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Differential expression and seasonal modulation of VGF peptides in sheep pituitary

Brancia, Carla and Nicolussi, Paola and Cappai, Pietro and La Corte, Giorgio and Possenti, Roberta and Ferri, Gian Luca (2005) Differential expression and seasonal modulation of VGF peptides in sheep pituitary. Journal of Endocrinology, Vol. 186 (1), p. 97-107. eISSN 1479-6805. Article.

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DOI: 10.1677/joe.1.05992

Abstract

The inducible gene vgf and its peptide products are relevant to the neuroendocrine regulation of homeostasis and reproduction in rodents. We show here that in the anterior pituitary of female sheep the somatotrope, gonadotrope, and lactotrope/thyrotrope cell populations each expressed vgf mRNA, but displayed a distinct profile of VGF immunoreactive peptides. ProVGF C-terminus and VGF443–588 immunoreactivities were found in lactotropes and thyrotropes, often in a subcellular location restricted to the Golgi area and suggestive of rapid peptide (or proVGF) release upon biosynthesis, while high molecular weight bands consistent with proVGF were shown in pituitary extracts. Distinct seasonal changes were revealed, proVGF C-terminus immunoreactive cells being largely identified as lactotropes during the summer (83·7±2·1% (mean±S.E.M.) versus 27·0±1·9% during the winter), as opposed to thyrotropes during the winter (73·0±1·9% versus 16·3±2·1% during the summer). Conversely, antisera to peptides adjacent to the VGF553–555 ‘Arg-Pro-Arg’ cleavage site, and to the N-terminus of the proVGF-derived peptide V, selectively labeled gonadotropes, indicating processing to small peptides not retaining the proVGF C-terminus in such cells. Finally, a peptide related to the VGF4–240 region was immunostained in somatotropes, shown in a Western blot as a band of relative molecular mass of approximately 16 000. In conclusion, a complex, endocrine cell-typespecific processing of proVGF was revealed. Further to the known inducibility of vgf mRNA upon a range of stimuli, discreet, selective modulations of VGF-peptide profile/s are suggested, possibly involved in specific neuro/ endocrine or modulatory mechanisms.

Item Type:Article
ID Code:1008
Status:Published
Refereed:Yes
Uncontrolled Keywords:VGF peptides, sheep pituitary, neuroendocrine regulation, veterinary endocrinology
Subjects:Area 07 - Scienze agrarie e veterinarie > VET/02 Fisiologia veterinaria
Divisions:002 Altri enti e centri di ricerca del Nord Sardegna > Istituto zooprofilattico sperimentale della Sardegna, Sassari
002 Altri enti e centri di ricerca del Nord Sardegna > Istituto zootecnico e caseario per la Sardegna, Olmedo
Publisher:Society for Endocrinology
eISSN:1479-6805
Publisher Policy:Depositato in conformità con la politica di copyright dell'Editore
Deposited On:18 Aug 2009 10:04

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