Inhibition of ATF-3 expression by B-Raf mediates the neuroprotective action of GW5074

被引:21
作者
Chen, Hsin-Mei [1 ]
Wang, Lulu [1 ]
D'Mello, Santosh R. [1 ]
机构
[1] Univ Texas Dallas, Dept Mol & Cell Biol, Richardson, TX 75083 USA
关键词
activating transcription factor-3; apoptosis; B-Raf; cerebellar granule neurons; c-Raf; neuroprotection;
D O I
10.1111/j.1471-4159.2008.05226.x
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
GW5074 a brain-permeable 3' substituted indolone, protects neurons from death in culture and in an in vivo paradigm of neurodegeneration. Using low potassium (LK) induced apoptosis of cerebellar granule neurons, we report here that the protective action of GW5074 is mediated through the activation of B-Raf. Over-expression of a kinase-dead form of B-Raf blocks the ability of GW5074 to neuroprotect, whereas over-expression of active forms of B-Raf protect even in the absence of GW5074. Although mitogen-activated protein kinase kinase (MEK) and extracellular signal-regulated protein kinase (ERK) are activated by GW5074, pharmacological inhibition of MEK-ERK signaling by U0126 or PD98059 does not reduce neuroprotection suggesting that B-Raf signals through a non-canonical signaling pathway. GeneChip microarray analyses identified activating transcription factor-3 (ATF-3) as a gene whose expression is induced by LK but that is negatively regulated by GW5074. Forced inhibition of ATF-3 expression using siRNA protects neurons against LK-induced apoptosis, whereas the over-expression of ATF-3 blocks GW5074-mediated neuroprotection. Not unexpectedly, expression of active B-Raf inhibits the apoptosis-associated increase in ATF-3 expression. We extended our work to include three other 3' substituted indolones - a commercially available inhibitor of RNA-dependent protein kinase and two novel compounds designated as SK4 and SK6. Like GW5074, RNA-dependent protein kinase inhibitor, SK4, and SK6 all inhibited c-Raf in vitro but activated B-Raf in neuronal cultures. All four compounds also inhibited ATF-3 expression. Taken together our results indicate that all four indolones mediate neuroprotection by a common mechanism which involves B-Raf activation, and that a downstream target of B-Raf is ATF-3.
引用
收藏
页码:1300 / 1312
页数:13
相关论文
共 49 条
[1]   NGF and GDNF ameliorate the increase in ATF3 expression which occurs in dorsal root ganglion cells in response to peripheral nerve injury [J].
Averill, S ;
Michael, GJ ;
Shortland, PJ ;
Leavesley, RC ;
King, VR ;
Bradbury, EJ ;
McMahon, SB ;
Priestley, JV .
EUROPEAN JOURNAL OF NEUROSCIENCE, 2004, 19 (06) :1437-1445
[2]   An old kinase on a new path: Raf and apoptosis [J].
Baccarini, M .
CELL DEATH AND DIFFERENTIATION, 2002, 9 (08) :783-785
[3]   Double-strand RNA dependent protein kinase (PKR) is involved in the extrastriatal degeneration in Parkinson's disease and Huntington's disease [J].
Bando, Y ;
Onuki, R ;
Katayama, T ;
Manabe, T ;
Kudo, T ;
Taira, K ;
Tohyama, M .
NEUROCHEMISTRY INTERNATIONAL, 2005, 46 (01) :11-18
[4]   Cell survival promoted by the Ras-MAPK signaling pathway by transcription-dependent and -independent mechanisms [J].
Bonni, A ;
Brunet, A ;
West, AE ;
Datta, SR ;
Takasu, MA ;
Greenberg, ME .
SCIENCE, 1999, 286 (5443) :1358-1362
[5]  
Borodezt K, 1998, J NEUROSCI RES, V53, P531, DOI 10.1002/(SICI)1097-4547(19980901)53:5<531::AID-JNR3>3.0.CO
[6]  
2-A
[7]   Raf-1 promotes cell survival by antagonizing apoptosis signal-regulating kinase 1 through a MEK-ERK independent mechanism [J].
Chen, J ;
Fuji, K ;
Zhang, LX ;
Roberts, T ;
Fu, H .
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 2001, 98 (14) :7783-7788
[8]   The c-Raf inhibitor GW5074 provides neuroprotection in vitro and in an animal model of neurodegeneration through a MEK-ERK and Akt-independent mechanism [J].
Chin, PC ;
Liu, L ;
Morrison, BE ;
Siddiq, A ;
Ratan, RR ;
Bottiglieri, T ;
D'Mello, SR .
JOURNAL OF NEUROCHEMISTRY, 2004, 90 (03) :595-608
[9]   c-Jun mediates axotomy-induced dopamine neuron death in vivo [J].
Crocker, SJ ;
Lamba, WR ;
Smith, PD ;
Callaghan, SM ;
Slack, RS ;
Anisman, H ;
Park, DS .
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 2001, 98 (23) :13385-13390
[10]   INDUCTION OF APOPTOSIS IN CEREBELLAR GRANULE NEURONS BY LOW POTASSIUM - INHIBITION OF DEATH BY INSULIN-LIKE GROWTH FACTOR-I AND CAMP [J].
D'MELLO, SR ;
GALLI, C ;
CIOTTI, T ;
CALISSANO, P .
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 1993, 90 (23) :10989-10993