Regulation of the class II-associated invariant chain gene in normal and mutant B lymphocytes.

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Abstract
The invariant chain protein is intracellularly associated with class II major histocompatibility proteins. In many cases, the expression of these molecules appears to be regulated in a similar manner. Contained within the promoter of the invariant chain gene are sequences (X and I.gamma.1) that are similar to the X and Y box elements of class II genes, suggesting that these sequences might be involved in its regulations. DNase I footprinting reveals additional cis-acting elements (I.gamma.2 and I.gamma.3) that contain sequence similarities to NF-.kappa.B and/or H2TF1/KBF1 recognition sequences. A series of fusion constructs with the chloramphenicol acetyltransferase reporter gene were used to analyze the role of these sequences (I.gamma.1, I.gamma.2, I.gamma.3, and X and Y elements) in both normal and mutant B lymphocytes. These data suggest that likelihood of multiple X box proteins in B cells, which can act as both negative and positive regulatory factors.