Neurons depend on a finely tuned transport machinery to keep their cell bodies and extensive processes connected. Increasing evidence suggests that organelle transport is impaired in diseases of motor neurons (MN), where cellular components have to move long distances along axons, and that transport defects may contribute to why MN are specifically affected in amyotrophic lateral sclerosis (ALS). The central hypothesis of this proposal is that impaired mitochondrial dynamics (i.e., transport, fusion, fission) is a primary lesion in ALS MN: when transport is impaired, mitochondria cannot traffic normally to and from crucial sites of energy utilization, such as synaptic terminals, resulting in mitochondrial mislocalization and dysfunction, which in turn causes energy depletion, impaired calcium homeostasis, and ultimately cell degeneration. In this proposal, we will investigate mitochondrial dynamics defects in primary MN from transgenic animal models expressing mutant SOD1, which causes a familial form of ALS. We will use a novel, photo-activatable, fluorescent protein targeted to mitochondria, (mito-Dendra), and live confocal cell imaging. We will investigate the correlations between mitochondrial dynamics defects, mitochondrial structural abnormalities and bioenergetic dysfunction. Our preliminary data strongly suggest that mitochondrial dynamics is abnormal in SOD1 mutant MN and that this abnormality correlates with impaired bioenergetics. First, we will characterize how mutant SOD1 affects mitochondrial transport and determine whether mitochondrial transport defects are specific to MN or if they affect other neural cell types. Furthermore, since ALS involves other cell types besides MN, we will determine whether astrocytes and microglia, which are directly implicated in ALS pathogenesis, play a role in impairing mitochondrial dynamics and function in MN. Second, we will determine how defective mitochondrial dynamics in mutant SOD1 MN affects the interactions with muscle cells at the neuromuscular junction (NMJ), in compartmentalized innervated MN-muscle co-cultures. Third, to verify that mitochondrial dynamics impairment is a primary defect in MN degeneration we will establish the role of mitochondrial transport in maintaining MN and NMJs in normal, wild type, MN, where anterograde mitochondrial transport has been impaired by a genetic approach, independent of mutant SOD1.

Public Health Relevance

Mitochondria are intracellular organelles dedicated to energy metabolism. Mitochondria must be transported along neurons and positioned where energy is needed. Defective mitochondrial transport results in disease. This proposal explores the new field of clinical research using a combination of novel experimental approaches, taking advantage of recently developed fluorescent microscopy techniques. A better understanding of the changes in the dynamics and function of mitochondria in ALS will contribute to identifying avenues of treatment. Furthermore, the system and models that we are developing to study mitochondrial transport defects will be applicable not only to ALS, but also to many other neurodegenerative disorders.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS062055-03
Application #
8010933
Study Section
Neural Oxidative Metabolism and Death Study Section (NOMD)
Program Officer
Gubitz, Amelie
Project Start
2009-01-15
Project End
2013-12-31
Budget Start
2011-01-01
Budget End
2011-12-31
Support Year
3
Fiscal Year
2011
Total Cost
$359,120
Indirect Cost
Name
Weill Medical College of Cornell University
Department
Neurology
Type
Schools of Medicine
DUNS #
060217502
City
New York
State
NY
Country
United States
Zip Code
10065
Palomo, Gloria M; Granatiero, Veronica; Kawamata, Hibiki et al. (2018) Parkin is a disease modifier in the mutant SOD1 mouse model of ALS. EMBO Mol Med 10:
Riar, Amanjot K; Burstein, Suzanne R; Palomo, Gloria M et al. (2017) Sex specific activation of the ER? axis of the mitochondrial UPR (UPRmt) in the G93A-SOD1 mouse model of familial ALS. Hum Mol Genet 26:1318-1327
Kawamata, Hibiki; Peixoto, Pablo; Konrad, Csaba et al. (2017) Mutant TDP-43 does not impair mitochondrial bioenergetics in vitro and in vivo. Mol Neurodegener 12:37
Konrad, Csaba; Kawamata, Hibiki; Bredvik, Kirsten G et al. (2017) Fibroblast bioenergetics to classify amyotrophic lateral sclerosis patients. Mol Neurodegener 12:76
Kawamata, Hibiki; Manfredi, Giovanni (2017) Proteinopathies and OXPHOS dysfunction in neurodegenerative diseases. J Cell Biol 216:3917-3929
Manfredi, Giovanni; Kawamata, Hibiki (2016) Mitochondria and endoplasmic reticulum crosstalk in amyotrophic lateral sclerosis. Neurobiol Dis 90:35-42
Palomo, Gloria M; Manfredi, Giovanni (2015) Exploring new pathways of neurodegeneration in ALS: the role of mitochondria quality control. Brain Res 1607:36-46
Ikiz, Burcin; Alvarez, Mariano J; Ré, Diane B et al. (2015) The Regulatory Machinery of Neurodegeneration in In Vitro Models of Amyotrophic Lateral Sclerosis. Cell Rep 12:335-45
Magrané, Jordi; Cortez, Czrina; Gan, Wen-Biao et al. (2014) Abnormal mitochondrial transport and morphology are common pathological denominators in SOD1 and TDP43 ALS mouse models. Hum Mol Genet 23:1413-24
Papa, Luena; Manfredi, Giovanni; Germain, Doris (2014) SOD1, an unexpected novel target for cancer therapy. Genes Cancer 5:15-21

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