Neuroscience 256 (2014) 36–42

INHIBITION OF MITOCHONDRIAL FISSION ATTENUATES Ab-INDUCED MICROGLIA APOPTOSIS N. XIE, a C. WANG, b Y. LIAN, a* C. WU, a H. ZHANG a AND Q. ZHANG a

There have been increasing studies on the effects of Ab on nerve cells and the effects of Ab on neurotoxicity have been implicated by several studies (Li et al., 2008; Feng et al., 2013). But there is a paucity of studies on the action of Ab on non-neuronal brain cells. Microglia are immunolike cells in CNS and participate in both innate and adaptive immune responses. Activated microglia are found at sites of neuronal degeneration in multiple pathological conditions such as cerebral ischemia and AD (Tambuyzer et al., 2009; Saijo and Glass, 2011). Microglia can be either neurotrophic or neurotoxic depending on the activation state (Luo et al., 2010); normally active microglia clear debris through phagocytosis to stimulate tissue repair and regulate transient inflammatory responses to pathogens, but sustained and excessive activation (‘‘overactivation’’) leads to release of cytotoxins that cause neurotoxicity. Alternatively, overactivation can lead to microglial apoptosis, resulting in uncontrolled inflammatory responses (Kim and Li, 2013). It has been reported that Ab could accelerate neurodegeneration by inducing the activation and apoptosis of microglial cells, which exert cytotoxic effects on neurons (Qin et al., 2002; Streit, 2004). However, the exact mechanisms of Ab-mediated microglial ‘‘overactivation’’ and apoptosis remain obscure. Mitochondrial fission has been reported to be involved in apoptosis and many neurodegenerative diseases (Cho et al., 2010). The Guanosine triphosphate (GTP)-binding protein, dynamin-related protein 1 (Drp-1) is a mitochondrial fission protein. It has been found that expression of Drp-1 promotes mitochondrial fragmentation, while the expression of a dominantnegative form of Drp-1 inhibits mitochondrial fission and thereby apoptosis (Karbowski, 2010). Mitochondrial division inhibitor (mdivi-1) is a highly efficient small molecule that selectively inhibits mitochondrial fission Drp1. It inhibits Drp1 GTPase activity by blocking the self-assembly of Drp1 in vitro and causes the rapid reversible and dose-dependent formation of netlike mitochondria in wild-type cells (Cassidy-Stone et al., 2008; Tanaka and Youle, 2008). Recent study has shown that pretreatment with mdivi-1 could provide neuroprotection against glutamate toxicity and oxygenglucose deprivation (OGD) in vitro and ischemic brain damage in vivo (Grohm et al., 2012). However, the role of mdivi-1 in Ab-induced microglia apoptosis remains unknown. In this study, we investigated whether mdivi-1 might attenuate Ab-induced microglia apoptosis. In addition, we also examined the potential protective mechanisms

a

Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China b Department of Internal Medicine, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China

Abstract—Mitochondrial division inhibitor 1 (mdivi-1), a selective inhibitor of mitochondrial fission protein dynamin-related protein 1 (Drp1), has been reported to display neuroprotective properties in different animal models. In the present study, we investigated the protective effect of mdivi-1 on b-amyloid protein (Ab)-induced cytotoxicity and its potential mechanisms in BV-2 and primary microglial cells. We found that mitochondrial fission was increased in Ab treatment and inhibition of mitochondrial fission by mdivi1 significantly reduced Ab-induced expression of CD11b (a marker of microglial activation), viability loss and apoptotic rate increase in BV-2 and primary microglial cells. Moreover, we also found that mdivi-1 treatment markedly reversed mitochondrial membrane potential loss, cytochrome c (CytC) release and caspase-3 activation. Altogether, our data suggested that mdivi-1 exerts neuroprotective effects against Ab-induced microglial apoptosis, and the underlying mechanism may be through inhibiting mitochondrial membrane potential loss, CytC release and suppression of the mitochondrial apoptosis pathway. Ó 2013 IBRO. Published by Elsevier Ltd. All rights reserved.

Key words: microglia, cytochrome c.

mdivi-1,

b-amyloid,

apoptosis,

INTRODUCTION Alzheimer’s disease (AD) is a neurodegenerative disorder of the CNS characterized by progressive deterioration of memory and cognition. Excessive accumulation of bamyloid protein (Ab) in the brain is known to play a critical role in the pathogenesis of AD (Gilbert, 2013). *Corresponding author. Address: Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China. Tel/fax: +86 371 66862121. E-mail address: [email protected] (Y. Lian). Abbreviations: AD, Alzheimer’s disease; Ab, b-amyloid protein; BALB, Bagg albino; CytC, cytochrome c; DMEM, Dulbecco’s modified eagle medium; Drp1, dynamin-related protein 1; FBS, fetal bovine serum; GTP, Guanosine triphosphate; HD, Huntington’s disease; Mdivi-1, mitochondrial division inhibitor 1; MTT, 3-(4, 5-dimethylthiazol-2-yl)-2, 5-dipheny- ltetrazolium bromide; PBS, phosphate buffered saline; PD, Parkinson’s disease; Rh-123, rhodamine 123; RT-PCR, Reverse transcription-PCR; TUNEL, terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling.

0306-4522/13 $36.00 Ó 2013 IBRO. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.neuroscience.2013.10.011 36

N. Xie et al. / Neuroscience 256 (2014) 36–42

initiated by mdivi-1, including the mitochondrial membrane potential levels and cytochrome c (CytC)dependent mitochondrial apoptosis pathway.

EXPERIMENTAL PROCEDURES

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kit (Roche Diagnostic, Indianpolis, IN, USA) according to the manufacturer’s instructions as described in our previous studies (Xie et al., 2010a,b). The percentage of apoptotic cells was calculated by counting approximately 500 cells.

Reagents

Flow cytometry analysis

All media components used in cell culture were obtained from Gibco Invitrogen Corporation (Carlsbad, CA, USA). Antibodies, including Drp1, total and cleaved caspase-3, were purchased from Cell Signaling Technology (Beverly, MA, USA). The antibodies of b-actin, CytC and CD11b were purchased from Santa Cruz Biotechnology (Santa Cruz, CA, USA).

Apoptotic cells were examined by flow cytometry as described previously (Wu et al., 2013). Briefly, cells (1  106) were washed once with phosphate buffered saline (PBS), and then suspended cells in 160 ll of Annexin V binding buffer (1) and 4 ll of Annexin Vfluorescein isothiocyanate at room temperature for 20 minutes and then counterstained with 4 ll propidium iodide, and finally analyzed using a FACScan flow cytometer (BECTON DICKINSON FACSCalibur). All Annexin V-positive cells were considered to have apoptosis. All data are representative of three independent experiments.

Cell culture Microglial cultures. Bagg albino (BALB)/c mice were purchased from Experimental Animal Center of the Zhengzhou University (Zhengzhou, China). Mice were housed, bred, and euthanized in accordance with protocols reviewed and approved by the Commission of the Zhengzhou University for ethics of experiments on animals in accordance with international standards. Mouse primary microglial cells were isolated from mixed glial cultures, as described previously (Deierborg, 2013). Briefly, cortices were dissected from newborn BALB/c mice and dissociated by mechanical disruption and trypsinization. Primary microglia were co-cultured with astrocytes in poly-D-lysine-coated 75-cm2 culture flasks in Dulbecco’s Modified Eagle Medium (DMEM) supplemented with 10% fetal bovine serum (FBS) and 1% Penicillin/Streptomycin. On days 10–14, microglial cells were harvested by shaking the cultures and collecting the floating cells. The cells were seeded into plastic tissue culture flasks. After incubation at 37 °C for 1 h, non-adherent cells were removed by replacing culture medium. The cells were grown in DMEM with 10% FBS and maintained at 37 °C and 5% CO2. BV-2 cell culture. The cells were purchased from Cell Center of the Peking Union Medical College (Beı´ jing, China) and cultured in DMEM medium with 5% FBS and 1% Penicillin/Streptomycin. Cultures were incubated at 37 °C and 5% CO2 in a fully humidified incubator. Cell viability assay Cell viability was assessed by the reduction of 3-(4, 5dimethylthiazol-2-yl)-2, 5-dipheny- ltetrazolium bromide (MTT). Briefly, 20 ll MTT (5 mg/ml, Sigma–Aldrich) was added to each well, and plates were incubated at 37 °C for 4 h and then quantifying the color formation by means of an Elisa plate reader at 570-nm wavelength using 200 ll MTT solubilization solution. TUNEL assay The apoptotic cells were determined by terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling (TUNEL) assay using a situ cell death detection

Reverse transcription-PCR (RT-PCR) Total RNA was extracted from the cells by use of the VERSA GENE RNA Tissue Kit (Gentra SYSTEMS; Minnesota) and RT-PCR was performed as described (Xie et al., 2010a). Briefly, first-strand cDNA was synthesized from 1 lg of total RNA using a Reaction Ready first-strand cDNA synthesis kit (SABioscience Corporation, Frederick, MD, USA). After incubation at 70 °C for 3 min and cooling down to 37 °C for 10 min, RT cocktail was added to the annealing mixture and further incubated at 37 °C for 60 min. The following primer pair was used: for CD11b: 5-GATGCTTACCTG GGTTATGCTTCT-3 (forward) and 5-CCGAGGTGC TCCTAAAACCA-3 (reverse). Western blot analysis To obtain cytosolic and mitochondrial protein extracts, the cells were subfractionized in homogenization buffer. The cytosolic and mitochondrial fractions were separately isolated by centrifugation as described previously (Jing et al., 2012). Thirty micrograms of protein were separated by sodium dodecyl sulfate (SDS)– polyacrylamide gel electrophoresis and then transferred onto nitrocellulose membrane. After blocking in 5% fatfree milk for 1 h, the membrane was incubated with the blocking solution containing the first antibody overnight at 4 °C. After washing, the blot was then incubated with a second antibody. The blot was washed again before being analyzed by the enhanced chemiluminescence (ECL) system (Amersham Pharmacia). The signals were quantified by densitometric analysis using a densitometer. Mitochondrial membrane potential The mitochondrial membrane potential was detected using rhodamine 123 (Rh-123) fluorescent dye. Rh-123 can enter the mitochondrial matrix and cause photoluminescent quenching dependent on mitochondrial transmembrane potential. Primary microglia and BV-2 cells were incubated with Rh-123 for 30 min at 37 °C.

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After incubation, cells were rinsed with PBS. The fluorescence was measured at an excitation wavelength of 488 nm and an emission wave length of 510 nm by fluorescence microplate reader. Statistical analysis Data was expressed as mean ± standard deviation (SD). The results were statistically analyzed using one-way analysis of variance (ANOVA) and the Newman–Keuls test. All statistical analyses were performed using SPSS version 17.0. P < 0.05 was considered statistically significant.

RESULTS Mdivi-1 attenuated Ab-induced microglia apoptosis The effect of mdivi-1 treatment on the expression of CD11b (the marker of microglial activation) in BV-2 cells is shown in Fig. 1. RT-PCR and Western blot analysis demonstrated that CD11b mRNA and protein levels increased in Ab treatment compared with the control. However, pretreatment with mdivi-1 significantly attenuated the changes of CD11b expression induced by Ab. Similar results were observed in mouse primary microglia treated with Ab and mdivi-1 (data not shown). To determine the effect of Ab on microglia, BV-2 and primary microglia were pre-incubated with mdivi-1 at different concentrations for 1 h prior to 24 h exposure of Ab 20 lM, and cell viability was detected by the MTT assay. As shown in Fig. 2, Ab significantly reduced cell viability compared to control-treated cells. However, incubation of mdivi-1 (2–20 lM) concentrationdependently reversed Ab-induced cell death, and the maximal rescue occurred at a concentration of 10 lM. To determine whether apoptosis played a role in Abinduced cell death, TUNEL assay and flow cytometric analysis were performed. We pretreated BV-2 and primary microglia for 1 h with 10 lM mdivi-1, and then

treated with 20 lM Ab for 24 h. Apoptotic cells were analyzed either by TUNEL assay (Fig. 3A) and flow cytometric analysis (Fig. 3B). We showed that co-exposure of BV-2 and primary microglia to mdivi-1 and Ab resulted in a significant decrease in apoptosis compared to cells treated with Ab alone (Fig. 3). Effect of mdivi-1on Drp1 expression Western blot analysis demonstrated that Drp1 level increased in the mitochondrial fraction and decreased in the cytosolic fraction in Ab treatment compared with the control in BV-2 cells. However, pretreatment with mdivi1 significantly attenuated the changes of Drp1 expression in mitochondria and cytosol induced by Ab (Fig. 4). Similar results were observed in mouse primary microglia treated with Ab and mdivi-1 (data not shown). Effect of mdivi-1 on mitochondrial membrane potential It has been indicated that microglia apoptosis induced by Ab was accompanied by the disruption of mitochondrial membrane potential (Liu et al., 2011), so we examined the effect of mdivi-1 on the mitochondrial membrane potential. When BV-2 cells were treated with 20 lM Ab for 24 h at 37 °C, a decrease in the retention of Rh-123 was observed. However, pretreatment with mdivi-1 prevented the decrease in the retention of Rh-123 induced by Ab (Fig. 5). Similar results were observed in mouse primary microglia treated with Ab and mdivi-1 (data not shown). Effect of mdivi-1 on CytC release and caspase-3 activation Our results showed that CytC release from mitochondria to the cytosol and the activated cleavage product of caspase-3 increased in Ab treatment compared with the control in BV-2 cells. However, pretreatment with

Fig. 1. The mRNA and protein expression of CD11b in microglia after mdivi-1 treatment. (A) RT-PCR analysis and quantitative analysis of CD11b in BV-2 cells after mdivi-1 pretreatment. (B) Western blots analysis and quantitative analysis of CD11b in BV-2 cells after mdivi-1 pretreatment. b-actin was used as an internal standard. Only their representative RT-PCR and Western blots are illustrated in this figure. Data are expressed as mean ± SD. ⁄P < 0.01 compared with control. #P < 0.01 compared with the group treated by Ab alone. con, control; mdi, mdivi-1; Ab, b-amyloid protein.

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Fig. 2. Protective effect of mdivi-1 on Ab-induced cytotoxicity in microglia. BV-2 and primary microglia were incubated with 20 lM Ab for 24 h. Mdivi-1 was added to the culture 1 h prior to Ab. Cell viability was determined by measuring MTT reduction. Data are expressed as percent of values in untreated control cultures, and are mean ± SD from three separated experiments with triplicates. ⁄P < 0.01 compared with control. #P < 0.01 compared with the group treated by Ab alone. con, control; mdi, mdivi-1; Ab, b-amyloid protein.

Fig. 3. Inhibition of Drp1 by mdivi-1 blocked Ab-induced apoptosis in microglia. BV-2 and primary microglia were exposed to 10 lM mdivi-1 for 1 h and then treated with 20 lM Ab for 24 h. (A) Apoptotic cells were determined by TUNEL assay. Photographs of representative TUNEL-stained cells are shown at the top. Results represent mean ± SD of three independent experiments. ⁄P < 0.01 compared with indicated groups. (B) Cell apoptosis was also assayed by flow cytometry after staining with annexin V and propidium iodide as described under ‘‘Experimental Procedures’’. These results are representative of three independent experiments. con, control; mdi, mdivi-1; Ab, b-amyloid protein.

mdivi-1 significantly suppressed CytC release and caspase-3 activation (Fig. 6). Similar results were observed in mouse primary microglia treated with Ab and mdivi-1 (data not shown). The effect of mdivi-1 on Ab-induced apoptosis may be, at least in part, mediated by regulating the release of CytC and caspase-3 activation.

DISCUSSION The traditional concept that microglia are killers of injured neurons is now recognized as inadequate and much

attention has been paid to possible therapeutic strategies aimed at inhibiting neurotoxic microglial activation while enhancing microglia-mediated neuroprotection (Polazzi and Monti, 2010; Choi et al., 2011). Indeed, there is clear experimental evidence that microglia can restrict the spread of neurodegeneration and promote neuronal regeneration. Alternatively, microglial overactivation or cell death may worsen preexisting neuropathology (Polazzi and Monti, 2010). Therefore, ideal microglia-targeted therapy should suppress overactivation while preserving those properties that promote neuronal survival and tissue

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Fig. 4. The protein levels of Drp1 in microglia after mdivi-1 treatment. Western blot analysis and quantitative analysis of Drp1 expression in BV-2 cells after mdivi-1 pretreatment. Cyclooxygenase (COX)-IV and b-actin were used as internal controls of mitochondrial and cytosolic subfractions, respectively. Only their representative Western blots are illustrated in this figure. Data are expressed as mean ± SD. ⁄ P < 0.01 compared with control. #P < 0.01 compared with the group treated by Ab alone. con, control; mdi, mdivi-1; Ab, b-amyloid protein; mito, mitochondria; cyto, cytoplasm.

Fig. 5. Effect of mdivi-1 on Ab-induced mitochondrial membrane potential alteration. BV-2 cells were treated with indicated concentrations of Ab with/without mdivi-1 for 24 h, then mitochondrial membrane potential alteration was measured by fluorescence microplate reader using rhodamine 123 staining. Results are shown as the mean ± standard error of the mean (SEM) and represent three independent experiments. ⁄P < 0.05 compared with control. # P < 0.05 compared with Ab alone. con, control; mdi, mdivi-1; Ab, bamyloid protein.

regeneration. In this study, it has been confirmed that Ab exerts cytotoxic effects on microglia in a dose-dependent manner, which is consistent with the finding of Shang et al (Shang et al., 2012). In addition, we found mitochondrial fission is up-regulated in Ab-treated microglia. Moreover, we investigated that inhibition of mitochondrial fission by mdivi-1 significantly attenuates Ab-induced overactivation and apoptotic cell death, the underlying mechanism maybe through mitochondria/ CytC pathway. These findings suggest that inhibiting mitochondrial fission may be a novel mechanism to protect against Ab-induced microglia apoptosis.

Excessive mitochondrial fission plays an important role in the development of neurodegenerative diseases, including AD, Huntington’s disease (HD) and Parkinson’s disease (PD) (Bueler, 2009; Manczak et al., 2011; Shirendeb et al., 2011). Mutant proteins of AD, HD and PD, interact with Drp1, which could activate the mitochondrial fission machinery and ultimately cause mitochondrial dysfunction and lead to neuronal cell death (Reddy et al., 2011). However, mitochondrial fission protein Drp1 is also required for neuronal survival and preventing mitochondrial fission impairs mitochondrial function and leads to the loss of mitochondrial DNA (Parone et al., 2008). Thus, mitochondrial fission may be a double-edged sword because, depending on cellular circumstances, mitochondrial fission may be beneficial in healthy circumstances, yet under stress, when intersecting with pro-apoptotic cascade or other signals, apoptotic mitochondrial fission occurs, contributing to neuronal injury. In this study, we found that Drp1-mediated mitochondrial fission is up-regulated in Ab-treated microglia. Upon induction of apoptosis, Drp1 is recruited from cytoplasm to mitochondria, where it preferentially localizes to potential sites of organelle division. Inhibition of Drp1 by overexpression of a dominant-negative mutant of Drp1 or knockdown of Drp1 could prevent the loss of the mitochondrial membrane potential and the release of CytC, exerting cytoprotective effects (Brooks et al., 2011). Mdivi-1 is a derivative of quinazolinone that acts as a selective inhibitor of the mitochondrial fission protein Drp1. Recent study demonstrates that mdivi-1 inhibits mitochondrial fission by blocking Drp1 self-assembly and GTP hydrolysis, attenuates apoptosis by inhibiting mitochondrial outer membrane permeabilization (MOMP), and inhibits CytC release during apoptosis (Cassidy-Stone et al., 2008). Furthermore, mdivi-1 could inhibit mitochondrial fission and protect primary neurons against glutamate excitotoxicity (Grohm et al., 2012). However, the role of mdivi-1 in Ab-treated microglia remains unknown. Mitochondria depolarization was considered as an irreversible step in the apoptosis process. Loss of mitochondrial membrane potential, which caused the intermembrane protein, such as CytC, to be released out of mitochondria and ultimately triggered caspase-3 activation (Sola et al., 2013). Caspase-3 activation led to DNA breakage, nuclear chromatin condensation and cell apoptosis. Mdivi-1 has been shown to afford its neuroprotection by its anti-apoptotic effects in various injury models (Qiu et al., 2013; Xie et al., 2013; Zhang et al., 2013), which is further confirmed by our data. In this study, we find that mdivi-1 prevented the loss of mitochondrial membrane potential, release of CytC and caspase-3 activation caused by Ab. Based on these findings, we presumed that inhibition of mitochondrial fission by mdivi-1 could reduce the loss of mitochondrial membrane potential, followed by reducing release of CytC and caspase-3 activation. Thus, the mitochondria/ CytC/caspase-3 pathway may be involved in the protective mechanism of mdivi-1 against microglial

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Fig. 6. The protein levels of CytC and activated fragment of caspase-3 in microglia after mdivi-1 treatment. (A) Western blots analysis and quantitative analysis of CytC in BV-2 cells after mdivi-1 pretreatment. (B) Western blots analysis and quantitative analysis of caspase-3 in BV-2 cells after mdivi-1 pretreatment. Cox-IV and b-actin were used as internal controls of mitochondrial and cytosolic subfractions, respectively. Only their representative Western blots are illustrated in this figure. Data are expressed as mean ± SD. ⁄P < 0.01 compared with control. #P < 0.01 compared with the group treated by Ab alone. con, control; mdi, mdivi-1; Ab, b-amyloid protein; CytC, cytochrome c; mito, mitochondria; cyto, cytoplasm.

apoptosis induced by Ab. However, since electron microscopy is the most intuitionistic method of mitochondrial fission, our results still require a further confirmation by electron microscopy.

CONCLUSION In summary, our findings suggest that the Drp1 inhibitor mdivi-1 inhibits mitochondrial fission and attenuates microglia apoptosis induced by Ab. The underlying mechanisms may be through inhibiting mitochondrial membrane potential loss, CytC release and suppression of the mitochondrial apoptosis pathway. Acknowledgements—This study was supported by a grant from National Natural Science Foundation of China (No. 81201012), the Youth Innovation Fund of the First Affiliated Hospital of the Zhengzhou University and China Postdoctoral Science Foundation Funded Project (No. 2012M511590).

REFERENCES Brooks C, Cho SG, Wang CY, Yang T, Dong Z (2011) Fragmented mitochondria are sensitized to Bax insertion and activation during apoptosis. Am J Physiol Cell Physiol 300:C447–C455. Bueler H (2009) Impaired mitochondrial dynamics and function in the pathogenesis of Parkinson’s disease. Exp Neurol 218:235–246. Cassidy-Stone A, Chipuk JE, Ingerman E, Song C, Yoo C, et al (2008) Chemical inhibition of the mitochondrial division dynamin reveals its role in Bax/Bak-dependent mitochondrial outer membrane permeabilization. Dev Cell 14:193–204. Cho DH, Nakamura T, Lipton SA (2010) Mitochondrial dynamics in cell death and neurodegeneration. Cell Mol Life Sci 67:3435–3447.

Choi DK, Koppula S, Suk K (2011) Inhibitors of microglial neurotoxicity: focus on natural products. Molecules 16:1021–1043. Deierborg T (2013) Preparation of primary microglia cultures from postnatal mouse and rat brains. Methods Mol Biol 1041:25–31. Feng X, Liang N, Zhu D, Gao Q, Peng L, et al (2013) Resveratrol inhibits beta-amyloid-induced neuronal apoptosis through regulation of SIRT1–ROCK1 signaling pathway. PLoS One 8:e59888. Gilbert BJ (2013) The role of amyloid beta in the pathogenesis of Alzheimer’s disease. J Clin Pathol 66:362–366. Grohm J, Kim SW, Mamrak U, Tobaben S, Cassidy-Stone A, et al (2012) Inhibition of Drp1 provides neuroprotection in vitro and in vivo. Cell Death Differ 19:1446–1458. Jing CH, Wang L, Liu PP, Wu C, Ruan D, et al (2012) Autophagy activation is associated with neuroprotection against apoptosis via a mitochondrial pathway in a rat model of subarachnoid hemorrhage. Neuroscience 213:144–153. Karbowski M (2010) Mitochondria on guard: role of mitochondrial fusion and fission in the regulation of apoptosis. Adv Exp Med Biol 687:131–142. Kim SJ, Li J (2013) Caspase blockade induces RIP3-mediated programmed necrosis in Toll-like receptor-activated microglia. Cell Death Dis 4:e716. Li G, Ma R, Huang C, Tang Q, Fu Q, et al (2008) Protective effect of erythropoietin on beta-amyloid-induced PC12 cell death through antioxidant mechanisms. Neurosci Lett 442:143–147. Liu YY, Sparatore A, Del Soldato P, Bian JS (2011) H2S releasing aspirin protects amyloid beta induced cell toxicity in BV-2 microglial cells. Neuroscience 193:80–88. Luo XG, Ding JQ, Chen SD (2010) Microglia in the aging brain: relevance to neurodegeneration. Mol Neurodegener 5:12. Manczak M, Calkins MJ, Reddy PH (2011) Impaired mitochondrial dynamics and abnormal interaction of amyloid beta with mitochondrial protein Drp1 in neurons from patients with Alzheimer’s disease: implications for neuronal damage. Hum Mol Genet 20:2495–2509. Parone PA, Da Cruz S, Tondera D, Mattenberger Y, James DI, et al (2008) Preventing mitochondrial fission impairs mitochondrial function and leads to loss of mitochondrial DNA. PLoS One 3:e3257.

42

N. Xie et al. / Neuroscience 256 (2014) 36–42

Polazzi E, Monti B (2010) Microglia and neuroprotection: from in vitro studies to therapeutic applications. Prog Neurobiol 92:293–315. Qin L, Liu Y, Cooper C, Liu B, Wilson B, et al (2002) Microglia enhance beta-amyloid peptide-induced toxicity in cortical and mesencephalic neurons by producing reactive oxygen species. J Neurochem 83:973–983. Qiu X, Cao L, Yang X, Zhao X, Liu X, et al (2013) Role of mitochondrial fission in neuronal injury in pilocarpine-induced epileptic rats. Neuroscience 245:157–165. Reddy PH, Reddy TP, Manczak M, Calkins MJ, Shirendeb U, et al (2011) Dynamin-related protein 1 and mitochondrial fragmentation in neurodegenerative diseases. Brain Res Rev 67:103–118. Saijo K, Glass CK (2011) Microglial cell origin and phenotypes in health and disease. Nat Rev Immunol 11:775–787. Shang YC, Chong ZZ, Wang S, Maiese K (2012) Prevention of betaamyloid degeneration of microglia by erythropoietin depends on Wnt1, the PI 3-K/mTOR pathway, Bad, and Bcl-xL. Aging (Albany NY) 4:187–201. Shirendeb U, Reddy AP, Manczak M, Calkins MJ, Mao P, et al (2011) Abnormal mitochondrial dynamics, mitochondrial loss and mutant huntingtin oligomers in Huntington’s disease: implications for selective neuronal damage. Hum Mol Genet 20:1438–1455. Sola S, Morgado AL, Rodrigues CM (2013) Death receptors and mitochondria: two prime triggers of neural apoptosis and differentiation. Biochim Biophys Acta 1830:2160–2166.

Streit WJ (2004) Microglia and Alzheimer’s disease pathogenesis. J Neurosci Res 77:1–8. Tambuyzer BR, Ponsaerts P, Nouwen EJ (2009) Microglia: gatekeepers of central nervous system immunology. J Leukoc Biol 85:352–370. Tanaka A, Youle RJ (2008) A chemical inhibitor of DRP1 uncouples mitochondrial fission and apoptosis. Mol Cell 29:409–410. Wu S, Ju GQ, Du T, Zhu YJ, Liu GH (2013) Microvesicles derived from human umbilical cord Wharton’s jelly mesenchymal stem cells attenuate bladder tumor cell growth in vitro and in vivo. PLoS One 8:e61366. Xie N, Li H, Wei D, LeSage G, Chen L, et al (2010a) Glycogen synthase kinase-3 and p38 MAPK are required for opioid-induced microglia apoptosis. Neuropharmacology 59:444–451. Xie N, Wang C, Lin Y, Li H, Chen L, et al (2010b) The role of p38 MAPK in valproic acid induced microglia apoptosis. Neurosci Lett 482:51–56. Xie N, Wang C, Lian Y, Zhang H, Wu C, et al (2013) A selective inhibitor of Drp1, mdivi-1, protects against cell death of hippocampal neurons in pilocarpine-induced seizures in rats. Neurosci Lett 545:64–68. Zhang N, Wang S, Li Y, Che L, Zhao Q (2013) A selective inhibitor of Drp1, mdivi-1, acts against cerebral ischemia/reperfusion injury via an anti-apoptotic pathway in rats. Neurosci Lett 535:104–109.

(Accepted 3 October 2013) (Available online 18 October 2013)

Inhibition of mitochondrial fission attenuates Aβ-induced microglia apoptosis.

Mitochondrial division inhibitor 1 (mdivi-1), a selective inhibitor of mitochondrial fission protein dynamin-related protein 1 (Drp1), has been report...
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