Retinal expression of gamma-crystallins in the mouse

PURPOSE. High levels of expression of a form of gamma-crystallin mRNA in mo use retina have been identified. Because the sis murine gamma-crystallins h ave generally been regarded as specific to the lens, the expression of thes e crystallins at the mRNA and protein levels in the retina were evaluated i n more detail. METHODS. Expression of gamma E/F-crystallin mRNA was examined by northern b lot analysis and reverse transcription-polymerase chain reaction (RT-PCR) a nalysis applied to murine retinal and lens total RNAs. For gamma A-D-crysta llin mRNAs, a multiplex RT-PCR was used on total cDNAs. The detection of to tal gamma-crystallin protein in the retina was performed using an antibody to bovine lens gamma-crystallins, applied to protein extracts in immunoblot analysis and to cryostat sections of ocular tissues in immunofluorescence studies. RESULTS. By RT-PCR, we confirmed expression of both gamma E- and gamma F-cr ystallin as well as all four (gamma h-gamma D) remaining crystallins at the mRNA level in the mouse retina. gamma-Crystallin proteins were also detect able in murine retina by immunoblot analysis, although at a lower level tha n in the lens. By immunocytochemistry, gamma-crystallins were local ized pa rticularly to the inner retina, outer plexiform layer, and the photorecepto rs during postnatal development. CONCLUSIONS. Our findings of gamma-crystallin mRNA and protein expression i n the retina indicate that none of the major crystallin classes is uniquely expressed in the lens. The expression of gamma-crystallins in the developi ng murine retina suggests a role analogous to the anti-stress properties es tablished fur thr small heat-shock protein alpha B-crystallin, perhaps in r esponse to varying exposure to light.