Purpose: Crystallins are expressed at high levels in lens fiber cells. Recent studies have revealed that several members of the α, β, and γ-crystallin family are also distributed in many non-lens tissues, though at lower levels. We observed that the use of retinal RNA as target for both custom I-Gene microarrays and Affymetrix GeneChips revealed significant expression of many crystallin genes. This prompted us to undertake a comprehensive investigation to delineate the baseline expression of crystallin genes in the adult mouse retina. Methods: Quantitative RT-PCR was carried out using gene specific primers (derived from the mouse genomic sequence) for each crystallin gene. Immunofluorescence studies using frozen sections of the mouse retinas were performed with crystallin-specific antibodies. Retinal lysates were analyzed by immunoblotting using antibodies specific to αA and αB crystallins and those produced against total β-crystallin and γ-crystallin fractions of bovine lenses. Results: Microarray analysis followed by quantitative RT-PCR revealed that mouse retinal cells express transcripts for 20 different members of the crystallin gene family; these are αA, αA-INS, αA-nov1, αB, βA1, βA2, βA3, βA4, βB1, βB2, βB3, γA, γC, γD, γE, γF, γS, μ, ζ, and λ-crystallin. The gene products of αA, αB, β-, and γ-crystallins are detected in the outer and inner nuclear layers of the retina by immunofluorescence analysis. In addition, αB and β-crystallins are detected in the photoreceptor inner segments. Retinal expression of these proteins was further confirmed by immunoblot analysis. Interestingly, our studies also showed a significant animal-to-animal variation in the expression level of some of the crystallins. Conclusions: Our results establish the expression of many crystallins in the adult mouse retina. Detection of crystallins in the retinal nuclear layers, though surprising, is consistent with their proposed role in cell survival and genomic stability. We suggest that crystallins play vital functions in protecting retinal neurons from damage by environmental and/or metabolic stress.
|Number of pages||10|
|State||Published - 2003|