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Query: UNIPROT:P01185 (vasopressin)
 23,126 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Most magnocellular hypothalamic neurons synthesize the precursor for either vasopressin (AVP) or oxytocin (OT). The AVP precursor is cleaved to give AVP, AVP-associated neurophysin (AVP-NP) and a glycopeptide (GP), whereas the OT precursor gives OT and OT-NP. In Brattleboro rats a frame-shift mutation in the AVP-NP-encoding region of the gene prevents the secretion of AVP by the cells and, in most AVP neurons, AVP itself is virtually undetectable. A small number of magnocellular neurons in homozygous Brattleboro rats contain very large accumulations of peptide in distended saccules of rough endoplasmic reticulum (RER), and this peptide is immunoreactive for AVP and C-terminal OT-NP, but not for OT, AVP-NP or GP (Pow et al., 1992). We have now shown that this results from somatic non-homologous crossing over of the AVP and OT genes, resulting in the production of hybrid mRNA molecules with the 5'end of the AVP sequence and the 3' end of the OT sequence (AVP/OT transcripts). In most cases, the crossing over occurs within the highly homologous B exons (Mohr et al., 1994). In addition to the production of AVP/OT hybrid transcripts, polymerase chain reaction (PCR) amplification of mRNA from the hypothalami of homozygous rats also reveals OT/AVP hybrid transcripts, with 5' OT sequences and 3' AVP sequences. Furthermore, both types of hybrid transcript are not restricted to homozygous Brattleboro rats but can also be found in normal Long Evans animals. To date, we have not been able to locate cells in which the OT/AVP hybrids are produced; all the magnocellular neurons with hybrid peptide accumulations in the RER so far studied have been shown by immunocytochemistry to be of the AVP/OT type. In both normal and homozygous Brattleboro rats large accumulations of peptide do occur in the RER of OT-producing neurons but the peptide is immunoreactive for OT and OT-NP but not for AVP, AVP-NP or GP. Such cells increase in number 10-fold after injection of 20 micrograms estradiol daily for 7 days (Pow et al., 1991). Why this apparently normal gene product accumulates within the RER remains to be determined.
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PMID:Production of hybrid oxytocin/vasopressin precursors and accumulation of oxytocin precursors in the rough endoplasmic reticulum of rat magnocellular neurons. 871 51

Arginine vasopressin messenger RNA is axonally transported in the rat hypothalamo-neurohypophysial system [for review see Mohr et al. (1993) In Vasopressin (eds Gross P., Richter D. and Robertson C. L.), pp. 119-129, John Libbey Eurotext]. Upon chronic dehydration (2% saline-feeding for seven days), vasopressin messenger RNA within this axonal compartment is dramatically increased and appears aggregated in a selected subset of axonal swellings confined to the median eminence and posterior pituitary. In this study, we analysed the axonal distribution of the vasopressin messenger RNA within the hypothalamo-neurohypophysial tracts of control and saline-fed animals, and compared this distribution to that of the vasopressin peptide. Our data further support a selective aggregation of the vasopressin messenger RNA in a subset of distal axonal swellings and/or terminals of the median eminence and posterior pituitary. The selective aggregation is observed not only in saline-fed animals, but also in control animals. Although the osmotic stimulus dramatically enhances the axonal transport of vasopressin messenger RNA, the consequent general distribution pattern of the messenger RNA in the hypothalamo-neurohypophysial system is not changed. However, the physiological perturbation does increase the number of vasopressin messenger RNA-containing swellings within the median eminence and the posterior pituitary. In both saline-fed and control animals, the level of messenger RNA label within individual swellings appeared roughly similar to that found in the perikaryal cytoplasm of extra-hypothalamic vasopressinergic neurons. A detailed comparison of the axonal compartmentalization of vasopressin messenger RNA and vasopressin peptide demonstrates that the axonal distribution of vasopressin messenger RNA does not precisely overlap that of vasopressin peptide along the hypothalamo-neurohypophysial tract. In seven-day saline-fed animals, the majority of the messenger RNA-containing swellings of the median eminence also contain detectable vasopressin peptide; however in the same animals, nearly all the messenger RNA-containing swellings of the posterior pituitary appear devoid of vasopressin peptide. Therefore, our work strongly suggests that at least in the posterior pituitary, the vasopressin messenger RNA might be selectively targeted and aggregated in a selected subset of axonal swellings containing little if any vasopressin, and hence very few neurosecretory granules. Given this evidence that vasopressin messenger RNA and neuropeptide are differentially compartmentalized in axons of magnocellular neurons, we propose that vasopressin messenger RNA and peptide probably rely on different intracellular transport systems with respect to packaging, transport and/or aggregation within these selected axonal locations.
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PMID:Differential compartmentalization of vasopressin messenger RNA and neuropeptide within the rat hypothalamo-neurohypophysial axonal tracts: light and electron microscopic evidence. 884 17