Cloning and characterization of the human IgH enhancer binding proteins HMG activating factor (HAF) 1 and 2
Abstract
The HE2 region of the human IgH enhancer is highly conserved in the murine IgH enhancer, and has been shown to be a B cell specific activation element in both enhancers. At the time this work was initiated, no DNA binding factors specific for the region had been cloned. I utilized southwestern screening technique, probing of an expression library with radiolabeled DNA, to isolate cDNAs encoding specific HE2 binding proteins. Two distinct, but related, cDNAs, HMG Activating Factors (HAF) 1 and 2, were cloned. Each encodes a transcription activator, as demonstrated by GAL4 fusion assays, and each bears the HMG box DNA binding motif. Both proteins bound to and activated from the sequence 5$\sp\prime$ AAACACAA 3$\sp\prime$, found in the human IgH enhancer, and the histone H1 promoter. Experiments demonstrated that the site bound by the HAF proteins is distinct from the regions previously shown to be critical for the B cell specific activity HE2, and mutations in the site were deleterious to HE2 function. Similar results were found with the related histone H1 promoter site. Expression of the antisense of either HAF cDNA substantially reduced transcription from a variety of reporter genes, and may indicate an essential role for HAF-1 and HAF-2 in the cell.
Subject Area
Molecular biology|Biochemistry
Recommended Citation
Stevens, Sean Michael, "Cloning and characterization of the human IgH enhancer binding proteins HMG activating factor (HAF) 1 and 2" (1993). Dissertations available from ProQuest. AAI9413912.
https://repository.upenn.edu/dissertations/AAI9413912