Thursday March 12 2009
CEA
Discovering new bioactive neuropeptides in the striatum secretome using in vivo microdialysis and versatile proteomics.
Mol Cell Proteomics (2009) 8 (5): 946-958.
CEA
The striatum, a major component of the brain basal nuclei, is central for planning and executing voluntary movements, and undergoes lesions in neurodegenerative disorders such as Huntington's disease. To perform highly integrated tasks, the striatum relies on a complex network of communication within and between brain regions, with a key role devoted to secreted molecules. To characterize the rat striatum secretome, we combined in vivo microdialysis together with proteomic analysis of trypsin-digests and peptidomic studies of native fragments. This versatile approach, carried out using different microdialysis probes and mass spectrometer devices, allowed evidencing with high confidence the expression of 88 proteins and 100 processed peptides. Their secretory pathways were predicted by in silico analysis. Whereas high molecular weight proteins were mainly secreted by classical mode (94%), low molecular weight proteins equally used classical and non-classical modes (53 and 47% respectively). In addition, our results suggested alternative secretion mechanisms not predicted by bioinformatic tools. Based on spectrum counting, we performed a relative quantification of secreted proteins and peptides in both basal and neuronal depolarization conditions. This allowed detecting a series of neuropeptide precursors, and a six-fold increase for neurosecretory protein VGF and proenkephalin (PENK) levels. A focused investigation and a long-peptide experiment led to the identification of new secreted non-opioid PENK peptides, referred to as PENK 114-133, PENK 239-260 and PENK 143-185. Moreover, we showed that injecting synthetic PENK 114-133 and PENK 239-260 into the striatum robustly increased glutamate release in this region. Thus, the combination of microdialysis and versatile proteomic methods shed new light on the secreted protein repertoire and evidenced novel neuropeptide transmitters.
Bernay B, Gaillard MC, Guryča V, Emadali A, Kuhn L, Bertrand A, Detraz I, Carcenac C, Savasta M, Brouillet E, Garin J, Elalouf JM (2009) Discovering new bioactive neuropeptides in the striatum secretome using in vivo microdialysis and versatile proteomics. Mol Cell Proteomics (sous presse).