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Poly(ADP-ribose) degradation by post-nuclear extracts from human cells
Laura Rossi1, Marco Denegri, Mauro Torti
1Istituto di Genetica Molecolare CNR, Pavia, Italy.
Biochimie
|March 12, 2003
Summary
Researchers found that cellular extracts can break down synthetic poly(ADP-ribose) into AMP. This process involves poly(ADP-ribose) glycohydrolase (PARG) and ADP-ribose-degrading enzymes, converting polymers into usable cellular energy units.
Area of Science:
- Cellular Biology
- Biochemistry
- Molecular Metabolism
Background:
- Poly(ADP-ribose) metabolism is primarily controlled by PARP-1 and PARG in the nucleus.
- Extranuclear PARP-like (V-PARP) and PARG enzymes exist, but poly(ADP-ribose) presence in this compartment is unconfirmed.
Purpose of the Study:
- To investigate the degradation of synthetic poly(ADP-ribose) in post-nuclear cellular extracts.
- To identify the enzymes and pathways involved in extranuclear poly(ADP-ribose) catabolism.
Main Methods:
- Utilized post-nuclear extracts from HeLa and HL60 cells.
- Incubated extracts with synthetic 32P-poly(ADP-ribose) polymers.
- Employed enzyme inhibition (PARG and ADP-ribose-degrading enzymes) to elucidate reaction steps.
Main Results:
- Post-nuclear extracts degraded synthetic poly(ADP-ribose) to ADP-ribose monomers and subsequently to AMP.
- The degradation involved a sequential action of PARG and Mg(2+)-dependent ADP-ribose-degrading activities.
- Enzyme inhibition studies confirmed the roles of PARG and ADP-ribose-degrading enzymes in the pathway.
Conclusions:
- Human cell post-nuclear fractions possess the enzymatic machinery to catabolize synthetic poly(ADP-ribose).
- The concerted action of PARG and ADP-ribose-degrading enzymes converts poly(ADP-ribose) into AMP, a usable energy unit.
- This study reveals a novel pathway for extranuclear poly(ADP-ribose) metabolism in mammalian cells.