Expression of SIX3, ZFP161 and ALK Genes in the Brain and Kidneys of3H1 Br Mutant Mice

Abstract

A newly identified mouse mutation, called Br, displays heritable phenotypic features of frontonasal dysplasia (FND) and multic0ystic renal hypodysplasia (MRHD). The Br mutation is mapped to distal murine chromosome 17, but the causative gene remains unknown. The objective of this project was to analyze expression of three positional candidate genes, Six3, Zfp161 and ALK, in their target tissues. Two of these genes, Six3 and the putative mouse TGIF homologue, Zfp161, are candidates for the neurodevelopmental disorder, holoprosencephaly (HPE). Previous reports indicate a possible pathogenic relationship between HPE and FND, implicating HPE candidate genes in development of FND. The third gene of interest, ALK, is a neural developmental gene, also involved in renal morphogenesis. Embryos were collected on gestational day (GD) 18, and brain and kidney tissues were extracted. RT-PCR experiments were performed and expression was visualized with ethidium bromide staining. All three genes were found to be expressed in all examined tissues. Expression of the Six3 gene in the kidney was not previously described in the literature. This implies a novel role of Six3 in the renal development. Detailed mutational analysis of identified Six3 expression will be useful for evaluating its role in Br mutation.