Special Seminar: Regulation of immune development by microRNAs

Mark Chong, Head of the Genomics and Immunology Laboratory at St Vincent’s Institute of Medical Research in Melbourne, Australia, will give a lecture "Regulation of immune development by microRNAs."

When Jun 28, 2017
from 11:00 AM to 12:30 PM
Where Marsico 6004
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We are interested in the role of microRNA pathways in the control of immune/hematopoietic cell development. The immune/hematopoietic system can be broadly divided into the two branches, myeloid and lymphoid. Myeloid lineages are short lived cells responsible for rapid non-specific (innate) immune defense, while lymphoid lineages are long-lived and responsible for mounting specific (acquired) immune responses. To investigate if the microRNA pathway is required for myeloid cell development, we examined the impact of ablating the RNase III enzymes Drosha and Dicer within the hematopoietic system of bone marrow chimeric mice. These enzymes are central to microRNA biogenesis. We found that myeloid development is entirely dependent on Drosha. However, this was only partly via the biogenesis of microRNAs. Instead, we found that Drosha also functions to repress the expression of protein-coding mRNAs by direct endonucleolytic cleavage. In myeloid cell development, Drosha is required to repress the expression of two mRNAs encoding inhibitors of myelopoisis that would otherwise prevent the development of these cells. This occurs by recognition and cleavage of stem-loop structures within these mRNA targets. This microRNA-independent function of Drosha will be discussed.