Translation of the Placenta Growth Factor mRNA is Severely Affected by a Small Open Reading Frame Localized in the 5′ Untranslated Region

Abstract

The recently identified placenta growth factor gene (PIGF) code for a protein related to the vascular permeability factor (VPF). We present evidence indicating that expressing of this gene could be regulated at the post-transcriptional level. The region upstream to the coding region of PIGF mRNA contains a small open reading frame (ORF), potentially coding for a peptide of 15 amino acids. The translation of different constructs in reticulocyte and wheat germ lysates as well as in COS-1 and CV-1 cells indicates that this short region is a translational inhibitory element since mutations in its two potential initiator codons increase PIGF synthesis in vivo. Using RNAse protection assay, we demonstrate that the PIGF mRNAs obtained from human term placenta and JEG choriocarcinoma cell line have a complete 5' untranslated region and, consequently, also the above mentioned small ORF. Finally, the analysis of a bovine PIGF genomic clone reveals that this small ORF is strongly conserved with respect to both putative peptide sequences and distance from the PIGF coding region.

Interleukin 6 Induces the Expression of Vascular Endothelial Growth Factor

“…Furthermore, during megakaryocytic differentiation, in which PDGF-B is produced, translation repression is removed by cis-acting elements (48). Similarly, the 5Ј-UTR of placenta growth factor, albeit shorter (less then 300 bp), is composed of 73% G ϩ C base pairs with a short open reading frame that has an inhibitory effect on translation (12). Our results also demonstrate a possible role for the 5Ј-UTR in VEGF expression.…”

“…Interestingly, VEGF contains a very long (1038 bp) 5Ј-UTR that was also noted in a related cytokine, Platelet-derived growth factor (PDGF), and found to contain all the DNA binding motifs described above. This 5Ј-UTR is characterized by a high G ϩ C content upstream to the translation initiation site which is also characteristic of 5Ј-UTRs corresponding to PDGF, placenta growth factor and TGF-␤ (12)(13)(14).…”

Identification of Placenta Growth Factor Determinants for Binding and Activation of Flt-1 Receptor

“…HU-VEC cells (Cambrex) were grown in endothelial basal medium (EBM-2) containing endothelial growth factor supplements (EGM-2 bullet kit, Cambrex). The cDNAs coding for hPlGF-1 (29) and hFlt-1 were cloned in the pcDNA3 (Invitrogen) mammalian expression vector, and the resulting plasmids were named pchPlGF-1 and pchFlt-1, respectively.…”

Posttranscriptional mRNA processing as a mechanism for regulation of human A1 adenosine receptor expression.

“…Upstream ATG codons are well known to be involved in the translational regulation of gene expression (11)(12)(13). These ATG codons tend to be inhibitory and are found in transcripts which code for critical regulatory proteins such as protooncoproteins, transcription factors, and inflammatory mediators (10,(14)(15)(16)(17)(18)(19)(20). However, this repression is constant and is not modulated with alternative transcripts or in a tissue-specific manner.…”