Abstract
Expression of the type XI collagen gene Col11a2 is regulated by three cartilage-specific enhancer elements. Two of these, named B/C and D/E, are located upstream of the gene, and one, named F/G, is in the first intron. Each enhancer binds Sox9, a key regulator of chondrogenesis. In addition, each enhancer contains other important sequences besides the Sox9-binding sites. The goal of the present work was to identify the other proteins besides Sox9 that bind and regulate the Col11a2 enhancers. Using the yeast one-hybrid screen, a protein was identified that bound to both the B/C and D/E enhancer elements. This protein, ribosomal protein L41 (RPL41), is a component of the large ribosomal subunit. It has also been reported to interact with the beta subunit of protein kinase CKII in stimulating phosphorylation of DNA topoisomerase II alpha, and its transcription is upregulated in some transformed cells, suggesting that this protein is multifunctional. To test the effect of RPL41 on the activity of the Col11a2 B/C and D/E enhancers, an RPL41 expression plasmid was constructed and transiently transfected into rat chondrosarcoma cells together with enhancer/reporter plasmids. RPL41 had no effect on the transcriptional activity of the D/E enhancer, but it decreased the activity of the B/C enhancer by approximately one-half. Experiments to identify the precise site of RPL41 binding in the B/C enhancer are ongoing. These results suggest a novel function for the ribosomal protein RPL41 in transcriptional regulation. Supported by NIH grant #AR 048839.
Published Version
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