CPP32 activation during dolichyl phosphate-induced apoptosis in U937 leukemia cells

Area of Science:

• Cellular Biology
• Biochemistry
• Molecular Biology

Background:

• Apoptosis, or programmed cell death, is a crucial biological process.
• Caspase-activated CPP32 (cysteine protease) is a key executioner protease in apoptosis.
• The role of dolichyl phosphate in regulating apoptosis is not fully understood.

Purpose of the Study:

• To investigate the effect of dolichyl phosphate on CPP32 activity and apoptosis in U937 cells.
• To elucidate the signaling pathways involved in dolichyl phosphate-induced apoptosis.

Main Methods:

• U937 cells were treated with dolichyl phosphate.
• CPP32 activity was measured.
• Apoptosis was assessed using specific peptide inhibitors (YVAD-cmk, Z-Asp-CH2-DCB, DEVD-CHO).
• Adenylate cyclase inhibitors (SQ 22536, 2',5'-dideoxyadenosine) were used to investigate the role of cAMP.
• Intracellular cAMP concentration was measured.

Main Results:

• Dolichyl phosphate treatment increased CPP32 activity and induced apoptosis in U937 cells.
• Peptide inhibitors specific to ICE family proteases blocked dolichyl phosphate-induced apoptosis.
• Adenylate cyclase inhibitors suppressed the increase in CPP32 activity.
• Dolichyl phosphate caused a transient increase in intracellular cAMP levels.

Conclusions:

• Dolichyl phosphate-induced apoptosis in U937 cells is mediated by CPP32 activation.
• The activation of CPP32 and subsequent apoptosis involve the modulation of cAMP synthesis via adenylate cyclase stimulation.
• This study reveals a novel signaling pathway linking dolichyl phosphate, cAMP, and apoptosis.