Differentiation-dependent chromatin alterations precede and accompany transcription of immunoglobulin light chain genes.

摘要: We have studied the nature of chromatin alterations along immunoglobulin light chain (IgL) genes during B cell development using cultured murine lines. Employing a fractionation procedure on micrococcal nuclease-treated nuclei, we demonstrate that transcriptionally active k IgL lacks canonical nucleosomal repeat and exhibits pronounced association with insoluble nuclear material but is processed by nuclease to soluble component apparently histone H1 enriched in high mobility group proteins. Of particular significance, utilizing variant plasmacytoma line has inactivated one allele via promoter deletion, transcription per se not responsible for these novel alterations. Furthermore, show encompassing germline (unrearranged) silent lambda alleles k-producing plasmacytomas exhibit some same unusual properties are displayed alleles. Finally, only occur lines lymphocyte lineage progressed past early pre-B stage; when inactive, both possess typical packaging co-fractionate H1-containing chromatin. These findings lead us propose model predicts stage-specific prior gene rearrangement transcription.