Small mouse cholangiocytes proliferate in response to H1 histamine receptor stimulation by activation of the IP3/CaMK I/CREB pathway.
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+)](i) 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.
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.
Heather
H
Francis
Shannon
S
Glaser
Sharon
S
Demorrow
Eugenio
E
Gaudio
Yoshiyuki
Y
Ueno
Julie
J
Venter
David
D
Dostal
Paolo
P
Onori
Antonio
A
Franchitto
Marco
M
Marzioni
Shelley
S
Vaculin
Bradley
B
Vaculin
Khurshed
K
Katki
Monique
M
Stutes
Jennifer
J
Savage
Gianfranco
G
Alpini
D000818:Animals; D027321:Anion Transport Proteins / Q000378:metabolism; D017920:Antiporters / Q000378:metabolism; D001653:Bile Ducts, Intrahepatic / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D054729:Calcium-Calmodulin-Dependent Protein Kinase Type 1 / Q000235:genetics / Q000378:metabolism*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism; D002461:Cell Line, Transformed; D049109:Cell Proliferation; D048429:Cell Size; D000242:Cyclic AMP / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000378:metabolism; D006632:Histamine / Q000031:analogs & derivatives / Q000494:pharmacology; D017442:Histamine Agonists / Q000494:pharmacology; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism*; D053552:Keratin-7 / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D010766:Phosphorylation / Q000187:drug effects; D034622:RNA Interference; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D011964:Receptors, Gastrointestinal Hormone / Q000378:metabolism; D011968:Receptors, Histamine / Q000235:genetics / Q000378:metabolism; D011969:Receptors, Histamine H1 / Q000502:physiology*; D064606:SLC4A Proteins; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology
D027321:Anion Transport Proteins; D017920:Antiporters; C492004:Creb1 protein, mouse; D017362:Cyclic AMP Response Element-Binding Protein; D017442:Histamine Agonists; D053552:Keratin-7; D043562:Receptors, G-Protein-Coupled; D011964:Receptors, Gastrointestinal Hormone; D011968:Receptors, Histamine; D011969:Receptors, Histamine H1; D064606:SLC4A Proteins; C029937:secretin receptor; C087869:histamine trifluoromethyl-toluidide; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D006632:Histamine; D015544:Inositol 1,4,5-Trisphosphate; D000242:Cyclic AMP; D054729:Calcium-Calmodulin-Dependent Protein Kinase Type 1; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C517598:Camk1 protein, mouse; D002118:Calcium