Distinct systemic distribution of salusin-α and salusin-β in the rat

Salusin-alpha and salusin-beta are multifunctional bioactive peptides that were initially predicted using in silico analyses. These peptides should be concomitantly biosynthesized from prosalusin in humans. However, little information is available yet on the biosynthesis and mode of presence of salusin-alpha and salusin-beta in non-human species. In the present study, we examined whether salusin-alpha and salusin-beta are conserved in the rat and whether salusin-alpha and salusin-beta allow distinct systemic distributions. Immunohistochemical analysis of rat tissues using a specific anti-rat salusin-alpha antibody detected immunoreactivity extensively in neuronal cells and fibers, and abundantly in the epithelial tissues throughout the organs. This distribution contrasts sharply with that of salusin-beta. which is mainly localized to the neuroendocrine and hematopoietic systems. Western blot analysis of rat spleen extracts showed the presence of cleaved fragments corresponding to putative rat salusin-alpha. Reverse-phase and gel filtration high performance liquid chromatography analyses coupled with radioimmunoassay detection of rat urine extracts revealed a major immunoreactive component that co-eluted with synthetic putative rat salusin-beta. These data support the processing of rat prosalusin into salusin-alpha and salusin-beta despite absent dibasic amino acids between the two. (C) 2010 Elsevier Inc. All rights reserved.