1: Genetics. 2005 Aug 3; [Epub ahead of print] Modeling Early Epstein-Barr Virus Infection in Drosophila melanogaster: the BZLF1 protein. Adamson AL, Wright N, Lajeunesse DR. University of North Carolina at Greensboro. Epstein-Barr virus (EBV) is the causative agent of infectious mononucleosis, and is associated with several forms of cancer, including lymphomas and nasopharyngeal carcinoma. The EBV immediate-early protein BZLF1 functions as a transcriptional activator of EBV early gene expression, and is essential for the viral transition between latent and lytic replication. In addition to its role in the EBV life cycle, BZLF1 (Z) also has profound effects upon the host cellular environment, including disruption of cell cycle regulation, signal transduction pathways, and transcription. In an effort to understand the nature of Z interactions with the host cellular environment, we have developed a Drosophila model of early EBV infection, where we have expressed Z in the Drosophila eye. Using this system, we have identified a highly conserved interaction between the Epstein-Barr virus Z protein and shaven, a Drosophila homolog of the human Pax2/5/8 family of genes. Pax5 is a well-characterized human gene involved with B cell development. The B-cell specific Pax5 also promotes the transcription of EBV latent genes from the Wp promoter. Our work clearly demonstrates that the Drosophila system is an appropriate and powerful tool in identifying the underlying genetic networks involved in human infectious disease. PMID: 16079238 [PubMed - as supplied by publisher] --------------------------------------------------------------- 2: Proc Natl Acad Sci U S A. 2004 Aug 24;101(34):12543-8. Epub 2004 Aug 13. Derivation of midbrain dopamine neurons from human embryonic stem cells. Perrier AL, Tabar V, Barberi T, Rubio ME, Bruses J, Topf N, Harrison NL, Studer L. Laboratory of Stem Cell and Tumor Biology, Division of Neurosurgery and Developmental Biology Program, and Cell Biology Program, Sloan-Kettering Institute, New York, NY 10021, USA. Human embryonic stem (hES) cells are defined by their extensive self-renewal capacity and their potential to differentiate into any cell type of the human body. The challenge in using hES cells for developmental biology and regenerative medicine has been to direct the wide differentiation potential toward the derivation of a specific cell fate. Within the nervous system, hES cells have been shown to differentiate in vitro into neural progenitor cells, neurons, and astrocytes. However, to our knowledge, the selective derivation of any given neuron subtype has not yet been demonstrated. Here, we describe conditions to direct hES cells into neurons of midbrain dopaminergic identity. Neuroectodermal differentiation was triggered on stromal feeder cells followed by regional specification by means of the sequential application of defined patterning molecules that direct in vivo midbrain development. Progression toward a midbrain dopamine (DA) neuron fate was monitored by the sequential expression of key transcription factors, including Pax2, Pax5, and engrailed-1 (En1), measurements of DA release, the presence of tetrodotoxin-sensitive action potentials, and the electron-microscopic visualization of tyrosinehydroxylase-positive synaptic terminals. High-yield DA neuron derivation was confirmed from three independent hES and two monkey embryonic stem cell lines. The availability of unlimited numbers of midbrain DA neurons is a first step toward exploring the potential of hES cells in preclinical models of Parkinson's disease. This experimental system also provides a powerful tool to probe the molecular mechanisms that control the development and function of human midbrain DA neurons. PMID: 15310843 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 3: Ann N Y Acad Sci. 2003 Jun;991:36-47. Midbrain dopaminergic neurons: determination of their developmental fate by transcription factors. Simon HH, Bhatt L, Gherbassi D, Sgado P, Alberi L. Center for Neuroscience, Department of Neuroanatomy, University of Heidelberg, 69120 Heidelberg, Germany. horst.simon@urz.uni-heidelberg.de Midbrain dopaminergic neurons are the main source of dopamine in the mammalian central nervous system and are associated with one of the most prominent human neurological disorders, Parkinson's disease. During development, they are induced in the ventral midbrain by an interaction between two diffusible factors, SHH and FGF8. The local identity of this part of the midbrain is probably determined by the combinatorial expression of three transcription factors, Otx2, Pax2, and Pax5. After the last cell division, the neurons start to express transcription factors that control further differentiation and the manifestation of cellular properties characteristic for adult dopaminergic neurons of the substantia nigra compacta and the ventral tegmentum. The first to appear is the LIM-homeodomain transcription factor, Lmx1b. It is essential for the survival of these neurons, and it regulates the expression of another transcription factor, Pitx3, an activator of tyrosine hydroxylase. Lmx1b is followed by the orphan steroid receptor Nurr1. It is essential for the expression of the dopaminergic phenotype. Several genes involved in dopamine synthesis, transport, release, and reuptake are regulated by Nurr1. This requirement is specific to the midbrain dopaminergic neurons, since other populations of the same neurotransmitter phenotype develop normally in absence of the gene. A day after Nurr1, two homeodomain transcription factors, engrailed-1 and -2, are expressed. In animals deficient in the two genes, the midbrain dopaminergic neurons are generated, but then fail to differentiate and disappear very rapidly. Interestingly, alpha-synuclein, a gene recently linked to familial forms of Parkinson's disease, is regulated by engrailed-1 and -2. PMID: 12846972 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 4: Gene. 2002 Jan 9;282(1-2):143-50. Functional equivalency of amphioxus and vertebrate Pax258 transcription factors suggests that the activation of mid-hindbrain specific genes in vertebrates occurs via the recruitment of Pax regulatory elements. Krelova J, Holland LZ, Schubert M, Burgtorf C, Benes V, Kozmik Z. Center for Integrated Genomics, Institute of Molecular Genetics, Flemingovo 2, 166 37 Praha 6, Czech Republic. Pax genes encode transcription factors that control key developmental decisions in various animal phyla. The Pax2/5/8 subfamily plays a key role in specification and/or maintenance of vertebrate mid-hindbrain boundary (MHB) region by directly regulating expression of other genes, most notably En2. In the invertebrate chordate amphioxus, expression of AmphiPax2/5/8 is found in many sites that are homologous to the regions of the vertebrate embryo expressing orthologous genes Pax2, Pax5 or Pax8. However, no co-expression of AmphiPax2/5/8 and AmphiEn is detected in the region of the neural tube that might correspond to the vertebrate MHB. Based on this observation and the absence of AmphiWnt expression in this region it appears that amphioxus does not have a MHB. Here we investigated the possibility that the AmphiPax2/5/8, as a key component of MHB development, has lost some of the properties of its vertebrate counterparts. We have analyzed both the DNA-binding and transactivation properties of AmphiPax2/5/8 as well as its ability to interact with the groucho co-repressor. In all these assays AmphiPax2/5/8 is indistinguishable from the human Pax5. In addition, we found two alternatively spliced AmphiPax2/5/8 isoforms that function similarly to the alternatively spliced isoforms of human Pax8. Analysis of the AmphiEn regulatory region provided no evidence for AmphiPax2/5/8 binding and transactivation. Therefore, in amphioxus, AmphiPax2/5/8, although capable of performing all the necessary functions has not been recruited for a developmental mechanism which usually sets up MHB development in vertebrates. PMID: 11814686 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 5: Nat Neurosci. 2001 Dec;4(12):1175-81. Distinct regulators control the expression of the mid-hindbrain organizer signal FGF8. Ye W, Bouchard M, Stone D, Liu X, Vella F, Lee J, Nakamura H, Ang SL, Busslinger M, Rosenthal A. Department of Molecular Biology, Genentech, 1 DNA Way, South San Francisco, California 94080, USA. Local expression of FGF8 at the mid/hindbrain boundary (MHB) governs the development of multiple neurons and support cells. Here we show that the paired-domain protein Pax2 is necessary and sufficient for the induction of FGF8 in part by regulating the expression of Pax5&8. A network of transcription and secreted factors, including En1, Otx2, Gbx2, Grg4 and Wnt1&4, that is established independently of Pax2, further refines the expression domain and level of FGF8 at the MHB through opposing effects on Pax2 activity. Our results indicate that the expression of local organizing factors is controlled by combinatorial interaction between inductive and modulatory factors. PMID: 11704761 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 6: Prog Neurobiol. 2001 Dec;65(5):473-88. Regionalisation and acquisition of polarity in the optic tectum. Nakamura H. Department of Molecular Neurobiology, Institute of Development, Aging and Cancer, Tohoku University, Seiryo-machi 4-1, Aoba-ku, 980-8575, Sendai, Japan. makamura@idac.tohoku.ac.jp The optic tectum differentiates from the alar plate of the mesencephalon and receives retinal fibres in a precise retinotopic manner. Here, mechanisms of tectum polarisation and regionalisation are reviewed. Misexpression of Pax2, Pax5 or En can change the fate of the presumptive diencephalon to that of the tectum. Ephrin A2 and A5 are expressed in a gradient in the tectum, caudal high and rostral low, and may play important roles in the formation of a precise retinotectal projection map. Retinal fibres that express receptors for these ligands, and which come from the temporal retina, are repulsed by the ligands and do not invade the caudal tectum. Both En1 and En2 can regulate posterior characteristics in the tectum by inducing ephrin A2 and A5. Transplantation experiments in chick have indicated that the mes/metencephalic boundary works as an organiser for the tectum and the cerebellum. Fgf8 is a candidate signalling molecule in the organiser. Pax2/5, En, and Fgf8 are in a positive feedback loop for their expression such that misexpression of one of these genes in the diencephalon turns on the feedback loop and can result in induction of an optic tectum. Otx2 and Gbx2 appear to repress each other's expression and contribute to defining the posterior border of the tectum. Misexpression of Otx2 in the metencephalon can change the fate of its alar plate to a tectum, and misexpression of Gbx2 in the mesencephalon can cause anterior shifting of the caudal limit of the tectum. The anterior border of the tectum may be determined as a result of repressive interactions between Pax6 and En1/Pax2. Along the dorsoventral axis of the mesencephalon, Shh contributes to ventralize the tissue; that is, Shh can change the fate of the presumptive tectum to that of the tegmentum that is the ventral structure. It is proposed that the brain vesicle that expresses Otx2, Pax2, and En1 may differentiate into the tectum. Publication Types: Review Review, Tutorial PMID: 11689282 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 7: Trends Neurosci. 2001 Jan;24(1):32-9. Regionalization of the optic tectum: combinations of gene expression that define the tectum. Nakamura H. Dept of Molecular Neurobiology, Institute of Development, Aging and Cancer, Tohoku University, Seiryo-machi 4-1, Aoba-ku, 980-8575, Sendai, Japan. nakamura@idac.tohoku.ac.jp The optic tectum differentiates from the alar plate of the mesencephalon. Here, the molecular mechanisms for differentiation of the tectum are reviewed. Mis-expression of Pax2, Pax5 or En can change the fate of the presumptive diencephalon to become the tectum. En, Fgf8, Pax2 and Pax5, exist in a positive feedback loop for their expression so that mis-expression of any of these genes acts on the feedback loop resulting in induction of the optic tectum in the diencephalon. Otx2 and Gbx2 can repress the expression of each other and contribute to the formation of the posterior border of the tectum. Mis-expression of Otx2 in the metencephalon changed the fate of its alar plate to the tectum. The anterior border of the tectum might be determined as a result of repressive interaction of Pax6 with En1 and Pax2. Along the dorsoventral axis of the mesencephalon, Shh contributes to the ventralization of the tissue, that is, the area affected by Shh differentiates into the tegmentum. It is proposed that the brain vesicle that expresses Otx2, Pax2 and En1 might differentiate into the tectum. Publication Types: Review PMID: 11163885 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 8: Development. 2000 Sep;127(17):3703-13. Functional equivalence of the transcription factors Pax2 and Pax5 in mouse development. Bouchard M, Pfeffer P, Busslinger M. Research Institute of Molecular Pathology, Dr Bohr-Gasse 7, A-1030 Vienna, Austria. Pax2 and Pax5 arose by gene duplication at the onset of vertebrate evolution and have since diverged in their developmental expression patterns. They are expressed in different organs of the mouse embryo except for their coexpression at the midbrain-hindbrain boundary (MHB), which functions as an organizing center to control midbrain and cerebellum development. During MHB development, Pax2 expression is initiated prior to Pax5 transcription, and Pax2(-/-) embryos fail to generate the posterior midbrain and cerebellum, whereas Pax5(-/-) mice exhibit only minor patterning defects in the same brain regions. To investigate whether these contrasting phenotypes are caused by differences in the temporal expression or biochemical activity of these two transcription factors, we have generated a knock-in (ki) mouse, which expresses a Pax5 minigene under the control of the Pax2 locus. Midbrain and cerebellum development was entirely rescued in Pax2(5ki/5ki) embryos. Pax5 could furthermore completely substitute for the Pax2 function during morphogenesis of the inner ear and genital tracts, despite the fact that the Pax5 transcript of the Pax2(5ki )allele was expressed only at a fivefold lower level than the wild-type Pax2 mRNA. As a consequence, the Pax2(5ki )allele was able to rescue most but not all Pax2 mutant defects in the developing eye and kidney, both of which are known to be highly sensitive to Pax2 protein dosage. Together these data demonstrate that the transcription factors Pax2 and Pax5 have maintained equivalent biochemical functions since their divergence early in vertebrate evolution. PMID: 10934015 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 9: EMBO J. 2000 May 15;19(10):2292-303. Transcriptional repression by Pax5 (BSAP) through interaction with corepressors of the Groucho family. Eberhard D, Jimenez G, Heavey B, Busslinger M. Research Institute of Molecular Pathology, Dr Bohr-Gasse 7, A-1030 Vienna, Austria and Departamento de Biologia Molecular i Cellular, CID-CSIC, Jordi Girona 18-26, 08034 Barcelona, Spain. Pax5 (BSAP) functions as both a transcriptional activator and repressor during midbrain patterning, B-cell development and lymphomagenesis. Here we demonstrate that Pax5 exerts its repression function by recruiting members of the Groucho corepressor family. In a yeast two-hybrid screen, the groucho-related gene product Grg4 was identified as a Pax5 partner protein. Both proteins interact cooperatively via two separate domains: the N-terminal Q and central SP regions of Grg4, and the octapeptide motif and C-terminal transactivation domain of Pax5. The phosphorylation state of Grg4 is altered in vivo upon Pax5 binding. Moreover, Grg4 efficiently represses the transcriptional activity of Pax5 in an octapeptide-dependent manner. Similar protein interactions resulting in transcriptional repression were also observed between distantly related members of both the Pax2/5/8 and Groucho protein families. In agreement with this evolutionary conservation, the octapeptide motif of Pax proteins functions as a Groucho-dependent repression domain in Drosophila embryos. These data indicate that Pax proteins can be converted from transcriptional activators to repressors through interaction with corepressors of the Groucho protein family. PMID: 10811620 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 10: Development. 2000 Jun;127(11):2357-65. Pax6 defines the di-mesencephalic boundary by repressing En1 and Pax2. Matsunaga E, Araki I, Nakamura H. Department of Molecular Neurobiology, Institute of Development, Aging and Cancer, Tohoku University, Seiryo-machi 4-1, Aoba-ku, Sendai 980-8575, Japan. Transcriptional factors and signaling molecules are responsible for regionalization of the central nervous system. In the early stage of neural development, Pax6 is expressed in the prosencephalon, while En1 and Pax2 are expressed in the mesencephalon. Here, we misexpressed Pax6 in the mesencephalon to elucidate the mechanism of the di-mesencephalic boundary formation. Histological analysis, expression patterns of diencephalic marker genes, and fiber trajectory of the posterior commissure indicated that Pax6 misexpression caused a caudal shift of the di-mesencephalic boundary. Pax6 repressed En1, Pax2 and other tectum (mesencephalon)-related genes such as En2, Pax5, Pax7, but induced Tcf4, a diencephalon marker gene. To know how Pax6 represses En1 and Pax2, we ectopically expressed a dominant-active or negative form of Pax6. The dominant-active form of Pax6 showed a similar but more severe phenotype than Pax6, while the dominant-negative form showed an opposite phenotype, suggesting that Pax6 acts as a transcriptional activator. Thus Pax6 may repress tectum-related genes by activating an intervening repressor. The results of misexpression experiments, together with normal expression patterns of Pax6, En1 and Pax2, suggest that repressive interaction between Pax6 and En1/Pax2 defines the di-mesencephalic boundary. PMID: 10804178 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 11: Development. 2000 Mar;127(5):1017-28. Pax2 and homeodomain proteins cooperatively regulate a 435 bp enhancer of the mouse Pax5 gene at the midbrain-hindbrain boundary. Pfeffer PL, Bouchard M, Busslinger M. Research Institute of Molecular Pathology, Dr Bohr-Gasse 7, A-1030 Vienna, Austria. Pax and homeodomain transcription factors are essential for the formation of an organizing center at the midbrain-hindbrain boundary (mhb) which controls the genesis of the midbrain and cerebellum in the vertebrate embryo. Pax2 and Pax5 are sequentially activated in this brain region, with Pax2 expression preceding that of Pax5. Using a transgenic reporter assay, we have now identified a conserved 435 bp enhancer in the 5' flanking region of mammalian Pax5 genes which directs lacZ expression in the correct temporal and spatial pattern at the mhb. This minimal enhancer is composed of two distinct elements, as shown by protein-binding assays with mhb-specific extracts. The proximal element contains overlapping consensus binding sites for members of the Pax2/5/8 and POU protein families, whereas a distal element is bound by homeodomain and zinc finger transcription factors. Expression analysis of transgenes carrying specific mutations in these recognition motifs identified the Pax- and homeodomain-binding sites as functional elements which cooperatively control the activity of the mhb enhancer. lacZ genes under the control of either the minimal enhancer or the endogenous Pax5 locus were normally expressed at the mhb in Pax5 mutant embryos, indicating that this enhancer does not depend on autoregulation by Pax5. In Pax2 mutant embryos, expression of the endogenous Pax5 gene was, however, delayed and severely reduced in lateral aspects of the neural plate which, on neural tube closure, becomes the dorsal mhb region. This cross-regulation by Pax2 is mediated by the Pax-binding site of the minimal enhancer which, upon specific mutation, resulted in severely reduced transgene expression in the dorsal part of the mhb. Together these data indicate that Pax2 and homeodomain proteins directly bind to and cooperatively regulate the mhb enhancer of Pax5. PMID: 10662641 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 12: Biochem Biophys Res Commun. 1999 Dec 20;266(2):532-41. A novel paired domain DNA recognition motif can mediate Pax2 repression of gene transcription. Havik B, Ragnhildstveit E, Lorens JB, Saelemyr K, Fauske O, Knudsen LK, Fjose A. Department of Molecular Biology, University of Bergen, Bergen, N-5020, Norway. The paired domain (PD) is an evolutionarily conserved DNA-binding domain encoded by the Pax gene family of developmental regulators. The Pax proteins are transcription factors and are involved in a variety of processes such as brain development, patterning of the central nervous system (CNS), and B-cell development. In this report we demonstrate that the zebrafish Pax2 PD can interact with a novel type of DNA sequences in vitro, the triple-A motif, consisting of a heptameric nucleotide sequence G/CAAACA/TC with an invariant core of three adjacent adenosines. This recognition sequence was found to be conserved in known natural Pax5 repressor elements involved in controlling the expression of the p53 and J-chain genes. By identifying similar high affinity binding sites in potential target genes of the Pax2 protein, including the pax2 gene itself, we obtained further evidence that the triple-A sites are biologically significant. The putative natural target sites also provide a basis for defining an extended consensus recognition sequence. In addition, we observed in transformation assays a direct correlation between Pax2 repressor activity and the presence of triple-A sites. The results suggest that a transcriptional regulatory function of Pax proteins can be modulated by PD binding to different categories of target sequences. Copyright 1999 Academic Press. PMID: 10600536 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 13: Development. 1999 Mar;126(6):1295-304. Characterization of an amphioxus paired box gene, AmphiPax2/5/8: developmental expression patterns in optic support cells, nephridium, thyroid-like structures and pharyngeal gill slits, but not in the midbrain-hindbrain boundary region. Kozmik Z, Holland ND, Kalousova A, Paces J, Schubert M, Holland LZ. Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Flemingovo 2, Czech Republic. On the basis of developmental gene expression, the vertebrate central nervous system comprises: a forebrain plus anterior midbrain, a midbrain-hindbrain boundary region (MHB) having organizer properties, and a rhombospinal domain. The vertebrate MHB is characterized by position, by organizer properties and by being the early site of action of Wnt1 and engrailed genes, and of genes of the Pax2/5/8 subfamily. Wada and others (Wada, H., Saiga, H., Satoh, N. and Holland, P. W. H. (1998) Development 125, 1113-1122) suggested that ascidian tunicates have a vertebrate-like MHB on the basis of ascidian Pax258 expression there. In another invertebrate chordate, amphioxus, comparable gene expression evidence for a vertebrate-like MHB is lacking. We, therefore, isolated and characterized AmphiPax2/5/8, the sole member of this subfamily in amphioxus. AmphiPax2/5/8 is initially expressed well back in the rhombospinal domain and not where a MHB would be expected. In contrast, most of the other expression domains of AmphiPax2/5/8 correspond to expression domains of vertebrate Pax2, Pax5 and Pax8 in structures that are probably homologous - support cells of the eye, nephridium, thyroid-like structures and pharyngeal gill slits; although AmphiPax2/5/8 is not transcribed in any structures that could be interpreted as homologues of vertebrate otic placodes or otic vesicles. In sum, the developmental expression of AmphiPax2/5/8 indicates that the amphioxus central nervous system lacks a MHB resembling the vertebrate isthmic region. Additional gene expression data for the developing ascidian and amphioxus nervous systems would help determine whether a MHB is a basal chordate character secondarily lost in amphioxus. The alternative is that the MHB is a vertebrate innovation. PMID: 10021347 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 14: Development. 1998 Aug;125(16):3063-74. Characterization of three novel members of the zebrafish Pax2/5/8 family: dependency of Pax5 and Pax8 expression on the Pax2.1 (noi) function. Pfeffer PL, Gerster T, Lun K, Brand M, Busslinger M. Research Institute of Molecular Pathology, Dr Bohr-Gasse 7, A-1030 Vienna, Austria. The mammalian Pax2, Pax5 and Pax8 genes code for highly related transcription factors, which play important roles in embryonic development and organogenesis. Here we report the characterization of all members of the zebrafish Pax2/5/8 family. These genes have arisen by duplications before or at the onset of vertebrate evolution. Due to an additional genome amplification in the fish lineage, the zebrafish contains two Pax2 genes, the previously known Pax[b] gene (here renamed as Pax2.1) and a novel Pax2.2 gene. The zebrafish Pax2.1 gene most closely resembles the mammalian Pax2 gene in its expression pattern, as it is transcribed first in the midbrain-hindbrain boundary region, then in the optic stalk, otic system, pronephros and nephric ducts, and lastly in specific interneurons of the hindbrain and spinal cord. Pax2.2 differs from Pax2.1 by the absence of expression in the nephric system and by a delayed onset of transcription in other Pax2.1 expession domains. Pax8 is also expressed in the same domains as Pax2.1, but its transcription is already initiated during gastrulation in the primordia of the otic placode and pronephric anlage, thus identifying Pax8 as the earliest developmental marker of these structures. The zebrafish Pax5 gene, in contrast to its mouse orthologue, is transcribed in the otic system in addition to its prominent expression at the midbrain-hindbrain boundary. The no isthmus (noi) mutation is known to inactivate the Pax2.1 gene, thereby affecting the development of the midbrain-hindbrain boundary region, pronephric system, optic stalk and otic region. Although the different members of the Pax2/5/8 family may potentially compensate for the loss of Pax2.1 function, we demonstrate here that only the expression of the Pax2.2 gene remains unaffected in noi mutant embryos. The expression of Pax5 and Pax8 is either not initiated at the midbrain-hindbrain boundary or is later not maintained in other expression domains. Consequently, the noi mutation of zebrafish is equivalent to combined inactivation of the mouse Pax2 and Pax5 genes with regard to the loss of midbrain-hindbrain boundary development. PMID: 9671580 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 15: Development. 1997 Oct;124(20):3919-28. The PAX gene egl-38 mediates developmental patterning in Caenorhabditis elegans. Chamberlin HM, Palmer RE, Newman AP, Sternberg PW, Baillie DL, Thomas JH. Department of Genetics, University of Washington, Seattle 98195-7360, USA. Mutations in the C. elegans gene egl-38 result in a discrete set of defects in developmental pattern formation. In the developing egg-laying system of egl-38 mutant hermaphrodites, the identity of four uterine cells is disrupted and they adopt the fate of their neighbor cells. Likewise, the identity of two rectal epithelial cells in the male tail is disrupted and one of these cells adopts the fate of its neighbor cell. Genetic analysis suggests that the egl-38 functions in the tail and the egg-laying system are partially separable, as different egl-38 mutations can preferentially disrupt the different functions. We have cloned egl-38 and shown that it is a member of the PAX family of genes, which encode transcription factors implicated in a variety of developmental patterning events. The predicted EGL-38 protein is most similar to the mammalian class of proteins that includes PAX2, PAX5 and PAX8. The sequence of egl-38 mutant DNA indicates that the tissue-preferential defects of egl-38 mutations result from substitutions in the DNA-binding paired domain of the EGL-38 protein. egl-38 thus provides the first molecular genetic insight into two specific patterning events that occur during C. elegans development and also provides the opportunity to investigate the in vivo functions of this class of PAX proteins with single cell resolution. PMID: 9374390 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 16: Genes Dev. 1997 Aug 15;11(16):2066-78. Comment in: Genes Dev. 1997 Aug 15;11(16):2023-8. The Pax2 homolog sparkling is required for development of cone and pigment cells in the Drosophila eye. Fu W, Noll M. Institute for Molecular Biology, Division II, University of Zurich, Switzerland. A new Drosophila Pax gene, sparkling (spa), implicated in eye development, was isolated and shown to encode the homolog of the vertebrate Pax2, Pax5, and Pax8 proteins. It is expressed in the embryonic nervous system and in cone, primary pigment, and bristle cells of larval and pupal eye discs. In spa(pol) mutants, a deletion of an enhancer abolishes Spa expression in cone and primary pigment cells and results in a severely disturbed development of non-neuronal ommatidial cells. Spa expression is further required for activation of cut in cone cells and of the Bar locus in primary pigment cells. We suggest close functional analogies between Spa and Pax2 in the development of the insect and vertebrate eye. PMID: 9284046 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 17: Proc Natl Acad Sci U S A. 1997 May 27;94(11):5703-8. Cooperation of Pax2 and Pax5 in midbrain and cerebellum development. Urbanek P, Fetka I, Meisler MH, Busslinger M. Research Institute of Molecular Pathology, Dr. Bohr-Gasse 7, A-1030 Vienna, Austria. Midbrain and cerebellum development depends on an organizing center that is located at the midbrain-hindbrain junction of the vertebrate embryo. Expression of the two closely related transcription factors Pax2 and Pax5 overlaps spatially and temporally in this region of the developing central nervous system. To study a possible interaction of these transcription factors in midbrain and cerebellum patterning, we have generated Pax5, Krd double mutant mice. The transgene-induced Krd mutation corresponds to an approximately 7-centimorgan chromosome 19 deletion that eliminates the entire Pax2 locus. The heterozygous Krd mutation deleting one Pax2 allele had no effect on midbrain and cerebellum development. Moreover, only minor developmental defects were previously observed at the midline of the inferior colliculus and anterior cerebellum in mice that were homozygous for a targeted Pax5 mutation. Similar morphological alterations were observed in 80% of all compound heterozygous Pax5 (+/-) Krd (+/-) mice. However, in the remaining 20% of compound heterozygotes, the inferior colliculi were missing, and the vermis of the cerebellum was severely disrupted due to the failure of the cerebellar primordia to fuse at the midline. Inactivation of the second Pax5 allele in Pax5 (-/-) Krd (+/-) mice resulted in complete loss of the posterior midbrain and cerebellum, as the tissue originating from the midbrain-hindbrain boundary region was deleted in the embryo as early as day 9.5. On the basis of these data, we propose that the cooperation of Pax2 and Pax5 is essential for normal functioning of the organizing center at the midbrain-hindbrain junction. PMID: 9159136 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 18: Proc Natl Acad Sci U S A. 1996 Nov 26;93(24):13870-5. The mouse Pax2(1Neu) mutation is identical to a human PAX2 mutation in a family with renal-coloboma syndrome and results in developmental defects of the brain, ear, eye, and kidney. Favor J, Sandulache R, Neuhauser-Klaus A, Pretsch W, Chatterjee B, Senft E, Wurst W, Blanquet V, Grimes P, Sporle R, Schughart K. GSF-National Research Center for Environment and Health, Institute of Mammalian Genetics, Oberschleissheim, Germany. We describe a new mouse frameshift mutation (Pax2(1Neu)) with a 1-bp insertion in the Pax2 gene. This mutation is identical to a previously described mutation in a human family with renal-coloboma syndrome [Sanyanusin, P., McNoe, L. A., Sullivan, M. J., Weaver, R. G. & Eccles, M. R. (1995) Hum. Mol. Genet. 4, 2183-2184]. Heterozygous mutant mice exhibit defects in the kidney, the optic nerve, and retinal layer of the eye, and in homozygous mutant embryos, development of the optic nerve, metanephric kidney, and ventral regions of the inner ear is severely affected. In addition, we observe a deletion of the cerebellum and the posterior mesencephalon in homozygous mutant embryos demonstrating that, in contrast to mutations in Pax5, which is also expressed early in the mid-hindbrain region, loss of Pax2 gene function alone results in the early loss of the mid-hindbrain region. The mid-hindbrain phenotype is similar to Wnt1 and En1 mutant phenotypes, suggesting the conservation of gene regulatory networks between vertebrates and Drosophila. PMID: 8943028 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 19: EMBO J. 1995 Nov 15;14(22):5638-45. Loss of p53 function through PAX-mediated transcriptional repression. Stuart ET, Haffner R, Oren M, Gruss P. Department of Molecular Cell Biology, Max-Planck Institute for Biophysical Chemistry, Gottingen, Germany. Direct interactions between the genes that regulate development and those which regulate the cell cycle would provide a mechanism by which numerous biological events could be better understood. We have identified a direct role for PAX5 in the control of p53 transcription. In primary human diffuse astrocytomas, PAX5 expression inversely correlated with p53 expression. The human p53 gene harbours a PAX binding site within its untranslated first exon that is conserved throughout evolution. PAX5 and its paralogues PAX2 and PAX8 are capable of inhibiting both the p53 promoter and transactivation of a p53-responsive reporter in cell culture. Mutation of the identified binding site eliminates PAX protein binding in vitro and renders the promoter inactive in cells. These data suggest that PAX proteins might regulate p53 expression during development and propose a novel alternative mechanism for tumour initiation or progression, by which loss of p53 function occurs at the transcriptional level. PMID: 8521821 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 20: Gene. 1995 Sep 11;162(2):267-70. Identification of DNA recognition sequences for the Pax3 paired domain. Chalepakis G, Gruss P. Max-Planck Institute for Biophysical Chemistry, Gottingen, Germany. The Pax gene family, encoding transcription factors, has been classified into four subfamilies according to their genomic organization, the sequences of the paired domains (PD) and the expression pattern. Pax1 and Pax9 constitute one subfamily, Pax2, Pax5 and Pax8 another, Pax3 and Pax7 another one and Pax4 and Pax6 the fourth subfamily. The PD exhibits DNA-binding activity, and is the most conserved functional motif in all Pax proteins. A high-resolution analysis of a PD structure has been performed [Xu et al., Cell 80 (1995) 639-650] and the DNA-binding characteristics of members of two Pax subfamilies (Pax2, Pax5 and Pax6) have been determined. Here, we have utilized a PCR-based selection approach to identify the DNA-binding sequences of the Pax3/PD, a member of a subfamily which has not yet been characterized. Comparison of the Pax3/PD-binding sequences with those of other PD proteins revealed both similarities and differences in the DNA-recognition sequence. This suggests that different Pax proteins can regulate the expression of the same target gene, but they can also regulate the expression of completely unrelated genes by binding to their DNA regulatory regions. PMID: 7557441 [PubMed - indexed for MEDLINE] ---------------------------------------------------------------