Deciphering the transport metabolomes of SLC26A3, SLC26A6 and SLC26A9 in the human gastrointestinal tract

SLC26A3、SLC26A6和SLC26A9阴离子转运体和/或其相互作用伙伴介导的Cl-和/或HCO3-转运失调是多种胃肠道（GI）疾病状态的根本原因或加重因素。这些SLC26亚型的转运功能已经在异源表达系统中进行了研究，并从胃肠道细胞系和敲除小鼠模型中获得了它们的生理相关性和调控。然而，对于人类胃肠道，SLC26与其他转运蛋白之间的功能相互作用、它们的分子相互作用伙伴以及它们在不同肠段中的调节途径，人们对其节段和隐窝到绒毛的表达模式知之甚少。为了概括SLC26A3/6/9在肠上皮不同区域从隐窝到上绒毛区域的胃肠道上皮细胞中的复杂运输代谢组，我们将使用具有三维和二维生长模式的人胃和肠样肠培养物。通过这种新的模型方法，我们将与其他项目组（P3和P4）一起研究SLC26A3/6/9在近天然人胃肠道上皮阴离子运输中的功能，研究SLC26A3/6/ 6的Cl-/HCO3-偶联比率。此外，我们将研究它们在细胞运输之外的肠道功能和病理生理中的作用：因此，我们将利用电生理学、荧光学、生化方法结合基因组编辑工具，研究它们在高脚杯粘液组成和分泌、腔内ph -微气候维持以及细菌附着和生存中的作用。我们将进一步探索SLC26A3/6/9与CFTR的功能和结构相互作用，以及其他项目组（P5）在异源表达系统中发现的SLC26A3新相互作用蛋白在人肠上皮中的作用。

Dysregulation of Cl- and/or HCO3- transport mediated by SLC26A3, SLC26A6 and SLC26A9 anion transporters and/or their interactions partners is the underlying cause or aggravating factor in a variety of gastrointestinal (GI) disease states. The transport function of these SLC26 isoforms has been studied in heterologous expression systems, and glimpses into their physiological relevance and regulation were obtained from gastrointestinal cell lines and knockout mouse models. However, for the human GI tract very little is known about the segmental and crypt-to-villus expression patterns, the functional interplay between SLC26 and other transporters, their molecular interaction partners, and their regulatory pathways in the different intestinal segments. To recapitulate the complex transport metabolome of SLC26A3/6/9 in GI epithelial cells in the different regions of the intestinal epithelium from the crypts to the upper villus area, we will use human gastric and intestinal enteroid cultures with three- and two-dimensional growth patterns. With this new model approach we will examine the function of SLC26A3/6/9 in anion transport in near-native human gastrointestinal epithelium, study the Cl-/HCO3- coupling ratios of SLC26A3/6 together with other project groups (P3 and P4). Moreover we will address their role in intestinal function and pathophysiology beyond cellular transport: thus we will investigate their role in goblet mucus composition and secretion, in luminal pH-microclimate maintenance, and in bacterial attachment and survival, using electrophysiological, fluorometric, biochemical methods in combination with genome editing tools. We will further explore the functional and structural interaction of SLC26A3/6/9 with CFTR, and the relevance of novel interacting proteins of SLC26A3 identified by other project groups (P5) in heterologous expression systems for their role in the human intestinal epithelium.