Tissue-specific alternative splicing of turkey preprovasoactive intestinal peptide messenger ribonucleic acid, its regulation, and correlation with prolactin secretion.

Abstract

Although vasoactive intestinal peptide (VIP) is a well characterized physiological PRL-releasing factor in avian species, its regulated expression is not fully understood. We cloned complementary DNAs encoding the prepro-turkey VIP (prepro-tVIP) molecule from an adult turkey hypothalamic complementary DNA library. When the amino acid sequence of the prepro-tVIP was compared to chicken and mammalian sequence, it was found that the isolated tVIP molecules lacked the 27-amino acid peptide histidine isoleucine (PHI) portion of the precursor protein. Several tissues showed an alternatively spliced tVIP transcript that lacked the PHI sequence. Only in the hypothalamus did tVIP-specific primer pairs and reverse transcription-polymerase chain reaction produce two alternatively spliced fragments. The larger hypothalamus-specific fragment was subjected to nucleotide sequence analysis and identified as containing the alternatively spliced PHI-containing exon, which encoded a 27-amino acid PHI peptide in addition to the 8 amino acids that flanked the peptide. Hypothalamic tVIP expression was shown to be up-regulated during the incubation phase of the reproductive cycle. The increased steady state level of tVIP messenger RNA appears to be regulated by nesting behavior, because nest deprivation dramatically suppressed its expression. Levels of the minor tVIP transcript containing both the PHI- and VIP-encoding exons did not significantly change between reproductive stages and were maintained at approximately 4-6% of the total tVIP transcript level. Our findings provide further evidence that VIP is the most important PRL-releasing factor in birds. Our study should serve as a useful model for determining whether PHI contributes in any way to the physiological role of PRL regulation. Revealing the tissue distribution of VIP and PHI gene expression and tissue-specific alternative splicing could contribute to an understanding of the physiological functions of the two peptides as well as their relative roles in PRL regulation.

Comparative Changes in the Serum Concentrations of Inhibin-B, Prolactin, Gonadotropins and Steroid Hormones at Different Reproductive States in Domestic Turkey Hens

“…Prolactin decreases reproductive activity by acting on the hypothalamus and inhibiting gonadotropin-releasing hormone release, acts on the pituitary to reduce LH-β subunit mRNA expression and LH release [56] and acts directly on the ovary, reducing steroidogenic enzyme mRNA expression, thus inhibiting steroid hormone production [57]. The prolonged elevation of the levels of prolactin during the incubation period has an antisteroidogenic effect on the ovary [58][59][60][61] in part via inhibition of steroidogenic enzyme gene expression [57].…”

Identification of a Potential Receptor for Both Peptide Histidine Isoleucine and Peptide Histidine Valine

“…Interestingly, the structures of goldfish PHIs appear to be more closely related to those of mammalian PHI/PHM (74 -78% identity) than those of avian PHI (59% identity). In chicken and turkey, the major form of transcripts is prepro-VIP (98%), which lacks the PHI-encoding region (40,43). A longer transcript, prepro-PHI/VIP, also exists but at much lower levels (about 2%).…”

Vasoactive intestinal peptide stimulates turkey prolactin gene expression by increasing transcription rate and enhancing mRNA stability

“…Changes in the number and size of VIP immunoreactive cells have been demonstrated to parallel plasma concentrations of PRL in chickens (Sharp et al 1989), turkeys (Mauro et al 1989) and doves (Cloues et al 1990). Hypothalamic VIP content, VIP mRNA abundance and the affinity of anterior pituitary VIP-binding sites have been shown to be positively correlated with the concentration of plasma PRL in turkeys (Mauro et al 1992, Rozenboim & El Halawani 1993, You et al 1995. Furthermore, in vivo administration of VIP has been shown to increase plasma PRL concentrations in ring doves (Lea & Vowles 1986), chickens (Macnamee et al 1986, Talbot et al 1991 and turkeys (Pitts et al 1994a).…”