Mark Black, PhD
Professor, Anatomy and Cell Biology
- Contact Information
- About Me
Neurons are the principal cells of the nervous system. Their main function is to receive and transmit information in the form of electrical signals. The structural basis for this information flow is the elongate neurite, of which there are two types, axons and dendrites. To develop a nervous system, neurons must extend their axons and dendrites over considerable disstances to establish contact with appropriate targets cells. My laboratory studies axonal and dendritic growth, focusing specifically on the elaboration of the neuronal cytoskeleton. The cytoskeleton consists of protein polymers that comprise an architectural framework that defines the external shape of the neuron and also organizes intracellular motility necessary to grow and maintain the axon and dendrites. The cytoskeleton consists of three principal polymer systems, microtubules, neurofilaments and actin filaments. We are dissecting the dynamic processes responsible for generating and maintaining these cytoskeletal systems in axons and dendrites, and defining how these processes contribute to neuronal morphogenesis.
Our current efforts address two broad problems. One concerns the transport of cytoskeletal components from their site of synthesis in the cell body into the axon to the axon tip. Cytoskeletal proteins are synthesized in the neuron soma and then delivered to the axon by active transport mechanisms referred to as slow axonal transport. The mechanisms of cytoskeletal transport in axons are unknown. Our working hypothesis is that the cytoskeletal polymers themselves are actively translocated by the axonal transport mechanisms , and that the polymer transport mechanisms contribute directly to the elaboration of the axonal cytoskeleton. The figures to the right show selected data supporting this hypothesis. The upper figure shows data demonstrating the movement of microtubules from the cell body into the axon of newly formed axons (Slaughter et al., 1997). More direct support for the polymer transport hypothesis is provided in the remaining figure and movie, which demonstrates that neurofilaments, one class of cytoskeletal polymers in neurons, are transported in axons (Roy et al., 2000). We are now attempting to define the motor protein(s) that power neurofilament transport in axons and also are expanding our studies to microtubules and actin filaments, the other principal cytoskeletal polymers in the axon.
A second problem we are investigating concerns the in vivo function of proteins known as microtubule-associated proteins. These are accessory proteins of microtubules that are hypothesized to modulate MT assembly, stability, and organization. We are attempting to test this hypothesis by directly exploring the functions of these proteins in living neurons. Our basic strategy is to either inactivate or over-express one or more of the microtubule-associated proteins and then evalulate the effects of these manipulations on axonal microtubules, axon growth, and neuronal morphogenesis (see for Tint et al 1998).
- Education, Training & Credentials
- Postdoctoral Fellowship, Department of Pharmacology, New York University Medical Center, New York, NY
- PhD, Department of Anatomy, School of Medicine, Case Western Reserve University, Cleveland, OH
- BS, Psychology, University of Illinois, Champaign, IL