Molecular Genetics Of Early Eye Development

National Eye Institute

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Abstract

We produced and characterized a mouse line that expressed a mutated Olfactomedin 1 (Olfm1) gene with a deletion of exons 4 and 5 and carried null mutations of the Olfactomedin 2 (Olfm2) and Olfactomedin 3 (Olfm3) genes. Most mice with triple mutations in Olfm1-3 genes died postnatally. Few surviving mice demonstrated changes in the retina and optic nerve that were significantly more severe than corresponding changes observed in mice with mutations or deletion of any of the analyzed olfactomedin domain-encoding genes. In particular, retinal ganglion cell death and optic nerve degeneration were more pronounced and detected much earlier in the triple mutant line than in any single mutant line. The level of Olfm1 expression was significantly higher than the levels of Olfm2 and Olfm3 expression in the retina and brain. Therefore, we produced mouse Olfm1 null mutant line in collaboration with Dr. Lijin Dong (Genetic Engineering Core Facility, NEI). Most of Olfm1 null mice died within first day after birth and only few mice survived into adulthood. These data indicated that Olfm1 protein plays a more prominent role in postnatal development than Olfm2 or Olfm3 proteins. A conditional Olfm1 knockout line was produced in collaboration with Dr. Lijin Dong (Genetic Engineering Core Facility, NEI) and effects of Olfm1 elimination from the retina and brain are under study. We continued the characterization of Olfm2 null mice. The synaptosomal membrane fraction of Olfm2 null mice showed a significant increase in Olfm1, GluR2 and GluR3 proteins as compared with wild-type littermates. Our data suggest that elimination of Olfm2 results in changes in the components of the AMPAR complex and other synaptic proteins leading to changes in the synaptic plasticity. We continue the characterization of previously produced double null olfm1a/olfm1b and klf6 null zebrafish. Analysis of the olfm1 distribution in different fractions of zebrafish brain demonstrated that olfm1 is preferentially localized in the synaptosomal membrane fraction. The amount of several proteins in the synaptosomal fraction of olfm1a/olfm1b zebrafish was significantly changed as compared with wild-type zebrafish. The functional consequences of these changes are under investigation. The CRISPR and TALEN technologies were used to produce null mutations in several genes involved in glaucoma (tmco1) or in synaptic functions (synaptotagmin1a). Zebrafish with null mutations in these genes are currently analyzed.