ROLE OF MICROTUBULES IN MITOCHONDRIAL DYNAMICS AND PARTITIONING VAISHNAVI ANANTHANARAYANAN ([email protected]) ASSISTANT PROFESSOR AND EMBO YOUNG INVESTIGATOR WELLCOME TRUST/DBT-INDIA ALLIANCE INTERMEDIATE FELLOW CENTRE FOR BIOSYSTEMS SCIENCE AND ENGINEERING INDIAN INSTITUTE OF SCIENCE 10.11.2019 Indian Academy of Sciences, 85th Annual Meeting, Hyderabad
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ROLE OF MICROTUBULES IN MITOCHONDRIAL DYNAMICS AND PARTITIONING
VAISHNAVI ANANTHANARAYANAN ([email protected])ASSISTANT PROFESSOR AND EMBO YOUNG INVESTIGATOR
WELLCOME TRUST/DBT-INDIA ALLIANCE INTERMEDIATE FELLOW CENTRE FOR BIOSYSTEMS SCIENCE AND ENGINEERING
INDIAN INSTITUTE OF SCIENCE
10.11.2019Indian Academy of Sciences, 85th Annual Meeting, Hyderabad
CYTOMOTORS LAB
QUANTITATIVE CYTOSKELETON BIOLOGY
Fission Yeast Myosin I Facilitates PI(4,5)P2 –mediated Anchoring of Cytoplasmic Dynein to
the Cortex. PNAS. (2017)
Motor protein regulationCytoskeleton organization
Role of Microtubules in Osteogenic Differentiation of Mesenchymal Stem Cells on 3D Nanofibrous Scaffolds. ACS Biomater. Sci. Eng. (2017)
Single-molecule imaging of cytoplasmic dynein in vivo reveals the mechanism of motor
activation and cargo capture
Cytoskeleton-organelle interactions
Association of mitochondria with microtubules inhibits mitochondrial fission by precluding the fission protein Dnm1. J. Biol. Chem. (2019)
Cortical tethering of mitochondria by the actor protein Mcp5 enables uniparental mitochondrial
inheritance. J. Cell Biol. (2019)
Role of mitochondria in symmetric cell division
Relationship between microtubule instability and mitochondrial fragmentation in neurodegeneration
Cellular response to pore-forming toxins (with Sandhya S. Visweswariah, IISc)
INTRODUCTION
MICROTUBULES ARE DYNAMIC SELF-ORGANISING POLYMERS
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Conde and Caceres, 2009
Microtubules Nucleus
TEXT
FUNCTION OF MICROTUBULES IN CELLS4
D. Gerlich and C. Blaukopf, IMB, Vienna
Microtubule
Motor
Cargo
Excerpt from ‘The Inner Life of the Cell’, XVIVO (Harvard)
MITOCHONDRIAL POSITIONING AND PARTITIONING
INTRODUCTION
Membrane-bound organelle
Required for a variety of cellular processes: ATP synthesis, calcium signalling, apoptosis, etc.
Mitochondrial network in the cell is dynamic-fission and fusion
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Mitochondrial inheritance during cell division - no de novo synthesis of mitochondria in daughter cells
Zeiss microscopy
INTRODUCTION
MITOCHONDRIAL DYSFUNCTION IN NEURODEGENERATIVE DISEASES
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Adapted from Chen et al., 2009
INTRODUCTION
MITOCHONDRIAL DYNAMICS7
MacDonald et al., 2014
Mfn1 knockout
Mfn1 WT
Chen et al., 2003
Mitochondrial movement along microtubule tracks
Fission inhibited Fusion inhibited
Jourdain et al., 2009 Bockler et al., 2017
MITOCHONDRIAL DYNAMICS AND PARTITIONING IN YEAST
8INTRODUCTION
Adapted from Westermann, 2000
Interphase
Sesaki et al., 1999
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WHAT IS THE MECHANISM OF MICROTUBULE-
MEDIATED MITOCHONDRIAL POSITIONING AND
PARTITIONING IN VIVO?
KEY QUESTION
INTRODUCTION
MICROTUBULES AND MITOCHONDRIA IN FISSION YEAST
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Jurgen Berger, MPI Chiron et al., 2008 Martin, 2009 Hoog et al., 2007
RESULTS
MITOCHONDRIA IN INTERPHASE OF FISSION YEAST
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Hoog et al., 2007
Microtubule Mitochondria
Before MBC After 25μg/ml MBC (+15 mins)
Microtubule MitochondriaMicrotubuleMitochondria
Mmb1
Fu et al., 2011
Mitochondria Mmb1 Merge
HYPOTHESIS
BINDING OF MITOCHONDRIA TO MICROTUBULES PREVENTS FISSIONWhat happens when the microtubules are made longer or
shorter (genetically)?
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Microtubule
Klp5∆6∆ (MTlong)
Klp4∆ (MTshort)
Wild-type (WT)
Klp5/Klp6 ‣ Heterodimer that walks to plus-end
of MT and induces catastrophe
Klp - Kinesin-like protein
Klp4‣ Homodimer that is required for polarised
growth of pombe, stabilises MT
(West et al., 2001, Tischer et al., 2009)
(Browning et al., 2000, Busch et al., 2004)
RESULTS
MITOCHONDRIA IN WT AND MUTANTS IN 3D
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WT
Microtubule MitochondriaMicrotubule
Mitochondria
Scale bar: 2μm
MTlong
MTshort
Deconvolved images
NUMBER OF MITOCHONDRIA PER CELL IS ALTERED, BUT TOTAL VOLUME IS NOT