This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Smith, J. Articles by Hinkle, P. M. Search for Related Content PubMed PubMed Citation Articles by Smith, J. Articles by Hinkle, P. M. Pubmed/NCBI databases Compound via MeSH Substance via MeSH

Activation of MAPK by TRH Requires Clathrin-Dependent Endocytosis and PKC but Not Receptor Interaction with ß-Arrestin or Receptor Endocytosis

Department of Pharmacology and Physiology and the Cancer Center, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642

Address all correspondence and requests for reprints to: Dr. Patricia M. Hinkle, Department of Pharmacology and Physiology, Box 711, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642. E-mail: Patricia_Hinkle{at}urmc.rochester.edu

To determine whether the interaction of the TRH receptor with ß-arrestin is necessary for TRH activation of MAPK, cells expressing either intact or truncated, internalization-defective TRH receptors were transfected with a ß-arrestin-green fluorescent protein conjugate. In cells expressing the wild-type pituitary TRH receptor, TRH caused translocation of the ß-arrestin-green fluorescent protein conjugate from the cytosol to the plasma membrane within 30 sec. After 5 min, the ß-arrestin-green fluorescent protein conjugate was visible in vesicles, where it colocalized with rhodamine-labeled TRH. In hypertonic sucrose, the ß-arrestin-green fluorescent protein conjugate translocated to the plasma membrane after TRH addition but did not internalize. In cells expressing the truncated TRH receptor, TRH did not cause translocation of the ß-arrestin-green fluorescent protein conjugate. TRH activated MAPK strongly in cells expressing intact or truncated TRH receptors, indicating that the receptor does not need to bind ß-arrestin or internalize. MAPK activation by TRH, epidermal growth factor, and phorbol ester was strongly inhibited by hypertonic sucrose and concanavalin A, which block movement of proteins into coated pits and coated pit assembly. Hypertonic sucrose did not affect MAPK activation in cells overexpressing MAPK kinase 1. Dominant negative dynamin, which blocks conversion of coated pits to vesicles, also reduced receptor internalization and TRH activation of MAPK. TRH activation of MAPK required PKC but was insensitive to pertussis toxin and did not require ras, epidermal growth factor receptor kinase, or PI3K. These results show that the TRH receptor itself does not need to bind ß-arrestin or undergo sequestration to activate MAPK but that the endocytic pathway must be intact.

This article has been cited by other articles:

				H. Nafisi, B. Banihashemi, M. Daigle, and P. R. Albert GAP1(IP4BP)/RASA3 Mediates G{alpha}i-induced Inhibition of Mitogen-activated Protein Kinase J. Biol. Chem., December 19, 2008; 283(51): 35908 - 35917. [Abstract] [Full Text] [PDF]

				L. Luo, N. Yano, and J. Z. Q. Luo The molecular mechanism of EGF receptor activation in pancreatic beta-cells by thyrotropin-releasing hormone Am J Physiol Endocrinol Metab, May 1, 2006; 290(5): E889 - E899. [Abstract] [Full Text] [PDF]

				G. J. Song and P. M. Hinkle Regulated Dimerization of the Thyrotropin-Releasing Hormone Receptor Affects Receptor Trafficking But Not Signaling Mol. Endocrinol., November 1, 2005; 19(11): 2859 - 2870. [Abstract] [Full Text] [PDF]

				C. A. Syme, P. A. Friedman, and A. Bisello Parathyroid Hormone Receptor Trafficking Contributes to the Activation of Extracellular Signal-regulated Kinases but Is Not Required for Regulation of cAMP Signaling J. Biol. Chem., March 25, 2005; 280(12): 11281 - 11288. [Abstract] [Full Text] [PDF]

				P.-W. Chen and G. S. Kroog Alterations in Receptor Expression or Agonist Concentration Change the Pathways Gastrin-Releasing Peptide Receptor Uses to Regulate Extracellular Signal-Regulated Kinase Mol. Pharmacol., December 1, 2004; 66(6): 1625 - 1634. [Abstract] [Full Text] [PDF]

				A. C. Hanyaloglu, R. M. Seeber, T. A. Kohout, R. J. Lefkowitz, and K. A. Eidne Homo- and Hetero-oligomerization of Thyrotropin-releasing Hormone (TRH) Receptor Subtypes. DIFFERENTIAL REGULATION OF beta -ARRESTINS 1 AND 2 J. Biol. Chem., December 20, 2002; 277(52): 50422 - 50430. [Abstract] [Full Text] [PDF]

				B. Banihashemi and P. R. Albert Dopamine-D2S Receptor Inhibition of Calcium Influx, Adenylyl Cyclase, and Mitogen-Activated Protein Kinase in Pituitary Cells: Distinct G{alpha} and G{beta}{gamma} Requirements Mol. Endocrinol., October 1, 2002; 16(10): 2393 - 2404. [Abstract] [Full Text] [PDF]

				V. K. Yadav, R. R. Sudhagar, and R. Medhamurthy Apoptosis During Spontaneous and Prostaglandin F2{alpha}-Induced Luteal Regression in the Buffalo Cow (Bubalus bubalis): Involvementof Mitogen-Activated Protein Kinases Biol Reprod, September 1, 2002; 67(3): 752 - 759. [Abstract] [Full Text] [PDF]

				P. R. Albert G Protein Preferences for Dopamine D2 Inhibition of Prolactin Secretion and DNA Synthesis in GH4 Pituitary Cells Mol. Endocrinol., August 1, 2002; 16(8): 1903 - 1911. [Abstract] [Full Text] [PDF]

				P. R. Albert Editorial: Dopamine-D2-Mediated Inhibition of TRH-Induced PLC Activation in Pituitary Cells--Direct or Indirect? Endocrinology, March 1, 2002; 143(3): 744 - 746. [Full Text] [PDF]