title: Isolation and growth factor inducibility of the Xenopus laevis Lmx1b gene.
abstract: This paper reports the cloning of the full length Xenopus laevis Lmx1b gene, Xlmx1b. Xlmx1b is a LIM homeodomain protein with high conservation to homologues identified in human, mouse, hamster and chick. In situ hybridisation and RT-PCR analysis showed that Xlmx1b has a specific temporal expression pattern which can be separated into three main spatial domains. An Xlmx1b probe hybridized to regions of the nervous system from stage 13 onwards; these regions included the placodes and otic vesicles, the eye and specific sets of neurons. Sectioning of in situ hybridised embryos confirmed the location of transcripts as discreet regions of staining in ventrolateral regions of the neural tube. From stage 27, transcripts could be detected in the capsule of pronephric glomus. Finally, transcripts were detected by Northern blot analysis in the developing fore and hind limbs. Xlmx1b transcripts were also detected by Northern blot analysis in eye, brain, muscle and mesonephros tissue in metamorphosing tadpoles. RT-PCR analysis showed that zygotic expression of Xlmx1b is initiated at stage 10.5 and the temporal sequence of Xlmx1b expression is identical in both neural and presumptive pronephros regions. The effects of the growth factors activin A, retinoic acid (RA) and basic fibroblast growth factor (bFGF) on the regulation of Xlmx1b were also studied. Xlmx1b was found to be upregulated by activin A and RA inhibited this upregulation in a concentration dependant manner. In contrast, bFGF had no effect on the regulation of Xlmx1b.
authors.affiliation: Cell and Molecular Development Group, Department of Biological Sciences, Warwick University, Coventry, UK.
authors.forename: Caroline E
authors.initials: CE
authors.lastname: Haldin
authors.forename: Sarjit
authors.initials: S
authors.lastname: Nijjar
authors.forename: Karine
authors.initials: K
authors.lastname: Massé
authors.forename: Mark W
authors.initials: MW
authors.lastname: Barnett
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Jones
mesh_terms: D028341:Activins / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D006224:Cricetinae; D004247:DNA / Q000235:genetics; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D005801:Genes, Homeobox; D018398:Homeodomain Proteins / Q000235:genetics*; D006801:Humans; D028322:Inhibin-beta Subunits / Q000494:pharmacology; D060850:LIM-Homeodomain Proteins; D051379:Mice; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D014157:Transcription Factors; D014212:Tretinoin / Q000494:pharmacology; D014982:Xenopus laevis / Q000196:embryology / Q000235:genetics* / Q000254:growth & development
chemical_list: D018398:Homeodomain Proteins; C112149:LIM homeobox transcription factor 1 beta; D060850:LIM-Homeodomain Proteins; D014157:Transcription Factors; C422405:activin A; D016222:Fibroblast Growth Factor 2; D028341:Activins; D014212:Tretinoin; D004247:DNA; D028322:Inhibin-beta Subunits