Leucine-Rich Repeat-Containing G Protein-Coupled Receptor-4 (LGR4, Gpr48) Is Essential for Renal Development in Mice

Leucine-rich repeat-containing G protein-coupled receptor (LGR)-4 is a G protein-coupled receptor (GPCR) with a seven-transmembrane domain structure. LGRs are evolutionally and structurally phylogenetic, classified into three subgroups and are members of the so-called orphan receptors whose ligands have yet to be identified. We generated knockout mice lacking <i>Lgr4</i><i>(Gpr48)</i> by targeted deletion of part of exon 18, which codes for the transmembrane and signal-transducing domains of the receptor. <i>Lgr4</i> null mice were born at much less than the 25% expected frequency from crosses of <i>Lgr4</i> heterozygous mice <i>(Lgr4</i>^+/–<i>)</i>. <i>Lgr4</i> null mice that survived in utero died shortly after birth in almost all cases. We observed striking renal hypoplasia in the null mice, accompanied by elevated concentration of plasma creatinine. Histological analysis of the P0 null mouse kidney showed a notable decrease in the total number and density of the glomerulus. Thus, the function of <i>Lgr4</i> is essential to regulate renal development in the mouse. This study suggests that the <i>Lgr4</i> gene is a new and important member of LGRs involved in a group of genes responsible for hereditary disease in the kidney.