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Marsha Ousman


I was born and raised in the warm, Caribbean island of Trinidad. Lived there until I graduated from high school...St. Joseph's Convent, then moved to New York City for college. I earned a BS in Biotechnology from York College, City University of New York. Eager to see the Midwest, I moved to Ann Arbor for graduate school. I completed my Ph.D. in Cellular and Molecular Biology in 2007 working with Ron Koenig and Kate Barald.


Bone Morphogenetic protein 4 (BMP4) is known to be important for normal development of the inner ear. BM4 is produced in specific regions of the developing inner ear, and its level of production changes during development. It has been found that the inhibition of BMP4 as well as an excess of Retinoic Acid (RA) cause the loss of semicircular canal formation in the inner ear. It has also been shown that RA down regulates transcription of BMP4 from a novel intron 2 promoter in the developing inner ear. Our overall goal is to understand the factors that control when, where and how much BMP4 is produced during inner ear development. Two different promoters-1B and a novel intron2 promoter, regulate the production of BMP4 in the inner ear, but the importance of each and the way each is regulated are not known. We are interested in determining where and when each of the BMP4 promoters is turned on during inner ear development and what happens if either (or both) of these BMP promoters is non-functional. If inner ear development were abnormal, then we would conclude that particular promoter is important for turning on BMP4 and for creating a normal inner ear. To carry out this study, we are creating transgenic mice where each promoter will be driving LacZ to see when and where BMP4 is expressed. We are also interested in what the sequence required for the activity of the 1B and intron 2 promoters. To do this, promoter deletions will be made and tested as luciferase constructs in the 2B1 cell line derived from otocysts of embryonic day 9.5 Immortomice. Interest also lies in the in vivo consequences of destroying the 1B or intron 2 promoters. To do this, we are making mice that will have inactivation mutations of the endogenous promoters and examine BMP4 expression. In mice that have the 1B or intron 2 promoter destroyed, RA down regulation will be studied. Knowing which promoter (s) is most important for BMP4 expression in the developing inner ear will allow us to test whether destruction of the RA response element in the promoter affects inner ear development and to study other factors that may regulate BMP4 expression in the inner ear development.