for 14 representative causative genes and whole-exome sequencing (WES) which was initially focused on 41 causative/candidate genes and subsequently expanded to other genes. We extracted rare variants (frequency of <0.01) and performed pathogenic assessment using refined American College of Medical Genetics and Genomics/Association for Molecular Pathology criteria and registered information in ClinVar. Twenty-seven pathogenic/likely pathogenic variants were identified in 30 patients through GPA performed for all 88 patients and in 4 patients through WES performed for 58 patients in whom no obvious disease-causing variants were revealed by GPA. They resided in previously known ANOS1 (6 variants in 7 patients), CHD7 (3 variants in 3 patients), FGFR1 (14 variants in 15 patients), PROKR2 (2 variants in 8 patients), and SOX10 (1 variant in 1 patient), and a hitherto unrecognized ZNF462 (1 variant in 1 patient). One patient had 2 variants. Additionally, potentially CHH-related variants were detected in 12 genes including SEMA4D and CDH2 postulated on the CHH-related molecular network. Furthermore, in the 41 CHH-related genes, the frequency of oligogenicity was significantly higher and the number of rare variants per individual was significantly larger in 54 CHH patients with no discernible pathogenic/likely pathogenic variants than in 100 control individuals. The results support the notion that CHH occurs not only as a monogenic disorder but also as an oligogenic/multifactorial disorder, and suggest the involvement of ZNF462, SEMA4D, and CDH2 variants in the development of CHH. Show less

Cyclic adenosine monophosphate-response element-binding protein-1-regulated transcription coactivator-1 (CRTC1), a cytoplasmic coactivator that translocates to the nucleus in response to cAMP, is associated with obesity. We previously reported that Show less

Although 17β-hydroxysteroid dehydrogenase type 3 (HSD17B3) deficiency is diagnosed when a testosterone/androstenedione (T/A-dione) ratio after human chorionic gonadotropin (hCG) stimulation is below 0.8, this cut-off value is primarily based on hormonal data measured by conventional immunoassay (IA) in patients with feminized or ambiguous genitalia. We examined two 46,XY Japanese patients with undermasculinized genitalia including hypospadias (patient 1 and patient 2). Endocrine studies by IA showed well increased serum T value after hCG stimulation (2.91 ng/mL) and a high T/A-dione ratio (4.04) in patient 1 at 2 weeks of age and sufficiently elevated basal serum T value (2.60 ng/mL) in patient 2 at 1.5 months of age. Despite such partial androgen insensitivity syndrome-like findings, whole exome sequencing identified biallelic ″pathogenic″ or ″likely pathogenic″ variants in HSD17B3 (c .188 C>T:p.(Ala63Val) and c .194 C>T:p.(Ser65Leu) in patient 1, and c.139 A>G:p.(Met47Val) and c.672 + 1 G>A in patient 2) (NM₀₀₀₁₉₇.2), and functional analysis revealed reduced HSD17B3 activities of the missense variants (∼ 43% for p.Met47Val, ∼ 14% for p.Ala63Val, and ∼ 0% for p.Ser65Leu). Thus, we investigated hCG-stimulated serum steroid metabolite profiles by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in patient 1 at 7 months of age and in patient 2 at 11 months of age as well as in five control males with idiopathic micropenis aged 1 - 8 years, and found markedly high T/A-dione ratios (12.3 in patient 1 and 5.4 in patient 2) which were, however, obviously lower than those in the control boys (25.3 - 56.1) and sufficiently increased T values comparable to those of control males. The elevated T/A-dione ratios are considered be due to the residual HSD17B3 function and the measurement by LC-MS/MS. Thus, it is recommended to establish the cut-off value for the T/A-dione ratio according to the phenotypic sex reflecting the residual function and the measurement method. Show less

Metformin, an AMP-activated protein kinase activator used to treat diabetes mellitus, has recently attracted attention as a promising anti-fibrotic agent. However, its anti-fibrotic effects on pleural fibroelastosis remain unknown. We induced mouse pleural fibroelastosis by intra-pleural coadministration of bleomycin and carbon and evaluated its validity as a preclinical model for human pleural fibrosis. We assessed the expression of the myofibroblast surface marker CD90 in the fibrotic pleura and the effects of metformin Show less

Age-related macular degeneration (AMD) is a major cause of blindness in the elderly. Previous sequencing studies of AMD susceptibility genes have revealed the association of rare coding variants in CFH, CFI, C3 and C9 in European population; however, the impact of rare or low-frequency coding variants on AMD susceptibility in other populations is largely unknown. To identify the role of low-frequency coding variants on exudative AMD susceptibility in a Japanese population, we analysed the association of coding variants of 34 AMD candidate genes in the two-stage design by a multiplex PCR-based target sequencing method. We used a total of 2,886 (1st: 827, 2nd: 2,059) exudative AMD cases including typical AMD, polypoidal choroidal vasculopathy, and retinal angiomatous proliferation and 9,337 (1st: 3,247 2nd: 6,090) controls. Gene-based analysis found a significant association of low-frequency variants (minor allele frequency (MAF) < 0.05) in CETP, C2 and CFB. The association of CETP remained after conditioned with all known genome-wide association study (GWAS) associated variants. In addition, when we included only disruptive variants, enrichment of rare variants (MAF < 0.01) was also observed after conditioned with all GWAS associated variants (P = 1.03 × 10−6, odds ratio (OR) = 2.48). Haplotype and conditional analysis of the C2-CFB-SKIV2L locus showed a low-frequency variant (R74H) in CFB would be individually associated with AMD susceptibility independent of the GWAS associated SNP. These findings highlight the importance of target sequencing to reveal the impact of rare or low-frequency coding variants on disease susceptibility in different ethnic populations. Show less

In populations of East Asian descent, we performed a replication study of loci previously identified in populations of European descent as being associated with obesity measures such as BMI and type 2 diabetes. We genotyped 14 single nucleotide polymorphisms (SNPs) from 13 candidate loci that had previously been identified by genome-wide association meta-analyses for obesity measures in Europeans. Genotyping was done in 18,264 participants from two general Japanese populations. For SNPs showing an obesity association in Japanese individuals, we further examined diabetes associations in up to 6,781 cases and 7,307 controls from a subset of the original, as well as from additional populations. Significant obesity associations (p < 0.1 two-tailed, concordant direction with previous reports) were replicated for 11 SNPs from the following ten loci in Japanese participants: SEC16B, TMEM18, GNPDA2, BDNF, MTCH2, BCDIN3D-FAIM2, SH2B1-ATP2A1, FTO, MC4R and KCTD15. The strongest effect was observed at TMEM18 rs4854344 (p = 7.1 × 10(-7) for BMI). Among the 11 SNPs showing significant obesity association, six were also associated with diabetes (OR 1.05-1.17; p = 0.04-2.4 × 10(-7)) after adjustment for BMI in the Japanese. When meta-analysed with data from the previous reports, the BMI-adjusted diabetes association was found to be highly significant for the FTO locus in East Asians (OR 1.13; 95% CI 1.09-1.18; p = 7.8 × 10(-10)) with substantial inter-ethnic heterogeneity (p = 0.003). We confirmed that ten candidate loci are associated with obesity measures in the general Japanese populations. Six (of ten) loci exert diabetogenic effects in the Japanese, although relatively modest in size, and independently of increased adiposity. Show less