Expression analysis of TALE family transcription factors during avian development

Abstract

The TALE family of homeodomain containing transcription factors consists of the Meis, Prep and Tgif, and the Pbx subfamily of proteins. Several TALE orthologues have been identified in amniotes, but no comprehensive analysis of their expression pattern during embryogenesis has been performed. Here, we report on TALE gene expression in the avian embryo. During embryonic development, Pbx genes are predominantly expressed in the neural ectoderm and paraxial mesoderm, although Pbx3 is restricted to the intermediate and lateral mesoderm, and anterior central nervous system. Members of the Meis, Prep, and Tgif subfamilies are expressed at high levels in the paraxial mesoderm, and display differential expression along the anterior-posterior and dorsoventral axes of the developing neural tube. Overall the expression patterns reported in this study are consistent with the known function of the TALE gene family in controlling early patterning of limb, neural tube and paraxial mesoderm tissues during embryogenesis.

Distinct and redundant expression and transcriptional diversity of MEIS gene paralogs during chicken development

“…We observed that from HH5 onward precardiac mesodermal (pm) cells expressed both genes, in a pattern similar to that shown by the pm marker gene Nkx2.5 (Schultheiss et al, 1997). These data corroborate and expand previous reports (e.g., Coy and Borycki, 2010), whose analysis was restricted to only one stage, at around HH4-HH5. Moreover, we did not find Meis2 expression at Hensen's node at any gastrulation stage analyzed, in contrast with what was reported by those authors at HH5.…”

“…Next, we examine the transcriptional diversity of Meis genes during development, in different embryonic tissues and regions of the central nervous system (CNS). Finally, we analyze the tissue distribution of Meis1/2 mRNAs in chicken embryos during early embryogenesis and organogenesis, using in situ hybridization (ISH) on whole-mounts and cryostat sections with chicken cold-labeled RNA probes, extending and complementing recent reports (Coy and Borycki, 2010). In particular, we focus on the comparison of Meis1 and Meis2 gene expression patterns in the chicken, confronting our results with previously published data from other vertebrates.…”

“…The present report is the first exhaustive study examining Meis expression in the chicken forebrain, not analyzed (Coy and Borycki, 2010) or scarcely explored in others works (Marklund et al, 2004;Ferran et al, 2007). From the beginning of neural tube closure (HH9), Meis1/2 expression became progressively established at the level of telencephalon, diencephalon, and midbrain, with some particular topographic differences between the two genes.…”

“…We could identify only two Meis genes, corresponding to Meis1 and Meis2 orthologous, in the current chicken genome assembly (2.1, May 2006), as recently reported (Coy and Borycki, 2010). Given the draft nature of the chicken genome sequence, we also searched the unassembled whole genome shotgun (WGS) sequence traces by BLASTN and tBLASTN using mouse and human Meis3 genes as queries (see the Experimental Procedures section).…”

“…Most tetrapods have three Meis genes (Biemar et al 2001;Coy and Borycki, 2010). In addition, alternative splicing (AS) of each of these genes produce several transcript isoforms (Moskow et al, 1995;Knoepfler et al, 1997;Yang et al, 2000;Williams et al, 2005;Hyman-Walsh et al, 2010), increasing the molecular diversity of the vertebrate MEIS proteins.…”