👤 Shizuko Nagao

Estrogen is synthesized throughout various tissues in the body, and its production is regulated by the rate-limiting enzyme aromatase (encoded by the Cyp19a1 gene). Notably, aromatase is also expressed in central nervous system cells, allowing for localized estrogen synthesis in regions such as the hypothalamus. Estrogens produced within these neurons are referred to as neuroestrogens. In this study, we investigated the role of neuroestrogens in the regulation of appetite through modulation of hypothalamic pathways in OVX, ArKO, and aromatase-restored mice. Estrogen suppresses appetite by influencing the expression of appetite-regulating peptides, including POMC and NPY, via MC4R. We explored the direct effects of neuroestrogens, independent from ovarian estrogen, on appetite suppression and the underlying molecular mechanisms. We monitored body weight and food intake and evaluated the expression of Cyp19a1, Mc4r, and other appetite-related genes. Our findings indicate that OVX and ArKO mice exhibited increased body weight and food consumption, which correlated with altered expression of Mc4r and Cyp19a1. Conversely, restoration of Cyp19a1 expression in a neuron specific manner significantly decreased food intake and increased Mc4r expression in the hypothalamus. Furthermore, neuroestrogens enhanced leptin responsiveness. Our results imply that neuroestrogens likely contribute to appetite regulation and may be relevant for body weight reduction. Show less

Glucose and insulin positively regulate glycolysis and lipogenesis through the activation of carbohydrate response element-binding protein (ChREBP) and sterol regulatory element-binding protein 1c (SREBP1c), but their respective roles in the regulation of gluconeogenic and ureagenic genes remain unclear. We compared the effects of the insulin antagonist S961 and Chrebp deletion on hepatic glycolytic, lipogenic, gluconeogenic, and ureagenic gene expression in mice. S961 markedly increased the plasma glucose, insulin, and 3-OH-butyrate concentrations and reduced the hepatic triglyceride content, but Chrebp deletion had no additive effect. We subsequently estimated the expression of genes involved in the pathways of glycolysis, gluconeogenesis, and lipogenesis. S961 potently decreased both Chrebp and Srebf1c, but Chrebp deletion weakly decreased Srebf1c mRNA expression. Both the S961 and Chrebp deletion caused decreases in glycolytic (Gck and Pklr) and lipogenic (Fasn, Scd1, Me1, Spot14, Elovl6) gene expression. S961 increased the expression of many gluconeogenic genes (G6pc, Fbp1, Aldob, Slc37a4, Pck), whereas Chrebp deletion reduced the expression of gluconeogenic genes other than Pck1. Finally, we checked the metabolites and gene expression in the ureagenesis pathway. S961 increased ureagenic gene (Arg1, Asl, Ass1, Cps1, Otc) expression, which was consistent with the metabolite data: there were reductions in the concentrations of glutamate and aspartate and increases in those of citrulline, ornithine, urea, and proline. However, Chrebp deletion had no additive effect on ureagenesis. In conclusion, insulin rather than glucose regulate ureagenic gene expression, whereas glucose and insulin regulate gluconegenic gene expression in opposite directions. Show less

The impact of Graves' hyperthyroidism treatment on lipid metabolism remains unclear. This prospective observational study aimed to clarify the changes in lipid profiles and associated metabolic pathways, including cholesterol synthesis, absorption, and low-density lipoprotein (LDL) receptor regulation, following treatment. Seventeen patients newly diagnosed with Graves' hyperthyroidism were enrolled and followed for 6 months after achieving euthyroid status. Serum lipids (total cholesterol, LDL-cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), triglycerides), apolipoproteins, non-cholesterol sterols (markers of cholesterol synthesis and absorption), proprotein convertase subtilisin/kexin type 9 (PCSK9), and lipoprotein lipase (LPL) levels were measured at baseline, at euthyroid status (Eu-0M), and 6 months after euthyroid status (Eu-6M). After treatment, serum total cholesterol, LDL-C, and HDL-C levels increased rapidly compared to baseline, while triglyceride levels showed a delayed but significant increase at Eu-6M. Levels of apolipoprotein (apo) AI, AII, B, and CIII increased significantly after treatment, whereas apo B-48 increased only at Eu-6M, and apo CII and apo E remained unchanged. Markers of cholesterol synthesis (lathosterol) and absorption (sitosterol, campesterol, and cholestanol) increased significantly after treatment, indicating enhanced cholesterol metabolism. Circulating PCSK9 levels increased significantly and remained elevated, while LPL levels did not change significantly. Treatment of Graves' hyperthyroidism rapidly increases cholesterol levels through enhanced cholesterol synthesis and absorption, possibly mediated by increased circulating PCSK9. Show less

This study aimed to establish variants in CBX1, encoding heterochromatin protein 1β (HP1β), as a cause of a novel syndromic neurodevelopmental disorder. Patients with CBX1 variants were identified, and clinician researchers were connected using GeneMatcher and physician referrals. Clinical histories were collected from each patient. To investigate the pathogenicity of identified variants, we performed in vitro cellular assays and neurobehavioral and cytological analyses of neuronal cells obtained from newly generated Cbx1 mutant mouse lines. In 3 unrelated individuals with developmental delay, hypotonia, and autistic features, we identified heterozygous de novo variants in CBX1. The identified variants were in the chromodomain, the functional domain of HP1β, which mediates interactions with chromatin. Cbx1 chromodomain mutant mice displayed increased latency-to-peak response, suggesting the possibility of synaptic delay or myelination deficits. Cytological and chromatin immunoprecipitation experiments confirmed the reduction of mutant HP1β binding to heterochromatin, whereas HP1β interactome analysis demonstrated that the majority of HP1β-interacting proteins remained unchanged between the wild-type and mutant HP1β. These collective findings confirm the role of CBX1 in developmental disabilities through the disruption of HP1β chromatin binding during neurocognitive development. Because HP1β forms homodimers and heterodimers, mutant HP1β likely sequesters wild-type HP1β and other HP1 proteins, exerting dominant-negative effects. Show less

The nuclear pore complex (NPC), a gateway for nucleocytoplasmic trafficking, is composed of ∼30 different proteins called nucleoporins. It remains unknown whether the NPCs within a species are homogeneous or vary depending on the cell type or physiological condition. Here, we present evidence for compositionally distinct NPCs that form within a single cell in a binucleated ciliate. In Show less

Few data exist as to whether dipeptidyl peptidase (DPP)-4 inhibitors affect cardio-renal interaction, which is a strong independent prognostic factor for cardiovascular disease (CVD), in diabetic patients. We evaluated the effects of a DPP-4 inhibitor on atherogenic low-density lipoprotein (LDL) heterogeneity and albuminuria in diabetics as an indicator of the severity of diabetic nephropathy. Type 2 diabetes patients (n = 47) inadequately controlled with diabetes therapy were treated with vildagliptin 50 mg bid for 8 weeks. LDL heterogeneity was evaluated on the basis of the patients' small dense (sd) LDL levels and sd-LDL proportion (sd-LDL/LDL cholesterol [LDL-C]). The level of albuminuria was evaluated on the basis of the urinary albumin-to-creatinine ratio (UACR). After 8 weeks of treatment, there was no significant change in serum LDL-C level, but the serum sd-LDL level had decreased significantly by 8.8 %, and the UACR had also decreased significantly by 44.6 %. Triglyceride (TG)-metabolism-related markers (TG, remnant-like particle cholesterol, apolipoprotein [apo] B, apoC-2, and apoC-3) had decreased significantly. The Δ (absolute change from baseline) sd-LDL values correlated positively with ΔTG-metabolism-related markers, but not with the Δ hemoglobin (Hb) A1c or Δ fasting blood sugar (ΔFBS). Furthermore, multivariate regression analysis revealed that Δsd-LDL proportion, but not ΔHbA1c or ΔFBS, was an independent predictor of ΔUACR (β = 0.292, p = 0.0016). Although this was a single-arm study, treatment of type 2 diabetes with vildagliptin might prevent the progression of CVD complicating diabetes by improving LDL heterogeneity, and it might improve renal function by decreasing albuminuria. A randomized controlled trial is warranted. Show less

Lymphatic lipid transport in the intestine of adult and ageing rats was compared. Adult (8-10 months old) and old (24-26 months old) male Wistar rats were cannulated into the mesenteric lymph under ethrane anesthesia. On the following day, lipid emulsion containing 35.4 mg/h of olive oil was infused intraduodenally for 7 h and lymph collected hourly was assayed for triglyceride and apolipoprotein A-IV (apo A-IV). The results showed there was no difference in lymphatic lipid and apo A-IV transport between adult and old rats. Since apo A-IV synthesis in the enterocytes is linked to the intracellular assembly of lipoprotein, it is likely that in addition to lymphatic transport, production of chylomicrons is not impaired in ageing rats. Show less