Hoxa 11 is upstream of Integrin alpha8 expression in the developing kidney.
Mutation of the functionally redundant Hoxa 11/Hoxd 11 genes gives absent or rudimentary kidneys resulting from a dramatic reduction of the growth and branching of the ureteric bud. To understand better the molecular mechanisms of Hoxa 11/Hoxd 11 function in kidney development, it is necessary to identify the downstream target genes regulated by their encoded transcription factors. To this end, we conducted a screen for Hoxa 11-responsive genes in two kidney cell lines. HEK293 cells, which usually do not express Hoxa 11, were modified to allow inducible Hoxa 11 expression. The mK10 cells, derived specifically for this study from Hoxa 11/Hoxd 11 double-mutant mice, were also modified to give cell populations with and without Hoxa 11 expression. Differential display, Gene Discovery Arrays, and Affymetrix genechip probe arrays were used to screen for genes up- or down-regulated by Hoxa 11. Nine genes, PDGF A, Cathepsin L, annexin A1, Mm.112139, Est2 repressor factor, NrCAM, ZNF192, integrin-associated protein, and GCM1, showed reproducible 3-fold or smaller changes in gene expression in response to Hoxa 11. One gene, the Integrin alpha8, was up-regulated approximately 20-fold after Hoxa 11 expression. The Integrin alpha8 gene is expressed together with Hoxa 11 in metanephric mesenchyme cells, and mutation of Integrin alpha8 gives a bud-branching morphogenesis defect very similar to that observed in Hoxa 11/Hoxd 11 mutant mice. In situ hybridizations showed a dramatic regional reduction in Integrin alpha8 expression in the developing kidneys of Hoxa 11/Hoxd 11 mutant mice. This work suggests that the Integrin alpha8 gene may be a major effector of Hoxa 11/Hoxd 11 function in the developing kidney.
Valerius
M Todd
MT
Division of Developmental Biology, Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229, USA.
Patterson
Larry T
LT
Feng
Yuxin
Y
Potter
S Steven
SS
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D017931:DNA Primers; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000235:genetics*; D006801:Humans; D039001:Integrin alpha Chains; D016023:Integrins / Q000235:genetics*; D007668:Kidney / Q000196:embryology*; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D016296:Mutagenesis; D015513:Oncogene Proteins / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011518:Proto-Oncogene Proteins; D011994:Recombinant Proteins / Q000378:metabolism; D014162:Transfection
D017931:DNA Primers; C489493:HOXD11 protein, human; D018398:Homeodomain Proteins; D039001:Integrin alpha Chains; D016023:Integrins; D015513:Oncogene Proteins; D011518:Proto-Oncogene Proteins; D011994:Recombinant Proteins; C487378:Tlx1 protein, mouse; C093856:integrin alpha8; C071250:TLX1 protein, human