Somatic nonhomologous crossing-over between neuropeptide genes in rat hypothalamic neurons.

Abstract

(NPv) and that ofthe oxytocin precursor (NPo) are identical in amino acid sequence, with the exception of one position, but the NPs differ at their N and C termini (3). A mutant (Brattleboro) rat strain exists in which homozygotes (BB) lack circulating VP due to a frameshift mutation in exon B of the VP gene; transcription of the mutant gene is almost normal but translation of the corresponding.mRNA yields a VP precursor with a different C terminus (6). Immunohisto chemical data have provided evidence that, in the BB rat, solitary neurons exist that contain VP together with NPo; the latter is coded by the OT precursor gene (7).We report here'the existence in the hypothalamus of wild-type and BB rats of several different types of hybrid transcripts that encode either VP/OT or OT/VP hybrid proteins.MATERIALS AND METHODS Animal. Brattleboro rats were either purchased from Harlan CPB (Austerlitz, The Netherlands) or bred in Oxford. In addition, Wistar rats were used.Preparao iof RNA. Total RNA was extracted from rat hypothalami using the guanidinium isothiocyanate/CsCI protocol or using RNAzol B (Angewandte Gentechnologie Systeme, Heidelberg) according to the protocol recommended by the manufacturer.P 1omea Chai R on (PCR) A a fr-om Revere Trascibed RNA. Rat hypothalamic RNA (extracted from two hypothalami) was converted into single-stranded cDNA using oligo(dT) by reverse transcription, followed by RNase A digestion, phenol extraction, and ethanol precipitation; 1/10th of the cDNA was subjected to PCR amplification. using 1 pM each of a combination of either a VP mRNA forward primer (5'-AGCAGAGCAGAGCTG-CACGC-3') and an OT mRNA reverse primer (5'-TTGAA-GAGGAAATCTGCTTT-3') or an OT mRNA forward primer (5'-ACCATCACCGACOGTGGATC-3') and a VP mRNA reverse primer (5'-TCAGTAGACCCGGGGCTTGG-3') (for sequence information see ref. 8). PCR conditions wereAbbreviations: RAG, recombination-activatig gene; VP, vasopressin; OT, oxytocin; GP, glycopeptide; NP, neurphysi; NPo, NP of the oxytocin precursor; NPv, NP of the vasopressin precursor.tTo whom reprint requests should be addressed. 11403The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.

Arginine vasotocin mRNA revealed by in situ hybridization in bovine pineal gland cells

“…The molecule detected by AVT immunohistochemistry could be a molecule closely related to both vasotocin and vasopressin but not identical with these nonapeptides. A non-homologous crossing-over between genes of neurohypophyseal nonapeptides has recently been shown in the rat hypothalamus (Mohr et al 1994). Also post-translational processing of the molecule translated from vasopressin and vasotocin mRNA might be tissue specific.…”