The chromogranin/secretogranins (or """"""""granins"""""""") are a family of regulated secretory proteins ubiquitously found in the cores of amine and peptide hormone and neurotransmitter secretory vesicles. Evidence has now been gathered in support of both intracellular and extracellular functions for this protein family. Within the cells of origin, a granulogenic or sorting role in the regulated pathway of hormone or neurotransmitter secretion has been documented, especially for its index member, chromogranin A (CgA). Granins also function as pro-hormones, giving rise by proteolytic processing to a large array of peptide fragments for which diverse autocrine, paracrine, and endocrine activities have been demonstrated in vitro, ex vivo and more recently in vivo. For example, CgA fragments vasostatin and catestatin control vasoreactivity and catecholamine release, and the CgA fragment pancreastatin elevates blood glucose. This proposal develops 2 specific aims, employing novel granins chimeric proteins, to investigate in situ, mechanisms whereby chromogranin (CgA) is sorted into catecholamine storage granule of sympathoadrenal chromaffin cells, and interacts with other secreted or membrane proteins of the secretory granule. The responses to be investigated are exocytosis and FRET (fluorescence resonance energy transfer) molecular communication resulting from protein-protein interaction.
In aim 1, we will use a series of CgA domains tagged with green fluorescent protein (GFP) or embryonic alkaline phosphatase (EAP), to identify in situ, the putative sorting signals within the primary structure of CgA (cis determinant) that mediate CgA's targeting to the chromaffin granule.
In aim 2, granin chimeric proteins will be used to investigate in the living cell, which determinants of the secretory apparatus (trans determinants) interact with CgA to influence sorting of the granin into the regulated secretory pathway and its storage within the core of the catecholamine storage granule. The results of these studies will enhance our knowledge of catecholamine/granins storage and release during sympathetic stimulation, leading to a better understanding of neuroendocrine secretory granule biogenesis .

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Scientist Development Award - Research & Training (K01)
Project #
5K01DK059628-05
Application #
6858705
Study Section
Diabetes, Endocrinology and Metabolic Diseases B Subcommittee (DDK)
Program Officer
Hyde, James F
Project Start
2004-06-01
Project End
2007-05-31
Budget Start
2005-06-01
Budget End
2007-05-31
Support Year
5
Fiscal Year
2005
Total Cost
$121,770
Indirect Cost
Name
University of California San Diego
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
804355790
City
La Jolla
State
CA
Country
United States
Zip Code
92093
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Stettler, Hansruedi; Beuret, Nicole; Prescianotto-Baschong, Cristina et al. (2009) Determinants for chromogranin A sorting into the regulated secretory pathway are also sufficient to generate granule-like structures in non-endocrine cells. Biochem J 418:81-91
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