TY - JOUR
T1 - Astrocytic poly(ADP-ribose) polymerase-1 activation leads to bioenergetic depletion and inhibition of glutamate uptake capacity
AU - Tang, Kim San
AU - Suh, Sang Won
AU - Alano, Conrad C.
AU - Shao, Zongjun
AU - Hunt, Waylon T.
AU - Swanson, Raymond A.
AU - Anderson, Christopher M.
N1 - Copyright:
Copyright 2010 Elsevier B.V., All rights reserved.
PY - 2010/3
Y1 - 2010/3
N2 - Poly(ADP-ribose) polymerase-1 (PARP-1) is a ubiquitous nuclear enzyme involved in genomic stability. Excessive oxidative DNA strand breaks lead to PARP-1-induced depletion of cellular NAD+, glycolytic rate, ATP levels, and eventual cell death. Glutamate neurotransmission is tightly controlled by ATP-dependent astrocytic glutamate transporters, and thus we hypothesized that astrocytic PARP-1 activation by DNA damage leads to bioenergetic depletion and compromised glutamate uptake. PARP-1 activation by the DNA alkylating agent, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), caused a significant reduction of cultured cortical astrocyte survival (EC50 = 78.2 ± 2.7 μM). HPLC revealed MNNG-induced time-dependent reductions in NAD+ (98%, 4 h), ATP (71%, 4 h), ADP (63%, 4 h), and AMP (66%, 4 h). The maximal [3H]glutamate uptake rate (Vmax) also declined in a manner that corresponded temporally with ATP depletion, falling from 19.3 ± 2.8 in control cells to 2.1 ± 0.8 nmol/ min/mg protein 4 h post-MNNG. Both bioenergetic depletion and loss of glutamate uptake capacity were attenuated by genetic deletion of PARP-1, directly indicating PARP-1 involvement, and by adding exogenous NAD+ (10 mM). In mixed neurons/astrocyte cultures, MNNG neurotoxicity was partially mediated by extracellular glutamate and was reduced by co-culture with PARP-1-/- astrocytes, suggesting that impairment of astrocytic glutamate uptake by PARP-1 can raise glutamate levels sufficiently to have receptor-mediated effects at neighboring neurons. Taken together, these experiments showed that PARP-1 activation leads to depletion of the total adenine nucleotide pool in astrocytes and severe reduction in neuroprotective glutamate uptake capacity.
AB - Poly(ADP-ribose) polymerase-1 (PARP-1) is a ubiquitous nuclear enzyme involved in genomic stability. Excessive oxidative DNA strand breaks lead to PARP-1-induced depletion of cellular NAD+, glycolytic rate, ATP levels, and eventual cell death. Glutamate neurotransmission is tightly controlled by ATP-dependent astrocytic glutamate transporters, and thus we hypothesized that astrocytic PARP-1 activation by DNA damage leads to bioenergetic depletion and compromised glutamate uptake. PARP-1 activation by the DNA alkylating agent, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), caused a significant reduction of cultured cortical astrocyte survival (EC50 = 78.2 ± 2.7 μM). HPLC revealed MNNG-induced time-dependent reductions in NAD+ (98%, 4 h), ATP (71%, 4 h), ADP (63%, 4 h), and AMP (66%, 4 h). The maximal [3H]glutamate uptake rate (Vmax) also declined in a manner that corresponded temporally with ATP depletion, falling from 19.3 ± 2.8 in control cells to 2.1 ± 0.8 nmol/ min/mg protein 4 h post-MNNG. Both bioenergetic depletion and loss of glutamate uptake capacity were attenuated by genetic deletion of PARP-1, directly indicating PARP-1 involvement, and by adding exogenous NAD+ (10 mM). In mixed neurons/astrocyte cultures, MNNG neurotoxicity was partially mediated by extracellular glutamate and was reduced by co-culture with PARP-1-/- astrocytes, suggesting that impairment of astrocytic glutamate uptake by PARP-1 can raise glutamate levels sufficiently to have receptor-mediated effects at neighboring neurons. Taken together, these experiments showed that PARP-1 activation leads to depletion of the total adenine nucleotide pool in astrocytes and severe reduction in neuroprotective glutamate uptake capacity.
KW - Astrocyte-neuron communication
KW - ATP depletion
KW - DNA damage
KW - Excitotoxicity
KW - NAD
UR - http://www.scopus.com/inward/record.url?scp=76549098903&partnerID=8YFLogxK
U2 - 10.1002/glia.20936
DO - 10.1002/glia.20936
M3 - Article
C2 - 19795500
AN - SCOPUS:76549098903
VL - 58
SP - 446
EP - 457
JO - GLIA
JF - GLIA
SN - 0894-1491
IS - 4
ER -