Potential role of adenylyl cyclase 8 signaling complexes in regulating insulin secretion from pancreatic beta cells

Novel insight into the role of A-kinase anchoring proteins (AKAPs) in ischemic stroke and therapeutic potentials

Ischemic stroke, a devastating disease associated with high mortality and disability worldwide, has emerged as an urgent public health issue. A-kinase anchoring proteins (AKAPs) are a group of signal-organizing molecules that compartmentalize and anchor a wide range of receptors and effector proteins and have a major role in stabilizing mitochondrial function and promoting neurodevelopmental development in the central nervous system (CNS). Growing evidence suggests that dysregulation of AKAPs expression and activity is closely associated with oxidative stress, ion disorder, mitochondrial dysfunction, and blood-brain barrier (BBB) impairment in ischemic stroke. However, the underlying mechanisms remain inadequately understood. This review provides a comprehensive overview of the composition and structure of A-kinase anchoring protein (AKAP) family members, emphasizing their physiological functions in the CNS. We explored in depth the molecular and cellular mechanisms of AKAP complexes in the pathological progression and risk factors of ischemic stroke, including hypertension, hyperglycemia, lipid metabolism disorders, and atrial fibrillation. Herein, we highlight the potential of AKAP complexes as a pharmacological target against ischemic stroke in the hope of inspiring translational research and innovative clinical approaches.

The glucagon-like peptide-1 (GLP-1) analogue semaglutide reduces alcohol drinking and modulates central GABA neurotransmission

Growing evidence indicates that the glucagon-like peptide-1 (GLP-1) system is involved in the neurobiology of addictive behaviors, and GLP-1 analogues may be used for the treatment of alcohol use disorder (AUD). Here, we examined the effects of semaglutide, a long-acting GLP-1 analogue, on biobehavioral correlates of alcohol use in rodents. A drinking-in-the-dark procedure was used to test the effects of semaglutide on binge-like drinking in male and female mice. We also tested the effects of semaglutide on binge-like and dependence-induced alcohol drinking in male and female rats, as well as acute effects of semaglutide on spontaneous inhibitory postsynaptic currents (sIPSCs) from central amygdala (CeA) and infralimbic cortex (ILC) neurons. Semaglutide dose-dependently reduced binge-like alcohol drinking in mice; a similar effect was observed on the intake of other caloric/noncaloric solutions. Semaglutide also reduced binge-like and dependence-induced alcohol drinking in rats. Semaglutide increased sIPSC frequency in CeA and ILC neurons from alcohol-naive rats, suggesting enhanced GABA release, but had no overall effect on GABA transmission in alcohol-dependent rats. In conclusion, the GLP-1 analogue semaglutide decreased alcohol intake across different drinking models and species and modulated central GABA neurotransmission, providing support for clinical testing of semaglutide as a potentially novel pharmacotherapy for AUD.

Signaling pathways in obesity: mechanisms and therapeutic interventions

Obesity is a complex, chronic disease and global public health challenge. Characterized by excessive fat accumulation in the body, obesity sharply increases the risk of several diseases, such as type 2 diabetes, cardiovascular disease, and nonalcoholic fatty liver disease, and is linked to lower life expectancy. Although lifestyle intervention (diet and exercise) has remarkable effects on weight management, achieving long-term success at weight loss is extremely challenging, and the prevalence of obesity continues to rise worldwide. Over the past decades, the pathophysiology of obesity has been extensively investigated, and an increasing number of signal transduction pathways have been implicated in obesity, making it possible to fight obesity in a more effective and precise way. In this review, we summarize recent advances in the pathogenesis of obesity from both experimental and clinical studies, focusing on signaling pathways and their roles in the regulation of food intake, glucose homeostasis, adipogenesis, thermogenesis, and chronic inflammation. We also discuss the current anti-obesity drugs, as well as weight loss compounds in clinical trials, that target these signals. The evolving knowledge of signaling transduction may shed light on the future direction of obesity research, as we move into a new era of precision medicine.

Emerging molecular technologies for light-mediated modulation of pancreatic beta-cell function

Background

Optogenetic modalities as well as optochemical and photopharmacological strategies, collectively termed optical methods, have revolutionized the control of cellular functions via light with great spatiotemporal precision. In comparison to the major advances in the photomodulation of signaling activities noted in neuroscience, similar applications to endocrine cells of the pancreas, particularly insulin-producing β-cells, have been limited. The availability of tools allowing light-mediated changes in the trafficking of ions such as K⁺ and Ca²⁺ and signaling intermediates such as cyclic adenosine monophosphate (cAMP), renders β-cells and their glucose-stimulated insulin secretion (GSIS) amenable to optoengineering for drug-free control of blood sugar.

Scope of review

The molecular circuit of the GSIS in β-cells is described with emphasis on intermediates which are targetable for optical intervention. Various pharmacological agents modifying the release of insulin are reviewed along with their documented side effects. These are contrasted with optical approaches, which have already been employed for engineering β-cell function or are considered for future such applications. Principal obstacles are also discussed as the implementation of optogenetics is pondered for tissue engineering and biology applications of the pancreas.

Major Conclusions

Notable advances in optogenetic, optochemical and photopharmacological tools are rendering feasible the smart engineering of pancreatic cells and tissues with light-regulated function paving the way for novel solutions for addressing pancreatic pathologies including diabetes.

microRNA-206 Regulates Pancreatic-β-Cell Function via Targeting Insulin-Like Growth Factor 1

Background: Diabetes mellitus (DM), a common metabolic disease, is featured with chronic hyperglycemia and dysfunction of pancreatic β-cells. Various evidences suggested that microRNAs (miR-NAs) were tightly related to the occurrence of DM and can be regulated in pancreatic-β-cells. However, whether or not microRNA-206 (miR-206) affects the development of DM and the specific mechanisms remains elusive. We designed this study to clarify the function and associated potential mechanism of miR-206 in pancreatic β-cells via the insulin-like growth factor 1 reporter (IGF1R)/phosphatidylinositide 3-kinase (PI3 K)/protein kinase B (AKT) signaling pathway, which may provide novel diagnostic or therapies for DM. Methods: In this research, the levels of miR-206 and insulin-like growth factor 1 (IGF1) were assessed using quantitative reverse transcription PCR (qRT-PCR) and/or Western bolt assay. Bioinformatics and dual luciferase reporter assays were adopted to illustrate the relationship between miR-206 and IGF1. INS-1 cells were stimulated with stimulatory glucose (16.7 mM) or basal glucose (3.3 mM) for 1 h, and the insulin content was examined by enzyme linked immunosorbent assay (ELISA). Besides, 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di-phenytetrazoliumromide (MTT) assay and flow cytometry (FCM) analysis were conducted to determine the INS1 cell viability and apoptosis. Furthermore, the related proteins in IGF1R/PI3 K/AKT pathway (IGF1R, p-AKT and AKT) were tested using Western blot assay, respectively. Results: Our data suggested that miR-206 level in the blood samples of DM patients was higher than that in healthy donors. IGF1 was identified as a direct target of miR-206. Moreover, we found that miR-206 negatively regulated IGF1 expression in INS-1 cells. It was also confirmed that miR-206 inhibitor led to an increase of total insulin content, an increase of INS-1 cell viability and a decrease of cell apoptosis. Accordingly, miR-206 inhibitor significantly enhanced IGF1R and p-AKT protein expression in INS-1 cells. All these findings were reversed by IGF1-siRNA co-transfection. Conclusion: Our observations clearly demonstrated that miR-206 could regulate the IGF1R/PI3K/AKT pathway by targeting IGF1, thereby regulating the cell viability of pancreatic β cells and the ability of pancreatic β cells to secrete insulin.