Journal of Neuroscience, Vol 14, 2225-2235, Copyright © 1994 by Society for Neuroscience
Increased levels of hemoglobin-derived and other peptides in Alzheimer's disease cerebellum
JR Slemmon, CM Hughes, GA Campbell and DG Flood
Department of Biochemistry, University of Rochester Medical Center, New York 14642.
Several studies point to the importance of peptides and proteolysis in
Alzheimer's disease (AD). Because of its ability to study small proteins
and peptides, reverse-phase HPLC was employed to study these species in AD.
Cerebellum was chosen for these initial studies because it does not show
significant neuronal loss but does show some pathology in AD. Examination
of over 600 peptide peaks per case revealed 15 that were elevated in AD.
Nine were fragments of hemoglobin, and the remainder included two species
of calmodulin, two of myelin basic protein, and one each of 67 kDa
neurofilament protein and PEP-19. The cleavage sites on hemoglobin were
after hydrophobic residues and immunolocalization was seen preferentially
around blood vessel walls and granule cells. The elevation of the
non-serum-derived peptides was characteristic of general metabolic changes
that occurred in AD cerebellum, and the presence of elevated hemoglobin
polypeptides indicated either possible disruption of the blood-brain
barrier or selective evasion of it by peptidaceous products. Further
studies are required to establish whether hemoglobin fragments have a role
in neurodegenerative processes such as AD.