Lhx1, a competence factor required for kidney field specification

CIRIO, MC; HALDIN, CE; COSENTINO, CC; HUKRIEDE, NEIL A.

Encuentro; Molecular Genetics and Developmental Biology annual retreat; 2011

In the vertebrate embryo, the kidney is derived from the intermediate mesoderm, which liesbetween the paraxial and lateral plate mesoderm. The LIM-class homeobox transcription factorlhx1 is expressed early in the intermediate mesoderm and is one of the first genes to beexpressed in the nephric mesenchyme. We investigated the role of Lhx1 in the events thatcontrol specification of renal progenitor cells from the intermediate mesoderm in Xenopusembryos. By overexpressing a constitutively-active form of Lhx1, we established its capacity toexpand the kidney field during the specification stage of kidney organogenesis. In addition, theability of Lhx1 to expand the kidney field diminishes as kidney organogenesis transitions to themorphogenesis stage. In a complimentary set of experiments, we determined that embryosdepleted of lhx1, show an almost complete loss of the kidney field. Using an explant culturesystem to induce kidney tissue, we confirmed that expression of genes from both proximal anddistal kidney structures is dramatically affected by the absence of lhx1. Taken together, ourresults demonstrate an essential role for Lhx1 in driving specification of the entire kidney fieldfrom the intermediate mesoderm.