Absence of MHC gene expression in lens and cloning of dbpB/YB-1, a DNA-binding protein expressed in mouse lens

Abstract

The status of major histocompatibility complex (MHC) class I and II gene expression in the normal mouse lens was examined. No mRNA for either class I or II genes was detectable in mouse lens, while the expression of MHC genes in other tissues generally matched immunohistochemical data from human tissues. However it was observed that MHC class I mRNA is present in the mouse lens-derived cell line alpha TN4-1. From a new-born mouse lens cDNA library a clone was obtained for the murine homologue of the DNA-binding protein dbpB/YB-1, a protein originally identified in human lymphocytes and proposed to be a negative regulator of MHC class II gene expression. Northern blots detect dbpB/YB-1 mRNA in all mouse tissues and cells examined, including both mouse lens and alpha TN4-1 cells, suggesting that dbpB/YB-1 has a general and widespread role.

RNA-binding proteins in mouse oocytes and embryos: Expression of genes encoding Y box, DEAD box RNA helicase, and polyA binding proteins

“…Multiple, closely related Y box genes have been identified in mouse [Gai et al, 1992;Shaughnessy et al, 1992]. A Y box sequence isolated from newborn lens, dbpB/YB1 [Shaughnessy et al, 1992], is 99.7% identical at the amino acid level to MSY1; at the nucleotide level, coding sequences are 99.4% identical and 5Ј-and 3Ј-UTRs are 92.5%, and 97.8% identical, respectively. The single nucleotide differences between MSY1 and dbpB/YB1 at nucleotides 206,207,258,303,711 are relevant to this study.…”

A macrophage migration inhibitory factor is expressed in the differentiating cells of the eye lens.

“…3). There is apparently no correlation between the expression of lOK/MIF and the level of major histocompatibility complex gene expression in the tissues (8), suggesting that lOK/MIF may have a function distinct from any role in the immune system.…”

“…The mouse lens cDNA clone was used as a probe. RNA was extracted, blotted, and hybridized as described (8 PCR Analysis of mRNA Distribution in Chicken Lens. Dissections, RNA extraction, and reverse transcription (RT)-PCR were as described (7).…”

“…encapsulated lens (18). Indeed, the mouse lens is part of the immunologically privileged anterior chamber of the eye and has no class I or class II major histocompatibility complex gene expression (8). The mature lens thus seems to have no direct interaction with the immune system.…”

Qa-1, a Nonclassical MHC Molecule with Immunomodulatory Functions, Is Ubiquitously Expressed in the Immune-Privileged Anterior Chamber of the Eye

“…15−17 Tissues within the AC of the eye have severely repressed or non-existent expression of MHC class Ia molecules. 18,19 This results in the effective avoidance of recognition by CD8+ T cells. A search for class Ib molecule expression in the immune-privileged eye has only recently begun.…”