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Thyrotropin-releasing hormone (TRH) receptor number determines the size of the TRH-responsive phosphoinositide pool. Demonstration using controlled expression of TRH receptors by adenovirus mediated gene transfer.

TitleThyrotropin-releasing hormone (TRH) receptor number determines the size of the TRH-responsive phosphoinositide pool. Demonstration using controlled expression of TRH receptors by adenovirus mediated gene transfer.
Publication TypeJournal Article
Year of Publication1994
AuthorsGershengorn MC, Heinflink M, Nussenzveig DR, Hinkle PM, Falck-Pedersen E
JournalJ Biol Chem
Volume269
Issue9
Pagination6779-83
Date Published1994 Mar 04
ISSN0021-9258
KeywordsAdenoviridae, Animals, Calcium, Female, Gene Expression, Gene Transfer Techniques, Genetic Vectors, HeLa Cells, Humans, KB Cells, Kinetics, Mammals, Phosphatidylinositols, Receptors, Thyrotropin-Releasing Hormone, Thyrotropin-Releasing Hormone, Time Factors, Uterine Cervical Neoplasms
Abstract

We use an adenovirus vector, AdCMVmTRHR, to express thyrotropin-releasing hormone (TRH) receptors (TRH-Rs) to determine whether the size of the hormone-responsive phosphoinositide pool in mammalian cells is directly related to receptor number. Infection of HeLa cells with increasing numbers of AdCMVmTRHR caused time-dependent graded expression of TRH-Rs. Measurement of cytoplasmic free Ca2+ in individual cells permitted quantitation of the fraction of cells responsive to TRH. Infection with 100 AdCMVmTRHR particles/cell or more led to TRH responsiveness in > or = 90% of HeLa cells. Measurement of prelabeled phosphoinositides hydrolyzed during prolonged TRH stimulation assesses the size of the TRH-responsive pool. In cells infected with AdCMVmTRHR for 24 h, the size of the TRH-responsive phosphoinositide pool increased with increasing TRH-R expression. The TRH-responsive pool also increased with time after infection as the number of TRH-Rs increased. Similar observations were made in GHY and KB cells. These data confirm our previous suggestion (Cubitt, A. B., Geras-Raaka, E., and Gershengorn, M. C. (1990) Biochem. J. 271, 331-336) that there are hormone-responsive and -unresponsive pools of cellular phosphoinositides and that the maximal size of the TRH-responsive pool is directly related to the number of TRH-Rs.

Alternate JournalJ Biol Chem
PubMed ID8120038
Grant ListDK19974 / DK / NIDDK NIH HHS / United States
DK43046 / DK / NIDDK NIH HHS / United States
GM41967 / GM / NIGMS NIH HHS / United States

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