title: Specific loss of protein kinase activities in senescent erythrocytes.
abstract: Rabbit erythrocytes of progressively increasing age were isolated using an avidin-biotin affinity technique and the activity of protein kinases and other enzymes was analyzed in cytosols and membranes from the isolated cells. The activities of cytosolic protein kinase C (PKC), cAMP-dependent kinase (PKA), and casein kinase type I and II (CKI and II) were all found to undergo an age-dependent decrease of twofold to fourfold over the 8-week lifespan of the cells. Membrane-associated tyrosine kinase showed little or no decrease, but membrane-associated CKI showed a dramatic eightfold decrease over the 8-week period. By contrast, various cytosolic enzymes, including lactate dehydrogenase, phosphoglycerate kinase, pyruvate kinase, and acid phosphatase, showed no change in activity over the same time period. Density-separated human erythrocytes showed qualitatively similar decreases in cytosolic protein kinase activities in the densest fractions, which contain the oldest cells. Our results show that aging erythrocytes undergo progressive loss of protein kinases that may adversely affect various cellular processes. The age-dependent loss of kinase activity reported here is one of the most striking manifestations of erythrocyte senescence yet to be reported.
authors.affiliation: Department of Biomedical Research, St Elizabeth's Medical Center, Tufts University, School of Medicine, Boston, MA 02135, USA.
authors.forename: H K
authors.initials: HK
authors.lastname: Jindal
authors.forename: Z
authors.initials: Z
authors.lastname: Ai
authors.forename: P
authors.initials: P
authors.lastname: Gascard
authors.forename: C
authors.initials: C
authors.lastname: Horton
authors.forename: C M
authors.initials: CM
authors.lastname: Cohen
mesh_terms: D000135:Acid Phosphatase / Q000097:blood; D000818:Animals; D003600:Cytosol / Q000201:enzymology; D004905:Erythrocyte Aging; D004910:Erythrocyte Membrane / Q000201:enzymology; D004912:Erythrocytes / Q000201:enzymology*; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000097:blood; D010735:Phosphoglycerate Kinase / Q000097:blood; D010750:Phosphoproteins / Q000097:blood; D011493:Protein Kinase C / Q000097:blood*; D011770:Pyruvate Kinase / Q000097:blood; D011817:Rabbits
chemical_list: D010750:Phosphoproteins; D007770:L-Lactate Dehydrogenase; D011770:Pyruvate Kinase; D011493:Protein Kinase C; D010735:Phosphoglycerate Kinase; D000135:Acid Phosphatase