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J. Biol. Chem., Vol. 283, Issue 5, 2614-2621, February 1, 2008
PKD1, PKD2, and Their Substrate Kidins220 Regulate Neurotensin Secretion in the BON Human Endocrine Cell Line*![]() ![]() ![]() ![]() ![]() ![]() 1
From the
Neurotensin (NT) is a gut peptide that plays an important role in gastrointestinal secretion, motility, and growth as well as the proliferation of NT receptor-positive cancers. Protein kinase D (PKD) family members (PKD1, 2, and 3) have been identified as important regulators of secretory transport at the trans-Golgi network. Previously, we showed that PKD1 contributes to stimulated NT secretion; however, the mechanisms are not entirely clear. Here, we show that Kidins220, which is a substrate of PKD proteins in neuroendocrine cells, is localized in the ends of the processes of BON cells, similar to the expression pattern of NT vesicles, and translocates to the membrane and large vesicle-like structures formed in response to phorbol 12-myristate 13-acetate treatment. The short hairpin RNA targeting Kidins220 inhibits NT secretion in parental BON cells or BON cells stably expressing the gastrin-releasing peptide receptor treated with either phorbol 12-myristate 13-acetate or bombesin, respectively. Furthermore, we demonstrate that endogenous PKD1, PKD2, and Kidins220 co-exist with NT-containing vesicles. Overexpression of the kinase-dead PKD1 abrogates Kidins220 expression and NT vesicle formation. Our data establish a physiological link between the PKD/Kidins220 pathway and NT-containing vesicles and suggest the role of this pathway in the regulation of hormone secretion. Because NT is an important gut hormone that affects secretion, inflammation, and both normal and tumor cell growth, our findings identify a novel signaling pathway that may be amenable to drug targeting for clinical applications.
Received for publication, September 7, 2007 , and in revised form, November 21, 2007. * This work was supported by National Institutes of Health Grants R37 AG10885, R01 DK48489, and P01 DK35608. 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: The University of Texas Medical Branch, 301 University Blvd., Galveston, TX 77555-0536. Tel.: 409-772-5612; Fax: 409-747-4819; E-mail: mevers{at}utmb.edu.
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