A single extracellular amino acid in Free Fatty Acid Receptor 2 defines antagonist species selectivity and G protein selection bias

Free Fatty Acid Receptor 2 is a GPCR activated by short chain fatty acids produced in high levels in the lower gut by microbial fermentation of non-digestible carbohydrates. A major challenge in studying this receptor is that the mouse ortholog does not have significant affinity for antagonists that are able to block the human receptor. Docking of exemplar antagonists from two chemical series to homology models of both human and mouse Free Fatty Acid Receptor 2 suggested that a single lysine - arginine variation at the extracellular face of the receptor might provide the basis for antagonist selectivity and mutational swap studies confirmed this hypothesis. Extending these studies to agonist function indicated that although the lysine - arginine variation between human and mouse orthologs had limited effect on G protein-mediated signal transduction, removal of positive charge from this residue produced a signalling-biased variant of Free Fatty Acid Receptor 2 in which Gi-mediated signalling by both short chain fatty acids and synthetic agonists was maintained whilst there was marked loss of agonist potency for signalling via Gq/11 and G12/13 G proteins. A single residue at the extracellular face of the receptor thus plays key roles in both agonist and antagonist function

医療データ解析へのサポートベクトルマシン(SVM)の応用

In our previous papers we proposed a novel screening methodbthat assists the diagnosis of Grave\u27s hyperthyrodism via two types of neural networks by making use of routine test data.This method can be applied by non-specialists during physical check-ups at a low cost and is expected to lead to rapid referrals for examination and treatment by thyroid specialists, that is,toimprove patient\u27QOL. In this report,we apply the support vector machine,which is a novel learning method building on kernels, to the classification problems of madical data such as Wisconsin breast cancer data or our screening of hyperthyroid.It turned out that the support vector machine ,after best turning of parameters based on the grid-search method,works quite well to correctly the lacated in the bordering area between two classes.Our results suggest that the SVM would work as a useful methods in our screening in addition to previous two types of neural networks

Risk of dementia with hearing impairment and social isolation

Abstract INTRODUCTION This study aimed to determine whether the concomitance of hearing impairment and isolation with lack of conversation, which is considered self‐evident but has not been investigated extensively, is associated with the occurrence of dementia. METHODS A total of 2745 participants were divided into four groups according to the presence/absence of hearing impairment and isolation with lack of conversation. The association of dementia with hearing impairment and isolation with lack of conversation was analyzed using Cox proportional hazards regression. RESULTS The combined hearing impairment and isolation with lack of conversation (hazard ratio: 1.69, 95% confidence interval: 1.09‐2.61) and non‐hearing impairment and isolation with lack of conversation (hazard ratio: 1.60, 95% confidence: 1.07‐2.39) were associated with the development of dementia. DISCUSSION These findings emphasize the importance of promoting high‐quality social relationships throughout life by adopting preventive measures against isolation with lack of conversation from the early stage of awareness of hearing impairment. Highlights Dementia affects 12.9% of those with hearing impairment and isolation. Hearing impairment and isolation are associated with increased risk of dementia. Addressing these risk factors may help reduce the risk of developing dementia. Preventing isolation and promoting quality social relationships is important

Ectodomain shedding of EGFR ligands serves as an activation readout for TRP channels.

Transient receptor potential (TRP) channels are activated by various extracellular and intracellular stimuli and are involved in many physiological events. Because compounds that act on TRP channels are potential candidates for therapeutic agents, a simple method for evaluating TRP channel activation is needed. In this study, we demonstrated that a transforming growth factor alpha (TGFα) shedding assay, previously developed for detecting G-protein-coupled receptor (GPCR) activation, can also detect TRP channel activation. This assay is a low-cost, easily accessible method that requires only an absorbance microplate reader. Mechanistically, TRP-channel-triggered TGFα shedding is achieved by both of a disintegrin and metalloproteinase domain-containing protein 10 (ADAM10) and 17 (ADAM17), whereas the GPCR-induced TGFα shedding response depends solely on ADAM17. This difference may be the result of qualitative or quantitative differences in intracellular Ca2+ kinetics between TRP channels and GPCRs. Use of epidermal growth factor (EGF) and betacellulin (BTC), substrates of ADAM10, improved the specificity of the shedding assay by reducing background responses mediated by endogenously expressed GPCRs. This assay for TRP channel measurement will not only facilitate the high-throughput screening of TRP channel ligands but also contribute to understanding the roles played by TRP channels as regulators of membrane protein ectodomain shedding

Shootins mediate collective cell migration and organogenesis of the zebrafish posterior lateral line system

The zebrafish sensory posterior lateral line is an excellent model system to study collective cell migration and organogenesis. Shootin1 is a cytoplasmic protein involved in neuronal polarization and axon guidance. Previous studies have shown that shootin1 couples actin filament retrograde flow with extracellular adhesive substrates at the leading edge of axonal growth cones, thereby producing mechanical force for the migration and guidance of axonal growth cones. However, the functions of shootin in peripheral cells remain unknown. Here we identified two novel shootin family members, shootin2 and shootin3. In zebrafish, shootin1 and shootin3 are expressed in the posterior lateral line primordium (PLLP) and neuromasts during embryonic development. A shootin1 mutant displayed a reduced speed of PLLP migration, while shootin1;shootin3 double mutation inhibited cell proliferation in the PLLP. Furthermore, our results suggest that shootin1 and shootin3 positively regulate the number of neuromasts and the number of cells in deposited neuromasts. Our study demonstrates that shootins mediate collective cell migration of the posterior lateral line primordium and formation of neuromasts in zebrafish