Mitochondrial Disease and Toxins

Non-gene'c, Exposure-related Mitochondrial Disease

(Mitochondrial Toxicity)

Kendall B. Wallace, Ph.D., DABT, ATS Professor & Associate Dean

University of Minnesota Medical School Duluth campus

Mitochondrial Disease

Mul'-organ clinical presenta'on Metabolic phenotype Progressive

E'ology

Gene'c Somatogenic/acquired (toxicity)

2

Mitochondrial Disease Etiology 1.Genetic

mutations to nuclear (nDNA) &/or mitochondrial DNA (mtDNA)

Heritable X-chromosome

Mito Map

3

Mitochondrial Electron Transport Chain

nDNA 35 4 10 10 12 mtDNA 7 0 1 3 2

4

Gene'c Mitochondria Disease Founda'ons

Mitochondrial Disease Etiology

2. Somatogenic/acquired Mitochondrial Toxicity

Pharmaceutical

Environmental

Occupational

5

Mito Ac'on Broadcasts (drug-induced mitochondrial disease)

May 1, 2009

Dr. James Dykens, Pfizer Pharmaceu'cals Drug Toxicity and Pharmaceu'cals

June 4, 2010 Dr. Katherine Sims from Massachuse[s General Hospital Mitochondrial Toxicity

6

Mul'ple Targets for Drug-induced Mitochondrial Toxicity

(Wallace, K.B. Curr Med Chem. 2015 May 13)

7

Chemical Targe'ng to Mitochondria

Drugs & chemicals are not distributed equally throughout the cell Cardiolipin

Electrical membrane poten'al

h[p://figshare.com/ar'cles/_Structure_of_Cardiolipin_/658399

8

Krebs Cycle

e- e-

e- e-

H+H+ H+H+

Cyt C e- e-

H+H+ O2 H+H+ H2O

ADP ATP

Cyt C

e-

O2

Q

H+`H+

NADH

NAD+

H+ H+ H+ H+H+H+

Cyt C

H+`

e- e- e-

Modified from: Peter S. Rabinwitch after Mandavilli et al, Mutation Research 509 (2002) 127151

2OH- OH-

Mitochondrial Electron Transport Chain

9

Transmembrane potentials: ~ 1 pH unit alkaline matrix ~ 180 mV negative matrix

Image modified from: h[p://www.westernspring.co.uk/how-small-gene'c-differences-give-racial-diversity/

Posi'vely charged chemicals are drawn from the cell contents into and accumulate in mitochondria

10

Acids & bases

K.B.Wallace, Mito AcEon Oct. 2, 2015

Pharmaceu'cal Uncouplers of Mitochondrial Respira'on:

Amphetamines, doxorubicin, Flufenamic acid, Diflunisal, Tolfenamic acid, Mefenamic acid, Diclofenac, Indomethacin, Naproxen, Nimuesulide

11

Chemical Inhibitors of Mitochondrial Electron Transport

Rotenone

Menadione Benzoquinone

Cyanide CO H2S

K.B.Wallace, Mito AcEon Oct. 2, 2015

Chemical Uncouplers of Mitochondrial RespiraEon Pentachlorophenol Heavy metals: Pb2+, As2+, Cd2+, Hg2+ Paraquat perfluorosulfonamide

12

OXIDATIVE PHOSPHORYLATION!

Chemical-induced Mitochondrionopathies

TCA!Cycle!

NAD+

NADH

METABOLISM!

Glucose

Pyruvate

LACTIC ACID

NAD+

NADH

IODOACETATE

DICHLOROACETATE

Acetyl CoA

oxida>on

NAD+

NADH

NAD+

NADH

FLUOROACETATE FLUOROACETAMIDE

VALPROIC ACID SALICYLATES

FaEy acids

mtDNA

GENETIC MECHANISMS!

replica>on

NUCLEOSIDE ANALOGUES

transcrip'on

ANTIBIOTICS

ROTENONE MALONYL CoA ANTIMYCIN A

CYANIDE

e- NAD+

NADH

[H+]

[H+]

PHENOLS, AMIDES AMPHIPHILIC CATIONS QUINONES

H+

ADP

ATP

transla'on

PROTEIN TRANSLOCALIZATION!

HSPs

PROTEASE INHIBITORS

13

The Bigger Picture of Mitochondrial Toxicity

Substrate delivery Molecular organizaEon

h[ps://en.wikipedia.org/wiki/Electron_transport_chain 14

15

Aspirin, Ibuprofen Valproic acid

Fluoroacetate Fluoroacetamide

Dichloroacetate



TCA!Cycle!

NAD+

NADH

METABOLISM!

Glucose

Pyruvate

LACTIC ACID

NAD+

NADH

IODOACETATE

DICHLOROACETATE

Acetyl CoA

oxida>on

NAD+

NADH

NAD+

NADH



FaEy acids mtDNA

GENETIC MECHANISMS!

replica>on


transcrip'on

ANTIBIOTICS


CYANIDE

e- NAD+

NADH

[H+]

[H+]


H+

ADP

ATP

transla'on


HSPs

PROTEASE INHIBITORS

Summary update

16

Molecular Targets for Mitochondrial Toxicity

From the mitochondrial or nuclear genome to protein incorporated into the mitochondrial structure Gene transla'on Protein synthesis Protein transloca'on and assembly

17



TCA!Cycle!

NAD+

NADH

METABOLISM!

Glucose

Pyruvate

LACTIC ACID

NAD+

NADH

IODOACETATE

DICHLOROACETATE

Acetyl CoA

oxida>on

NAD+

NADH

NAD+

NADH



FaEy acids

mtDNA

GENETIC MECHANISMS!

replica>on


transcrip'on

ANTIBIOTICS


CYANIDE

e- NAD+

NADH

[H+]

[H+]


H+

ADP

ATP

transla'on


HSPs

PROTEASE INHIBITORS

18

Depolarize membrane poten'al Protease inhibitors

nDNA muta'ons Cytosolic ribosomes Precursor processing

19



TCA!Cycle!

NAD+

NADH

METABOLISM!

Glucose

Pyruvate

LACTIC ACID

NAD+

NADH

IODOACETATE

DICHLOROACETATE

Acetyl CoA

oxida>on

NAD+

NADH

NAD+

NADH



FaEy acids

mtDNA

GENETIC MECHANISMS!

replica>on


transcrip'on

ANTIBIOTICS


CYANIDE

e- NAD+

NADH

[H+]

[H+]


H+

ADP

ATP

transla'on


HSPs

PROTEASE INHIBITORS

20

mtDNA replica'on and transla'on

21

h[ps://www.flickr.com/photos/5winfographics/9034866105 22

23

Examples of NRTIs

h[p://www.hva'nn.is/frodleiksmolar/hvad-er-rna/

24

An'bio'cs Chloramphenicol Tetracycline Linezolid

Mitochondrial Protein Synthesis Inhibitors



TCA!Cycle!

NAD+

NADH

METABOLISM!

Glucose

Pyruvate

LACTIC ACID

NAD+

NADH

IODOACETATE

DICHLOROACETATE

Acetyl CoA

oxida>on

NAD+

NADH

NAD+

NADH



FaEy acids

mtDNA

GENETIC MECHANISMS!

replica>on


transcrip'on

ANTIBIOTICS


CYANIDE

e- NAD+

NADH

[H+]

[H+]


H+

ADP

ATP

transla'on


HSPs

PROTEASE INHIBITORS

25

Other uncharacterized Environmental Mitochondrial Toxici'es

Cigare[e smoke Air pollu'on, par'culates Poly aroma'c hydrocarbons (PAHs) Herbicides 2,4-dichlorophenoxyace'c acid (2,4-D), dinoseb

mtDNA genotoxicants, mutagens etc.

26

27

Reports of demonstrated mitochondrial toxicity represent a hazard that may or may not be a real risk under normal or intended exposure condi'ons. hazard versus risk

Extended Readings Dykens, J.A. and Will, Y. (2007) The significance of mitochondrial toxicity tes'ng in drug

development. Drug Discovery Today, 12, 777-785. Wallace, K.B. Mitochondrial Off-Targets of Drug Therapy. 2008. Trends in Pharmacological

Sciences. 29, 361-366. Cohen BH. (2010) Pharmacologic effects on mitochondrial func'on. Dev. Disabil Res Rev. 16,

189-199. Begriche, K., Massart, J., Robin, M.-A., Borgne-Sanchez, A., and Fromenty, B. (2011). Drug-

induced toxicity on mitochondria and lipid metabolism: Mechanis'c diversity and deleterious consequences for the liver. J. Hepatology 54, 773-794.

Meyer JN, Leung MC, Rooney JP, Sendoel A, Hengartner MO, Kisby GE, Bess AS. (2013). Mitochondria as a target of environmental toxicants. Toxicol Sci. 134, 1-17

Wallace, K.B. (2014). Drug-induced mitochondrial neuropathy in children: A conceptual framework for cri'cal windows of development. J. Child Neurology 29, 1241-1248.

Wallace, K.B. (2015). Mul'ple targets for drug-induced mitochondrial toxicity. (Current Medicinal Chemistry, 22, in press).

28

Mitochondrial Disease v. Mitochondrial Toxicity

Genetic v. Environmental

Thank you

29

Health & Medicine

Mitochondrial Disease and Toxins