In JoVE (1)
Other Publications (10)
- Developmental Dynamics : an Official Publication of the American Association of Anatomists
- Anatomical Science International
- Birth Defects Research. Part A, Clinical and Molecular Teratology
- American Journal of Medical Genetics. Part A
- Biochemical and Biophysical Research Communications
- Development (Cambridge, England)
- Mechanisms of Development
- The Journal of Neuroscience : the Official Journal of the Society for Neuroscience
- Birth Defects Research. Part B, Developmental and Reproductive Toxicology
- Fetal Diagnosis and Therapy
Articles by Munekazu Komada in JoVE
चूहे के लिए ऊंचा प्लस भूलभुलैया Munekazu Komada1, Keizo Takao1,2, Tsuyoshi Miyakawa2 1Genetic Engineering and Functional Genomics Unit, Frontier Technology Center, Graduate School of Medicine, Kyoto University, 2Institute for Comprehensive Medical Science Division of Systems Medicine, Fujita Health University बुलंद प्लस भूलभुलैया परीक्षण चूहों में व्यवहार की तरह चिंता को मापने के लिए सबसे व्यापक रूप से प्रयोग किया जाता परीक्षणों के एक है. यहाँ, हम एक परीक्षण के संचालन के लिए विस्तृत प्रक्रियाओं दिखा फिल्म उपस्थित थे.
Other articles by Munekazu Komada on PubMed
Expression of the Mouse Fgf15 Gene is Directly Initiated by Sonic Hedgehog Signaling in the Diencephalon and Midbrain Developmental Dynamics : an Official Publication of the American Association of Anatomists. Feb, 2005 | Pubmed ID: 15614767 Sonic hedgehog (Shh) is a secreted molecule that is thought to regulate tissue growth and patterning in vertebrate embryos. Although it has been reported that Gli transcription factors mediate Shh signaling to the nucleus, little is known about developmental target genes of Gli. In the previous genetic study, we showed that Shh is required for Fgf15 expression in the diencephalon and midbrain. Here, we examined whether Fgf15 is a direct target of Shh signaling through Gli. Shh was expressed in the midline cells and Fgf15 in the medial region of the diencephalon/midbrain by the seven-somite stage. The Fgf15 expression domain coincided with that of Gli1 and overlapped with that of Gli2 at this stage. Fgf15 expression in the diencephalon/midbrain was greatly reduced in the seven-somite Shh mutant embryos. Transgenic analysis showed that the 3.6-kb 5'-flanking region of the Fgf15 gene is sufficient for induction of Fgf15 in the medial/ventral diencephalon/midbrain. Luciferase assay showed that the 3.6-kb Fgf15 enhancer/promoter was activated by Gli2. A Gli-binding site was located 1 kb upstream of the transcription start site and was required for expression in the medial/ventral diencephalon/midbrain in transgenic embryos and for activation in luciferase assay. These findings indicate that Fgf15 is directly regulated by Shh signaling through Gli proteins.
Signaling Cascade Coordinating Growth of Dorsal and Ventral Tissues of the Vertebrate Brain, with Special Reference to the Involvement of Sonic Hedgehog Signaling Anatomical Science International. Mar, 2005 | Pubmed ID: 15794128 The vertebrate brain is a complex and highly organized structure with numerous neurons and glial cells. During development, undifferentiated progenitor cells proliferate from neural stem/precursor cells and gradually restrict their fates according to their environment. Differentiated cells are arranged precisely to accomplish their function and to maintain integrity as a whole brain. In this respect, cells must receive signals to know where and when they determine their fates. Secreted and membrane molecules convey the information between cells. The secreted glycoprotein Sonic hedgehog (Shh) is one of such signaling molecules. Sonic hedgehog is widely known to specify ventral neuronal types according to the concentration of Shh, whereas differentiation of dorsal neurons is largely independent of Shh. However, in the diencephalon and midbrain, dorsal parts are also affected in Shh-mutant embryos. Detailed analysis demonstrated that Shh signaling indirectly regulates the growth of the dorsal tissue in these regions. One of the fibroblast growth factor (FGF) members, namely FGF15, has been reported to be downstream to Shh signaling in the mouse embryonic brain. Luciferase assays and transgenic analysis revealed that the Fgf15 gene is a direct target of Shh. Downregulation of Tcf4 and upregulation of Bmp4 in Shh mutants suggest that Wnt and BMP signals from the dorsal midline are also involved in the dorsal brain phenotype. These data suggest the coordinating role of the Shh-FGF15-Wnt/BMP signaling cascade between the ventral and dorsal parts of the brain.
Sequential Developmental Changes in Holoprosencephalic Mouse Embryos Exposed to Ethanol During the Gastrulation Period Birth Defects Research. Part A, Clinical and Molecular Teratology. Jul, 2007 | Pubmed ID: 17393481 Prenatal exposure to ethanol induces holoprosencephalic malformations in both humans and laboratory animals. However, its teratogenic window for inducing holoprosencephaly is narrow, and the teratogenic mechanism is not well understood. In the present study, we examined the morphological changes in the craniofacial structures of mouse embryos/fetuses at intervals following ethanol treatment and evaluated gene expression patterns in the embryos.
Embryogenesis of Holoprosencephaly American Journal of Medical Genetics. Part A. Dec, 2007 | Pubmed ID: 17963261 Holoprosencephaly (HPE) is a malformation of the human brain caused primarily by incomplete division of the prosencephalon into two halves and is often associated with various facial anomalies. Although HPE is rather rare in newborns (1/10,000-15,000 births), it is frequently encountered in therapeutic abortuses (>1/250). To date, nine gene mutations responsible for human HPE have been identified, but the pathogenetic mechanisms of the craniofacial anomalies in HPE have just begun to be understood. Here, we summarize our studies on human embryos with HPE and discuss the embryogenesis and the underlying molecular mechanisms of HPE malformations under the following headings: pathology, pathogenesis, and critical period of development.
Expression of Fgf15 is Regulated by Both Activator and Repressor Forms of Gli2 in Vitro Biochemical and Biophysical Research Communications. May, 2008 | Pubmed ID: 18279667 Fibroblast growth factor 15 (Fgf15) is expressed in the medial region of diencephalon and midbrain by the seven-somite stage. In the previous studies, we showed that Sonic hedgehog signaling through Gli protein is required for Fgf15 expression in this region. The Fgf15 expression domain overlapped with that of Gli2 and the Gli-binding site (GliBs) is located in the 3.6-kb 5'-flanking enhancer/promoter region of the Fgf15 gene. In this study, we identified the two additional Gli-binding sites in row, called Gli-responsive elements (GliREs). Chromatin immunoprecipitation assay indicated that Gli2 directly binds to GliREs. The results from luciferase assays indicated that the Gli2 activator form binds to the GliBS and that the Gli2 repressor form binds to the GliREs. These findings suggest that the repressor form of Gli2 preferentially binds to the GliREs to control Fgf15 expression.
Hedgehog Signaling is Involved in Development of the Neocortex Development (Cambridge, England). Aug, 2008 | Pubmed ID: 18614579 Sonic hedgehog (Shh) function is essential for patterning and cell fate specification, particularly in ventral regions of the central nervous system. It is also a crucial mitogen for cerebellar granule neuron precursors and is important in maintenance of the stem cell niche in the postnatal telencephalon. Although it has been reported that Shh is expressed in the developing dorsal telencephalon, functions of Shh in this region are unclear, and detailed characterization of Shh mRNA transcripts in situ has not been demonstrated. To clarify the roles of Shh signaling in dorsal pallium (neocortex primordium) development, we have knocked out the Shh and Smo genes specifically in the early developing dorsal telencephalon by using Emx1cre mice. The mutants showed a smaller dorsal telencephalon at E18.5, which was caused by cell cycle kinetics defects of the neural progenitor/stem cells. The cell cycle length of the progenitor/stem cells was prolonged, and the number of cycle-exiting cells and neurogenesis were decreased. Birth-date analysis revealed abnormal positioning of neurons in the mutants. The characteristics of the subventricular zone, ventricular zone and subplate cells were also affected. Weak immunoreactivity of Shh was detected in the dorsal telencephalon of wild types. Reduced Shh immunoreactivity in mutant dorsal telencephalons supports the above phenotypes. Our data indicate that Shh signaling plays an important role in development of the neocortex.
The Cyst-branch Difference in Developing Chick Lung Results from a Different Morphogen Diffusion Coefficient Mechanisms of Development. Mar-Apr, 2009 | Pubmed ID: 19073251 The developing avian lung is formed mainly by branching morphogenesis, but there is also a unique cystic structure, the air sac, in the ventral region. It has been shown that mesenchymal tissue is responsible for the differential development of a cystic or branched structure, and that the transcription factor Hoxb may be involved in determining this regional difference. We have previously developed two scenarios for branch-cyst transition, both experimentally and theoretically: increased production or increased diffusion of FGF. The aim of the present study was to discover whether one of these scenarios actually operates in the ventral region of the chick lung. We found that the FGF10 level was lower while the diffusion of FGF10 was more rapid in the ventral lung, indicating that the second scenario is more plausible. There are two possibilities as to why the diffusion of FGF10 differs between the two regions: (1) diffusion is facilitated by the looser tissue organisation of the ventral lung mesenchyme; (2) stronger expression of heparan sulphate proteoglycan (HSPG) in the dorsal lung traps FGF and decreases the effective diffusion coefficient. Mathematical analysis showed that the dorsal-ventral difference in the amount of HSPG is not sufficient to generate the observed difference in pattern, indicating that both extracellular matrix and tissue architecture play a role in this system. These results suggest that the regional cystic-branched difference within the developing chick lung results from a difference in the rate of diffusion of morphogen between the ventral and dorsal regions due to differential levels of HSPG and a different mesenchymal structure.
Mice with Altered Myelin Proteolipid Protein Gene Expression Display Cognitive Deficits Accompanied by Abnormal Neuron-glia Interactions and Decreased Conduction Velocities The Journal of Neuroscience : the Official Journal of the Society for Neuroscience. Jul, 2009 | Pubmed ID: 19571127 Conduction velocity (CV) of myelinated axons has been shown to be regulated by oligodendrocytes even after myelination has been completed. However, how myelinating oligodendrocytes regulate CV, and what the significance of this regulation is for normal brain function remain unknown. To address these questions, we analyzed a transgenic mouse line harboring extra copies of the myelin proteolipid protein 1 (plp1) gene (plp1(tg/-) mice) at 2 months of age. At this stage, the plp1(tg/-) mice have an unaffected myelin structure with a normally appearing ion channel distribution, but the CV in all axonal tracts tested in the CNS is greatly reduced. We also found decreased axonal diameters and slightly abnormal paranodal structures, both of which can be a cause for the reduced CV. Interestingly the plp1(tg/-) mice showed altered anxiety-like behaviors, reduced prepulse inhibitions, spatial learning deficits and working memory deficit, all of which are schizophrenia-related behaviors. Our results implicate that abnormalities in the neuron-glia interactions at the paranodal junctions can result in reduced CV in the CNS, which then induces behavioral abnormalities related to schizophrenia.
Methylnitrosourea Induces Neural Progenitor Cell Apoptosis and Microcephaly in Mouse Embryos Birth Defects Research. Part B, Developmental and Reproductive Toxicology. Jun, 2010 | Pubmed ID: 20549696 Prenatal exposure to methylnitrosourea (MNU), an alkylating agent, induces microcephaly in mice. However, its pathogenetic mechanism has not been clarified, especially that in the development of the cerebral cortex.
Prenatal Findings in Congenital Leukemia: a Case Report Fetal Diagnosis and Therapy. 2011 | Pubmed ID: 21293111 We here describe a case of congenital leukemia that ended in intrauterine fetal demise at 30 weeks of gestation. Acute enlargement of the fetal trunk, elevated pulsatility index of the umbilical artery with concomitant decline of pulsatility index of the middle cerebral artery, pleural effusion, and polyhydramnios preceded the fetal death. Diagnosis of congenital myeloid leukemia was suggested by microscopic examination of the placental tissue, revealing immature myeloid precursors filling the lumina of fetal vessels in the umbilical cord and chorionic villi. Extensive vascular involvement of the placenta by leukemic cells was considered to be a primary cause of the fetal death.