Alternatively polyadenylated vasoactive intestinal peptide mRNAs are differentially regulated at the level of stability

Abstract

The role of cis-acting destabilizing RNA sequences in the determination of endocrine gene expression has been investigated using a novel paradigm, in which the differential regulation of two alternatively polyadenylated RNA transcripts may be observed both in vivo and in vitro. In the rat anterior pituitary gland in vivo, we have shown that, after the termination of an estrogen stimulus, a 1.7-kilobase (kb) vasoactive intestinal peptide (VIP) RNA containing an extensive 3'-untranslated region (UTR), is preferentially down-regulated with respect to a 1.0 kb VIP transcript that is uniquely abundant in this tissue. Differential regulation of the anterior pituitary VIP transcripts can be modeled in an explant culture system in which we defined both transcriptional and posttranscriptional phases of VIP gene regulation in vitro, and showed that selective down-regulation of the 1.7-kb transcript is posttranscriptional. Inhibitors of transcription and translation have also allowed us to show in vitro that differential regulation of VIP transcripts occurs through an active process that appears to involve the synthesis of a labile, destabilizing factor. In order to confirm the role of RNA destabilization as the primary mechanism of differential posttranscriptional regulation, we have also performed cell-free stability assays in which explant extracts were incubated with 32P-labeled run-off transcripts corresponding to the two alternatively polyadenylated VIP RNAs. The resultant estimates of RNA half-life showed significantly lower values for the synthetic VIP transcript containing the 3'-UTR. Our findings demonstrate the presence of functional destabilizing sequences in the 3'-UTR of the rat VIP RNA which appear to act in the physiological control of VIP gene expression.

RB and RB2/p130 genes demonstrate both specific and overlapping functions during the early steps of in vitro neural differentiation of marrow stromal stem cells

“…It is worth noting that an increased AChe expression in cells infected with Ad-CMV-Rb or Ad-CMVRb2/p130 did not correspond to an equivalent increase in mRNA levels ( Figure 8). These data further confirm that the AChe gene (as well as VIP) exhibits a multilevel regulation of expression [53][54][55][56] and that an increase in enzymatic activity is not necessarily accompanied by an increase in mRNA level.…”

“…In fact, these genes have a complex regulation at transcriptional, posttranscriptional, translational and post-translational levels. [53][54][55][56] For this reason, the detection of their mRNAs is useful only to determine that the cholinergic pathway has been triggered.…”

The Significance of Vasoactive Intestinal Peptide in Immunomodulation

“…Northern blot analysis of mRNA from spleen lymphocytes showed two transcripts for VIP: a predominant form of 1.0 kb and a less abundant form of approximately 1.7 kb (Leceta et al, 1996). Although the 1.7-kb mRNA is preferentially expressed in most tissues, the 1.0-kb transcript predominates in the anterior pituitary gland (Lara et al, 1994), a product resulting from the utilization of the proximal polyadenylation signal of the prepro-VIP/PHI gene (Chew et al, 1994). This could also be the case in lymphoid cells (Gomariz et al, 1994b).…”

Vasoactive Intestinal Peptide in Thymus: Synthesis, Receptors and Biological Actions

“…Although the 1.7 kb mRNA is preferentially expressed in most tissues, the lowest molecular form predominates in the rat anterior pituitary gland [34]. This transcript is the result of the utilization of the proximal polyadenylation signal of the preproVIP/PHI gene [35]. This could also occur in the lymphoid cells.…”