The Experts below are selected from a list of 252 Experts worldwide ranked by ideXlab platform
Andreas Kispert - One of the best experts on this subject based on the ideXlab platform.
-
inhibition of sox2 dependent activation of shh in the ventral Diencephalon by tbx3 is required for formation of the neurohypophysis
Development, 2013Co-Authors: Markoliver Trowe, Li Zhao, Annacarina Weiss, Vincent M Christoffels, Douglas J Epstein, Andreas KispertAbstract:Tbx2 and Tbx3 are two highly related members of the T-box transcription factor gene family that regulate patterning and differentiation of a number of tissue rudiments in the mouse. Both genes are partially co-expressed in the ventral Diencephalon and the infundibulum; however, a functional requirement in murine pituitary development has not been reported. Here, we show by genetic lineage tracing that Tbx2+ cells constitute the precursor population of the neurohypophysis. However, Tbx2 is dispensable for neurohypophysis development as revealed by normal formation of this organ in Tbx2 -deficient mice. By contrast, loss of Tbx3 from the ventral Diencephalon results in a failure to establish the Tbx2+ domain in this region, and a lack of evagination of the infundibulum and formation of the neurohypophysis. Rathke's pouch is severely hypoplastic, exhibits defects in dorsoventral patterning, and degenerates after E12.5. In Tbx3 -deficient embryos, the ventral Diencephalon is hyperproliferative and displays an abnormal cellular architecture, probably resulting from a failure to repress transcription of Shh . We further show that Tbx3 and Tbx2 repress Shh by sequestering the SRY box-containing transcription factor Sox2 away from a Shh forebrain enhancer ( SBE2 ), thus preventing its activation. These data suggest that Tbx3 is required in the ventral Diencephalon to establish a Shh− domain to allow formation of the infundibulum.
-
wnt signaling affects gene expression in the ventral Diencephalon and pituitary gland growth
Developmental Dynamics, 2008Co-Authors: Mary Anne Potok, Andreas Kispert, Andrea Hunt, Michelle L Brinkmeier, Michael Leitges, Sally A CamperAbstract:We examined the role of WNT signaling in pituitary development by characterizing the pituitary phenotype of three WNT knockout mice and assessing the expression of WNT pathway components. Wnt5a mutants have expanded domains of Fgf10 and bone morphogenetic protein expression in the ventral Diencephalon and a reduced domain of LHX3 expression in Rathke's pouch. Wnt4 mutants have mildly reduced cell differentiation, reduced POU1F1 expression, and mild anterior lobe hypoplasia. Wnt4, Wnt5a double mutants exhibit an additive pituitary phenotype of dysmorphology and mild hypoplasia. Wnt6 mutants have no obvious pituitary phenotype. We surveyed WNT expression and identified transcripts for numerous Wnts, Frizzleds, and downstream pathway members in the pituitary and ventral Diencephalon. These findings support the emerging model that WNT signaling affects the pituitary gland via effects on ventral Diencephalon signaling, and suggest additional Wnt genes that are worthy of functional studies. Developmental Dynamics 237:1006–1020, 2008. © 2008 Wiley-Liss, Inc.
Makoto Ishibashi - One of the best experts on this subject based on the ideXlab platform.
-
expression dynamics of the lim homeobox genes lhx1 and lhx9 in the Diencephalon during chick development
The International Journal of Developmental Biology, 2008Co-Authors: Hirotomo Saitsu, Kohei Shiota, Makoto IshibashiAbstract:The Diencephalon is the caudal part of the developing forebrain, which corresponds to prosomeres 1 to 3. The mature Diencephalon is functionally and anatomically divided into well-defined nuclei. Previous researches have shown that LIM-homeobox genes are important transcription factors during Diencephalon regionalization in mice. Here we examined expression patterns of several chick orthologs of LIM-homeobox genes. Lhx1 and Lhx9 were expressed in the Diencephalon from early stages and their expression in the Diencephalon became restricted to prosomeres 1 and 2 in distinct fashions. Then we also studied the regulatory effects of possible upstream signals by in ovo electroporation. Lhx1 was found to be up-regulated by Shh signaling. Whereas Lhx9 was up-regulated by Wnt3a and Fgf15, it was down-regulated by Shh. Our data suggest that the LIM-homeobox genes, Lhx1 and Lhx9, regulated by ventral and/or dorsal signals, may play important roles in controlling regionalization of the Diencephalon during chick development.
-
expression of the mouse fgf15 gene is directly initiated by sonic hedgehog signaling in the Diencephalon and midbrain
Developmental Dynamics, 2005Co-Authors: Hirotomo Saitsu, Rika Nakayama, Kohei Shiota, Munekazu Komada, Misao Suzuki, Jun Motoyama, Makoto IshibashiAbstract: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. Developmental Dynamics 232:282–292, 2005. © 2004 Wiley-Liss, Inc.
Jiawei Zhou - One of the best experts on this subject based on the ideXlab platform.
-
expression of ventral Diencephalon enriched genes in zebrafish
Developmental Dynamics, 2010Co-Authors: Sen Li, Yi Chen, Jiawei ZhouAbstract:Dopaminergic (DA) neurons in the vertebrate di- and mesencephalon play essential roles in movement control, endocrine modulation and many other important physiological activities. To identify genes that may regulate the specification and differentiation of diencephalic DA neurons in zebrafish, the spatial and temporal expression pattern of a set of genes was investigated. In situ hybridization analysis revealed that expression of DNA binding inhibitor 3 (Id3), early B cell factor 2 (Ebf2), Ebf3, Iroquois related homeobox 1 (Irx1), Kruppel-like factor 7 (Klf7), mab-21-like 1 (Mab21l1), fatty acid binding protein 7 (Fabp7) and stathmin-like 4 (Stmn4), were enriched in the Diencephalon of zebrafish. Among these genes, Id3 was expressed specifically in a subset of DA neurons in the ventral Diencephalon, with co-expression of neurogenin1 (Ngn1). Alteration of expression levels of Id3 inhibited maturation of developing DA neurons. Taken together, our study provides genetic characteristics of DA neurons in the Diencephalon of zebrafish. Developmental Dynamics 239:3368-3379, 2010. (C) 2010 Wiley-Liss, Inc.
Koichi Kawakami - One of the best experts on this subject based on the ideXlab platform.
-
patterning the zebrafish Diencephalon by the conserved zinc finger protein fezl
Development, 2007Co-Authors: Jaeyeon Jeong, Zev Einhorn, Priya Mathur, Lishan Chen, Koichi KawakamiAbstract:The forebrain constitutes the most anterior part of the central nervous system, and is functionally crucial and structurally conserved in all vertebrates. It includes the dorsally positioned telencephalon and eyes, the ventrally positioned hypothalamus, and the more caudally located Diencephalon [from rostral to caudal: the prethalamus, the zona limitans intrathalamica (ZLI), the thalamus and the pretectum]. Although antagonizing Wnt proteins are known to establish the identity of the telencephalon and eyes, it is unclear how various subdivisions are established within the Diencephalon - a complex integration center and relay station of the vertebrate brain. The conserved forebrain-specific zinc-finger-containing protein Fezl plays a crucial role in regulating neuronal differentiation in the vertebrate forebrain. Here, we report a new and essential role of zebrafish Fezl in establishing regional subdivisions within the Diencephalon. First, reduced activity of fezl results in a deficit of the prethalamus and a corresponding expansion of the ZLI. Second, Gal4-UAS-mediated fezl overexpression in late gastrula is capable of expanding the prethalamus telencephalon and hypothalamus at the expense of the ZLI and other fore- and/or mid-brain regions. Such altered brain regionalization is preceded by the early downregulation of wnt expression in the prospective Diencephalon. Finally, fezl overexpression is able to restore the anterior forebrain and downregulate wnt expression in Headless- and/or Tcf3 (also known as Tcf7l1a)-deficient embryos. Our findings reveal that Fezl is crucial for establishing regional subdivisions within the Diencephalon and may also play a role in the development of the telencephalon and hypothalamus.
Sidney B Auerbach - One of the best experts on this subject based on the ideXlab platform.
-
effects of selective serotonin and serotonin noradrenaline reuptake inhibitors on extracellular serotonin in rat Diencephalon and frontal cortex
Naunyn-schmiedebergs Archives of Pharmacology, 2003Co-Authors: Tracy Matthews Felton, Tommy B Kang, Stephan Hjorth, Sidney B AuerbachAbstract:Some clinical reports suggest that tricyclic antidepressants which block both noradrenaline and serotonin (5-HT) reuptake (SNRIs) are more effective than selective 5-HT reuptake inhibitors (SSRIs) in treating severe depression. Moreover, one neurochemical study reported larger increases in extracellular 5-HT in rat frontal cortex in response to the tricyclic antidepressant imipramine compared to the SSRI fluoxetine. However, imipramine, which blocks both 5-HT and noradrenaline reuptake, also binds with relatively high affinity to receptors for noradrenaline, histamine and acetylcholine. Thus, to test the hypothesis that compounds that inhibit both 5-HT and noradrenaline reuptake produce larger increases in 5-HT efflux, we compared the effects of acute systemic administration of several SNRIs and SSRIs. Extracellular 5-HT was measured using microdialysis probes implanted in the Diencephalon and frontal cortex of unanesthetized rats. We tested the SSRIs paroxetine (0.3–10 mg/kg), citalopram (10–20 mg/kg) and fluoxetine (10 mg/kg), the nonselective tricyclic antidepressant imipramine (20 mg/kg) and the more selective SNRIs duloxetine (3–30 mg/kg) and venlafaxine (30–50 mg/kg). During the lights-off period, paroxetine and duloxetine increased 5-HT in the Diencephalon ~300 and ~200%, respectively. During the lights-on period, paroxetine and duloxetine each increased 5-HT ~400% in the Diencephalon. In the frontal cortex, both paroxetine and duloxetine increased 5-HT ~200%. Citalopram and venlafaxine each increased 5-HT in the Diencephalon ~300%. Fluoxetine and imipramine increased 5-HT in the Diencephalon by ~125 and ~80%, respectively. Thus, these results do not support the hypothesis that compared to SSRIs, compounds which inhibit both 5-HT and noradrenaline reuptake have a larger acute effect on extracellular 5-HT.