Synthesis and turnover of β2-microglobulin in Ad12-transformed cells defective in assembly and transport of class I major histocompatibility complex molecules

Sigal Vinograd Mey-Tal, Chana Schechter, Rachel Ehrlich

Research output: Contribution to journalArticlepeer-review

Abstract

In primary embryonal fibroblasts from transgenic mice expressing H-2 genes and a miniature swine class I transgene (PD1), transformation with the highly oncogenic Ad12 results in a reduction in peptide transporter and proteasome-associated (LMP2 and LMP7) gene expression, and suppression in transport and cell surface expression of all class I antigens. The selective suppression in transport of H-2 (but not of PD1) molecules in cells reconstituted for the expression of peptide transporter and LMP genes implied that an additional factor(s) is involved in the assembly of class I complexes. Here we show that the β2m, H-2Db, and H-2Kb genes are transcribed and translated in Ad12-transformed cells. However, unlike normal and E1Ad5-transformed cells, in which β2m is either secreted unbound or bound to class I heavy chains, in Ad12-transformed cells significant amounts of β2m are retained in the cell bound to the membrane, but free of class I heavy chains. This abnormal turnover of β2m in the Ad12-transformed cells suggests the existence of a novel β2m-binding molecule(s) that sequesters β2m, and this process may provide a mechanism by which transformation with Ad12 may subvert class I complex formation.

Original languageEnglish
Pages (from-to)353-361
Number of pages9
JournalJournal of Biological Chemistry
Volume272
Issue number1
DOIs
StatePublished - 1997

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