We are expanding the range of assay techniques that will allow us to understand the sulfation code in chondroitin glycosaminoglycan (GAG) chains. These assay techniques take advantage of specific chromatography techniques (ion exchange, hydrophilicity) to separate the different disaccharides and monosaccharides that comprise the GAG chain. This is the only technique capable of doing this. We have also initiated mass specrtrophotometric analysis of these separated GAG chains to begin to determine the sequence of sulfations on the different parts of the GAG chain. We have completed experiments that demonstrate a local signaling mechanism in the growth cone that responds to chondroitin sulfate. These experiments demonstrate that the direction and rate of microtubule polymerization are selectively altered in growth cones that respond to chondroitin sulfate proteoglycans. We are conducting experiments to evaluate novel intracellular signaling mechanisms in response to GAG chains. Growth cones turn in response to bound GAG chains. We have used this property of growth cone turning to assay the activity of drugs and other compounds. In particular, we have determined that the activity of myosin II molecular motors are essential for this growth cone turning. Both myosin IIA and IIB appear to be involved in growth cone turning. Modification of their activity by drugs may ultimately prove to be a useful therapeutic approach for treatment of brain injury. Because many of these mechanisms are also found in injury to heart and blood vessels, these approaches may have a more general applicability.
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