Expression of a novel splice variant of FRMD7 in developing human fetal brains that is upregulated upon the differentiation of NT2 cells

FRMD7 mutations are associated with X-linked idiopathic congenital nystagmus (ICN); however, the underlying mechanisms whereby mutations of FRMD7 lead to ICN remain unclear. In a previous study, the first FRMD7 splice variant (FRMD7-S) was cloned and identified, and FRMD7-S was hypothesized to play a significant role in neuronal differentiation and development. The present study investigated a novel multiple exon-skipping mRNA splice variant of FRMD7, termed FRMD7_SV2, which was detected in NT2 cells using northern blotting. The mRNA expression levels of FRMD7_SV2 in the developing human fetal brain were examined using reverse transcription polymerase chain reaction (PCR), while the expression levels in NT2 cells treated with retinoid acid (RA) or bone morphogenetic protein-2 were investigated using quantitative PCR. The results revealed that the expression of FRMD7_SV2 was spatially and temporally restricted in human fetal brain development, and was upregulated upon RA-induced neuronal differentiation of the NT2 cells. These results indicated that as a novel splice variant of FRMD7, FRMD7_SV2 may play a role in neuronal development.