title: A comparative expression analysis of four MRX genes regulating intracellular signalling via small GTPases.
abstract: The X chromosomal mental retardation genes have attained high interest in the past. A rough classification distinguishes syndromal mental retardation (MRXS) and nonsyndromal mental retardation (MRX) conditions. The latter are suggested to be responsible for human specific development of cognitive abilities. These genes have been shown to be engaged in chromatin remodelling or in intracellular signalling. During this analysis, we have compared the expression pattern in the mouse of four genes from the latter class of MRX genes: Ophn1, Arhgef6 (also called alphaPix), Pak3, and Gdi1. Ophn1, Pak3, and Gdi1 show a specific neuronal expression pattern with a certain overlap that allows to assign these signalling molecules to the same functional context. We noticed the highest expression of these genes in the dentate gyrus and cornu ammonis of the hippocampus, in structures engaged in learning and memory. A completely different expression pattern was observed for Arhgef6. In the CNS, it is expressed in ventricular zones, where neuronal progenitor cells are located. But Arhgef6 expression is also found in other non-neural tissues. Our analysis provides evidence that these signalling molecules are involved in different spatio-temporal expression domains of common signalling cascades and that for most tissues considerable functional redundancy of Rho-mediated signalling pathways exists.
authors.affiliation: Department of Human Genetics, University of Ulm, Albert-Einstein-Allee 11, Ulm 89081, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Kohn
authors.forename: Peter
authors.initials: P
authors.lastname: Steinbach
authors.forename: Horst
authors.initials: H
authors.lastname: Hameister
authors.forename: Hildegard
authors.initials: H
authors.lastname: Kehrer-Sawatzki
mesh_terms: D000818:Animals; D001921:Brain / Q000196:embryology / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000378:metabolism; D003598:Cytoskeletal Proteins; D020690:GTPase-Activating Proteins; D020730:Guanine Nucleotide Dissociation Inhibitors / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism; D017403:In Situ Hybridization; D008607:Intellectual Disability / Q000235:genetics / Q000378:metabolism*; D008297:Male; D051379:Mice; D009687:Nuclear Proteins / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D012313:RNA / Q000032:analysis; D064067:Rho Guanine Nucleotide Exchange Factors; D017422:Sequence Analysis, DNA; D015398:Signal Transduction; D013737:Testis / Q000378:metabolism; D054462:p21-Activated Kinases
chemical_list: C576603:ARHGEF6 protein, human; C576604:Arhgef6 protein, mouse; D018797:Cell Cycle Proteins; D003598:Cytoskeletal Proteins; C086796:GDP dissociation inhibitor 1; D020690:GTPase-Activating Proteins; D020730:Guanine Nucleotide Dissociation Inhibitors; D020662:Guanine Nucleotide Exchange Factors; D009687:Nuclear Proteins; C498439:Ophn1 protein, mouse; D010750:Phosphoproteins; D064067:Rho Guanine Nucleotide Exchange Factors; D012313:RNA; C515911:PAK3 protein, human; C515912:Pak3 protein, mouse; D017346:Protein Serine-Threonine Kinases; D054462:p21-Activated Kinases