Seth  Blackshaw, PhD Assistant Professor Telephone Number:   443-287-5609 Fax Number:   410-614-9568 The Solomon H. Snyder Department of Neuroscience Johns Hopkins University School of Medicine 725 North Wolfe St. Baltimore, MD 21205 Room:  329 Broadway Research Building sblack@jhmi.edu

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  Functional genomics of cell specification in retina and hypothalamus.

The vertebrate central nervous systems is comprised of many hundreds of functionally distinct subtypes of neurons and glia, but surprisingly little is known about how this amazing diversity of cell types is specified.   My lab is focused on exploring this question, with an eye to eventually using the molecular pathways identified in these studies as a means to genetically probe the function of specific cell types.   As part of the Center for High-Throughput Biology at Hopkins, my lab seeks to apply cutting-edge technology to both rapidly identify and functionally characterize genes that regulate cell fate specification in mammalian retina and hypothalamus.  Projects currently underway in the lab include:

We have used SAGE and in situ hybridization-based analysis to test the cellular expression pattern of genes expressed in dynamic patterns in the developing mouse retina.  We are now functionally analyzing genes that are selectively expressed in the four major retinal cell types that differentiate postnatally in the mouse – specifically rod photoreceptors, bipolar neurons, amacrine cells and Muller glia.  These genes include transcription factors, regulators of signal transduction, and noncoding RNAs.  Using overexpression, knockdown and genetic strategies, we have found that many of these candidate genes do indeed regulate retinal cell fate specification, and are exploring the molecular pathways by which they act.

      We seek to characterize the cascade of transcription factors, and their target sites, which are involved in the course of the development of a retinal progenitor cell to a terminally differentiated neuron or glia.  We have used bioinformatic approaches to identify putative cis-regulatory sites in the promoters of genes specifically expressed in rod and cone photoreceptors, as well as Muller glia and mitotic progenitor cells.  We are now using protein microarrays to identify transcription factors that bind these sequences and in vivo electroporation to examine their cellular expression patterns in the developing retina.

The mammalian hypothalamus is a the central regulator of a broad set of behaviors ranging from the sleep-wake cycle to the care of offspring, but little is known about or how hypothalamic neuronal subtypes are specified during development.   We have recently completed a large-scale microarray and in situ hybridization-based screen to identify genes selectively expressed in specific neuronal subtypes in the developing mouse hypothalamus.  We are now using functional strategies like we have used in our studies of retinal development to determine the contribution of candidate genes to hypothalamic cell specification, and to investigate the involvement of these cell types in hypothalamic-regulated behaviors.