The six layers of the normal human cortex, the seat of all cognitive functions, are formed during fetal development by neurons migrating over long distances from their sites of origin. The cortical layers are formed from the innermost to the outermost, with each wave of migrating neurons having to move past the previous one of their way to their destination. Malfunction of this process results in serious clinical syndromes such as lissencephaly, in which there are fewer layers of neurons in the cortex, with essentially no gyrations, or alternatively the layer structure is lost. Studies of the molecular mechanisms, which govern neuronal migration, will give better understanding of the etiology of these syndromes. Perhaps even more importantly, the same mechanisms control the migration of those few neurons, which in an adult are capable of replacing cells in those parts of the cortex, which were damaged either by injury or neurodegenerative diseases. The ability to stimulate neuronal migration could provide an efficient approach to the treatment of such diseases as Alzheimer and Parkinson's. Genes uniquely responsible for neuronal migration have only recently been cloned. They include LIS1 and doublecortin (DCX), associated with X-linked double-cortex syndrome in women. The two proteins function in the regulation of the microtubules and interact with tubulin and associated proteins. They also seem to interest with one another. Lis 1 has been known for some time to be a part of an enzymatic complex known as the brain platelet-activating factor acetylhydrolase (PAF-AH) isoform lb. We have carried out extensive studies into the catalytic subunits of this protein, and we will continue our research into Lis I and DCX. Variants of both proteins were successfully expressed and purified from E. coli, following refolding from inclusion bodies. We are now pursuing the crystallization of both using a novel approach developed in the laboratory to overcome crystallization problems in protein with significant content of Lys and Glu. We will also attempt to crystallize complexes of Lisi and DCX with downstream signaling partners.
Showing the most recent 10 out of 19 publications
