Angotzi Anna Rita, Leal Esther, Puchol Sara, Cerdá-Reverter José M, Morais Sofia
Department of Fish Physiology and Biotechnology, Instituto de Acuicultura de Torre de la Sal, IATS-CSIC, Torre la Sal s/n, Ribera de Cabanes, 12595 Castellon, Spain.
Lucta S.A., Innovation Division, Animal Science Unit, UAB Research Park, 08193 Bellaterra, Spain.
Anim Nutr. 2022 Aug 31;11:293-308. doi: 10.1016/j.aninu.2022.08.010. eCollection 2022 Dec.
In this study, we investigated the transcriptional spatio-temporal dynamics of the taste 1 receptor () gene family repertoire in seabream ( []), during larval ontogeny and in adult tissues. In early larval development, expression arises heterochronously, i.e. the extraoral taste-related perception in the gastrointestinal tract (GIT) anticipates first exogenous feeding (at 9 days post hatching [dph]), followed by the buccal/intraoral perception from 14 dph onwards, supporting the hypothesis that the early onset of the molecular machinery underlying expression in the GIT is not induced by food but rather genetically hardwired. During adulthood, we characterized the expression patterns of within specific tissues ( = 4) distributed in oropharingeal, GIT and brain regions substantiating their functional versatility as chemosensory signaling players to a variety of biological functions beyond oral taste sensation. Further, we provided for the first time direct evidences in fish for mRNA co-expression of a subset of genes (mostly , i.e. the common subunit of the heterodimeric T1R complexes for the detection of "sweet" and "umami" substances), with the selected gut peptides ghrelin (), cholecystokinin (), hormone peptide yy () and proglucagon (). Each peptide defines the enteroendocrine cells (ECCs) identity, and establishes on morphological basis, a direct link for T1R chemosensing in the regulation of fish digestive processes. Finally, we analyzed the spatial gene expression patterns of 2 taste signaling components functionally homologous to the mammalian subunit gustducin, namely and , and demonstrated their co-localization with the in EECs, thus validating their direct involvement in taste-like transduction mechanisms of the fish GIT. In conclusion, data provide new insights in the evolutionary conservation of gut sensing in fish suggesting a conserved role for nutrient sensors modulating entero-endocrine secretion.
在本研究中，我们调查了海鲷（Sparus aurata）幼体发育过程中和成体组织中味觉1受体（T1R）基因家族全部基因的转录时空动态。在幼体早期发育阶段，T1R表达异步出现，即胃肠道（GIT）中与口外味觉相关的感知先于首次外源摄食（孵化后9天[dph]）出现，随后从14 dph开始出现颊部/口内感知，这支持了以下假设：GIT中T1R表达的分子机制的早期启动不是由食物诱导的，而是由基因决定的。在成年期，我们对分布在口咽、GIT和脑区的特定组织（n = 4）中的T1R表达模式进行了表征，证实了它们作为化学感应信号参与者在多种生物学功能（而非仅口腔味觉）中的功能多样性。此外，我们首次在鱼类中提供了直接证据，证明一部分T1R基因（主要是T1R2，即用于检测“甜味”和“鲜味”物质的异二聚体T1R复合物的共同亚基）的mRNA与选定的肠道肽胃饥饿素（ghrelin）、胆囊收缩素（cholecystokinin）、肽YY（peptide YY）和胰高血糖素原（proglucagon）共表达。每种肽都定义了肠内分泌细胞（ECCs）的身份，并在形态学基础上建立了T1R化学感应与鱼类消化过程调节之间的直接联系。最后，我们分析了与哺乳动物味觉传导素亚基功能同源的两种味觉信号成分（T1R3-like和PLCβ2-like）的空间基因表达模式，并证明它们与ECCs中的T1R共定位，从而验证了它们直接参与鱼类GIT的类味觉转导机制。总之，这些数据为鱼类肠道感知的进化保守性提供了新的见解，表明营养传感器在调节肠内分泌分泌方面具有保守作用。
