Coordination of immunoglobulin DJ(H) transcription and D-to-J(H) rearrangement by promoter-enhancer approximation

A. Alessandrini, S. V. Desiderio

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63 Scopus citations


The genes that encode the variable regions of immunoglobulin (Ig) heavy chains are encoded by three DNA segments: V(H), D, and J(H). During B-cell development these segments are brought together by a pair of site-specific DNA rearrangements. The first of these joins a D segment to a J(H) segment; the second brings a V(H) segment in apposition to a DJ(H) unit. B-cell precursors that have undergone D-to-J(H) joining express transcripts that initiate at the 5' flanks of rearranged D segments (DJ(H) transcription). In this study we have examined the coordination of D-to-J(H) rearrangement and DJ(H) transcription. The B-lymphoid progenitor cell line HAFTL-1 undergoes D-to-J(H) rearrangement when propagated in culture. In progeny of a single HAFTL-1 cell clone, joining of distal D segments (D(SP2) and D(FL16)) to J(H) is accompanied by an increase in the steady-state level of transcripts initiating 5' of the D coding region. Steady-state transcription of a D(SP2) gene segment was undetectable prior to rearrangement and was observed to increase at least 20-fold upon joining to J(H). In contrast, transcription from the 5' flank of D(Q52), which lies within 700 bp of the J(H) cluster, was detected prior to rearrangement and did not increase significantly after rearrangement. The 5' flank of a D(SP2) segment was found to support expression of a heterologous gene upon transfection into B progenitor cell lines. Expression from this D(SP2) promoter was at least 30-fold higher in the presence of the Ig heavy-chain enhancer, in either orientation, than in its absence. A DNA fragment spanning the interval from -165 to +19 bp relative to the major D(SP2) transcriptional start site retained enhancer-dependent promoter activity. These observations imply that activation of D(SP2)J(H) and D(FL16)J(H) transcription is coordinated with D-to-J(H) rearrangement by approximation of enhancer-dependent D promoter elements to the Ig heavy-chain enhancer. This interpretation is consistent with our observation that the D(Q52) segment, which is closely linked to the J(H) cluster, is transcribed both before and after rearrangement.

Original languageEnglish (US)
Pages (from-to)2096-2107
Number of pages12
JournalMolecular and cellular biology
Issue number4
StatePublished - 1991

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology


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