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Transgene expression of prion protein induces crinophagy in intermediate pituitary cells
Author(s) -
van Rosmalen Jos W.G.,
Martens Gerard J.M.
Publication year - 2007
Publication title -
developmental neurobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.716
H-Index - 129
eISSN - 1932-846X
pISSN - 1932-8451
DOI - 10.1002/dneu.20330
Subject(s) - transgene , biology , xenopus , proopiomelanocortin , microbiology and biotechnology , green fluorescent protein , prohormone , medicine , endocrinology , gene , biochemistry , hormone
The cellular form of the prion protein (PrP C ) is a plasma membrane‐anchored glycoprotein whose physiological function is poorly understood. Here we report the effect of transgene expression of Xenopus PrP C fused to the C‐terminus of the green fluorescent protein (GFP‐PrP C ) specifically in the neuroendocrine intermediate pituitary melanotrope cells of Xenopus laevis . In the transgenic melanotrope cells, the level of the prohormone proopiomelanocortin (POMC) in the secretory pathway was reduced when the cells were (i) exposed for a relatively long time to the transgene product (by physiologically inducing transgene expression), (ii) metabolically stressed, or (iii) forced to produce unfolded POMC. Intriguingly, although the overall ultrastructure was normal, electron microscopy revealed the induction of lysosomes taking up POMC secretory granules (crinophagy) in the transgenic melanotrope cells, likely causing the reduced POMC levels. Together, our results indicate that in neuroendocrine cells transgene expression of PrP C affects the functioning of the secretory pathway and induces crinophagy. © 2006 Wiley Periodicals, Inc. J Neurobiol 67: 81–96, 2007