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PubMed2005

The Vgamma2/Vdelta2 T-cell repertoire in Macaca fascicularis: functional responses to phosphoantigen stimulation by the Vgamma2/Jgamma1.2 subset.

Circulating Vgamma2/Vdelta2 T cells in human and non-human primates respond to small molecular weight non-peptidic phosphoantigens in a major histocompatibility complex (MHC)-unrestricted manner. These responses are encoded by the Vgamma2/Jgamma1.2 chain of the T-cell receptor and are positively selected during early development to create a biased repertoire in adults. We characterized the Vgamma2 chain in cynomolgus macaques (Macaca fascicularis) to develop a non-human primate model for studying the effects of infection and therapy on the circulating Vgamma2/Vdelta2 T-cell subset. The cynomolgus macaque Vgamma2 chain was highly homologous to the Vgamma2 chain from human beings and rhesus macaques (Macaca mulatta), though we noted conserved substitutions in critical residues within the CDR3 for both macaque species. Despite these substitutions, Vgamma2/Vdelta2+ T cells from cynomolgus monkeys exhibited polyclonal responses to two different phosphoantigens. Proliferative responses were observed with both isopentenylpyrophosphate and alendronate, but stronger interferon-gamma secretory responses were observed with isopentenylpyrophosphate. In vitro stimulation and expansion led to selective outgrowth of the Vgamma2/Jgamma1.2 subset, with a marked shift in the Vgamma2 spectratype. As a result of the less biased starting repertoire for Vgamma2, the cynomolgus macaque constitutes a sensitive model for examining the effects of in vitro or in vivo treatments on the Vgamma2/Vdelta2 T-cell population. Our studies establish the value of cynomolgus macaques as a model for Vgamma2/Vdelta2 T-cell responses to non-peptidic antigens, and further evidence the remarkable evolutionary conservation of this unusual, phosphoantigen-responsive T-cell subset that is found only in primate species.

Alendronate↗
PubMed2005

ELAV multimerizes on conserved AU4-6 motifs important for ewg splicing regulation.

ELAV is a gene-specific regulator of alternative pre-mRNA processing in Drosophila neurons. Since ELAV/Hu proteins preferentially bind to AU-rich regions that are generally abundant in introns and untranslated regions, it has not been clear how gene specificity is achieved. Here we used a combination of in vitro biochemical experiments together with phylogenetic comparisons and in vivo analysis of Drosophila transgenes to study ELAV binding to the last ewg intron and splicing regulation. In vitro binding studies of ELAV show that ELAV multimerizes on the ewg binding site and forms a defined and saturable complex. Further, sizing of the ELAV-RNA complex and a series of titration experiments indicate that ELAV forms a dodecameric complex on 135 nucleotides in the last ewg intron. Analysis of the substrate RNA requirements for ELAV binding and complex formation indicates that a series of AU(4-6) motifs spread over the entire binding site are important, but not a strictly defined sequence element. The importance of AU(4-6) motifs, but not spacing between them, is further supported by evolutionary conservation in several melanogaster species subgroups. Finally, using transgenes we demonstrate in fly neurons that ELAV-mediated regulation of ewg intron 6 splicing requires several AU(4-6) motifs and that introduction of spacer sequence between conserved AU(4-6) motifs has a minimal effect on splicing. Collectively, our results suggest that ELAV multimerization and binding to multiple AU(4-6) motifs contribute to target RNA recognition and processing in a complex cellular environment.

AT Rich Sequence↗
PubMed2002

The Drosophila retained/dead ringer gene and ARID gene family function during development.

The recently discovered ARID family of proteins interact with DNA through a phylogenetically conserved sequence termed the A/T Interaction Domain (ARID). The retained/dead ringer (retn/dri) gene of Drosophila melanogaster is a founding member of the ARID gene family, and of the eARID subfamily. This subfamily exhibits an extended region of sequence similarity beyond the core ARID motif and a separate conserved domain termed the REKLES domain. retn/dri is involved in a range of developmental processes, including axis patterning and muscle development. The retn/dri ARID motif has been shown by in vitro studies to exhibit sequence-specific DNA binding activity. Here we demonstrate that the ARID domain is essential for the in vivo function of retn/dri during embryonic development by showing that a mutant form of RETN/DRI, deleted for part of the ARID domain and unable to bind DNA in vitro, cannot rescue the retn/dri mutant phenotype. In the presence of wild-type RETN/DRI this construct acts as a dominant negative, providing additional support for the proposal that RETN/DRI acts in a multiprotein complex. In contrast, we are yet to find an in vivo role for the REKLES domain, despite its clear evolutionary conservation. Finally, we have used germline clone analysis to reveal a requirement for retn/dri in the Drosophila preblastoderm syncytial mitoses.

Amino Acid Motifs↗
PubMed2001

Mutations in the Drosophila dTAK1 gene reveal a conserved function for MAPKKKs in the control of rel/NF-kappaB-dependent innate immune responses.

In mammals, TAK1, a MAPKKK kinase, is implicated in multiple signaling processes, including the regulation of NF-kappaB activity via the IL1-R/TLR pathways. TAK1 function has largely been studied in cultured cells, and its in vivo function is not fully understood. We have isolated null mutations in the Drosophila dTAK1 gene that encodes dTAK1, a homolog of TAK1. dTAK1 mutant flies are viable and fertile, but they do not produce antibacterial peptides and are highly susceptible to Gram-negative bacterial infection. This phenotype is similar to the phenotypes generated by mutations in components of the Drosophila Imd pathway. Our genetic studies also indicate that dTAK1 functions downstream of the Imd protein and upstream of the IKK complex in the Imd pathway that controls the Rel/NF-kappaB like transactivator Relish. In addition, our epistatic analysis places the caspase, Dredd, downstream of the IKK complex, which supports the idea that Relish is processed and activated by a caspase activity. Our genetic demonstration of dTAK1's role in the regulation of Drosophila antimicrobial peptide gene expression suggests an evolutionary conserved role for TAK1 in the activation of Rel/NF-kappaB-mediated host defense reactions.

Amino Acid Sequence↗
PubMed1996

Transcriptional regulator of programmed cell death encoded by Caenorhabditis elegans gene ces-2.

The ces (for cell-death specification) genes of the nematode Caenorhabditis elegans control the cell-death fate of individual cell types and are candidates for being the regulators of an evolutionarily conserved general pathway of programmed cell death. Here we present what we believe is the first molecular characterization of a ces gene. We cloned the gene ces-2, which is required to activate programmed cell death in the sister cells of the serotoninergic neurosecretory motor (NSM) neurons, and found that ces-2 encodes a basic region leucine-zipper (bZIP) transcription factor. The CES-2 protein is most similar to members of the PAR (proline- and acid-rich) subfamily of bZIP proteins and has DNA-binding specificity like that of PAR-family proteins. An oncogenic form of the mammalian PAR-family protein, hepatic leukaemia factor (HLF), is reported to effect programmed cell death in mammalian cells. On the basis of these observations, we suggest that some CES-2/PAR family transcription factors are evolutionary conserved regulators of programmed cell death.

Amino Acid Sequence↗
PubMed1998

Identification of a TRAF (TNF receptor-associated factor) gene in Caenorhabditis elegans.

Many members of the tumor necrosis factor (TNF) receptor superfamily and the interleukin-1 (IL-1) receptor engage intracellular signaling pathways including the nuclear factor kappaB (NF-kappaB)-, c-jun N-terminal kinase (JNK)-, and extracellular signal-regulated kinase (ERK) pathways by direct or indirect interaction with TNF receptor-associated factor (TRAF) molecules. To date, six mammalian members of the TRAF family have been identified. Searching public databases with a sequence pattern comprising 19 conserved amino acid residues derived from the carboxyl-terminal part of the TRAF homology domain, we found significant sequence homologies to a stretch of genomic DNA from Caenorhabditis elegans which encodes 1 of 12 exons of a putative protein. The sequence of this putative protein shows up to 29% sequence identity to the mammalian TRAFs and is therefore designated C. elegans TRAF (CeTRAF). The CeTRAF molecule has an amino-terminal RING finger motif followed by four zinc finger structures and a carboxyl-terminal TRAF domain, a composition which is also found in most of the mammalian TRAFs. Reverse transcription-PCR and sequencing analysis of the respective amplicon clearly demonstrates that CeTRAF is in fact transcribed in C. elegans. The existence of a member of the TRAF family in C. elegans provides strong evidence for evolutionary conserved pathways linking cell surface receptors to activation of JNK, ERK, and NF-kappaB.

Amino Acid Sequence↗
PubMed2004

Functional roles for evolutionarily conserved Spt4p at centromeres and heterochromatin in Saccharomyces cerevisiae.

The kinetochore (centromeric DNA and associated proteins) mediates the attachment of chromosomes to the mitotic spindle apparatus and is required for faithful chromosome transmission. We established that evolutionarily conserved Saccharomyces cerevisiae SPT4, previously identified in genetic screens for defects in chromosome transmission fidelity (ctf), encodes a new structural component of specialized chromatin at kinetochores and heterochromatic loci, with roles in kinetochore function and gene silencing. Using chromatin immunoprecipitation assays (ChIP), we determined that kinetochore proteins Ndc10p, Cac1p, and Hir1p are required for the association of Spt4p to centromeric (CEN) loci. Absence of functional Spt4p leads to altered chromatin structure at the CEN DNA and mislocalization of the mammalian CENP-A homolog Cse4p to noncentromeric loci. Spt4p associates with telomeres (TEL) and HMRa loci in a Sir3p-dependent manner and is required for transcriptional gene silencing. We show that a human homolog of SPT4 (HsSPT4) complements Scspt4-silencing defects and associates with ScCEN DNA in an Ndc10p-dependent manner. Our results highlight the evolutionary conservation of pathways required for genome stability in yeast and humans.

Centromere↗
PubMed1998

SVOP, an evolutionarily conserved synaptic vesicle protein, suggests novel transport functions of synaptic vesicles.

We describe a novel synaptic vesicle protein called SVOP that is distantly related to the synaptic vesicle proteins SV2A, SV2B, and SV2C (20-22% sequence identity). Both SVOP and SV2 contain 12 transmembrane regions. However, SV2 is highly glycosylated, whereas SVOP is not. Databank searches revealed that closely related homologs of SVOP are present in Caenorhabditis elegans and Drosophila (48% sequence identity), suggesting that SVOP is evolutionarily ancient. In contrast, no invertebrate orthologs of SV2 were detected. The sequences of SVOP and SV2 exhibit homology with transport proteins, in particular with mammalian organic cation and anion transporters. SVOP and SV2 are more distantly related to eukaryotic and bacterial phosphate, sugar, and organic acid transporters. SVOP is expressed at detectable levels only in brain and endocrine cells where it is primarily localized to synaptic vesicles and microvesicles. SVOP is present in all brain regions, with particularly high levels in large pyramidal neurons of the cerebral cortex. Immunocytochemical staining of adjacent rat brain sections for SVOP and SV2 demonstrated that SVOP and SV2 are probably coexpressed in most neurons. Although the functions of SV2 and SVOP remain obscure, the evolutionary conservation of SVOP, its hydrophobic nature, and its homology to transporters strongly support a role in the uptake of a novel, as yet unidentified component of synaptic vesicles. Thus synaptic vesicles contain two classes of abundant proteins with 12 transmembrane regions that are related to transporters, nonglycosylated SVOP and highly glycosylated SV2, suggesting that the transport functions of synaptic vesicles may be more complex than currently envisioned.

Adrenal Glands↗
PubMed2006

Odd-skipped genes encode repressors that control kidney development.

Odd-skipped family of proteins (Odd in Drosophila and Osr in vertebrates) are evolutionarily conserved zinc finger transcription factors. Two Osr genes are present in mammalian genomes, and it was recently reported that Osr1, but not Osr2, is required for murine kidney development. Here, we show that in Xenopus and zebrafish both Osr1 and Osr2 are necessary and sufficient for the development of the pronephros. Osr genes are expressed in early prospective pronephric territories, and morphants for either of the two genes show severely impaired kidney development. Conversely, overexpression of Osr genes promotes formation of ectopic kidney tissue. Molecularly, Osr proteins function as transcriptional repressors during kidney formation. We also show that Drosophila Odd induces kidney tissue in Xenopus. This might be accomplished through recruitment of Groucho-like co-repressors. Odd genes may also be required for proper development of the Malpighian tubules, the Drosophila renal organs. Our results highlight the evolutionary conserved involvement of Odd-skipped transcription factors in the development of kidneys.

Animals↗
PubMed1995

SMC2, a Saccharomyces cerevisiae gene essential for chromosome segregation and condensation, defines a subgroup within the SMC family.

We characterized the SMC2 (structural maintenance of chromosomes) gene that encodes a new Saccharomyces cerevisiae member of the growing family of SMC proteins. This family of evolutionary conserved proteins was introduced with identification of SMC1, a gene essential for chromosome segregation in budding yeast. The analysis of the putative structure of the Smc2 protein (Smc2p) suggests that it defines a distinct subgroup within the SMC family. This subgroup includes the ScII, XCAPE, and cut14 proteins characterized concurrently. Smc2p is a nuclear, 135-kD protein that is essential for vegetative growth. The temperature-sensitive mutation, smc2-6, confers a defect in chromosome segregation and causes partial chromosome decondensation in cells arrested in mitosis. The Smc2p molecules are able to form complexes in vivo both with Smc1p and with themselves, suggesting that they can assemble into a multimeric structure. In this study we present the first evidence that two proteins belonging to two different subgroups within the SMC family carry nonredundant biological functions. Based on genetic, biochemical, and evolutionary data we propose that the SMC family is a group of prokaryotic and eukaryotic chromosomal proteins that are likely to be one of the key components in establishing the ordered structure of chromosomes.

Amino Acid Sequence↗
PubMed2002

The KLHL1-antisense transcript ( KLHL1AS) is evolutionarily conserved.

Spinocerebellar ataxia type 8 (SCA8) is caused by a CTG expansion in an untranslated, endogenous antisense RNA that overlaps the Kelch-like 1 ( KLHL1) gene. The normal function of this transcript is currently unknown. We have now identified the promoter region for the KLHL1-antisense ( KLHL1AS) RNA and report that a Klhl1as transcript is present in the mouse as well. Human and mouse KLHL1AS are transcribed from homologous promoter regions in the first intron of KLHL1 and extend through the transcription and translation start sites as well as the first splice donor sequence of KLHL1. We found that the mouse Klhl1as RNA is not spliced and terminates in a polyadenylation site in the Klhl1 promoter region, whereas both the present and previous work show that human KLHL1AS is highly variably spliced into processed transcripts that contain up to six exons. Mouse Klhl1as transcript was detected in RNA isolated from the cerebellum and from total adult brain and total fetal tissue, and at a low level in testis and ovary. Similarly, human KLHL1AS is expressed in various brain tissues, including the cerebellum, the tissue most affected by SCA8, and was detected at low levels in testis and kidney. The evolutionary conservation of this antisense/sense transcriptional organization strongly indicates that KLHL1AS transcripts play a significant biological role in both human and mouse, presumably as a regulator of KLHL1 expression.

Animals↗
PubMed2005

Identification of a new pebp2alphaA2 isoform from zebrafish runx2 capable of inducing osteocalcin gene expression in vitro.

UNLABELLED: The zebrafish runx2b transcription factor is an ortholog of RUNX2 and is highly conserved at the structural level. The runx2b pebp2alphaA2 isoform induces osteocalcin gene expression by binding to a specific region of the promoter and seems to have been selectively conserved in the teleost lineage. INTRODUCTION: RUNX2 (also known as CBFA1/Osf2/AML3/PEBP2alphaA) is a transcription factor essential for bone formation in mammals, as well as for osteoblast and chondrocyte differentiation, through regulation of expression of several bone- and cartilage-related genes. Since its discovery, Runx2 has been the subject of intense studies, mainly focused in unveiling regulatory targets of this transcription factor in high vertebrates. However, no single study has been published addressing the role of Runx2 in bone metabolism of low vertebrates. While analyzing the zebrafish (Danio rerio) runx2 gene, we identified the presence of two orthologs of RUNX2, which we named runx2a and runx2b and cloned a pebp2alphaA-like transcript of the runx2b gene, which we named pebp2alphaA2. MATERIALS AND METHODS: Zebrafish runx2b gene and cDNA were isolated by RT-PCR and sequence data mining. The 3D structure of runx2b runt domain was modeled using mouse Runx1 runt as template. The regulatory effect of pebp2alphaA2 on osteocalcin expression was analyzed by transient co-transfection experiments using a luciferase reporter gene. Phylogenetic analysis of available Runx sequences was performed with TREE_PUZZLE 5.2. and MrBayes. RESULTS AND CONCLUSIONS: We showed that the runx2b gene structure is highly conserved between mammals and fish. Zebrafish runx2b has two promoter regions separated by a large intron. Sequence analysis suggested that the runx2b gene encodes three distinct isoforms, by a combination of alternative splicing and differential promoter activation, as described for the human gene. We have cloned a pebp2alphaA-like transcript of the runx2b gene, which we named pebp2alphaA2, and showed its high degree of sequence similarity with the mammalian pebp2alphaA. The cloned zebrafish osteocalcin promoter was found to contain three putative runx2-binding elements, and one of them, located at -221 from the ATG, was capable of mediating pebp2alphaA2 transactivation. In addition, cross-species transactivation was also confirmed because the mouse Cbfa1 was able to induce the zebrafish osteocalcin promoter, whereas the zebrafish pebp2alphaA2 activated the murine osteocalcin promoter. These results are consistent with the high degree of evolutionary conservation of these proteins. The 3D structure of the runx2b runt domain was modeled based on the runt domain of mouse Runx1. Results show a high degree of similarity in the 3D configuration of the DNA binding regions from both domains, with significant differences only observed in non-DNA binding regions or in DNA-binding regions known to accommodate considerable structure flexibility. Phylogenetic analysis was used to clarify the relationship between the isoforms of each of the two zebrafish Runx2 orthologs and other Runx proteins. Both zebrafish runx2 genes clustered with other Runx2 sequences. The duplication event seemed, however, to be so old that, whereas Runx2b clearly clusters with the other fish sequences, it is unclear whether Runx2a clusters with Runx2 from higher vertebrates or from other fish.

Amino Acid Sequence↗
PubMed1996

Cloning of Schizosaccharomyces pombe rph16+, a gene homologous to the Saccharomyces cerevisiae RAD16 gene.

The RAD16 gene is involved in the nucleotide excision repair of UV damage in the transcriptional silenced mating type loci (Terleth et al., 1990 and Bang et al., 1992) and in non-transcribed stands of active genes in Saccharomyces cerevisiae (Verhage et al., 1994). Using touchdown-PCR with primers derived from various domains of the S. cerevisiae Rad 16 protein, a specific Schizosaccharomyces pombe probe was isolated. This probe was used to obtain the complete RAD16 homologous gene from a S. pombe chromosomal bank. DNA sequence analysis of the rph16+ gene revealed an open reading frame of 854 amino acids. Comparison of the amino acid sequences of the Rhp16 and Rad16 proteins showed a high level of conservation: 68% similarity. The Rhp16 protein sequence contains the two Zn-finger motifs and the putative helicase domains as found in the Rad16 protein. Like the RAD16, the rph16+ gene is UV-inducible (Bang et al., 1995). In analogy with the rad16 mutant, the rhp16 disruption mutant is viable and grows normally, indicating that the gene does not have an essential function. The rhp16 disruption mutant is not sensitive for UV but is sensitive for cisplatin. The rhp16+ gene cloned behind the GAI 1 promoter partially complements the UV sensitivity and the defect in the non-transcribed strand DNA repair of a S. cerevisiae rad16 mutant, indicating functional homology between the rhp16+ and RAD16 genes. The structural and functional homology between the two genes suggests that the RAD16 dependent subpathway of NER for the repair of non-transcribed DNA is evolutionary conserved.

Adenosine Triphosphatases↗
PubMed2006

Gene function and expression level influence the insertion/fixation dynamics of distinct transposon families in mammalian introns.

BACKGROUND: Transposable elements (TEs) represent more than 45% of the human and mouse genomes. Both parasitic and mutualistic features have been shown to apply to the host-TE relationship but a comprehensive scenario of the forces driving TE fixation within mammalian genes is still missing. RESULTS: We show that intronic multispecies conserved sequences (MCSs) have been affecting TE integration frequency over time. We verify that a selective economizing pressure has been acting on TEs to decrease their frequency in highly expressed genes. After correcting for GC content, MCS density and intron size, we identified TE-enriched and TE-depleted gene categories. In addition to developmental regulators and transcription factors, TE-depleted regions encompass loci that might require subtle regulation of transcript levels or precise activation timing, such as growth factors, cytokines, hormones, and genes involved in the immune response. The latter, despite having reduced frequencies of most TE types, are significantly enriched in mammalian-wide interspersed repeats (MIRs). Analysis of orthologous genes indicated that MIR over-representation also occurs in dog and opossum immune response genes, suggesting, given the partially independent origin of MIR sequences in eutheria and metatheria, the evolutionary conservation of a specific function for MIRs located in these loci. Consistently, the core MIR sequence is over-represented in defense response genes compared to the background intronic frequency. CONCLUSION: Our data indicate that gene function, expression level, and sequence conservation influence TE insertion/fixation in mammalian introns. Moreover, we provide the first report showing that a specific TE family is evolutionarily associated with a gene function category.

Animals↗
PubMed1996

Biochemistry, molecular biology, and genetics of the oligosaccharyltransferase.

Asparagine-linked glycosylation is a highly conserved protein modification reaction that occurs in all eukaryotes. The initial stage in the biosynthesis of N-linked glycoproteins, catalyzed by the enzyme oligosaccharyltransferase (OST), involves the transfer of a preassembled high-mannose oligosaccharide from a dolichol-linked oligosaccharide donor onto asparagine acceptor sites in nascent proteins in the lumen of the rough endoplasmic reticulum. Biochemical, molecular biological, and genetic studies conducted during the past 5 years have resulted in an explosive growth in our knowledge concerning the OST. Although the basic biochemical properties of the enzyme were determined more than a decade ago using intact microsomal membranes, recent studies provide novel insight into the catalytic mechanism of the enzyme. The OST was recently purified as a large heteroligomeric membrane protein complex; the sequences of many of the subunits have been determined from both fungal and vertebrate sources. Consistent with the evolutionary conservation of N-linked glycosylation, protein sequence comparisons reveal significant homologies between vertebrate, invertebrate, plant, and fungal OST subunits. Yeast molecular genetic methods have been instrumental in the functional characterization of the OST subunits, and have proven to be powerful tools for the identification of novel gene products that influence oligosaccharide transfer in vivo.

Animals↗
PubMed2001

The expanded human kallikrein (KLK) gene family: genomic organisation, tissue-specific expression and potential functions.

The tissue kallikreins are serine proteases encoded by highly conserved multi-gene families. The rodent kallikrein (KLK) families are particularly large, consisting of 13-26 genes clustered in one chromosomal locus. It has been recently recognised that the human KLK gene family is of a similar size (15 genes) with the identification of another 12 related genes (KLK4-KLK15) within and adjacent to the original human KLK locus (KLK1-3) on chromosome 19q13.4. The structural organisation and size of these new genes is similar to that of other KLK genes except for additional exons encoding 5' or 3' untranslated regions. Moreover, many of these genes have multiple mRNA transcripts, a trait not observed with rodent genes. Unlike all other kallikreins, the KLK4-KLK15 encoded proteases are less related (25-44%) and do not contain a conventional kallikrein loop. Clusters of genes exhibit high prostatic (KLK2-4, KLK15) or pancreatic (KLK6-13) expression, suggesting evolutionary conservation of elements conferring tissue specificity. These genes are also expressed, to varying degrees, in a wider range of tissues suggesting a functional involvement of these newer human kallikrein proteases in a diverse range of physiological processes.

Amino Acid Sequence↗
PubMed1998

Conservation of PDX-1 structure, function, and expression in zebrafish.

Development of the mammalian pancreas has been studied extensively in mice. The stages from budding of the pancreatic anlaga through endocrine and exocrine cell differentiation and islet formation have been described in detail. Recently, the homeodomain transcription factor PDX-1 has been identified as an important factor in the proliferation and differentiation of the pancreatic buds to form a mature pancreas. To evaluate the possibility of using zebrafish as a model for the genetic analysis of pancreas development, we have cloned and characterized PDX-1 from this organism. The deduced sequence of zebrafish PDX-1 contains 246 amino acids and is 95% identical to mammalian PDX-1 in the homeodomain. We also cloned zebrafish preproinsulin complementary DNA as a marker for islet tissue. By in situ hybridization we demonstrate that PDX-1 and insulin are coexpressed during embryonic development and in adults, although PDX-1 expression appears to be biphasic. Insulin expression apparently begins before 44 hpf, the earliest stage examined in this study. Additionally, very high levels of PDX-1 expression were observed in the pyloric caeca, the accessory digestive organs that also are derived from the proximal region of the intestine in teleosts. Finally, our data show that the evolutionary conservation of zebrafish PDX-1 extends to its DNA binding properties. Zebrafish PDX-1 was equally as effective as mouse PDX-1 in stimulating insulin gene transcription, and maximum promoter activation was dependent on the presence of four intact A elements. The demonstration of this capability suggests that transcriptional regulatory mechanisms that control pancreatic development and insulin gene expression have been conserved among vertebrates.

Amino Acid Sequence↗
PubMed2005

Analysis of paralogous pontin and reptin gene expression during mouse development.

Evolutionarily conserved from yeast to human, the paralogous DNA helicases Pontin (Pont) and Reptin (Rept) are simultaneously recruited in multi-protein chromatin complexes that function in different aspects of DNA metabolism (transcription, replication and repair). When assayed, the two proteins were found to be essential for viability and to play antagonistic roles, suggesting that the balance of Pont/Rept regulates epigenetic programmes critical for development. Consistent with this, the two helicases are provided in the same embryonic territories during Drosophila development. In Xenopus, while transcribed in the same regions early in embryogenesis, pont and rept adopt significantly different patterns afterwards. Here we report that the two genes follow highly resembling transcription patterns in mouse embryos, with prominent expression in limb buds and branchial arches, organs undergoing mesenchymal-epithelial interactions and in motoneurones from cranial and spinal regions. Thus, simultaneous expression during development appears to constitute another feature of the evolutionary conservation of pont and rept genes.

Animals↗