Immunoglobulin light chains dictate vesicular transport-dependent and -independent routes for IgM degradation by the ubiquitin-proteasome pathway

Yechiel Elkabetz, Anat Kerem, Lilach Tencer, Dorit Winitz, Ron R. Kopito, Shoshana Bar-Nun

Research output: Contribution to journalArticlepeer-review

Abstract

Degradation of IgM μ heavy chains in light chain-negative pre-B cells is independent of vesicular transport, as is evident by its insensitivity to brefeldin A or cell permeabilization. Conversely, by the same criteria, degradation of the secretory μs heavy chain in light chain-expressing B cells depends on vesicular transport. To investigate whether the presence of conventional light chains or the developmental stage of the B-lymphocytes dictates the degradative route taken by μ, we express in 70Z/3 pre-B cells either λ ectopically or κ by lipopolysaccharides-stimulated differentiation into B cells and show their assembly with μ heavy chains. The resulting sensitivity of μ degradation to brefeldin A and cell permeabilization demonstrates that conventional light chains, a hallmark of B cell differentiation, are necessary and sufficient to divert μ from a vesicular transport-independent to a vesicular transport-dependent degradative route. Although both routes converge at the ubiquitin-proteasome degradation pathway, only in light chain-expressing cells is vesicular transport a prerequisite for μ ubiquitination.

Original languageEnglish
Pages (from-to)18922-18929
Number of pages8
JournalJournal of Biological Chemistry
Volume278
Issue number21
DOIs
StatePublished - 23 May 2003

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