HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 280, Issue 48, 39818-39826, December 2, 2005

This Article Full Text Full Text (PDF) All Versions of this Article: 280/48/39818    most recent M507193200v1 Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted 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 Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Mulcahy, L. R. Articles by Nillni, E. A. Search for Related Content PubMed PubMed Citation Articles by Mulcahy, L. R. Articles by Nillni, E. A. Social Bookmarking                      What's this?

Prohormone-Convertase 1 Processing Enhances Post-Golgi Sorting of Prothyrotropin-releasing Hormone-derived Peptides^*

Lawrence R. Mulcahy, Charles A. Vaslet, and Eduardo A. Nillni¶1

From the ^¶Department of Medicine, Division of Endocrinology, Brown University Medical School, Rhode Island Hospital, Providence, Rhode Island 02903 and the Department of Molecular and Cellular Biology and Biochemistry and the Department of Pathology and Laboratory Medicine, Brown University, Providence, Rhode Island 02912

Rat prothyrotropin-releasing hormone (pro-TRH) is endoproteolyzed within the regulated secretory pathway of neuroendocrine cells yielding five TRH peptides and seven to nine other unique peptides. Endoproteolysis is performed by two prohormone convertases, PC1 and PC2. Proteolysis of pro-TRH begins in the trans-Golgi network and forms two intermediates that are then differentially processed as they exit the Golgi and are packaged into immature secretory granules. We hypothesized that this initial endoproteolysis may be necessary for downstream sorting of pro-TRH-derived peptides as it occurs before Golgi exit and thus entry into the regulated secretory pathway. We now report that when pro-TRH is transiently expressed in GH4C1 cells, a neuroendocrine cell line lacking PC1, under pulse-chase conditions release is constitutive and composed of more immature processing intermediates. This is also observed by radioimmunoassay under steady-state conditions. When a mutant form of pro-TRH, which has the dibasic sites of initial processing mutated to glycines, is expressed in AtT20 cells, a neuroendocrine cell line endogenously expressing PC1, both steady-state and pulse-chase experiments revealed that peptides derived from this mutant precursor are secreted in a constitutive fashion. A constitutively secreted form of PC1 does not target pro-TRH peptides to the constitutive secretory pathway but results in sorting to the regulated secretory pathway. These results indicated that initial processing action of PC1 on pro-TRH in the trans-Golgi network, and not a cargo-receptor relationship, is important for the downstream sorting events that result in storage of pro-TRH-derived peptides in mature secretory granules.

Received for publication, July 1, 2005 , and in revised form, September 23, 2005.

^* This work was supported in part by NINDS Grant 1R01NS045231 and NIDDK Grant RO1 DK 1-58148 from the National Institutes of Health (to E. A. N.) and National Research Service Predoctoral Fellowship 1F31DA016875-01 from the National Institute on Drug Abuse (to L. R. M.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

¹ To whom correspondence should be addressed: Division of Endocrinology, 55 Claverick St., Rm. 430, Providence, RI 02903. Tel.: 401-444-5733; Fax: 401-444-4694; E-mail: Eduardo_Nillni{at}Brown.edu.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				A. Romero, I. Cakir, C. A. Vaslet, R. C. Stuart, O. Lansari, H. A. Lucero, and E. A. Nillni Role of a Pro-sequence in the Secretory Pathway of Prothyrotropin-releasing Hormone J. Biol. Chem., November 14, 2008; 283(46): 31438 - 31448. [Abstract] [Full Text] [PDF]

				M. Perello, R. Stuart, and E. A. Nillni Prothyrotropin-releasing Hormone Targets Its Processing Products to Different Vesicles of the Secretory Pathway J. Biol. Chem., July 18, 2008; 283(29): 19936 - 19947. [Abstract] [Full Text] [PDF]

				L. E. Pritchard and A. White Neuropeptide Processing and Its Impact on Melanocortin Pathways Endocrinology, September 1, 2007; 148(9): 4201 - 4207. [Abstract] [Full Text] [PDF]

				J. D. Dikeakos and T. L. Reudelhuber Sending proteins to dense core secretory granules: still a lot to sort out J. Cell Biol., April 23, 2007; 177(2): 191 - 196. [Abstract] [Full Text] [PDF]