Autoregulatory loop and retinoic acid repression regulate pou2/pou5f1 gene expression in the zebrafish embryonic brain

Abstract

Zebrafish pou5f1, also known as pou2, encodes a POU-family transcription factor that is transiently expressed in the prospective midbrain and anterior hindbrain during gastrulation, governing brain development. In the present study, we found that the main regulatory elements reside in the proximal upstream DNA sequence from ؊2.2 to ؊0.12 kb (the ؊2.2/؊0.1 region). The electrophoretic gel mobility shift assay (EMSA) revealed four functional octamer sequences that can associate with zebrafish Pou2/Pou5f1. The expression of mutated reporter constructs, as well as EMSA, suggested that these four octamer sequences operate in a cooperative manner to drive expression in the mid/hindbrain. We also identified a retinoic acid (RA) -responsive element in this proximal region, which was required to repress transcription in the posterior part of the embryo. These data provide a scheme wherein pou2/pou5f1 expression in zebrafish embryos is regulated by both an autoregulatory loop and repression by RA emanating from the posterior mesoderm. Developmental Dynamics 237:1373-1388, 2008.

Pou2, a class V POU-type transcription factor in zebrafish, regulates dorsoventral patterning and convergent extension movement at different blastula stages

“…In this regard, one should mention that the transient expression of pou2 in zebrafish gastrulae is regulated by retinoic acid (RA) and an autoregulatory mechanism (Parvin et al, 2008), as was shown for Oct-3/4 (Niwa, 2007;Schoorlemmer et al, 1994), corroborating the functional conservation between pou2 and Oct-3/4.…”

“…To further confirm the biochemical activities of Pou2, we examined the effects of pou2 and its modified genes in HEK293T cells on the transcriptional activities of the Luc-2.2 reporter, in which pou2 upstream DNA drives transcription depending on four octamer sequences (Parvin et al, 2008). Wild-type pou2 and Oct-3/4 significantly activated Luc-2.2 and vp-pou2 showed much higher enhancing activities, whereas en-pou2 abrogated Luc-2.2 expression (Fig.…”

“…The 2.2-kb upstream pou2 DNA, which drives transcription in embryos through four octamer sequences, as well as the same upstream region lacking the four octamer sequences (Parvin et al, 2008), was ligated into the MCS of pGL4.10[luc2] (Promega) (pLuc-2.2 and pLucD4OS, respectively).…”

DNA Demethylase Activity Maintains Intestinal Cells in an Undifferentiated State Following Loss of APC

“…As RA can directly represses transcription of pou5f1 in the zebrafish by binding to a RARE in the pou5f1 promoter (Parvin et al, 2008) and since a related POU family transcription factor activates expression of aldh1a1 (Guimond et al, 2002), we examined the expression of pou5f1 in apc mcr embryos and found it elevated (Figure 3D). Furthermore, treatment of apc mcr embryos with RA reduced the expression of pou5f1 (Figure 3D).…”

Evolution of gene regulation of pluripotency - the case for wiki tracks at genome browsers

“…Concordantly, Parvin et al [64] describe the zebrafish pou2 proximal promoter, including putative Octamer motifs (which may be bound by pou2) and retinoic-acid responsive elements (which may be bound by nuclear receptors). According to Parvin et al [64], no 'meaningful sequence similarities' between the upstream sequences of pou2 and Oct4 can be identified, though. UCSC data support that the proximal enhancer (CR2 region) is conserved in eutheria and marsupials, and the distal enhancer (CR4 region, highlighted in pink) is conserved at least in eutheria.…”