In vivo multiplex quantitative analysis of 3 forms of alpha melanocyte stimulating hormone in pituitary of prolyl endopeptidase deficient mice

Abstract

Background: In vitro reactions are useful to identify putative enzyme substrates, but in vivo validation is required to identify actual enzyme substrates that have biological meaning. To investigate in vivo effects of prolyl endopeptidase (PREP), a serine protease, on alpha melanocyte stimulating hormone (α-MSH), we developed a new mass spectrometry based technique to quantitate, in multiplex, the various forms of α-MSH.

The Metabolic Serine Hydrolases and Their Functions in Mammalian Physiology and Disease

“…407,408 In mice with a gene-trap cassette inserted into the PREP locus, PREP protein is abolished and α-MSH is also elevated. 399 Consistent with the observation that exogenous administration of neuropeptides such as SP improves learning and memory in rodents, 409 inhibition of PREP in aged rodents 410 or monkeys treated with the dopaminergic neurotoxin MPTP 411 causes cognitive enhancements.…”

“…397 These clan SC peptidases, like other members of the SH superfamily and distinct from serine proteases that belong to clans such as trypsin (PA) or subtilisin (SB), are characterized by a GXSXG motif surrounding the active site serine, a Ser-Asp-His catalytic triad, and adopt or are predicted to adopt an α/β hydrolase fold. Substrates for SH peptidases include polypeptides such as circulating hormones (e.g., glucagon-like peptide-1) 23 or neuropeptides (e.g., melanocyte-stimulating hormone), 399 as well as intact proteins (e.g., collagen), 400 and therefore the action of these peptidases can regulate endocrine signaling or modulate extracellular scaffolding proteins. Clan SC subfamily S9A contains two members, PREP and PREPL.…”

Hypothalamic prolyl endopeptidase (PREP) regulates pancreatic insulin and glucagon secretion in mice

“…BayGenomics clone RRM213 (Mutant Mouse Regional Resource Centers, www.mmrrc.org) was identified as having an insertion in the second intron of the PREP gene in a 129-strain ES cell (9). As protein coding begins in the first exon, the resulting protein in the gene-trap mice would include the first 40 amino acids of this 710-residue protein before the inserted β-galactosidase, as previously reported (9). Founder chimeric mice were bred to B6 for at least 10 generations.…”

Translational research on prolyl oligopeptidase inhibitors: the long road ahead

“…Recently, reports appeared in the literature on experiments with PREP-negative mice. On one hand, these reports support a role of PREP in the degradation of a melanocyte-stimulating hormone and other peptides [23,24]. On the other, Di Daniel et al provided the first solid evidence that PREP has actions in neurons that do not require its peptidase activity [25].…”