Abe and Pamela to present at Student Seminar on Thursday (22.April) at noon in 2-501 BSB

Abe and Pamela will be presenting Student Seminar this week in 2-501 BSB at noon. I have asked the speakers to provide a brief overview for their talks. Hope to see you there!

Background for Abe’s talk

Gene Therapy for a Dominant Negative Deafness Mutation

For the past several years I have been working toward gene therapy for a dominantly inherited deafness mutation. This mutation is in a gap junction protein expressed abundantly in the cochlea and it prevents the formation of functional gap junction channels that are necessary for the intercellular transport of ions and other small molecules within the cochlea. The result of this dominant-negative mutation is significant hearing loss.

Our lab has a transgenic mouse model of this disease and I have been experimenting with ways to improve or delay the deafness phenotype in the animals. Much of my time has been spent investigating the transduction properties of different viral vectors when introduced to the developing mouse cochlea and designing and testing siRNA to selectively knockdown expression of the mutant allele. An analogy that you will hear me use to describe my research is that of a flower garden: The wild-type connexin that make up the gap junction network in your cochlea are like beautiful flowers that you have planted in front of your house. The dominant-negative mutant connexins are like weeds that are over-growing the flowers. Using RNA interference to suppress expression of the mutant allele is analogous to weeding the garden.

At student seminar on Thursday I will briefly report on my progress with the weeding, but I will spend most of my time discussing a new therapeutic idea and our experimental design to test it: the other option for making your flower garden look better is to forget about the weeds and simply plant more flowers. We have undertaken an experiment to genetically “plant more flowers” by crossing the dominant-negative mutant mice with transgenic mice that overexpress wild-type connexins. I know that this probably isn’t the best way to tend a flower garden, but it may be good enough to at least make the front of your house look presentable. Could the same be true of gap junctions in the cochlea?

(I hope that gardening enthusiasts will forgive my imperfect analogy…perhaps you can help me think of a better one?)

Background for Pamela’s talk

Our lab studies a rare heterogeneous syndromic form of retinal degeneration, Bardet-Biedl Syndrome (BBS, OMIM), to gain insight into normal retinal development as well as to understand the pathophysiology involved in common vision disorders.  At least fourteen genes (BBS1BBS14) are reported to individually cause BBS.  We utilize both the mouse and zebrafish as models to further study both cellular and molecular events underlying BBS.   Knockout mouse lines as well as a knockin mouse model for BBS all recapitulate the human BBS phenotype of retinal degeneration.  Interestingly, death of the photoreceptors is preceded by mislocalization of rhodopsin, suggesting that there is a defect in intracellular transport in Bbs mutant mice.  Additionally, we have adapted a cone-based vision assay to test visual acuity in the zebrafish.

I have focused my research on studying one of these genes, BBS3 (OMIM).  A member of the Ras family of small GTP-binding proteins, BBS3 is postulated to play a role in vesicular transport.  We have previously identified a second longer transcript of BBS3, BBS3L, and have demonstrated that the BBS3L transcript is specifically required for retinal organization and function in both the zebrafish and mouse.

To further elucidate the functional differences between the two BBS3 transcripts, both transcripts were placed under the control of the heat-shock-inducible promoter to allow for temporal control of gene expression.  Temporal regulation allows us to easily assess protein localization at later points in development, and allows us to more closely recapitulate the expression of bbs3L as this transcript is not endogenously expressed until after 42hpf.  Using this tool, we can now ask questions concerning the role of BBS3 in different cell types over the course of development.  Moreover, I’m continuing efforts to further evaluate the molecular and biological processes behind the retinal degeneration observed in the human disease Bardet-Biedl Syndrome (BBS) with respect to the two BBS3 transcripts.

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Posted on April 19, 2010, in Student Seminar and tagged , , , , , , , , , , , . Bookmark the permalink. Leave a comment.

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