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Phospholipase C activation and Ca 2+ mobilization by cloned human somatostatin receptor subtypes 1–5, in transfected COS‐7 cells
Author(s) -
Akbar Mohammed,
Okajima Fumikazu,
Tomura Hideaki,
Majid Mohammed Abdul,
Yamada Yuichiro,
Seino Susumu,
Kondo Yoichi
Publication year - 1994
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(94)00603-2
Subject(s) - forskolin , pertussis toxin , transfection , phospholipase c , somatostatin , somatostatin receptor 3 , somatostatin receptor 2 , g protein , receptor , microbiology and biotechnology , phospholipase d , medicine , endocrinology , stimulation , adenylate kinase , somatostatin receptor , cyclase , phospholipase , chemistry , biology , cell culture , signal transduction , biochemistry , enzyme , genetics
We transfected the COS‐7 cells with cDNAs encoding different human somatostatin receptor (hSSTR) subtypes, and found that hSSTR subtypes mediate not only the inhibition of forskolin‐induced cAMP accumulation but also the stimulation of phospholipase C (PLC) and Ca 2+ mobilization. Activation of PLC by 1 μM somatostatin (SRIF) was in the order of: hSSTR5 ⪢ hSSTR2 ⪢ hSSTR3 ⪢ hSSTR4 ⪢ hSSTR1. Pertussis toxin (PTX) treatment completely or partially reversed the PLC activation. 1 nM SRIF was equally effective for adenylate cyclase (AC) inhibition in a PTX‐sensitive manner, in all the cells expressing different hSSTRs, except for hSSTR1. Nevertheless, SRIF stimulated AC even in the presence of forskolin at higher doses of SRIF in PTX‐treated hSSTR5‐expressing cells. We conclude that the cloned hSSTRs differentially couple to PTX‐sensitive and ‐insensitive G‐proteins to modulate PLC, Ca 2+ mobilization and AC.