Javier Rey-Campos

Fhx(Foxj2) expression is activated during spermatogenesis and very early in embryonic development

FHX (FOXJ2) is a recently characterized human fork head transcriptional activator that binds DNA with a dual sequence specificity. We have cloned the cDNA for the mouse orthologue Foxj2 and characterized its expression in the gonads and along the early pre-implantation development of the mouse. In the testis, Foxj2 is expressed from pachytene spermatocytes to round spermatids, but not in spermatogonia. In addition to the germ lineage, only Sertoli cells of the testis showed expression of Foxj2. In the ovary, only granulosa cells of the follicles express the factor. Neither mature spermatozoa nor oocytes showed expression of Foxj2. Foxj2 expression is early activated in zygotic development, being detected since as early as 8-cell stage embryos. Both cell layers of the blastocyst: the trophectoderm (TE) and the inner cell mass (ICM), express Foxj2.

Functional domains of FOXJ2

FOXJ2 is a fork head transcriptional activator, the expression of which starts very early in embryonic development and it is distributed widely in the adult. Here, we describe the characterization of domains that are important for its function. FOXJ2 is localized constitutively at the nucleus of the cell. Two tyrosine residues and a stretch of basic amino acid residues at the N and C-terminal ends of the fork head domain, respectively, are important for its nuclear targeting. These residues are conserved strongly among all members of the fork head family, suggesting that they could be involved in the nuclear translocation mechanism of all fork head factors. In addition to the AB domain, we have found, at least, two other transactivation domains: Domain I, at the N terminus, and the H/P domain, rich in histidine and proline residues. Although the AB domain shows the strongest transactivation capacity, all three domains are required for full FOXJ2 transcriptional activity. Furthermore, a fourth region rich in proline and glutamine residues and with no intrinsic transactivation function, the P/Q domain, appears to play an important role in the FOXJ2-mediated transactivation mechanism. Although FOXJ2 can be phosphorylated in two serine residues, this post-translational modification did not appear to be essential for transactivation. Finally, we have found that the W2 wing of the fork head domain of FOXJ2 is dispensable for specific DNA binding, although it could have a weak stabilizing role for the DNA-FOXJ2 complex.

DmFoxF, a novel Drosophila fork head factor expressed in visceral mesoderm

DmFoxF is a novel Drosophila fork head domain factor, which is expressed in the visceral mesoderm of the embryo. Our data suggest that DmFoxF is the fly orthologue of the vertebrates FOXF1 and FOXF2 transcription factors. DmFoxF shares homology with FOXF1 and FOXF2 in its fork head domain, and it is able to specifically bind DNA sequences recognized by these vertebrate fork head factors. In stage 10-11 embryos, the DmFoxF protein is detected into the nuclei of cells of the presumptive visceral mesoderm. It localizes at the segmental cell clusters of the mesoderm, which will eventually develop to surround the midgut endoderm. DmFoxF is also expressed in the proctodeal mesoderm, which will develop into the visceral mesoderm of the hindgut.

EVG, the Remnants of a Primordial Bilaterian’s Synteny of Functionally Unrelated Genes

Extant genomes are the result of repeated duplications and subsequent divergence of primordial genes that assembled the genomes of the first living beings. Increased information on genome maps of different species is revealing conserved syntenies among different vertebrate taxa, which allow to trace back the history of current chromosomes. However, inferring neighboring relationships between genes of more primitive genomes has proven to be very difficult. Most often, the ancestral arrangements of genes have been lost by multiple histories of internal duplications, chromosomal breaks, and large-scale genomic rearrangements. Here we describe a gene arrangement of nonrelated genes that seems to have endured evolution, at least from the separation of the two major clades of bilateria: deuterostomia and protostomia, approximately 1 billion years ago. In its simplest conception, this gene cluster, named EVG, groups the genes for a glucose transporter, an enolase, and a vesicle-associated membrane protein (VAMP). EVG might represent the evolutionary remnants of the gene organization of an ancient bilaterian genome.