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Neuroendocrine secretory protein 7B2: structure, expression and functions
M Mbikay1, N G Seidah, M Chrétien
1Diseases of Aging Program, Ottawa Health Research Institute, Ottawa Hospital, University of Ottawa, Ottawa, Ontario, Canada Y1K 4K9. mmbikay@ohri.ca
The Biochemical Journal
|July 6, 2001
Summary
The acidic protein 7B2 acts as a chaperone for proprotein convertase 2 (PC2) in neuroendocrine cells. 7B2 deficiency causes lethal Cushing's disease, highlighting its critical role in regulating hormone secretion.
Area of Science:
- Neuroendocrinology
- Molecular Biology
- Protein Chemistry
Background:
- 7B2 is an acidic secretory granule protein conserved across species, featuring a highly conserved polyproline motif.
- It functions as a specific chaperone for proprotein convertase 2 (PC2), facilitating its maturation and transport.
- The PC2-7B2 interaction regulates proteolytic activation of prohormones in the neuroendocrine system.
Purpose of the Study:
- To elucidate the role of the 7B2 protein in neuroendocrine function and regulation.
- To investigate the mechanism by which 7B2 interacts with PC2.
- To explore the implications of 7B2 dysfunction in human neuroendocrine diseases.
Main Methods:
- Sequence analysis to identify conserved motifs.
- Biochemical studies on the interaction between 7B2 and PC2.
- Phenotypic analysis of 7B2-null mutant mice.
Main Results:
- 7B2 binds to inactive proPC2, aiding its trafficking and maturation in the secretory pathway.
- 7B2-null mice exhibit Cushing's disease due to corticotropin hypersecretion and early mortality.
- 7B2 is implicated in secretory granule formation and secretion regulation, though mechanisms require further study.
Conclusions:
- The PC2-7B2 chaperone system represents a novel paradigm for regulated prohormone processing in neuroendocrine cells.
- 7B2 is essential for survival, likely due to its role in regulating ACTH secretion.
- Dysregulation of 7B2 structure or expression may contribute to neuroendocrine disorders.