Syne2 (spectrin repeat containing, nuclear envelope 2) encodes a giant scaffolding protein that binds cytoplasmic F-actin, tethering the nucleus to the cytoplasm. SYNE2 is highly expressed in the retina. Mutations in Syne2 are associated with Emery–Dreifuss muscular dystrophy and dilated cardiomyopathy. This spontaneous mutation, cpfl8 (cone photoreceptor function loss 8), was identified as a glutamine to stop codon substitution at residue 4660 (Q4660*). Mice were first identified by an abnormally low cone ERG response. The cpfl8 mutation disrupts photoreceptor development causing significant apoptotic loss of cone cells, which is seen by birth and peaks at day 5 postpartum, resulting in fewer than normal cone cells. There is also mislocalization of various cell types in the retina. The rod photoreceptors, which also show increased apoptotic loss, mislocalize to the inner nuclear layer, and defective migration during development misplaces the horizontal cells, bipolar cells, and some Muller glia. Histology at 5 days of age shows a lack of normal synapse formation, at 8 days of age the outer plexiform layer is not properly developed, and at 12 days of age it is much thinner than normal with ectopic cells throughout the retina. At 1 month the inner and outer nuclear layer, and inner and outer segment layers are all thinner than normal, but there is no evidence of significant photoreceptor loss between 1 and 6 months of age. Ectopic cells persist in the inner and outer nuclear layers in the adult, and ectopic synapses, which show normal morphology by electron microscopy, are also found there. Homozygotes have a very low cone b-wave ERG response and a decreased rod ERG response at twenty-six days and at six months of age. Additionally the nuclear envelope in truncal skin fibroblasts is malformed, with varied size and increased blebbing. This strain may be useful for studying nuclear scaffolding and migration in the retina.

The cpfl8 (cone photoreceptor function loss 8), mutation in Syne2 (spectrin repeat containing, nuclear envelope 2) disrupts early retinal development resulting in very low cone b-wave response and decreased rod ERG response. Additionally the nuclear envelope in truncal skin fibroblasts is malformed, with varied size and increased blebbing. This strain may be useful for studying nuclear scaffolding and migration in the retina.

This strain is hosted by NIH's MMRRC, which partners with JAX for the distribution of this and other strains. For additional information and to purchase, please visit the MMRRC site.