Switching-on of serotonergic calcium signaling in activated hepatic stellate cells.
OBJECTIVE
To investigate serotonergic Ca²+ signaling and the expression of 5-hydroxytryptamine (5-HT) receptors, as well as Ca²+ transporting proteins, in hepatic stellate cells (HSCs).


METHODS
The intracellular Ca²+ concentration [Ca²+](i) of isolated rat HSCs was measured with a fluorescence microscopic imaging system. Quantitative PCR was performed to determine the transcriptional levels of 5-HT receptors and endoplasmic reticulum (ER) proteins involved in Ca²+ storage and release in cultured rat HSCs.


RESULTS
Distinct from quiescent cells, activated HSCs exhibited [Ca²+](i) transients following treatment with 5-HT, which was abolished by U-73122, a phospholipase C inhibitor. Upregulation of 5-HT(2A) and 5-HT(2B) receptors, but not 5-HT₃, was prominent during trans-differentiation of HSCs. Pretreatment with ritanserin, a 5-HT₂ antagonist, inhibited [Ca²+](i) changes upon application of 5-HT. Expression of type 1 inositol-5'-triphosphate receptor and type 2 sarcoplasmic/endoplasmic reticulum Ca²+ ATPase were also increased during activation of HSCs and serve as the major isotypes for ER Ca²+ storage and release in activated HSCs. Ca²+ binding chaperone proteins of the ER, including calreticulin, calnexin and calsequestrin, were up-regulated following activation of HSCs.


CONCLUSIONS
The appearance of 5-HT-induced [Ca²+](i) response accompanied by upregulation of metabotropic 5-HT₂ receptors and Ca²+ transporting/chaperone ER proteins may participate in the activating process of HSCs.
Department of Physiology and Institute of Lifelong Health, Yonsei University Wonju College of Medicine, Wonju, Gangwon-Do 220-701, South Korea.
Kyu-Sang
KS
Park
Pyo-Jin
PJ
Sin
Dong Hyeon
DH
Lee
Seung-Kuy
SK
Cha
Min-Jeong
MJ
Kim
Na-Hyun
NH
Kim
Soon-Koo
SK
Baik
Seong-Woo
SW
Jeong
In Deok
ID
Kong
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling; D004721:Endoplasmic Reticulum / Q000378:metabolism; D055166:Hepatic Stellate Cells / Q000166:cytology*; D007150:Immunohistochemistry / Q000379:methods; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000378:metabolism; D008297:Male; D008856:Microscopy, Fluorescence / Q000379:methods; D011485:Protein Binding; D051381:Rats; D017207:Rats, Sprague-Dawley; D011985:Receptors, Serotonin / Q000378:metabolism; D012701:Serotonin / Q000378:metabolism*; D015854:Up-Regulation
D053496:Inositol 1,4,5-Trisphosphate Receptors; D011985:Receptors, Serotonin; D012701:Serotonin; D002118:Calcium
Gastroenterology. 2005 Jan;128(1):121-37
15633129
Alcohol Clin Exp Res. 2005 Nov;29(11 Suppl):121S-131S
16344596
Hepatology. 1994 Oct;20(4 Pt 1):800-3
7523265
Science. 2003 Apr 4;300(5616):65-7
12677047
Am J Physiol. 1997 May;272(5 Pt 1):L795-806
9176241
Am J Physiol Gastrointest Liver Physiol. 2007 Apr;292(4):G975-82
17204544
Dev Neurosci. 2003 Mar-Aug;25(2-4):245-56
12966221
Eur J Pharmacol. 2000 Dec 27;410(2-3):165-181
11134668
Pharmacol Ther. 2001 Nov-Dec;92(2-3):179-212
11916537
Cell. 1990 Apr 20;61(2):197-9
2184940
J Cell Biol. 2001 Sep 3;154(5):961-72
11524434
J Cell Mol Med. 2006 Jan-Mar;10(1):76-99
16563223
Proc Natl Acad Sci U S A. 2000 Aug 15;97(17):9508-13
10944220
J Biol Chem. 1999 Mar 5;274(10):6203-11
10037706
Bioessays. 1999 Jan;21(1):38-46
10070252
Hepatology. 1996 Oct;24(4):855-64
8855188
Korean J Gastroenterol. 2003 Aug;42(2):134-41
14532718
Virchows Arch B Cell Pathol Incl Mol Pathol. 1990;59(6):349-57
1705733
J Submicrosc Cytol Pathol. 1992 Apr;24(2):193-203
1600511
Nat Immunol. 2006 Jan;7(1):25-32
16357855
Am J Physiol Gastrointest Liver Physiol. 2004 Aug;287(2):G417-24
14764443
Hepatology. 1983 Jul-Aug;3(4):559-66
6862368
Biochim Biophys Acta. 1999 Apr 14;1418(1):158-64
10209220
Yonsei Med J. 2008 Jun 30;49(3):459-71
18581597
J Cell Biol. 2000 Sep 18;150(6):1499-506
10995453
Proc Natl Acad Sci U S A. 1990 Feb;87(3):928-32
2300586
Am J Pathol. 2006 Sep;169(3):861-76
16936262
Hepatology. 1992 Feb;15(2):234-43
1735526
Kidney Int Suppl. 1996 May;54:S39-45
8731193
Mol Cell Biol. 2004 Feb;24(4):1758-68
14749390
Exp Biol Med (Maywood). 2008 Nov;233(11):1385-8
18703754
Science. 2006 Apr 7;312(5770):104-7
16601191
J Biol Chem. 2000 Jan 28;275(4):2247-50
10644669
J Clin Invest. 1993 Oct;92(4):1795-804
8408632
Int J Biochem Cell Biol. 2005 Feb;37(2):260-6
15474971
World J Gastroenterol. 2007 Nov 21;13(43):5750-3
17963303
Hepatology. 2001 Apr;33(4):956-62
11283860
Methods. 2001 Dec;25(4):402-8
11846609
Am J Physiol. 1995 Oct;269(4 Pt 1):G532-41
7485505
Dev Cell. 2004 Feb;6(2):193-203
14960274
Hepatobiliary Pancreat Dis Int. 2006 Feb;5(1):96-100
16481292
Am J Pathol. 1986 Dec;125(3):611-9
3799820
J Gastroenterol Hepatol. 1998 Sep;13(S1):S19-S32
28976701