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Introduction: Endothelial cells have a crucial function in transporting and exchanging various nutrients. O-GlcNAcylation, mediated by O-GlcNAc transferase (OGT), involves the addition of N-acetylglucosamine to proteins and serves as an intracellular nutrient sensing mechanism. However, the role of O-GlcNAcylation in endothelial cells remains poorly understood. Objective: This study investigated the role of O-GlcNAcylation in endothelial cells. Methods: Endothelial-cell-specific Ogt -knockout mice (Ogt-ECKO) were generated by crossing Ogt-floxed mice (Ogt-flox) with VE-Cadherin Cre ERT2 mice. Ogt-ECKO mice and Ogt-flox control mice were subjected to a normal or high-fat diet, and their body weight, glucose metabolism, and lipid metabolism were examined. Results: Ogt-ECKO mice exhibited reduced body weight compared with Ogt-flox control mice under a high-fat diet. Lipid absorption was significantly impaired in Ogt-ECKO mice. Changes in the intercellular junctions of small intestinal lacteal endothelial cells from a button-like to a zipper-like configuration were observed. Furthermore, Ogt-ECKO mice showed decreased expression of VEGFR3. The administration of a nitric oxide donor restored lipid absorption and reversed the morphological alterations in Ogt-ECKO mice. Conclusions: These findings demonstrate the critical role of O-GlcNAcylation in endothelial cells in lipid absorption in the intestine through the modulation of lacteal junction morphology. These results provide novel insight into the metabolic regulatory mechanisms under physiological conditions and have implications for the development of new therapeutic strategies for obesity.

Objective: To analyze the association between the dietary protein/energy ratio and percentages of dietary animal and plant protein and obesity in Japanese patients with type 2 diabetes. Design: This was a cross-sectional study. Obesity was defined as BMI ≥25 kg/m2. Data were collected for all study participants and stratified according to age and sex. Diet was assessed via a food frequency questionnaire. Setting: 26 clinics participating in the Japan Diabetes Clinical Data Management Study Group (JDDM) from December 2014 to December 2019. Participants: 1567 Japanese out patients with type 2 diabetes (63.1% men; mean age 62.3 ± 11.6 years). Results: In all participants, multivariate analysis with adjustment by major confounders showed a significant inverse association in those in the highest quartile of the protein/energy ratio (mean 17.7%) with obesity (OR = 0.588, 95% CI = 0.435-0.794; p trend = 00.007), but after the addition of vegetable intake it became non-significant. In the age- and sex-stratified analysis, a high protein/energy ratio (mean 15.6%) was inversely associated with obesity in older women only (OR = 0.280, 95% CI = 0.123-0.638), which remained significant after adjustment of individual food groups correlated with protein. No association between percentages of dietary animal or plant protein and obesity was found. Conclusions: In older women only, a higher dietary protein/energy ratio was associated with lower obesity after adjustment by confounders and individual food groups correlated with protein intake. Future longitudinal research that includes data on food groups as well as age- and sex-stratification of participants is recommended to further clarify this relationship.

Objective: The intestine is an important organ for nutrient metabolism via absorption and endocrine systems. Nutrients regulate O-GlcNAcylation, a post-translational modification of various proteins by O-GlcNAc transferase (OGT). We have previously shown that general OGT knockout induced severe weight loss and hypoglycaemia in mice, but little is known about how O-GlcNAcylation in the intestine modulates nutrient metabolism, especially glucose metabolism, through absorption. We aimed to reveal the roles of O-GlcNAcylation in glucose absorption by the small intestine and elucidate the mechanism by which O-GlcNAcylation regulates sodium-glucose cotransporter 1 (SGLT1) expression. Methods: First, we fasted normal mice and examined the changes in glucose transporters and O-GlcNAcylation in the intestine. Then, we generated two lines of small intestine-specific OGT-deficient mice (congenital: Ogt-VKO, tamoxifen-inducible: Ogt-iVKO) and observed the changes in body weight and in glucose and lipid metabolism. Finally, we investigated Sglt1 gene regulation by O-GlcNAcylation using enteroendocrine STC-1 cells. Results: Fasting decreased O-GlcNAcylation in the intestinal epithelium of normal mice. The Ogt-VKO mice showed significantly lower non-fasted blood glucose levels and were underweight compared with litter matched controls. Glycaemic excursion in the Ogt-VKO mice was significantly lower during the oral glucose tolerance test but comparable during the intraperitoneal glucose tolerance test. Furthermore, the Ogt-VKO mice exhibited lower Sglt1 expression in the small intestine compared with the control mice. We obtained similar results using the Ogt-iVKO mice only after tamoxifen administration. The oral d-xylose administration test revealed that the intestinal sugar absorption was diminished in the Ogt-iVKO mice and that GLP-1 secretion did not sufficiently increase after glucose gavage in the Ogt-iVKO mice. When using STC-1 cells, O-GlcNAcylation increased Sglt1 mRNA via a PKA/CREB-dependent pathway. Conclusion: Collectively, loss of O-GlcNAcylation in the intestine reduced glucose absorption via suppression of SGLT1 expression; this may lead to new treatments for malabsorption, obesity and diabetes.

Homing peptides to the spinal cord were identified and isolated using phage display technology. In vivo biopanning was performed by intravenous systemic injection of a phage library to screen specific peptides targeting the spinal cord of mice. Analyses of the sequences of targeted phages yielded two candidate peptides targeting the spinal cord: SP1 (C-LHQSPHI-C) and SP2 (C-PTNNPRS-C). These peptides were synthesized and intravenously injected into mice to evaluate their tissue specificity and potential as gene delivery carriers. The complexes between SP1 or SP2 peptides and the plasmid vector expressing the reporter gene could induce gene transduction in the spinal cord through systemic injection without gene expression in the brain, liver, and kidney. In addition, intravenous injection of the complex between SP1 and the vectors induced interleukin-4 expression in the spinal cord, resulting in effective suppression of lipopolysaccharide-induced hyperalgesia. Therefore, intravenously administered spinal cord homing peptides complexed with a plasmid vector provided tissue-specific treatment featuring gene delivery to the CNS through systemic circulation. This novel method of gene delivery is feasible and has great potential for clinical application. Keywords: homing peptides, gene delivery, spinal cord, systemic circulation, targeting

Astrocyte- and microglia-targeting peptides were identified and isolated using phage display technology. A series of procedures, including three cycles of both in vivo and in vitro biopanning, was performed separately in astrocytes and in M1 or M2 microglia, yielding 50–58 phage plaques in each cell type. Analyses of the sequences of this collection identified one candidate homing peptide targeting astrocytes (AS1[C-LNSSQPS-C]) and two candidate homing peptides targeting microglia (MG1[C-HHSSSAR-C] and MG2[C-NTGSPYE-C]). To determine peptide specificity for the target cell in vitro, each peptide was synthesized and introduced into the primary cultures of astrocytes or microglia. Those peptides could bind to the target cells and be selectively taken up by the corresponding cell, namely, astrocytes, M1 microglia, or M2 microglia. To confirm cell-specific gene delivery to M1 microglia, the complexes between peptide MG1 and siRNA-interferon regulatory factor 5 were prepared and intrathecally injected into a mouse model of neuropathic pain. The complexes successfully suppressed hyperalgesia with high efficiency in this neuropathic pain model. Here, we describe a novel gene therapy for the treatment neuropathic pain, which has a high potential to be of clinical relevance. This strategy will ensure the targeted delivery of therapeutic genes while minimizing side effects to non-target tissues or cells.

Studies from Western countries suggest that smokers tend to display greater abdominal obesity than non-smokers, despite showing lower weight. Whether this holds true in a leaner population requires clarification. Using indices of abdominal obesity including visceral adipose tissue, we examined whether lifetime cigarette smoking is associated with unfavorable fat distribution among Japanese men.From 2006 to 2008, we conducted a cross-sectional investigation of a community-based sample of Japanese men at 40–64 years old, free of cardiovascular diseases and cancer. Areas of abdominal visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) were calculated using computed tomography. We divided participants into four groups: never-smokers; and tertiles of pack-years of smoking among ever-smokers. Using multivariable linear regression, we calculated adjusted means of obesity indices (VAT, SAT, VAT-SAT ratio [VSR], and waist-hip ratio [WHR]) for each group, and mean differences between consecutive groups.We analyzed 513 men (median age, 58.2 years; current smokers, 40.1%). Two-thirds showed body mass index (BMI)

Glucose-stimulated insulin secretion (GSIS) by pancreatic β cells is biphasic. However, the physiological significance of biphasic GSIS and its relationship to diabetes are not yet fully understood. This study demonstrated that impaired first-phase GSIS follows fasting, leading to increased blood glucose levels and brain glucose distribution in humans. Animal experiments to determine a possible network between the brain and β cells revealed that fasting-dependent hyperactivation of AMP-activated protein kinase in the hypothalamus inhibited first-phase GSIS by stimulating the α-adrenergic pancreatic nerve. Furthermore, abnormal excitability of this brain-β cell neural axis was involved in diabetes-related impairment of first-phase GSIS in diabetic animals. Finally, pancreatic denervation improved first-phase GSIS and glucose tolerance and ameliorated severe diabetes by preventing β cell loss in diabetic animals. These results indicate that impaired first-phase GSIS is critical for brain distribution of dietary glucose after fasting. Furthermore, β cells in individuals with diabetes mistakenly sense that they are under conditions that mimic prolonged fasting. The present study provides additional insight into both β cell physiology and the pathogenesis of β cell dysfunction in type 2 diabetes.

Renal sinus fat is partially characteristic of peri-vascular adipose tissue, however, RSF volume (RSFV) is associated with visceral adipose tissue (VATV). Therefore, the ratio of RSFV to VATV (RSFV/VATV ratio) can distinguish the importance of RSF as an extension of VAT versus its perivascular effects. We assessed the association of RSFV/VATV ratio with coronary artery calcification score (CACS) in 189 patients with suspected coronary artery disease. RSFV of the right kidney and VATV were quantified by using image data of unenhanced abdominal CT. CACS were measured on unenhanced ECG-gated CT images. This article contains data on explanatory scheme of how to measure RSFV on unenhanced abdominal CT, CT indication and exclusion criteria of study population, sex-adjusted association between RSFV with risk factors of coronary vascular diseases and metabolic indices, multivariate linear regression analysis with CACS as the dependent variable in the total study population. The data are supplemental to our original research article describing detailed association between RSFV/VATV ratio and CACS including sub-groups analyses classified by the age of 70 “Renal sinus fat volume on computed tomography in middle-aged patients at risk for cardiovascular disease and its association with coronary artery calcification” Murakami et al. [1]. Keywords: Renal sinus fat, Coronary calcification, Atherosclerosis, Visceral adipose tissue, Computed tomography