Alpini G, Ulrich C, Roberts S, Phillips J O, Ueno Y, Podila P V, Colegio O, LeSage G D, Miller L J, LaRusso N F
Center for Basic Research in Digestive Diseases, Mayo Medical School, Clinic, and Foundation, Rochester, Minnesota 55905, USA.
Am J Physiol. 1997 Feb;272(2 Pt 1):G289-97. doi: 10.1152/ajpgi.1997.272.2.G289.
Cholangiocytes, the epithelial cells that line intrahepatic bile ducts, participate in bile secretion via basal and agonist-stimulated transport of solutes and water. On the basis of subtle structural differences between cholangiocytes lining small vs. large bile ducts, as well as known phenotypic variations among transporting epithelia in other organs, we demonstrated that cholangiocytes are functionally heterogeneous along the intrahepatic biliary tree of normal rats. In studies reported here, we confirm and extend the concept of functional heterogeneity of cholangiocytes by employing the bile duct-ligated (BDL) rat model of cholestasis associated with selective cholangiocyte proliferation. Using novel isolation and separatory techniques, we prepared subpopulations of pure small, medium, and large cholangiocytes from BDL rats and compared them with regard to gene expression and basal or agonist-responsive transport activities. Although transcripts for gamma-glutamyl transpeptidase and cytokeratin 19, two cholangiocyte-specific proteins, and glyceraldehyde-3-phosphate dehydrogenase, a housekeeping gene, were in all three subpopulations, genes for several proteins involved in solute transport [Cl-/HCO3- exchanger, cystic fibrosis transmembrane conductance regulator (CFTR), and secretin receptor] were expressed only in medium and large cholangiocytes. Consistent with these findings, secretin increased intracellular levels of adenosine 3',5'-cyclic monophosphate (cAMP) and 36Cl- efflux rates in medium and large cholangiocytes but not in small cholangiocytes. Also, forskolin/8-(4-chlorophenylthio)-cAMP stimulated 36Cl- efflux rates only in medium and large cholangiocytes, consistent with selective functional expression of CFTR in these subpopulations. These results support the molecular and functional heterogeneity of cholangiocytes within the intrahepatic biliary ductal system and are consistent with the notion that hormone-regulated transport of solutes after BDL occurs principally in medium and large cholangiocytes in a fashion similar to that observed in normal rat liver.
胆管细胞是肝内胆管内衬的上皮细胞，通过溶质和水的基底转运及激动剂刺激转运参与胆汁分泌。基于小胆管和大胆管内衬胆管细胞之间细微的结构差异，以及其他器官中转运上皮细胞已知的表型变化，我们证明了正常大鼠肝内胆管树中的胆管细胞在功能上是异质性的。在本文报道的研究中，我们通过使用与选择性胆管细胞增殖相关的胆汁淤积胆管结扎（BDL）大鼠模型，证实并扩展了胆管细胞功能异质性的概念。我们使用新颖的分离和分选技术，从BDL大鼠中制备了纯的小、中、大胆管细胞亚群，并比较了它们在基因表达以及基底或激动剂反应性转运活性方面的差异。尽管γ-谷氨酰转肽酶和细胞角蛋白19这两种胆管细胞特异性蛋白以及管家基因甘油醛-3-磷酸脱氢酶的转录本在所有三个亚群中都存在，但几种参与溶质转运的蛋白（Cl⁻/HCO₃⁻交换体、囊性纤维化跨膜传导调节因子（CFTR）和促胰液素受体）的基因仅在中、大胆管细胞中表达。与这些发现一致，促胰液素增加了中大胆管细胞而非小胆管细胞内的3',5'-环磷酸腺苷（cAMP）水平和³⁶Cl⁻流出率。此外，福斯可林/8-（4-氯苯硫基）-cAMP仅刺激中大胆管细胞的³⁶Cl⁻流出率，这与CFTR在这些亚群中的选择性功能表达一致。这些结果支持肝内胆管系统中胆管细胞的分子和功能异质性，并与BDL后激素调节的溶质转运主要发生在中大胆管细胞中这一观点一致，其方式类似于在正常大鼠肝脏中观察到的情况。
