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

Marvin C. Gershengorn, Marcos Heinflink, Daniel R. Nussenzveig, Patricia M. Hinkle, Erik Falck-Pedersen

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21 Scopus citations


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 ≥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.

Original languageEnglish (US)
Pages (from-to)6779-6783
Number of pages5
JournalJournal of Biological Chemistry
Issue number9
StatePublished - Jan 1 1994


ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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