Department of Health Sciences, School of Medicine, University of Piemonte Orientale, Via Solaroli, 17, 28100 Novara, Italy.
Department of Biochemistry and Biophysics, University of Kalyani, Kalyani 741235, West Bengal, India.
Cells. 2024 Jul 16;13(14):1204. doi: 10.3390/cells13141204.
Bitter taste receptors (TAS2Rs) expressed in extraoral tissues represent a whole-body sensory system, whose role and mechanisms could be of interest for the identification of new therapeutic targets. It is known that TAS2R46s in pre-contracted airway smooth muscle cells increase mitochondrial calcium uptake, leading to bronchodilation, and that several SNPs have been identified in its gene sequence. There are very few reports on the structure-function analysis of TAS2Rs. Thus, we delved into the subject by using mutagenesis and in silico studies. We generated a cellular model that expresses native TAS2R46 to evaluate the influence of the four most common SNPs on calcium fluxes following the activation of the receptor by its specific ligand absinthin. Then, docking studies were conducted to correlate the calcium flux results to the structural mutation. The analysed SNPs differently modulate the TAS2R46 signal cascade according to the altered protein domain. In particular, the SNP in the sixth transmembrane domain of the receptors did not modulate calcium homeostasis, while the SNPs in the sequence coding for the fourth transmembrane domain completely abolished the mitochondrial calcium uptake. In conclusion, these results indicate the fourth transmembrane domain of TAS2R46 is critical for the intrinsic receptor activity.
苦味受体 (TAS2Rs) 在口腔外组织中的表达代表了一种全身感觉系统，其作用和机制可能对识别新的治疗靶点具有重要意义。已知预收缩的气道平滑肌细胞中的 TAS2R46 增加线粒体钙摄取，导致支气管扩张，并且已经在其基因序列中鉴定出几个 SNP。关于 TAS2R 的结构-功能分析的报道很少。因此，我们通过使用突变和计算机研究深入研究了这一主题。我们生成了一种表达天然 TAS2R46 的细胞模型，以评估其特定配体苦艾素激活受体后，四个最常见的 SNP 对钙流的影响。然后进行对接研究，将钙流结果与结构突变相关联。根据改变的蛋白结构域，分析的 SNP 以不同的方式调节 TAS2R46 信号级联。特别是，受体第六跨膜域中的 SNP 不会调节钙稳态，而编码第四跨膜域的 SNP 则完全消除了线粒体钙摄取。总之，这些结果表明 TAS2R46 的第四跨膜域对于内在受体活性至关重要。
