James E. Haley, Associate Professor
B.S., Wagner College, NY
M.S., Long Island University, NY
Ph.D., Saint John's University, NY.
Professional Interest:
Neuron-Glia Interactions Metabolic Interactions:
The focus of my research, with undergraduate student participation, is in the area of Neurobiology. I am currently examining the interaction, in vitro, between astrocytes and neurons. These interactions are critical during development of the nervous system and in the maintenance of neurons. We have found that cultured rat brain astrocytes selectively, by about four fold, bind purified axolemma (neuronal) membranes when compared to purified myelin and red blood cell membranes at 4 C. Neuron-glia interaction occurs between four and 24 hours after the addition of axolemma and shows saturation kinetics of binding, suggesting a receptor mediated binding. Subsequent studies reveal that the axolemma membranes selectively induce a redistribution of incorporated H-glucosamine radioactivity into the Triton X-100 insoluble TI), cytoskeletal fraction.
The major cytoskeletal proteins, including the glial fibrillary acidic protein (GFAP, an astrocyte marker protein), vimentin, and actin are found in the Tl fraction. Examination of the Tl fraction, H-labeled, glycoproteins by two-dimensional gel electrophoresis followed by fluorography shows selective incorporation into high molecular weight proteins between 200 and 140 Kdal. with a pl around 5.8 to 6.5. Identification of these proteins by Western blot analysis, using specific antibodies against rat neural cell adhesion molecules (N-CAM) and against other cell surface glycoproteins, is underway.
Previous studies, in collaboration with Dr. Robert Ledeen of The Albert Einstein College of Medicine, clearly showed an in vivo metabolic interaction between the optic neuron and the adjoining myelin producing oligodendrocyte. These interactions were shown using methods associated with axoplasmic transport of primarily lipids down the optic neuron. Precursors used to label lipids, such as P-phosphate, H-glycerol, H-inositol, and C-serine, showed transfer of radioactivity from the neuron to the oligodendrocyte. Further studies are underway to elucidate these interactions.
Cyclic AMP:
Another related area of research dealt with the observation that the addition of Myelin
membranes to cultured astrocytes significantly increases, by about five fold, the
intracellular production of cyclic Adenosine monophosphate (cAMP) within about eight hours
at 37deg.C. Control experiments with 10-50 uM forskolin treatment of astrocytes showed a
more rapid, within 15 minutes to two hours, and a dose dependent increase in cAMP levels.
Axolemma, red blood cell membranes, or controls with no additional membranes had no effect
on cAMP levels. These results correlate very well with the morphological observation that
cultured astrocytes also appear to phagocytize the myelin membranes as well. The
phagocytic activity of astrocytes for myelin was also demonstrable in brains of
individuals with multiple sclerosis as previously described.
Publications:
Guernelli, G., Rubenacker, C., Haley, J., Chiu, F.C., and Norton, W.T.
1990. Metabolic neuron-glial interactions in culture. Tans. Amer. Soc.
Neurochem. 22: 217.
Golly, F., Haley, J., and Ledeen. R.W. 1992. Axon-Myelin transfer of phospholipid precursors: labeling of myelin phosphoinositides through axonal transport. Mol. Neurobio. 6: 179-190.
Haley, J.E., Montemarano, M., Pathapati, J., and Chiu, F.C. 1995.
Characterization of N-CAMs in cultured astrocytes and purified axolemma from rat
brains. Trans. Amer. Soc. Neurochem. 26: 1.
Address:
Manhattan College/College of Mount Saint Vincent
Department of Biology
Science Hall
Riverdale, NY 10471
Phone:718-405-3389(Mount)
Fax:718-405-3719 (Mount)
E-mail address: jhaley@mountsaintvincent.edu