IBN-9603542 Baas Neurons are the principal cells that make up the nervous system. They consist of a rounded cell body and two types of elongate extensions. One type of extension is called an axon while the other type is called a dendrite. Axons are specialized to transmit information, while dendrites are specialized to receive information. In order for the neuron to extend axons and dendrites, it must elaborate within them complex arrays of cytoskeletal elements. These cytoskeletal elements provide architectural support for axons and dendrites, and also act as railways for the transport of substances from the cell body down their lengths. One of the most important of the cytoskeletal elements is the microtubule. The microtubule is an intrinsically polar structure, and as a result of this polarity, the microtubule can direct the types of substances that are transported into axons and dendrites. Fundamental to the differentiation of axons and dendrites is the establishment of very different microtubule arrays in each type of process. Axonal and dendritic microtubules differ in many respects, including how they are organized relative to their polarity. The axonal microtubule array has been extensively studied, but the dendritic microtubule array has received far less attention. The overall goal of this grant application is to elucidate the cellular and molecular means by which the dendritic microtubule array is established, and how it becomes different from the axonal microtubule array. The proposed experiments involve direct observations within living neurons as well as high resolution studies using the electron microscope.
