Upregulation of functional ryanodine receptors during in vitro aging of human diploid fibroblasts.
We demonstrate for the first time that cellular aging in vitro is accompanied by a dramatic elevation in the levels of ryanodine receptor-bearing Ca2+ channels. These channels normally reside within microsomal membranes and gate Ca2+ release from intracellular stores. We therefore measured cytosolic Ca2+ levels in 'young' (30 mean population doublings, MPDs) and 'senescent' (53 to 58 MPDs) human diploid fibroblasts (HDFs). Application of the known ryanodine receptor modulators, caffeine or cyclic adenosine diphosphate-ribose (cADPr), triggered cytosolic Ca2+ signals in both young and senescent cells. The signal magnitude however was significantly greater in senescent compared with young HDFs. In parallel, incubation with a highly specific anti-ryanodine receptor antiserum resulted in specific immunofluorescence only in senescent HDFs. We envisage that elevated levels of functional ryanodine receptors may underlie the defective Ca2+ handling and cellular degeneration that occurs with aging.
Huang
M S
MS
Department of Geriatrics, University of Arkansas for Medical Sciences, Little Rock, Arkansas, 72205, USA.
Adebanjo
O
O
Moonga
B S
BS
Goldstein
S
S
Lai
F A
FA
Lipschitz
D A
DA
Zaidi
M
M
D000246:Adenosine Diphosphate Ribose / Q000031:analogs & derivatives / Q000494:pharmacology; D000906:Antibodies / Q000276:immunology / Q000378:metabolism; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D016922:Cellular Senescence / Q000502:physiology*; D036563:Cyclic ADP-Ribose; D005347:Fibroblasts; D005455:Fluorescent Antibody Technique; D006801:Humans; D008856:Microscopy, Fluorescence; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism*; D015854:Up-Regulation / Q000502:physiology*
D000906:Antibodies; D019837:Ryanodine Receptor Calcium Release Channel; D036563:Cyclic ADP-Ribose; D000246:Adenosine Diphosphate Ribose; D002110:Caffeine; D002118:Calcium