Biomedical subjects

J Aruga

Publications and source records attributed to J Aruga.

At least 19 recordsLinked to original sources

PubMed2001

Promoter structure and gene expression of the mouse inositol 1,4,5-trisphosphate receptor type 3 gene.

Inositol 1,4,5-trisphosphate receptor type 3 (IP(3)R3) is a ubiquitously expressed IP(3)R gene in the IP(3)R gene family. We identified an upstream region of the mouse IP(3)R3 genomic DNA. Transcription start points for the IP(3)R3 gene were found to be located mainly at four sites between nucleotide position -325 and -285 relative to the first ATG codon. The major start point was mapped around -325. Transcription promotion ability was detected between -325 and -285 in an IP(3)R3 proximal promoter sequence. The promoter had no TATA-box but was highly GC-rich and contained two putative Sp1-binding sites. There was no sequence similarity between promoter regions of IP(3)R3 and IP(3)R2, another ubiquitous gene, except for GC-boxes. By using a series of 5'-truncation versions and a transient luciferase assay, we detected multiple common and cell-type-dependent regulatory regions within the distal promoter sequence downstream from -4.0 kb that function positively or negatively. The IP(3)R3 gene was highly transcribed in the kidney, spleen, heart, and skeletal muscle, and this tissue distribution pattern was nearly complementary to that of IP(3)R2. We found that IP(3)R3 gene expression was repressed in retinoic acid-treated and neural differentiated P19 mouse embryonic carcinoma cells.

3T3 Cells↗

PubMed2001

Xmeis1, a protooncogene involved in specifying neural crest cell fate in Xenopus embryos.

Meis1 (Myeloid Ecotropic viral Integration Site 1) is a homeobox gene that was originally isolated as a common site of viral integration in myeloid tumors of the BXH-2 recombinant inbred mice strain. We previously isolated a Xenopus homolog of Meis1 (Xmeis1). Here we show that Xmeis1 may play a significant role in neural crest development. In developing Xenopus embryos, Xmeis1 displays a broad expression pattern, but strong expression is observed in tissue of neural cell fate, such as midbrain, hindbrain, the dorsal portion of the neural tube, and neural crest derived branchial arches. In animal cap explants, overexpression of Xmeis1b, an alternatively spliced form of Xmeis1, induces expression of neural crest marker genes in the absence of mesoderm. Moreover, Xmeis1b induces XGli-3 and XZic3, pre-pattern genes involved at the earliest stages of neural crest development, and like these two genes, can induce ectopic pigmented cell masses when overexpressed in developing embryos. Misexpression of Xmeis1b also induces ectopic expression of neural crest markers along the antero-posterior axis of the neural tube in developing Xenopus embryos. In contrast, Xmeis1a, another splice variant, is much less effective at inducing these effects. These data suggest that Xmeis1b is involved in neural crest cell fate specification during embryogenesis, and can functionally intersect with the Gli/Zic signal transduction pathway.

Alternative Splicing↗

PubMed2001

Physical and functional interactions between Zic and Gli proteins.

Zic and Gli family proteins are transcription factors that share similar zinc finger domains. Recent studies indicate that Zic and Gli collaborate in neural and skeletal development. We provide evidence that the Zic and Gli proteins physically and functionally interact through their zinc finger domains. Moreover, Gli proteins were translocated to cell nuclei by coexpressed Zic proteins, and both proteins regulated each other's transcriptional activity. Our result suggests that the physical interaction between Zic and Gli is the molecular basis of their antagonistic or synergistic features in developmental contexts and that Zic proteins are potential modulators of the hedgehog-mediated signaling pathway.

3T3 Cells↗

PubMed2001

Xenopus Polycomblike 2 (XPcl2) controls anterior to posterior patterning of the neural tissue.

A novel gene, Xenopus Polycomblike 2 (XPcl2), which encodes a protein similar to Drosophila Polycomblike was cloned and characterized. Polycomblike belongs to the Polycomb group proteins, which maintain stable expression patterns for the clustered homeotic genes in the Drosophila embryo by forming multimeric complexes on chromatin. XPcl2 shows greater amino acid sequence homology to human and mouse M96 (hPcl2, mPcl2) than Xenopus Pcl1 (XPcl1), mouse Tctex3 (mPcl1) and human PHF1 (hPcl1), indicating that at least two types of Polycomblike genes are conserved between amphibians and mammals. XPcl2 mRNA is present both maternally and zygotically, and the temporal expression profile is distinct from XPcl1, another member of the Polycomblike family in Xenopus. XPcl2 is highly expressed in the anterior-dorsal region of Xenopus following the neurula stage in a manner similar to XPcl1. Overexpression of XPcl2 disturbs the development of the anterior central nervous system, eye and cement gland. In the XPcl2-overexpressing embryo, a hindbrain marker, Krox20, and a spinal cord marker, HoxB9, are expressed more posteriorly, suggesting an alteration in the anterior-posterior patterning of the neural tissue. In addition, XPcl2 represses Zic3- and noggin-induced anterior neural markers, but not neural crest markers in animal cap explants. These results indicate that XPcl2 regulates anterior neural tissue development and the anterior-posterior patterning of the neural tissue.

Amino Acid Sequence↗

PubMed2001

Behavioral abnormalities of Zic1 and Zic2 mutant mice: implications as models for human neurological disorders.

Zic1 and Zic2 encode closely related zinc finger proteins expressed in dorsal neural tube and its derivatives. In previous studies, we showed that the homozygous Zic1 null mutation (Zic1-/-) results in cerebellar malformation with severe ataxia and that holoprosencephaly and spina bifida occur in homozygotes for Zic2 knockdown mutation (Zic2kd/kd). Since human ZIC2 haploinsufficiency is a cause of holoprosencephaly, the Zic2kd/kd mice are regarded as an animal model for holoprosencephaly in humans. In this study, the behavioral characteristics of the Zic1 and Zic2 mutant mice were investigated in heterozygotes (Zic1-/+ or Zic2kd/+), and significant abnormalities were found in the hanging, spontaneous locomotor activity, stationary rod (Zic1-/+), acoustic startle response, and prepulse inhibition tests (Zic2kd/+). The abnormalities in the Zic1-/+ mice may be explained in part by the hypotonia caused by hypoplasia of the cerebellar anterior vermis, and these mice are regarded as a model of Joubert syndrome. In contrast, the sensorimotor gating abnormality in the Zic2kd/+ mice may be attributable to the presumed abnormality in the dorsomedial forebrain, which was strongly affected in the Zic2kd/kd mice. Zic2kd/+ mice can serve as a model for diseases involving sensorimotor gating abnormalities, such as schizophrenia.

Animals↗

PubMed2000

Molecular properties of Zic proteins as transcriptional regulators and their relationship to GLI proteins.

Zic family genes encode zinc finger proteins, which play important roles in vertebrate development. The zinc finger domains are highly conserved between Zic proteins and show a notable homology to those of Gli family proteins. In this study, we investigated the functional properties of Zic proteins and their relationship to the GLI proteins. We first established an optimal binding sequence for Zic1, Zic2, and Zic3 proteins by electrophoretic mobility shift assay-based target selection and mutational analysis. The selected sequence was almost identical to the GLI binding sequence. However, the binding affinity was lower than that of GLI. Consistent results were obtained in reporter assays, in which transcriptional activation by Zic proteins was less dependent on the GLI binding sequence than GLI1. Moreover, Zic proteins activated a wide range of promoters irrespective of the presence of a GLI binding sequence. When Zic and GLI proteins were cotransfected into cultured cells, Zic proteins enhanced or suppressed sequence-dependent, GLI-mediated transactivation depending on cell type. Taken together, these results suggest that Zic proteins may act as transcriptional coactivators and that their function may be modulated by the GLI proteins and possibly by other cell type-specific cofactors.

Base Sequence↗

PubMed2000

Transcription factors Zic1 and Zic2 bind and transactivate the apolipoprotein E gene promoter.

We have used the yeast one-hybrid system to identify transcription factors that bind to specific sequences in proximal regions of the apolipoprotein E gene promoter. The sequence between -163 and -124, that has been previously defined as a functional promoter element, was used as a bait to screen a human brain cDNA library. Ten cDNA clones that encoded portions of the human Zic1 (five clones) and Zic2 (five clones) transcription factors were isolated. Electrophoretic mobility shift assays confirmed the presence of a binding site for Zic1 and Zic2 in the -136/-125 region. Displacement of binding with oligonucleotides derived from adjacent sequences within the APOE promoter revealed the existence of two additional Zic-binding sequences in this promoter. These sequences were identified by electrophoretic mobility shift assays and mutational analysis in regions -65/-54 and -185/-174. Cotransfection of Zic1 and Zic2 expression vector and different APOE promoter-luciferase reporter constructs in U87 glioblastoma cell line showed that the three binding sites partially contributed to the trans-stimulation of the luciferase reporter. Ectopic expression of Zic1 and Zic2 in U87 cells also trans-stimulated the expression of the endogenous gene, increasing the amount of apolipoprotein E produced by glial cells. These data indicate that Zic proteins might contribute to the transcriptional activity of the apolipoprotein E gene and suggest that apolipoprotein E could mediate some of the developmental processes in which Zic proteins are involved.

Animals↗

PubMed2000

A 5' segment of the mouse Zic1 gene contains a region specific enhancer for dorsal hindbrain and spinal cord.

Zic1 encodes a zinc finger protein, which is required for the development of the dorsal neural tissue. The gene is a mammalian homologue of the Drosophila odd-paired. We examined the regulatory elements in the 5' flanking region of the Zic1 gene as an initial step to understanding how the Zic1 expression is restricted to the dorsal neural tissue. When a 2.9-kb fragment of the 5' flanking segment of the mouse Zic1 gene was linked to the E. coli beta-galactosidase gene, the enzyme was consistently expressed in the dorsal half of the embryonic spinal cord and in the vestibulocochlear nucleus in all four transgenic mouse lines. The transgene expression mimics the Zic1 expression with respect to the region where it occurs. But this is not so for the neuronal cell types. This suggests that the segment contains a region-specific enhancer. In vivo and in vitro deletion analyses indicated that there are essential regions between -2.0 and -0.9 kb and within the proximal 0.9 kb. The distal element is necessary for the transgene expression in the embryonic dorsal spinal cord whereas the adult vestibulocochlear nucleus expression is regulated by both elements. In these regions, there are sequences similar to the binding sequences for potential regulatory proteins.

5' Untranslated Regions↗

PubMed2000

Zic2 regulates the kinetics of neurulation.

Mutation in human ZIC2, a zinc finger protein homologous to Drosophila odd-paired, causes holoprosencephaly (HPE), which is a common, severe malformation of the brain in humans. However, the pathogenesis is largely unknown. Here we show that reduced expression (knockdown) of mouse Zic2 causes neurulation delay, resulting in HPE and spina bifida. Differentiation of the most dorsal neural plate, which gives rise to both roof plate and neural crest cells, also was delayed as indicated by the expression lag of a roof plate marker, Wnt3a. In addition the development of neural crest derivatives such as dorsal root ganglion was impaired. These results suggest that the Zic2 expression level is crucial for the timing of neurulation. Because the Zic2 knockdown mouse is the first mutant with HPE and spina bifida to survive to the perinatal period, the mouse will promote analyses of not only the neurulation but also the pathogenesis of human HPE.

Animals↗

PubMed2000

A novel member of the Xenopus Zic family, Zic5, mediates neural crest development.

We characterized Xenopus Zic5 which belongs to a novel class of the Zic family. Zic5 is more specifically expressed in the prospective neural crest than other Zic genes. Overexpression of Zic5 in embryos led to ectopic expression of the early neural crest markers, Xsna and Xslu, with the loss of epidermal marker expression. In Zic5-overexpressing animal cap explants, there was marked induction of neural crest markers, without mesodermal and anterior neural markers. This was in contrast to other Xenopus Zic genes, which induce both anterior and the neural crest markers in the same assay. Injection of a dominant-negative form of Zic5 can block neural crest formation in vivo. These results indicate that Zic5 expression converts cells from an epidermal fate to a neural crest cell fate. This is the first evidence for neural crest tissue inductive activity separate from anterior neural tissue inductive activity in a Zic family gene.

Amino Acid Sequence↗

PubMed2000

Zic3 is involved in the left-right specification of the Xenopus embryo.

Establishment of left-right (L-R) asymmetry is fundamental to vertebrate development. Several genes involved in L-R asymmetry have been described. In the Xenopus embryo, Vg1/activin signals are implicated upstream of asymmetric nodal related 1 (Xnr1) and Pitx2 expression in L-R patterning. We report here that Zic3 carries the left-sided signal from the initial activin-like signal to determinative factors such as Pitx2. Overexpression of Zic3 on the right side of the embryo altered the orientation of heart and gut looping, concomitant with disturbed laterality of expression of Xnr1 and Pitx2, both of which are normally expressed in the left lateral plate mesoderm. The results indicate that Zic3 participates in the left-sided signaling upstream of Xnr1 and Pitx2. At early gastrula, Zic3 was expressed not only in presumptive neuroectoderm but also in mesoderm. Correspondingly, overexpression of Zic3 was effective in the L-R specification at the early gastrula stage, as revealed by a hormone-inducible Zic3 construct. The Zic3 expression in the mesoderm is induced by activin (beta) or Vg1, which are also involved in the left-sided signal in L-R specification. These findings suggest that an activin-like signal is a potent upstream activator of Zic3 that establishes the L-R axis. Furthermore, overexpression of the zinc-finger domain of Zic3 on the right side is sufficient to disturb the L-R axis, while overexpression of the N-terminal domain on the left side affects the laterality. These results suggest that Zic3 has at least two functionally important domains that play different roles and provide a molecular basis for human heterotaxy, which is an L-R pattern anomaly caused by a mutation in human ZIC3.

Animals↗

PubMed1999

Zic1 regulates the patterning of vertebral arches in cooperation with Gli3.

Skeletal abnormalities are described that appeared in Zic1-deficient mice. These mice show multiple abnormalities in the axial skeleton. The deformities are severe in the dorsal parts of the vertebrae, vertebral arches, but less so in the vertebral bodies (spina bifida occulta). The proximal ribs are deformed having ectopic processes. The abnormalities found in the vertebral arches can be traced back to disturbed segmental patterns of dorsal sclerotome. The Zic1/Gli3 double mutants showed severe abnormalities of vertebral arches not found in single mutants. The abnormalities in the vertebral arches were less severe in Zic1/Pax1 mutants than Zic1/Gli3 mutants, but significantly more pronounced than in Zic1 single mutants. The three genes may act synergistically in the development of the vertebral arches.

Animals↗

PubMed1998

Mouse Zic1 is involved in cerebellar development.

Zic genes encode zinc finger proteins, the expression of which is highly restricted to cerebellar granule cells and their precursors. These genes are homologs of the Drosophila pair-rule gene odd-paired. To clarify the role of the Zic1 gene, we have generated mice deficient in Zic1. Homozygous mice showed remarkable ataxia during postnatal development. Nearly all of the mice died within 1 month. Their cerebella were hypoplastic and missing a lobule in the anterior lobe. A bromodeoxyuridine labeling study indicated a reduction both in the proliferating cell fraction in the external germinal layer (EGL), from 14 d postcoitum, and in forward movement of the EGL. These findings suggest that Zic1 may determine the cerebellar folial pattern principally via regulation of cell proliferation in the EGL.

Animals↗

PubMed1998

Xenopus Zic family and its role in neural and neural crest development.

We characterized two new members of the Zic family, Xenopus Zic1 and Zic2. They are very similar to mouse Zic1 and Zic2 in the protein coding region including the zinc finger domain. In early gastrula, Zic1 expression was restricted to the prospective neural plate region whereas Zic2 was expressed widely in the ectoderm. We observed enhanced neural and neural crest-derived tissue formation in the Zic1 or Zic2 overexpressed embryos and neural and neural crest marker induction in the Zic1 or Zic2 overexpressed animal cap explants. Our findings suggest that Zic1 and Zic2 have essentially the same properties as Zic3 and that the Xenopus Zic family may act cooperatively in the initial phase of neural and neural crest development.

Amino Acid Sequence↗

PubMed1997

Xenopus Zic3, a primary regulator both in neural and neural crest development.

Xenopus Zic3 is a Xenopus homologue of mouse Zic and Drosophila pair-rule gene, odd-paired. We show here that Zic3 has significant roles both in neural and neural crest development in Xenopus embryo. Expression of Zic3 is first detected in prospective neural plate region at gastrulation. Onset of the expression was earlier than most proneural genes and followed chordin expression. The expression was induced by blockade of BMP4 signal. Overexpression of Zic3 resulted in hyperplastic neural and neural crest derived tissue. In animal cap explant, the overexpression of Zic3 induced expression of all the proneural genes and neural crest marker genes. These findings suggest that Zic3 can determine the ectodermal cell fate and promote the earliest step of neural and neural crest development.

Animals↗

PubMed1997

The expression of the mouse Zic1, Zic2, and Zic3 gene suggests an essential role for Zic genes in body pattern formation.

We examined the expression of Zic1, Zic2, and Zic3 genes in the mouse embryo by means of in situ hybridization. Zic genes were found as a group of genes coding for zinc finger proteins that are expressed in a restricted manner in the adult mouse cerebellum. We showed that the genes are the vertebrate homologues of Drosophila odd-paired, which may play an essential role in parasegmental subdivision and in visceral mesoderm development. The expression of the three Zic genes was first detected at gastrulation in a spatially restricted manner. At neurulation, the expression became restricted to the dorsal neural ectoderm and dorsal paraxial mesoderm. During organogenesis, the three genes were expressed in specific regions of several developing organs, including dorsal areas of the brain, spinal cord, paraxial mesenchyme, and epidermis, the marginal zone of the neural retina and distal regions of the developing limb. For all stages, significant differences in the spatial expression of Zic1, Zic2, and Zic3 were observed. Furthermore, the expression of Zic genes in Pax3, Wnt-1, and Wnt-3a mutant embryos suggested that Zic genes are not primarily regulated by the three genes which were expressed in dorsal areas similar to Zic genes. However, in open brain, a mutant with severe neural tube defects, and in the Wnt-3a mutant mice, the expression of Zic genes was changed. The changed expression pattern in Wnt-3a mutant mice suggests that Zic genes in the neural tube are regulated by the factors from notochord. Our findings suggest that Zic genes are involved in many developmental processes. Furthermore, analysis of gene expression patterns in different mouse mutants indicated that Zic genes may act upstream of many known developmental regulatory genes.

Animals↗

PubMed1996

Distribution of a reeler gene-related antigen in the developing cerebellum: an immunohistochemical study with an allogeneic antibody CR-50 on normal and reeler mice.

We have immunohistochemically investigated the expression of a reeler gene-related antigen in the mouse cerebellum by using a monoclonal antibody, CR-50. This antibody probes a distinct allelic antigen present in normal but not in reeler mutant mice, and this antigen is localized in the brain regions in which morphological abnormalities occur in reeler mice (Ogawa et al., Neuron 14: 899-912, 1995). The developing normal cerebellum showed transient immunoreactivity to CR-50 in a limited set of neurons and in the extracellular space near the pial surface. An early population of CR-50-labeled cells emerged on embryonic day (E) 13 along the dorsal cerebellar surface, comprising the nuclear transitory zone (NTZ). Bromodeoxyuridine labeling revealed the time of origin of these cells to be at E11-12. From E14 to E18, some CR-50-labeled cells were stacked in the inner border of the external granular layer (EGL), whereas others were scattered in deep areas, such as the cerebellar nuclei and the surrounding intermediate zone or white matter. In the first postnatal week, these subcortical structures became immunonegative. However, CR-50 antigen was continuously produced until the second postnatal week by another population of cells occupying i) the premigratory zone (PMZ), the inner half of the EGL, and ii) the internal granular layer (IGL). These later CR-50-positive cells were smaller than the earlier type and showed the morphology typical of granule neurons. Both types of CR-50-labeled cells were positive for a DNA-binding protein, zic. By treating living cerebellar slices with CR-50, the extracellular antigen was localized as a puncutate staining pattern in the NTZ, PMZ, and molecular layer (ML), but not in the subcortical regions and IGL. Purkinje cells were negative for CR-50 and aligned as a monolayer adjacent to the PMZ, though their dendritic trees were closely associated with the extracellular CR-50-antigen in the PMZ and ML. Staining of dissociated cells suggested that the extracellular antigen is initially present throughout the surfaces of the CR-50/anti-zic double positive neurons, and is then rearranged to concentrate on their processes contacting with Purkinje cells. The spatiotemporal expressions of the CR-50 antigen in the cerebellum are consistent with the possibility that this antigen is involved in cell-cell interactions related to the histogenetic assembly of Purkinje cells.

Animals↗

PubMed1996

Identification and characterization of Zic4, a new member of the mouse Zic gene family.

The mouse Zic genes encode zinc-finger (Zf) proteins expressed only in the cerebellum of the adult brain. The genes are the vertebrate homologues of the Drosophila pair-rule gene, odd-paired (opa). We identified a novel gene, Zic4, which belongs to the Zic gene family, through a genomic and cDNA cloning study. Zic4 is highly similar to Zic1, Zic2 and Zic3, especially in its Zf motif. An analysis of the genomic organization of Zic4 showed that the gene shares a common exon-intron boundary with Zic1, Zic2, Zic3 and opa. The chromosomal location of Zic4 was determined to be mouse chromosome 9 in the vicinity of Zic1, using an interspecific backcross panel. An RNase protection study showed that Zic4 is expressed only in the cerebellum during the adult stage, as are the other Zic genes. The temporal profile of mRNA expression in the developing cerebellum is similar to that of Zic3 which has a peak on postnatal day 5. These findings suggest that Zic4 is a gene which works cooperatively with other Zic genes during cerebellar development.

Amino Acid Sequence↗