Activation of caspase-2 mediates the apoptosis induced by GTP-depletion in insulin-secreting (HIT-T15) cells

Endocrinology. 2002 May;143(5):1695-704. doi: 10.1210/endo.143.5.8810.


This study investigated the possible involvement of a specific caspase(s) (a family of aspartate-specific cysteine proteases) in programmed cell death of islet beta-cells due to sustained GTP depletion. Treatment (up to 48 h) with 3 microg/ml mycophenolic acid (MPA), which specifically depletes intracellular guanine nucleotides, reduced cell-cycle progression from G1 phase into S and G2/M phases (as assessed by flow cytometry) and, subsequently, induced apoptosis of HIT-15 cells (transformed pancreatic beta-cells). The latter was accompanied by a marked increase of caspase-2 activity (+343%) and moderate activation of caspase-9 (+150%) and caspase-3 (+145%). Importantly, only caspase-2 activation preceded induction of apoptosis. There was no change in activity of caspase-1, -4, -5, -6, and -8. Release of the mitochondrial protein cytochrome c into cytosol was also observed at a late stage. Cotreatment of cells with a permeable pan-caspase inhibitor (Z-VAD-FMK) blocked GTP depletion-induced cell death in a dose-dependent manner. A specific caspase-2 inhibitor (Z-VDVAD-FMK), but not a caspase-3 inhibitor (DEVD-CHO), was also capable of restoring cell viability. Interestingly, activation of caspase-2 leads to caspase-3 activation because the caspase-2 inhibitor abrogated caspase-3 activity. Our results indicate that, while activation of multiple caspases are involved in the execution phase of GTP depletion-induced apoptosis, caspase-2 appears to play the major role in the initiation of this program. This study revealed a novel, caspase-2 mediated form of apoptosis that may be consequent to impaired mitogenesis.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Antibiotics, Antineoplastic / pharmacology
  • Apoptosis / physiology*
  • Blotting, Western
  • Caspase 2
  • Caspase Inhibitors
  • Caspases / metabolism
  • Caspases / physiology*
  • Cell Line
  • Cricetinae
  • Cytochrome c Group / metabolism
  • Cytosol / drug effects
  • Cytosol / metabolism
  • DNA Fragmentation
  • Enzyme Activation / physiology
  • Enzyme Inhibitors / pharmacology
  • Flow Cytometry
  • Guanosine Triphosphate / physiology*
  • Insulin / metabolism*
  • Insulin Secretion
  • Islets of Langerhans / drug effects
  • Islets of Langerhans / enzymology
  • Islets of Langerhans / physiology*
  • Isoenzymes / antagonists & inhibitors
  • Isoenzymes / metabolism
  • Mitochondria / drug effects
  • Mitochondria / metabolism
  • Mycophenolic Acid / pharmacology
  • Precipitin Tests


  • Antibiotics, Antineoplastic
  • Caspase Inhibitors
  • Cytochrome c Group
  • Enzyme Inhibitors
  • Insulin
  • Isoenzymes
  • Guanosine Triphosphate
  • Caspase 2
  • Caspases
  • Mycophenolic Acid