Photoperiod-dependent proteolytic processing of neuropeptide precursors
Loading...
Files
Date
Authors
Publisher
Philipps-Universität Marburg
Abstract
Body weight in seasonal animals such as the Siberian hamster (Phodopus sungorus) is regulated by a complex interaction of neuropeptides in a hypothalamic network of neurons that integrates environmental photoperiod inputs. Most of these energy balance-regulating neuropeptides derive from larger biologically inactive precursors and have to undergo post-translational processing by endo- and exoproteolytic cleavage. In the current PhD thesis we investigated the effect of photoperiod on the expression of prohormone convertases 1 (PC1/3), 2 (PC2), carboxypeptidase D and E (CPD and CPE) and the proteolytic processing of the neuropeptide precursor pro-opiomelanocortin (POMC) within key energy balance regulating centres of the hypothalamus. We compared mRNA levels and protein distribution of the enzymes PC1/3, PC2, CPD and CPE and the neuropeptide precursor POMC and its derived peptides ACTH, a-MSH and ß-endorphin in selected hypothalamic areas of either long day (LD, 16h light: 8h dark) or short day (SD, 8h light: 16h dark) acclimated Siberian hamsters. Messenger RNA and immunoreactivity of PC1/3 enzyme and neuropeptides cleaved by PC1/3 such as ACTH in the ARC, and orexin A in the LH, were not affected by photoperiod changes. In contrast increased levels of PC2 mRNA and protein were associated with a higher abundance of the mature neuropeptides a-MSH and ß-endorphin in SD. CPE immunoreactivity was increased in SD and after leptin injection suggesting increased terminal activation of neuropeptides subsequent to processing by PC2. The photoperiod-driven regulatory mechanism by differential activity of the major neuroendocrine enzymes on a posttranslational level observed in this study could be an additional universal control point for selective maturation of energy balance related neuropeptides.
Review
Metadata
License
This item has been published with the following license: In Copyright