Project description:The magnocellular neurons (MCNs) of the supraoptic nucleus (SON) and paraventricular nucleus (PVN) of the hypothalamus are the principal site of biosynthesis of prepropeptide precursor of the antidiuretic hormone vasopressin (VP). This precursor is processed during anterograde axonal transportation to terminals in the posterior pituitary gland, where biologically active VP is stored until released into the general circulation in response to physiological activation of the SON by osmotic cues. By binding to V2-type receptors located in the kidney, VP decreases the amount of water lost in urine. Osmotic activation of the SON is accompanied by a dramatic morphological and functional remodelling. We have sought to understand the mechanistic basis of this plasticity in terms of the differential expression of genes. To identify such genes, we adopted an unbiased global approach based on Suppressive Subtractive Hybridisation-Polymerase Chain Reaction (SSH-PCR) Using this method, we generated libraries of clones putatively differentially expressed in control vs dehydrated SON. In order to rapidly screen these libraries, 1152 clones were subjected to microarray analysis, resulting in the identification of 459 differentially expressed transcripts. cDNA clones corresponding 56 of these RNAs were sequenced, revealing many of them to be novel ESTs. Four transcripts were shown by in situ hybridisation (ISH) to be significantly up- or down-regulated in the SON following dehydration. These genes may represent novel effectors or mediators of SON physiological remodelling. Keywords: dehydration, SON, NIA
Project description:Branchiomotor neurons are an important class of cranial motor neurons that innervate the branchial-arch-derived muscles of the face, jaw and neck. They arise in the ventralmost progenitor domain of the rhombencephalon characterized by expression of the homeodomain transcription factors Nkx2.2 and Phox2b. Phox2b in particular plays a key role in the specification of branchiomotor neurons. In its absence, generic neuronal differentiation is defective in the progenitor domain, and no branchiomotor neurons are produced. Conversely, ectopic expression of Phox2b in spinal regions of the neural tube promotes cell cycle exit and neuronal differentiation and at the same time induces genes and an axonal phenotype characteristic for branchiomotor neurons. How Phox2b exerts its pleiotropic functions, both as a proneural gene and a neuronal subtype determinant, has remained unknown. To gain further insight into the genetic programme downstream of Phox2b we searched for novel Phox2b-regulated genes by cDNA microarray (here NIA 15k slides) analysis of facial branchiomotor neuron precursors from heterozygous and homozygous Phox2b mutant embryos. Keywords: Phox2b-regulated genes identification
Project description:Branchiomotor neurons are an important class of cranial motor neurons that innervate the branchial-arch-derived muscles of the face, jaw and neck. They arise in the ventralmost progenitor domain of the rhombencephalon characterized by expression of the homeodomain transcription factors Nkx2.2 and Phox2b. Phox2b in particular plays a key role in the specification of branchiomotor neurons. In its absence, generic neuronal differentiation is defective in the progenitor domain, and no branchiomotor neurons are produced. Conversely, ectopic expression of Phox2b in spinal regions of the neural tube promotes cell cycle exit and neuronal differentiation and at the same time induces genes and an axonal phenotype characteristic for branchiomotor neurons. How Phox2b exerts its pleiotropic functions, both as a proneural gene and a neuronal subtype determinant, has remained unknown. To gain further insight into the genetic programme downstream of Phox2b we searched for novel Phox2b-regulated genes by cDNA microarray (here NIA 15k slides) analysis of facial branchiomotor neuron precursors from heterozygous and homozygous Phox2b mutant embryos. Keywords: Phox2b-regulated genes identification Four biological replicates each in dye swap