Mechanical deformation induced apoptosis in human proximal renal tubular epithelial cells is caspase dependent.
OBJECTIVE
Ureteral obstruction (UO) results in apoptosis of renal tubular epithelial cells. We postulated that mechanical deformation and inflammation contribute to the cellular loss that occurs as a result of UO and it is mediated through altered heat shock protein 70 (HSP-70) expression and the caspase cascade.


METHODS
Human HK-2 renal tubular cells were subjected to mechanical stretch. Cell viability and apoptosis were assessed by flow cytometry; HSP-70 and caspase 3 protein expression by Western blotting, and caspase 3 activity by fluorescence substrates.


RESULTS
Mechanical stretch caused direct apoptosis induction and it also primed for tumor necrosis factor-alpha induced apoptosis, which was caspase 3 dependent. Although HSP-70 protein expression was increased during mechanical stretch, the protective effects of HSP-70 were only seen after further induction by heat shocking.


CONCLUSIONS
Altering HSP-70 expression and manipulating the caspase cell death proteases represent a novel pathway to protect against renal tubular cell apoptosis and the potential for progression to renal failure in UO.
Power
Richard E
RE
Department of Surgerr Mater Misericordiae University Hospital, Conway Institute of Biomolecular and Biomedical Research and Dublin Molecular Medical Centre, University College Dublin, Ireland.
Doyle
Belinda T
BT
Higgins
Debra
D
Brady
Hugh R
HR
Fitzpatrick
John M
JM
Watson
R William G
RW
D017209:Apoptosis; D061945:Caspase Inhibitors; D020169:Caspases / Q000502:physiology*; D002478:Cells, Cultured; D004847:Epithelial Cells; D018840:HSP70 Heat-Shock Proteins / Q000502:physiology*; D006801:Humans; D007687:Kidney Tubules, Proximal / Q000166:cytology*; D013314:Stress, Mechanical; D014517:Ureteral Obstruction / Q000473:pathology
D061945:Caspase Inhibitors; D018840:HSP70 Heat-Shock Proteins; D020169:Caspases