Limits...
Miro1 deficiency in amyotrophic lateral sclerosis.

Zhang F, Wang W, Siedlak SL, Liu Y, Liu J, Jiang K, Perry G, Zhu X, Wang X - Front Aging Neurosci (2015)

Bottom Line: Miro1, a RhoGTPase also referred to as Rhot1, is a key regulator of mitochondrial movement linking mitochondria and motor proteins.Glutamate excitotoxicity is one of the major pathophysiological mechanisms implicated in the pathogenesis of ALS, and we found that excessive glutamate challenge lead to significant reduction of Miro1 expression in spinal cord motor neurons both in vitro and in mice.Taken together, these findings show Miro1 deficiency in ALS patients and ALS animal models and suggest glutamate excitotoxicity as a likely cause of Miro1 deficiency.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Case Western Reserve University Cleveland, OH, USA ; Department of Neurosurgery, Shandong Provincial Hospital, Shandong University Jinan, China.

ABSTRACT
Proper transportation of mitochondria to sites with high energy demands is critical for neuronal function and survival. Impaired mitochondrial movement has been repeatedly reported in motor neurons of amyotrophic lateral sclerosis (ALS) patients and indicated as an important mechanism contributing to motor neuron degeneration in ALS. Miro1, a RhoGTPase also referred to as Rhot1, is a key regulator of mitochondrial movement linking mitochondria and motor proteins. In this study, we investigated whether the expression of Miro1 was altered in ALS patients and ALS animal models. Immunoblot analysis revealed that Miro1 was significantly reduced in the spinal cord tissue of ALS patients. Consistently, the decreased expression of Miro1 was also noted only in the spinal cord, and not in the brain tissue of transgenic mice expressing ALS-associated SOD1 G93A or TDP-43 M337V. Glutamate excitotoxicity is one of the major pathophysiological mechanisms implicated in the pathogenesis of ALS, and we found that excessive glutamate challenge lead to significant reduction of Miro1 expression in spinal cord motor neurons both in vitro and in mice. Taken together, these findings show Miro1 deficiency in ALS patients and ALS animal models and suggest glutamate excitotoxicity as a likely cause of Miro1 deficiency.

No MeSH data available.


Related in: MedlinePlus

Expression of Miro1 in spinal cords motor neurons treated with glutamate. (A) Representative immunoblot and quantification analysis of the expression of Miro1 in motor neurons (DIV 5) treated with different doses of glutamate for 24 h. (B) Representative immunoblot and quantification analysis of the expression of Miro1 in motor neurons (DIV 5) at different time points after 25 μM glutamate treatment. (C) Representative immunoblot and quantification analysis of the expression of Miro1 in motor neurons treated with 25 μM glutamate and/or 20 μM MK801 for 24 h. Equal protein amounts (10 μg) were loaded and confirmed by GAPDH. Data are means ± s.e.m. All experiments were repeated three times. Statistics: one-way ANOVA followed by Tukey’s multiple comparison test. *p < 0.05, **p < 0.01, ***p < 0.001, compared with untreated control neurons.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4443026&req=5

Figure 4: Expression of Miro1 in spinal cords motor neurons treated with glutamate. (A) Representative immunoblot and quantification analysis of the expression of Miro1 in motor neurons (DIV 5) treated with different doses of glutamate for 24 h. (B) Representative immunoblot and quantification analysis of the expression of Miro1 in motor neurons (DIV 5) at different time points after 25 μM glutamate treatment. (C) Representative immunoblot and quantification analysis of the expression of Miro1 in motor neurons treated with 25 μM glutamate and/or 20 μM MK801 for 24 h. Equal protein amounts (10 μg) were loaded and confirmed by GAPDH. Data are means ± s.e.m. All experiments were repeated three times. Statistics: one-way ANOVA followed by Tukey’s multiple comparison test. *p < 0.05, **p < 0.01, ***p < 0.001, compared with untreated control neurons.

Mentions: Many ALS patients demonstrate elevated extracellular glutamate levels in the spinal cord, and glutamate excitotoxicity has been implicated in the pathogenesis of both sALS and fALS (Rothstein, 1995; Bruijn et al., 2004; Jaiswal, 2013). We further employed rat primary spinal cord cultured motor neurons challenged with glutamate as a model to investigate the potential cause of Miro1 deficiency in sALS. Primary motor neurons (day in vitro 5: DIV 5) were treated with different doses of glutamate (0–50 μM) for 24 h. Treatment with glutamate resulted in a significant dose-dependent decrease of Miro1 in spinal cord motor neurons starting at a concentration of 5 μM (Figure 4A). A further time course study using a sublethal dose of glutamate (25 μM) revealed that Miro1 levels were decreased within 2 h following glutamate treatment (Figure 4B), preceding neuronal death that was only observed 8 h later (Wang et al., 2015) (data not shown). As expected, and consistent with previous studies (Ackerley et al., 2000; Donnelly et al., 2013), this glutamate-induced Miro1 reduction was completely abolished by glutamate receptor blocker MK-801 (Figure 4C).


Miro1 deficiency in amyotrophic lateral sclerosis.

Zhang F, Wang W, Siedlak SL, Liu Y, Liu J, Jiang K, Perry G, Zhu X, Wang X - Front Aging Neurosci (2015)

Expression of Miro1 in spinal cords motor neurons treated with glutamate. (A) Representative immunoblot and quantification analysis of the expression of Miro1 in motor neurons (DIV 5) treated with different doses of glutamate for 24 h. (B) Representative immunoblot and quantification analysis of the expression of Miro1 in motor neurons (DIV 5) at different time points after 25 μM glutamate treatment. (C) Representative immunoblot and quantification analysis of the expression of Miro1 in motor neurons treated with 25 μM glutamate and/or 20 μM MK801 for 24 h. Equal protein amounts (10 μg) were loaded and confirmed by GAPDH. Data are means ± s.e.m. All experiments were repeated three times. Statistics: one-way ANOVA followed by Tukey’s multiple comparison test. *p < 0.05, **p < 0.01, ***p < 0.001, compared with untreated control neurons.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4443026&req=5

Figure 4: Expression of Miro1 in spinal cords motor neurons treated with glutamate. (A) Representative immunoblot and quantification analysis of the expression of Miro1 in motor neurons (DIV 5) treated with different doses of glutamate for 24 h. (B) Representative immunoblot and quantification analysis of the expression of Miro1 in motor neurons (DIV 5) at different time points after 25 μM glutamate treatment. (C) Representative immunoblot and quantification analysis of the expression of Miro1 in motor neurons treated with 25 μM glutamate and/or 20 μM MK801 for 24 h. Equal protein amounts (10 μg) were loaded and confirmed by GAPDH. Data are means ± s.e.m. All experiments were repeated three times. Statistics: one-way ANOVA followed by Tukey’s multiple comparison test. *p < 0.05, **p < 0.01, ***p < 0.001, compared with untreated control neurons.
Mentions: Many ALS patients demonstrate elevated extracellular glutamate levels in the spinal cord, and glutamate excitotoxicity has been implicated in the pathogenesis of both sALS and fALS (Rothstein, 1995; Bruijn et al., 2004; Jaiswal, 2013). We further employed rat primary spinal cord cultured motor neurons challenged with glutamate as a model to investigate the potential cause of Miro1 deficiency in sALS. Primary motor neurons (day in vitro 5: DIV 5) were treated with different doses of glutamate (0–50 μM) for 24 h. Treatment with glutamate resulted in a significant dose-dependent decrease of Miro1 in spinal cord motor neurons starting at a concentration of 5 μM (Figure 4A). A further time course study using a sublethal dose of glutamate (25 μM) revealed that Miro1 levels were decreased within 2 h following glutamate treatment (Figure 4B), preceding neuronal death that was only observed 8 h later (Wang et al., 2015) (data not shown). As expected, and consistent with previous studies (Ackerley et al., 2000; Donnelly et al., 2013), this glutamate-induced Miro1 reduction was completely abolished by glutamate receptor blocker MK-801 (Figure 4C).

Bottom Line: Miro1, a RhoGTPase also referred to as Rhot1, is a key regulator of mitochondrial movement linking mitochondria and motor proteins.Glutamate excitotoxicity is one of the major pathophysiological mechanisms implicated in the pathogenesis of ALS, and we found that excessive glutamate challenge lead to significant reduction of Miro1 expression in spinal cord motor neurons both in vitro and in mice.Taken together, these findings show Miro1 deficiency in ALS patients and ALS animal models and suggest glutamate excitotoxicity as a likely cause of Miro1 deficiency.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Case Western Reserve University Cleveland, OH, USA ; Department of Neurosurgery, Shandong Provincial Hospital, Shandong University Jinan, China.

ABSTRACT
Proper transportation of mitochondria to sites with high energy demands is critical for neuronal function and survival. Impaired mitochondrial movement has been repeatedly reported in motor neurons of amyotrophic lateral sclerosis (ALS) patients and indicated as an important mechanism contributing to motor neuron degeneration in ALS. Miro1, a RhoGTPase also referred to as Rhot1, is a key regulator of mitochondrial movement linking mitochondria and motor proteins. In this study, we investigated whether the expression of Miro1 was altered in ALS patients and ALS animal models. Immunoblot analysis revealed that Miro1 was significantly reduced in the spinal cord tissue of ALS patients. Consistently, the decreased expression of Miro1 was also noted only in the spinal cord, and not in the brain tissue of transgenic mice expressing ALS-associated SOD1 G93A or TDP-43 M337V. Glutamate excitotoxicity is one of the major pathophysiological mechanisms implicated in the pathogenesis of ALS, and we found that excessive glutamate challenge lead to significant reduction of Miro1 expression in spinal cord motor neurons both in vitro and in mice. Taken together, these findings show Miro1 deficiency in ALS patients and ALS animal models and suggest glutamate excitotoxicity as a likely cause of Miro1 deficiency.

No MeSH data available.


Related in: MedlinePlus