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Tianhong Pan, MD, PhD; Wenjie Xie, MD; Pawan Rawal,MD

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Presentation on theme: "Tianhong Pan, MD, PhD; Wenjie Xie, MD; Pawan Rawal,MD"— Presentation transcript:

1 Rapamycin Protects Against Rotenone-induced Apoptosis Through Autophagy Induction
Tianhong Pan, MD, PhD; Wenjie Xie, MD; Pawan Rawal,MD Joseph Jankovic, MD; Weidong Le, MD, PhD Department of Neurology, Baylor College of Medicine, Houston, TX AAN, Seattle, 04/30/2009

2 This Study Was Supported by
DISCLOSURE This Study Was Supported by Diana Helis Henry Medical Research Foundation Carolyn Weiss Law Seed Funding National Parkinson Foundation grant to the Baylor College of Medicine Center of Excellence


4 Pathogenesis of Neurodegeneration in Parkinson’s Disease
Genetic factors (DJ-1, PINK1, LRRK2, etc) Environmental toxin Aging Mitochondrial Dysfunction Mutations in -synuclein ATP Free radicals Mutation in parkin, UCHL1  -synuclein aggregation Mutation in ATP13A2 UPS dysfunction ALP dysfunction Accumulation of Aggregated/ Misfolded Proteins UPS = Ubiquitin Proteasome System ALP = Autophagy Lysosome Pathway Dopaminergic neuron death

5 Protein Degradation Routes
Ubiquitin-proteasome system (UPS) Protein Degradation Autophagy-lysosome pathway (ALP)

6 ALP in mammalian cells Macroautophagy CMA (Autophagy) Microautophagy
Various Signals CMA Cytosolic protein eg. -synuclein Bafilomycin A1 (Baf1) Lysosome Cytosolic Chaperon (hsc70) 3-methyladenine (3MA) Enzymes mTOR Cytosolic protein-molecular chaperone complex Autophagosome fuses with lysosome Misfolded/aggregated proteins or cell components Lamp2a Amino and fatty acids are released into cytoplasma Autophagosome/ Mitophahgosome Two concentric membranes engulf cell components or aggregated proteins to be degraded Autophagolysosome Autophagic Vacuoles (AVs) Microautophagy Mitophagy Pan et al. Brain (2008), 131, ALP = Autophagy Lysosome Pathway

7 Autophagy (Macroautophagy)
A process of bulk degradation of Long-lived, stable proteins Entire organelles (eg. mitochondria) Aggregated proteins that fail to be degraded by UPS

8 HYPOTHESIS Autophagy enhancement may prevent accumulation of aggregated/misfolded proteins and of damaged mitochondria, postulated to be two major pathogenic mechanisms of neurodegeneration associated with PD.

9 OBJECTIVE To explore the potential neuroprotective effects of autophagy enhancement on neurotoxin-induced injury and its possible mechanisms

10 REAGENTS Rapamycin Rotenone FDA-approved antibiotic and immuno-
suppressant Enhances autophagy via inhibition of mammalian target of rapamycin (mTOR), a negative regulator of autophagy Rotenone An inhibitor of mitochondrial complex I, used as a model for neurotoxin-induced neurodegeneration in PD

11 METHODS The human neuroblastoma SH-SY5Y cells were treated with rapamycin at various concentrations for different time durations The cells were exposed to rotenone with/without rapamycin pretreatment on both small interference RNA of Atg5 (Atg5 siRNA)-transfected cells, in which the autophagy was suppressed, and non-transfected cells. After specific treatment, the cells were either harvested for protein isolation for Elisa assay or immunoblotting assay, or were fixed for immunostaining assay and electron microscopy analysis.


13 Rapamycin Enhanced Autophagy in SH-SY5Y Cells
LC3: Autophagy Marker ; Con = Control; Rapa = Rapamycin

14 Rapamycin Protected Against Rotenone-Induced Apoptosis
Con = control; Rapa = Rapamycin; Rot = Rotenone

15 Autophagy Inhibition Blocked Rapamycin’s Neuroprotection
Con = control; Rapa = Rapamycin; Rot = Rotenone

16 Rapamycin Protected Mitochondrial Function
Con = control; Rapa = Rapamycin; Rot = Rotenone

17 Rapamycin Enhanced Degradation of Ubiquitinated Proteins
Rapa = Rapamycin; Rot = Rotenone

18 Injured Mitochondria Cleared via Autophagy

19 CONCLUSION 1 Rapamycin exerts a neuroprotective role by interfering with pro-apoptotic insults via enhanced clearance of misfolded/aggregated proteins and/or of dysfunctional mitochondria through autophagy enhancement.

20 Anti-apoptosis via Autophagy Enhancement by Rapamycin

21 CONCLUSION 2 Autophagy enhancers, such as rapamycin, may be considered potential therapeutic agents for the treatment of PD.

22 Therapeutic Targets for PD Misfolded/Aggregated
Proteins Injured Mitochondria

23 Novel Therapeutic Strategy for PD
Autophagy Enhancement

24 Acknowledgement Parkinson’s Disease Center and Movement Disorder Clinic: Joseph Jankovic, MD Parkinson’s Disease Research Lab: Weidong Le, MD, PhD Pawan Rawal, MD Yunchen Wu, MD, PhD Wenjie Xie, MD Institutional Core Grant #CA16672 High Resolution Electron Microscopy facility, UTMDACC Kenneth Dunner

25 Parkinson’s Disease Center and Movement Disorders Clinic

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