Francis Heather, Glaser Shannon, Demorrow Sharon, Gaudio Eugenio, Ueno Yoshiyuki, Venter Julie, Dostal David, Onori Paolo, Franchitto Antonio, Marzioni Marco, Vaculin Shelley, Vaculin Bradley, Katki Khurshed, Stutes Monique, Savage Jennifer, Alpini Gianfranco
Central Texas Veterans Health Care System, Scott & White and Texas A&M Health Science Center College of Medicine, Medical Research Bldg., 702 SW H.K. Dodgen Loop, Temple, TX, 76504, USA.
Am J Physiol Cell Physiol. 2008 Aug;295(2):C499-513. doi: 10.1152/ajpcell.00369.2007. Epub 2008 May 28.
Cholangiopathies are characterized by the heterogeneous proliferation of different-sized cholangiocytes. Large cholangiocytes proliferate by a cAMP-dependent mechanism. The function of small cholangiocytes may depend on the activation of inositol trisphosphate (IP(3))/Ca(2+)-dependent signaling pathways; however, data supporting this speculation are lacking. Four histamine receptors exist (HRH1, HRH2, HRH3, and HRH4). In several cells: 1) activation of HRH1 increases intracellular Ca(2+) concentration levels; and 2) increased Ca(2+) levels are coupled with calmodulin-dependent stimulation of calmodulin-dependent protein kinase (CaMK) and activation of cAMP-response element binding protein (CREB). HRH1 agonists modulate small cholangiocyte proliferation by activation of IP(3)/Ca(2+)-dependent CaMK/CREB. We evaluated HRH1 expression in cholangiocytes. Small and large cholangiocytes were stimulated with histamine trifluoromethyl toluidide (HTMT dimaleate; HRH1 agonist) for 24-48 h with/without terfenadine, BAPTA/AM, or W7 before measuring proliferation. Expression of CaMK I, II, and IV was evaluated in small and large cholangiocytes. We measured IP(3), Ca(2+) and cAMP levels, phosphorylation of CaMK I, and activation of CREB (in the absence/presence of W7) in small cholangiocytes treated with HTMT dimaleate. CaMK I knockdown was performed in small cholangiocytes stimulated with HTMT dimaleate before measurement of proliferation and CREB activity. Small and large cholangiocytes express HRH1, CaMK I, and CaMK II. Small (but not large) cholangiocytes proliferate in response to HTMT dimaleate and are blocked by terfenadine (HRH1 antagonist), BAPTA/AM, and W7. In small cholangiocytes, HTMT dimaleate increased IP(3)/Ca(2+) levels, CaMK I phosphorylation, and CREB activity. Gene knockdown of CaMK I ablated the effects of HTMT dimaleate on small cholangiocyte proliferation and CREB activation. The IP(3)/Ca(2+)/CaMK I/CREB pathway is important in the regulation of small cholangiocyte function.
胆管病的特征是不同大小胆管细胞的异质性增殖。大胆管细胞通过依赖环磷酸腺苷（cAMP）的机制增殖。小胆管细胞的功能可能依赖于三磷酸肌醇（IP(3)）/钙离子（Ca(2+)）依赖性信号通路的激活；然而，支持这一推测的数据尚缺。存在四种组胺受体（HRH1、HRH2、HRH3和HRH4）。在几种细胞中：1）HRH1的激活会增加细胞内钙离子浓度水平；2）细胞内钙离子（Ca(2+)）水平的升高与钙调蛋白依赖性蛋白激酶（CaMK）的钙调蛋白依赖性刺激以及环磷酸腺苷反应元件结合蛋白（CREB）的激活相关联。HRH1激动剂通过激活IP(3)/Ca(2+)依赖性的CaMK/CREB来调节小胆管细胞的增殖。我们评估了胆管细胞中HRH1的表达。在用/不用特非那定、BAPTA/AM或W7处理后，用组胺三氟甲基甲苯胺（HTMT马来酸盐；HRH1激动剂）刺激小胆管细胞和大胆管细胞24 - 48小时，然后测量增殖情况。评估了小胆管细胞和大胆管细胞中CaMK I、II和IV的表达。我们测量了用HTMT马来酸盐处理的小胆管细胞中的IP(3)、Ca(2+)和cAMP水平、CaMK I的磷酸化以及CREB的激活（在有/无W7的情况下）。在用HTMT马来酸盐刺激的小胆管细胞中进行CaMK I基因敲低，然后测量增殖和CREB活性。小胆管细胞和大胆管细胞表达HRH1、CaMK I和CaMK II。小胆管细胞（而非大胆管细胞）对HTMT马来酸盐有增殖反应，并被特非那定（HRH1拮抗剂）、BAPTA/AM和W7阻断。在小胆管细胞中，HTMT马来酸盐增加了IP(3)/Ca(2+)水平、CaMK I磷酸化和CREB活性。CaMK I基因敲低消除了HTMT马来酸盐对小胆管细胞增殖和CREB激活的影响。IP(3)/Ca(2+)/CaMK I/CREB通路在小胆管细胞功能的调节中起重要作用。
