Differential distribution of VGF-derived peptides in the adrenal medulla and evidence for their selective modulation

Abstract

While vg f gene knockout mice are hyperactive and hypermetabolic, surprisingly the TLQP-21 brain VGF peptide increased energy consumption, suggesting that opposing regulatory effects could be exerted by peptides alternatively cleaved from the VGF precursor. Using antisera to the VGF precursor C-terminus and three cleavage products, we revealed a distinct differential distribution in adrenal, certain peptides (VGF [422][423][424][425][426][427][428][429][430] : PGH peptides) being found throughout bovine and swine medulla, while C-terminus and TLQP peptides were confined to adrenaline cells in the above species and in rat and C-terminally shortened forms (VGF 604-612 : HVLL peptides) to nor-adrenaline cells. Random abattoir samples of bovine and swine adrenal contained 520G40 and 450G60 pmol/g (meanGS.E.M. respectively) of C-terminus peptides and similar or lower amounts of others.Upon gel chromatography, bona fide VGF precursor,~7 . 5 and~3. 5 kDa forms were revealed by C-terminus assays, HVLL peptides being limited to small fragments. TLQP peptides included~7 . 5 kDa form and peaks accounting for TLQP-21 and predicted TLQP-30 and TLQP-42. Low molecular weight (MW) PGH peptides were revealed, together with a high MW form possibly encompassing the VGF precursor N-terminus. In acutely stressed swine, a striking increase was seen for C-terminus and TLQP peptides, with no significant differences for PGH peptides. A similar response was found in rat TLQP peptides showing a major increase upon an acute swimming stress and 30 min thereafter. A differential processing of the VGF precursor encompassing many areas of its primary sequence and selective modulations of its derived peptides occur in adrenal medullary cells, possibly relevant to adaptive homeostatic responses.

Selective expression of TLQP-21 and other VGF peptides in gastric neuroendocrine cells and modulation by feeding

“…The comparable distribution we observed in the two species, as shown previously for the pancreas and adrenal glands (Cocco et al 2007, D'Amato et al 2008, fits well with the largely conserved sequence of the VGF precursor from rat to human, including virtually all its internal cleavage sites (Salton et al 2000). The far higher reactivity found in pig for human (compared with rat) VGF C-terminus antibodies suggests that swine VGF, which is yet to be sequenced, may be similar to the human form in its C-terminal region.…”

“…Of these, the high MW form we observed close to the void volume might correspond to a product cleaved at the rat VGF 431-433 putative cleavage site (Arg-Arg-Lys, Salton et al 2000) and encompassing an extensive domain towards the VGF N-terminus. In the adrenal gland, PGH peptides were also present in a comparable profile of molecular forms; however, PGH immunoreactivity was broadly localised in the whole medulla, while TLQP peptides were confined to adrenalin cells (D'Amato et al 2008). The same or similar peptides were also found in human, in ECL tumour cells (Rindi et al 2007).…”

“…Hence, the rat VGF 556-565 peptide was synthesised and conjugated at its C-terminus (Brancia et al 2005). The rat VGF [422][423][424][425][426][427][428][429][430] 'PGH' peptide, immediately preceding a putative Arg-ArgLys cleavage site, was conjugated via an N-terminal tyrosine , D'Amato et al 2008. The VGF fusion protein antiserum has been described previously in detail (Ferri et al 1992).…”

“…These include peptides encompassing the VGF C-terminal portion, TLQP-21 and TLQP-62 peptides, and the recently identified peptides NERP-1 and -2 (Trani et al 2002, Bartolomucci et al 2007, Yamaguchi et al 2007, Bozdagi et al 2008. While vgf gene expression is distinctly modulated in multiple models and conditions (Levi et al 2004), differential processing and modulation of VGF peptides have been shown so far in the pituitary (Brancia et al 2005), adrenal glands (D'Amato et al 2008) and pancreas (Cocco et al 2007).…”

Chronic intracerebroventricular injection of TLQP-21 prevents high fat diet induced weight gain in fast weight-gaining mice

“…However, E may stimulate b3-ARinduced adenylate-cyclase activity [4] and dose-dependently activate lipolysis in vivo [13]. Accordingly, the mechanism which we hypothesize for the effects of TLQP-21 on adipose tissue is the following: TLQP-21 acting centrally (mechanism still to be determined) would decrease sympathetic tone, resulting in overall decreased NE release in the eWAT nerve endings, thus determining an up-regulation of b3-AR (and to a lower extent also of b1-AR and b2-AR); additionally, TLQP-21 would determine increased E release from chromaffin cells in the adrenal medulla [of note, a recent study identified TLQPimmunostaining in E-but not in NE-chromaffin cells in the adrenal medulla of bovine, swine and rat [23]; the net result would be increased E-stimulated b-AR mediated catabolic effects in the fat pads and resulting resistance to obesity. In agreement, preliminary data from our group show that central TLQP-21 may limit immobilization-induced NE release while increasing late E release (Bartolomucci et al, unpublished observations).…”