Atypical protein kinase C (PKCzeta/lambda) is a convergent downstream target of the insulin-stimulated phosphatidylinositol 3-kinase and TC10 signaling pathways.

Insulin stimulation of adipocytes resulted in the recruitment of atypical PKC (PKCzeta/lambda) to plasma membrane lipid raft microdomains. This redistribution of PKCzeta/lambda was prevented by Clostridium difficile toxin B and by cholesterol depletion, but was unaffected by inhibition of phosphatidylinositol (PI) 3-kinase activity. Expression of the constitutively active GTP-bound form of TC10 (TC10Q/75L), but not the inactive GDP-bound mutant (TC10/T31N), targeted PKCzeta/lambda to the plasma membrane through an indirect association with the Par6-Par3 protein complex. In parallel, insulin stimulation as well as TC10/Q75L resulted in the activation loop phosphorylation of PKCzeta. Although PI 3-kinase activation also resulted in PKCzeta/lambda phosphorylation, it was not recruited to the plasma membrane. Furthermore, insulin-induced GSK-3beta phosphorylation was mediated by both PI 3-kinase-PKB and the TC10-Par6-atypical PKC signaling pathways. Together, these data demonstrate that PKCzeta/lambda can serve as a convergent downstream target for both the PI 3-kinase and TC10 signaling pathways, but only the TC10 pathway induces a spatially restricted targeting to the plasma membrane

Uncertainty in action-value estimation affects both action choice and learning rate of the choice behaviors of rats

The estimation of reward outcomes for action candidates is essential for decision making. In this study, we examined whether and how the uncertainty in reward outcome estimation affects the action choice and learning rate. We designed a choice task in which rats selected either the left-poking or right-poking hole and received a reward of a food pellet stochastically. The reward probabilities of the left and right holes were chosen from six settings (high, 100% vs. 66%; mid, 66% vs. 33%; low, 33% vs. 0% for the left vs. right holes, and the opposites) in every 20–549 trials. We used Bayesian Q-learning models to estimate the time course of the probability distribution of action values and tested if they better explain the behaviors of rats than standard Q-learning models that estimate only the mean of action values. Model comparison by cross-validation revealed that a Bayesian Q-learning model with an asymmetric update for reward and non-reward outcomes fit the choice time course of the rats best. In the action-choice equation of the Bayesian Q-learning model, the estimated coefficient for the variance of action value was positive, meaning that rats were uncertainty seeking. Further analysis of the Bayesian Q-learning model suggested that the uncertainty facilitated the effective learning rate. These results suggest that the rats consider uncertainty in action-value estimation and that they have an uncertainty-seeking action policy and uncertainty-dependent modulation of the effective learning rate

Atypical Protein Kinase C (PKCλ/ζ) is a convergent downstream target of the insulin stimulated phosphatidylinositol 3-kinase and TC10 signalling pathways

Insulin stimulation of adipocytes resulted in the recruitment of atypical PKC (PKCζ/λ) to plasma membrane lipid raft microdomains. This redistribution of PKCζ/λ was prevented by Clostridium difficile toxin B and by cholesterol depletion, but was unaffected by inhibition of phosphatidylinositol (PI) 3-kinase activity. Expression of the constitutively active GTP-bound form of TC10 (TC10Q/75L), but not the inactive GDP-bound mutant (TC10/T31N), targeted PKCζ/λ to the plasma membrane through an indirect association with the Par6-Par3 protein complex. In parallel, insulin stimulation as well as TC10/Q75L resulted in the activation loop phosphorylation of PKCζ. Although PI 3-kinase activation also resulted in PKCζ/λ phosphorylation, it was not recruited to the plasma membrane. Furthermore, insulin-induced GSK-3β phosphorylation was mediated by both PI 3-kinase-PKB and the TC10-Par6-atypical PKC signaling pathways. Together, these data demonstrate that PKCζ/λ can serve as a convergent downstream target for both the PI 3-kinase and TC10 signaling pathways, but only the TC10 pathway induces a spatially restricted targeting to the plasma membrane

Continuous release of O2−/ONOO− in plasma-exposed HEPES-buffered saline promotes TRP channel-mediated uptake of a large cation

Although the externally controllable extracellular supply of the short-lived reactive oxygen and nitrogen species, such as O2•−, •NO, and ONOO−, could potentially manipulate cellular functions, their simple administration to cells is likely to be ineffective due to their rapid deactivation. In this study, we found a method of a continuous supply of O2•−/ONOO− over a few minutes, which is triggered by irradiation of a nonequilibrium atmospheric pressure plasma to commonly used organic buffers (e.g., 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid, HEPES). In addition, a continuous low-dose O2•−/ONOO− supply was shown to induce a physiologically relevant Ca2+ response and subsequently the uptake of a large cation mediated by transient receptor potential channel family member(s). Our results provide a novel approach to the continuous O2•−/ONOO− supply, requiring controllable and mass-volume treatments

Lipid raft microdomain compartalization of TC10 is required for insulin signalling and Glut4 Translocation

Recent studies indicate that insulin stimulation of glucose transporter (GLUT)4 translocation requires at least two distinct insulin receptor-mediated signals: one leading to the activation of phosphatidylinositol 3 (PI-3) kinase and the other to the activation of the small GTP binding protein TC10. We now demonstrate that TC10 is processed through the secretory membrane trafficking system and localizes to caveolin-enriched lipid raft microdomains. Although insulin activated the wild-type TC10 protein and a TC10/H-Ras chimera that were targeted to lipid raft microdomains, it was unable to activate a TC10/K-Ras chimera that was directed to the nonlipid raft domains. Similarly, only the lipid raft-localized TC10/ H-Ras chimera inhibited GLUT4 translocation, whereas the TC10/K-Ras chimera showed no significant inhibitory activity. Furthermore, disruption of lipid raft microdomains by expression of a dominant-interfering caveolin 3 mutant (Cav3/DGV) inhibited the insulin stimulation of GLUT4 translocation and TC10 lipid raft localization and activation without affecting PI-3 kinase signaling. These data demonstrate that the insulin stimulation of GLUT4 translocation in adipocytes requires the spatial separation and distinct compartmentalization of the PI-3 kinase and TC10 signaling pathways

Scoring systems for differentiating gastrointestinal stromal tumors and schwannomas from leiomyomas in the stomach

There is no practical predictive model for the diagnosis of gastrointestinal stromal tumors (GISTs). To establish a practical predictive model for the diagnosis of subepithelial lesions in the stomach, we reviewed patients with GISTs (n = 89), schwannomas (n = 7), and leiomyomas (n = 28). The tumor was more frequently found along the gastric cardia in the leiomyoma group (57.1%) than in the GIST/schwannoma group (2.1%, P < .01). Contrast enhancement (57.3% vs 0%, P < .01) and intra-tumoral necrosis (34.4% vs 0.0%, P < .01) were more frequently observed in the GIST/schwannoma group than in the leiomyoma group. On endoscopic ultrasonography, 58.3% of GISTs/schwannomas showed uneven echogenicity, whereas the echogenicity was uneven in 21.4% of leiomyomas (P < .01). There were no differences between the tumor color and the presence or absence of ulcer formation, tumor bleeding, irregularity of the tumor margin, cystic spaces, and hyperechoic spots between the 2 groups. Based on these results, we developed a 2-step diagnostic algorithm for GISTs/schwannomas. The first step comprises 1 endoscopic feature: a cardiac or non-cardiac location. Tumors with a cardiac location were judged as leiomyomas and those with a non-cardiac location were judged as GISTs/schwannomas, with 96.9% sensitivity and 57.1% specificity for GIST/schwannoma diagnosis. The second step comprises a combination of endoscopic (non-cardiac location), radiologic (positive contrast enhancement and intra-tumoral necrosis), and endosonographic (uneven echogenicity) features for a total of 4 points. We assigned 1 point to each feature. Tumors with scores of 2 to 4 were judged as GISTs/schwannomas, with 81.3% sensitivity and 92.9% specificity for GIST/schwannoma diagnosis. Our predictive model will be a practical guide for the management of gastric subepithelial lesions

Site-specific differences in T lymphocyte composition of the gastric mucosa after Helicobacter pylori eradication

In our earlier work, we revealed that inflammation of the lesser curvature of the gastric body and antrum could constitute independent risk factors for gastric cancer development, while inflammation of the greater curvature was not. The aims of this study were as follows: first, to reveal the differences between T lymphocyte populations of the gastric antrum and the greater and lesser curvatures of the gastric body in patients after Helicobacter pylori eradication; second, to analyze the correlation between the composition of the stomach-resident T lymphocytes and time from H. pylori eradication; and third, to evaluate the sex differences in T lymphocyte subsets after H. pylori eradication. To investigate site-specific differences in stomach-resident T lymphocytes after H. pylori eradication, we performed flow cytometry analysis on samples taken from the gastric antrum, greater curvature of the gastric body, and lesser curvature of the gastric body of 20 patients. We also analyzed the correlation between the composition of the stomach-resident T lymphocytes and the time from H. pylori eradication. The lymphocyte subsets of the antrum and lesser curvature of the body were similar. In contrast, compared to those in the greater curvature of the gastric body, CD4(+)/CD3(+) lymphocyte subsets (43.8 +/- 19.4% vs 31.7 +/- 14.6%) were elevated in the lesser curvature of the body, whereas CD8(+)/CD3(+) (67.1 +/- 21.3% vs 80.4 +/- 12.0%), CD7(+)/CD3(+) (91.2 +/- 4.6% vs 93.7 +/- 3.8%), CCR4(+)/CD3(+) (7.7 +/- 8.1% vs 10.4 +/- 7.0%), CD45RA(+)/CD3(+)CD4(+) (27.2 +/- 24.8% vs 39.5 +/- 20.8%), and CD45RA(+)/CD3(+)CD4(-) (14.2 +/- 11.1% vs 18.7 +/- 11.5) were lower. Linear regression analysis showed a negative correlation between the time after H. pylori eradication and CD4(+)/CD3(+) (P < .05, R-2 = 0.198). There were no significant differences between men and women with respect to the lymphocyte populations. These results indicate that there are site-specific differences in lymphocyte composition in the stomach after H. pylori eradication

Endoscopic findings of gastric neoplasms in familial adenomatous polyposis are associated with the phenotypic variations and grades of dysplasia

Patients with familial adenomatous polyposis (FAP) are at increased risk of developing gastric neoplasms. However, endoscopic findings have not been sufficiently investigated. We investigated the phenotypic expression of gastric adenoma (low-grade dysplasia) and gastric cancer (high-grade dysplasia or carcinoma) in patients with FAP and clarified their relationships to endoscopic findings. Of 29 patients with FAP who underwent esophagogastroduodenoscopy between 2005 and 2020, 11 (38%) had histologically confirmed gastric neoplasms, including 23 lesions of gastric adenoma and 9 lesions of gastric cancer. The gastric neoplasms were classified into 3 phenotypes (gastric, mixed, or intestinal type) according to the immunostaining results and evaluated for location (U or M region: upper or middle third of the stomach or L region: lower third of the stomach), color (same as the background mucosa, whitish, or reddish), macroscopic type (elevated, flat, or depressed), background mucosal atrophy (present or absent), fundic gland polyps in the surrounding mucosa (present or absent), and morphologic changes in tumor size. Elevated whitish gastric adenomas were further subdivided by macroscopic type (flat elevated, protruded, or elevated with a central depression) and color (milky- or pinkish-white). The gastric adenomas included gastric (11/23, 48%), mixed (4/23, 17%), and intestinal (8/23, 35%) phenotypes. In contrast, no lesions of gastric cancers showed a gastric phenotype (0/9, 0%), while 5 (56%) and 4 (44%) lesions were intestinal and mixed phenotypes, respectively. Gastric cancers were significantly more likely than gastric adenomas to present as reddish depressed lesions with gastric atrophy. All gastric-type adenomas occurred in non-atrophic mucosa, in mucosa with fundic gland polyps in the periphery, in the U or M region, and as flat elevated or protruded lesions with a milky-white color. Half of the lesions increased in size. Meanwhile, the typical endoscopic features of intestinal-type adenomas included occurrence in the L region and elevated pinkish-white lesions with central depression. None of the intestinal-type adenomas increased in size during the observation period. We believe that these endoscopic features will be useful for the prompt diagnosis and appropriate management of gastric neoplasms in patients with FAP

Esculentin-2CHa-Related Peptides Modulate Islet Cell Function and Improve Glucose Tolerance in Mice with Diet-Induced Obesity and Insulin Resistance

The frog skin host-defense peptide esculentin-2CHa (GFSSIFRGVA10KFASKGLGK D20LAKLGVDLVA30CKISKQC) displays antimicrobial, antitumor, and immunomodulatory properties. This study investigated the antidiabetic actions of the peptide and selected analogues. Esculentin-2CHa stimulated insulin secretion from rat BRIN-BD11 clonal pancreatic β-cells at concentrations greater than 0.3 nM without cytotoxicity by a mechanism involving membrane depolarization and increase of intracellular Ca2+. Insulinotropic activity was attenuated by activation of KATP channels, inhibition of voltage-dependent Ca2+ channels and chelation of extracellular Ca2+. The [L21K], [L24K], [D20K, D27K] and [C31S,C37S] analogues were more potent but less effective than esculentin-2CHa whereas the [L28K] and [C31K] analogues were both more potent and produced a significantly (P < 0.001) greater maximum response. Acute administration of [L28K]esculentin-2CHa (75 nmol/kg body weight) to high fat fed mice with obesity and insulin resistance enhanced glucose tolerance and insulin secretion. Twice-daily administration of this dose of [L28K]esculentin- 2CHa for 28 days had no significant effect on body weight, food intake, indirect calorimetry or body composition. However, mice exhibited decreased non-fasting plasma glucose (P < 0.05), increased non-fasting plasma insulin (P < 0.05) as well as improved glucose tolerance and insulin secretion (P < 0.01) following both oral and intraperitoneal glucose loads. Impaired responses of isolated islets from high fat fed mice to established insulin secretagogues were restored by [L28K]esculentin-2CHa treatment. Peptide treatment was accompanied by significantly lower plasma and pancreatic glucagon levels and normalization of α-cell mass. Circulating triglyceride concentrations were decreased but plasma cholesterol and LDL concentrations were not significantly affected. The data encourage further investigation of the potential of esculentin-2CHa related peptides for treatment of patients with type 2 diabetes