Research Overview of the Lab. of Molecula Biology, Tohoku University Graduate School of Agricultural Science(Recent Topics of the Agricultunal Biological Science in Tohoku University)

In our laboratory, mainly three different projects described below are now carried out. 1) "Generation and application of the cell membrane permeabilized protein", 2) "Studies on epigenetic regulation of eukaryotic genes through analyses of actin-related proteins" and 3) "Generation of the oxytocin receptor KO (OXTR-/-) mice, and molecular physiological and behavioral analysis of the oxytocin receptor KO (OXTR-/-) mice." In the first project, we generated recombinant Cre protein fused to TAT PTD (protein transduction domain), and the application of this protein into several primary cells prepared from mouse, showed significant recombinase activity. In the second project, we studied epigenetic regulation of eukaryotic genes through analyses of actin-related proteins. In the third project, we obtained several new findings in reproduction, sociosexual behaviors and in physiology of energy/temperature homeostasis of mice as the functions of oxytocin/oxytocin receptor system in vivo, using the oxytocin and its receptor genes deficient (OXT-/- and OXTR-/-) mice. Here we introduce a little about those three projects, respectively

Systemic co-administration of low-dose oxytocin and glucagon-like peptide 1 additively decreases food intake and body weight

Introduction: GLP-1 receptor agonists are the number one drug prescribed for the treatment of obesity and type 2 diabetes. These drugs are not, however, without side effects, and in an effort to maximize therapeutic effect while minimizing adverse effects, gut hormone co-agonists received considerable attention as new drug targets in the fight against obesity. Numerous previous reports identified the neuropeptide oxytocin (OXT) as a promising anti-obesity drug. The aims of this study were to evaluate OXT as a possible co-agonist for GLP-1 and examine the effects of its co-administration on food intake (FI) and body weight (BW) in mice. Methods: FI and c-Fos levels were measured in the feeding centers of the brain in response to an intraperitoneal injection of saline, OXT, GLP-1, or OXT/GLP-1. The action potential frequency and cytosolic Ca2+ ([Ca2+]i) in response to OXT, GLP-1, or OXT/GLP-1 were measured in ex vivo paraventricular nucleus (PVN) neuronal cultures. Finally, FI and BW changes were compared in diet-induced obese mice treated with saline, OXT, GLP-1, or OXT/GLP-1 for 13 days. Results: Single injection of OXT/GLP-1 additively decreased FI and increased c-Fos expression specifically in the PVN and supraoptic nucleus. Seventy percent of GLP-1 receptor-positive neurons in the PVN also expressed OXT receptors, and OXT/GLP-1 co-administration dramatically increased firing and [Ca2+]i in the PVN OXT neurons. The chronic OXT/GLP-1 co-administration decreased BW without changing FI. Conclusion: Chronic OXT/GLP-1 co-administration decreases BW, possibly via the activation of PVN OXT neurons. OXT might be a promising candidate as an incretin co-agonist in obesity treatment

Oxytocin Enhances Demethylation Through TET Enzyme Expression in Neurons of Aged Mice: Oxytocin as a Potential Antiaging Peptide

While it is well‐documented that plasma oxytocin (OXT) levels decline with age, the underlying mechanisms remain elusive. This study aimed to elucidate the physiological mechanisms contributing to this age‐related decrease in plasma OXT and the possible use of OXT supplementation on improving age‐related decline of neural function. Comparing young (9 weeks) and aged (> 45 weeks) mice, aged mice showed reduced plasma OXT levels, an increase in the inflammation marker hs‐CRP, and decreased OXT‐positive neurons in the hypothalamus. Aged mice showed signs of epigenetic changes in the hypothalamus as indicated by decreased ten‐eleven translocation (TET) family mRNA expression, decreased 5‐hydroxymethylcytosine (5hmC) positive neurons, and downregulated mitochondrial respiratory complex IV (COX IV) expression. Nasal application of OXT (10 μg/day) for 10 days to aged mice resulted in normalized plasma OXT and inflammation levels and a recovery of OXT‐positive neurons, TET2 mRNA levels, 5hmC positive neurons, and COX IV expression. Directly confirming a role for OXTR signaling, TET2, COX IV, and 5hmC in the hypothalamus and hippocampus were also found to be decreased in oxytocin receptor (OXTR) null mice, compared with age‐matched WT mice. Furthermore, we show that methylation as a result of aging decreases OXT production in hypothalamic neurons, thereby reducing circulating plasma OXT levels, which can be reversed by nasal OXT treatment. The data presented here suggest that aging, DNA methylation, mitochondrial dysfunction, inflammation, and senescence are interconnected in a vicious cycle, which can be successfully interrupted by OXT treatment

Traditional Japanese medicine Kamikihito ameliorates sucrose preference, chronic inflammation and obesity induced by a high fat diet in middle-aged mice

The high prevalence of obesity has become a pressing global public health problem and there exists a strong association between increased BMI and mortality at a BMI of 25 kg/m2 or higher. The prevalence of obesity is higher among middle-aged adults than among younger groups and the combination of aging and obesity exacerbate systemic inflammation. Increased inflammatory cytokines such as interleukin 6 and tumor necrosis factor alpha (TNFα) are hallmarks of obesity, and promote the secretion of hepatic C-reactive protein (CRP) which further induces systematic inflammation. The neuropeptide oxytocin has been shown to have anti-obesity and anti-inflammation effects, and also suppress sweet-tasting carbohydrate consumption in mammals. Previously, we have shown that the Japanese herbal medicine Kamikihito (KKT), which is used to treat neuropsychological stress disorders in Japan, functions as an oxytocin receptors agonist. In the present study, we further investigated the effect of KKT on body weight (BW), food intake, inflammation, and sweet preferences in middle-aged obese mice. KKT oral administration for 12 days decreased the expression of pro-inflammatory cytokines in the liver, and the plasma CRP and TNFα levels in obese mice. The effect of KKT administration was found to be different between male and female mice. In the absence of sucrose, KKT administration decreased food intake only in male mice. However, while having access to a 30% sucrose solution, both BW and food intake was decreased by KKT administration in male and female mice; but sucrose intake was decreased in female mice alone. In addition, KKT administration decreased sucrose intake in oxytocin deficient lean mice, but not in the WT lean mice. The present study demonstrates that KKT ameliorates chronic inflammation, which is strongly associated with aging and obesity, and decreases food intake in male mice as well as sucrose intake in female mice; in an oxytocin receptor dependent manner

Targeting oxytocin receptor (Oxtr)-expressing neurons in the lateral septum to restore social novelty in autism spectrum disorder mouse models

© 2020, The Author(s). Autism spectrum disorder (ASD) is a continuum of neurodevelopmental disorders and needs new therapeutic approaches. Recently, oxytocin (OXT) showed potential as the first anti-ASD drug. Many reports have described the efficacy of intranasal OXT therapy to improve the core symptoms of patients with ASD; however, the underlying neurobiological mechanism remains unknown. The OXT/oxytocin receptor (OXTR) system, through the lateral septum (LS), contributes to social behavior, which is disrupted in ASD. Therefore, we selectively express hM3Dq in OXTR-expressing (OXTR+) neurons in the LS to investigate this effect in ASD mouse models developed by environmental and genetic cues. In mice that received valproic acid (environmental cue), we demonstrated successful recovery of impaired social memory with three-chamber test after OXTR+ neuron activation in the LS. Application of a similar strategy to Nl3R451C knock-in mice (genetic cue) also caused successful recovery of impaired social memory in single field test. OXTR+ neurons in the LS, which are activated by social stimuli, are projected to the CA1 region of the hippocampus. This study identified a candidate mechanism for improving core symptoms of ASD by artificial activation of DREADDs, as a simulation of OXT administration to activate OXTR+ neurons in the LS

Kir6.2 channel activity is regulated by interaction of transmembrane domains 1 and 2 through I167 in the bundle‐crossing gate

ATP‐sensitive potassium (KATP) channel in pancreatic β‐cells is composed of four pore‐forming inward rectifier potassium (Kir) 6.2 subunits and four regulatory sulfonylurea receptor (SUR) 1 subunits and regulate insulin secretion. Kir6.2 consists of a N‐terminal region, an outer transmembrane helix (TM1), an intramembrane region that functions as a potassium selectivity filter, an inner transmembrane helix (TM2) that forms a bundle‐crossing gate, and a C‐terminal cytoplasmic domain. Mutations in the Kir6.2 subunit can cause neonatal diabetes with severe neurological features (DEND syndrome). The DEND syndrome‐inducing I167L mutation of Kir6.2 increases the open probability (Po) of the KATP channel. To investigate the gating mechanism impacted by this mutation in Kir6.2 alone, we used C‐terminus‐truncated Kir6.2 channels to ascertain the impact of I167 mutations on Po in Kir6.2 channels in the absence of SUR1. We found that I167L and I167F mutations showed an increased Po while the Po of other mutations (I167A, I167V) were unchanged when compared to wild‐type channels. By mutating residues in TM1 (W68, L72, F75) that may interact with I167, we found that a double mutation of I167L and F75A normalized the Po. These results would suggest that I167 may play an important role in stabilizing the open state of Kir6.2 channels

Three-color Flow Cytometry for the Diagnosis of Mature B-cell Malignant Lymphoma based on the Kappa/Lambda Ratio of CD45-gated CD19-positive Cells

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