STOCK Opn4^tm1.1Yau/J

Stock number: 021153
Research areas: Neurobiology Research, Research Tools

Description

Tau-lacZ targeting of the Opn4 (opsin 4 (melanopsin)) gene enables X-gal labeling of axons, cell bodies, and proximal dendrites of retinal ganglion cells that photoentrain light signals to the primary circadian pacemaker in the suprachiasmatic nucleus (SCN).

Detailed description

Opn4 (opsin 4 (melanopsin)) encodes a G-protein coupled receptor/photopigment found in mammalian retinal ganglion cells (RGCs) that photoentrain light signals from the eyes through the retinohypothalamic tract to the primary circadian pacemaker in the suprachiasmatic nucleus (SCN).

In this Opn4 knockout mutation, most of exons 1-9 and the intervening sequence are replaced by tau-lacZ. Tau-lacZ codes for a protein composed of the β-galactosidase enzyme fused to a signal sequence from tau (an actin-associated protein), which allows the fusion protein to be preferentially transported down axons to presynaptic terminals. In retinas from heterozygous animals, β-galactosidase and OPN4 immunoreactivities colocalize in ganglion cells. X-gal staining of β-galactosidase activity marks axons, cell bodies, and proximal dendrites are labeled.

Deletion of activity in homozygotes eliminates the intrinsic photosensitivity of retinal ganglion cells originally expressing melanopsin, leading to defects in various non-image-forming visual functions such as pupillary light reflex and circadian photoentrainment. The homozygotes are viable and fertile.

Development

Tau-lacZ and a loxP-flanked pgk-neomycin cassette replace fragments of exons 1 and 9 and the intervening sequence. The mutation was created in 129.1 embryonic stem (ES) cells. Resulting chimeric animals were bred with C57BL/6 mice. The neomycin cassette has been excised. This strain was maintained on a unknown, mixed genetic background by the donating lab.

Allele

Symbol: Opn4^tm1.1Yau
Name: targeted mutation 1.1, King-Wai Yau
MGI accession ID: MGI:5520169
Generation method: Targeted
Attributes: Reporter; Null/Knockout
Marker symbol: Opn4
Marker name: opsin 4 (melanopsin)
Chromosome: 14
Strain of origin: 129
Expressed genes: lacZ,beta-galactosidase,E. coli
Site of expression: Tau-lacZ in this allele enables X-gal labeling of axons, cell bodies, and proximal dendrites of retinal ganglion cells.
Molecular note: Tau-lacZ and a loxP-flanked pgk-neomycin cassette replace fragments of exons 1 and 9 and the intervening sequence. Cre-mediated recombination removed the neomycin cassette.