Tidbits from the United Mitochondrial Disease Foundation Scientific Conference

[Guest guest]

Listmates,

I just wanted to give you a little feedback from the United Mitochondrial

Disease Foundation conference I attended last week. The first three days

were on the advances in the science of mitochondrial disease and

mitochondrial function, and the last day was about autism. I'll review the

autism part later, but these are the tidbits from the main conference, mainly.

Wherever you have a condition of oxidative stress, there is the potential

of suffering damage to the mitochondrion. Please see the article below

talking about that issue in Down syndrome and some other genetic

conditions. In other words, even if you have a genetic disease involving

non-mitochondrial related nuclear DNA, and non-mitochondrial pathologies,

that does not mean mitochondria are irrelevant to the disease process.

The amount of mitochondria in cells varies considerably in different tissue

types from thousands to just a few. It made me take notice when I learned

that platelets, which got severely deficient in me as a teenager, only have

about four mitochondria, for instance. Perhaps this makes them more

vulnerable to mitochondrial " hits " .

I think the most striking thing that was discussed is how mitochondria

replicate and how the process is really designed to help us get rid of

mitochondria whose mtDNA has become defective, and promote the

multiplication of the healthier mtDNA. Since mitochondrial DNA is more

vulnerable than nuclear DNA to acquiring genetic defects, it makes sense

that the mitochondria would have a system that can more easily

correct. For them, it is pretty much the survival of the fittest.

Once the membrane potential of the mitochondrion has been compromised, that

sets up the mitochondrion for destruction through autophagy, when membrane

surrounds the mitochondrion, and the mitochondrion becomes digested in a

autophagosomal compartment where its ingredients are recycled.

No one at the conference talked about this, but in the abstracts below,

oxalate is shown to be an example of something that can rapidly reduce the

membrane potential in the mitochondrion, so it is pretty clear that

exposure to larger than physiological levels of oxalate in someone with an

existing mitochondrial disorder would further compromise their

mitochondrial function, and perhaps encourage their death, because oxalate

is capable of knocking out all four of the complexes in the electron

transport chain. That's what reduces the membrane potential. This is one

of the environmental influence that destroys mitochondrial function that

can fairly easily be controlled.

At the conference, there were some wonderful films that came from various

labs showing that healthy mitochondria live in networks and form these long

tubules that are very active. They discussed both the process of fission,

where a mitochondrion splits off or divides, or fusion, which one speaker

called mitochondrial " dating " . In that process a mitochondrion joins the

network or joins another mitochondrion to share its inner contents before

splitting again. After fission, when a mitochondrion divides, the weaker

mitochondrion with the lower membrane potential will be set up for

destruction. This was all fascinating to watch happening on video!

There were also some astonishing data showing that the best way to generate

new mitochondria is through exercise. That produces the factor,

PGC1-alpha, and it helps mitochondria increase in number. They also talked

about bezafibrate (a PPAR panagonist) being used to expand mitochondrial

populations. This would also help form more peroxisomes, but this class of

drugs can also hurt mitochondrial function, so there appears to be a lot of

debate about the practicality and risk of this type of drug that was not

really discuseed at the conference.

The safer " build up your mitochondria with exercise " strategy got me

thinking about the advice given to people with fibromyalgia, telling them

that regular exercise improves their disease and they should exercise even

though they are already in so much pain. It makes sense that if any of

their issues were mitochondrial, exercise in time would help give them a

healthier set of mitochondria. Fibromyalgia generally shows up later in

life, after the mtDNA may have suffered loss. This connection of fibro

with mitochondria is being explored now. See below.

I remember learning in graduate school something else reinforced at the

conference.... the concept that the mitochondrial DNA in one organ may not

necessarily match the mitochondrial DNA in another organ, because local

issues determine which mitochondria survive and get replicated. We are

likely conceived with a mixed set (heteroplasmy). For this reason you

cannot assume that if you've measured muscle mitochondria, for instance,

that the rest of the body will be just the same. There were some

fascinating studies looking at this at the conference. This is the study

of mosaicism...a nice term that reminds us that there are differences in

mitochondria similar to what you find in a mosaic made of tile.

For a good discussion of mosaicism, please see:

http://www.the-scientist.com/blog/display/57199/

Even in the gamete, in the oocyte (since you only inherit your mother's

mitochondria), before each of us was conceived, the different mitochondria

may have had a genetic diversity that was already fated when the mother

with the oocyte was an embryo herself!

I was glad to hear there is hope that we could " select " for a better

representation of mitochondria as long as we keep away from environmental

influences that would make issues get worse and select for weakened mtDNA.

That made me think of how many children I saw in wheelchairs after the

parent conference started. Staying inactive might be a way to make it more

certain that a child's mitochondria will get worse. I think there will be

a lot more study of this issue.

These were the high points of the conference in my mind.

I was very glad to see that buccal testing (swabbing for cells in the cheek

that are being sloughed off) seems to provide reliable data on

mitochondrial defects, and it is a WORLD less invasive and less expensive

than doing a muscle biopsy. All I can do on that issue is cheer!

Dr. Bruce Cohen spoke on supplements and treatments on the autism day, but

these are doses that come from the mito community.

These were the main suggestions:

Coenzyme Q10 540 mgs/day

L-carnitine 990 mg/day

Riboflavin (no amt. specified)

Alpha lipoic acid 600 mgs/day

creatine monophosphate (dose not specified)

L-arginine (dose not specified)

Folinic acid (dose specified)

I will say that others at the conference (including posters) uniformly

suggested 200 mgs/kg/day on the arginine. That is a HUGE amount.

I don't remember a dose being given for creatine monophosphate, but another

study below used 5-10 grams a day in those with neuromuscular disease.

I'm hoping the cross-pollination we had at the conference is going to pay

off in spades!

Supporting abstracts below.

Eur J Pharmacol. 2008 Jan 28;579(1-3):330-6. Epub 2007 Oct 16.

Mitochondrial dysfunction in an animal model of hyperoxaluria: a

prophylactic approach with fucoidan.

Veena CK, phine A, Preetha SP, Rajesh NG, Varalakshmi P.

Department of Medical Biochemistry, Dr. ALM. Post Graduate Institute of

Basic Medical Sciences, University of Madras, Taramani Campus, Chennai -

600 113, India.

Abstract

Oxalate/calcium oxalate toxicity is mediated through generation of reactive

oxygen species in a process that partly depends upon events that induce

mitochondrial damage. Mitochondrial dysfunction is an important event

favoring stone formation. The objective of the present study was to

investigate whether mitochondria is a target for oxalate/calcium oxalate

and the plausible role of naturally occurring glycosaminoglycans from

edible seaweed, fucoidan in ameliorating mitochondrial damage. Male albino

rats of Wistar strain were divided into four groups and treated as follows:

Group I: vehicle treated control, Group II: hyperoxaluria was induced with

0.75% ethylene glycol in drinking water for 28 days, Group III: fucoidan

from F. vesiculosus (5 mg/kg b.wt, s.c) from the 8th day of the

experimental period, Group IV: ethylene glycol+fucoidan treated rats. The

tricarboxylic acid (TCA) cycle enzymes like succinate dehydrogenase,

isocitrate dehydrogenase, malate dehydrogenase and respiratory complex

enzyme activities were assessed to evaluate mitochondrial function.

Oxidative stress was assessed based on the activities of antioxidant

enzymes, level of reactive oxygen species, lipid peroxidation and reduced

glutathione. Mitochondrial swelling was also analyzed. Ultra structural

changes in renal tissue were analyzed with electron microscope.

Hyperoxaluria induced a decrease in the activities of TCA cycle enzymes and

respiratory complex enzymes. The oxidative stress was evident by the

decrease in antioxidant enzymes, glutathione and an increase in reactive

species and lipid peroxidation in mitochondria. Mitochondrial damage was

evident by increased mitochondrial swelling. Administration of fucoidan,

decreased reactive oxygen species, lipid peroxidation (P<0.05),

mitochondrial swelling and increased the activities of antioxidant enzymes

and glutathione levels (P<0.05) and normalized the activities of

mitochondrial TCA cycle and respiratory complex enzymes (P<0.05). From the

present study, it can be concluded that mitochondrial damage is an

essential event in hyperoxaluria, and fucoidan was able to effectively

prevent it and thereby the renal damage in hyperoxaluria.

PMID: 18001705 [PubMed - indexed for MEDLINE]

Kidney Int. 2004 Nov;66(5):1890-900.

Mitochondrial dysfunction is a primary event in renal cell oxalate toxicity.

Cao LC, Honeyman TW, Cooney R, Kennington L, Scheid CR, Jonassen JA.

Department of Physiology, University of Massachusetts, Medical School,

Worcester, Massachusetts 01655-0127, USA.

Abstract

BACKGROUND: In cultured renal epithelial cells, exposure to oxalate, a

constituent of many kidney stones, elicits a cascade of responses that

often leads to cell death. Oxalate toxicity is mediated via generation of

reactive oxygen species (ROS) in a process that depends at least in part

upon lipid signaling molecules that are generated through membrane events

that culminate in phospholipase A2 (PLA2) activation. The present studies

asked whether mitochondria, a major site of ROS production, were targets of

oxalate toxicity, and if so, whether mitochondrial responses to oxalate

were mediated by PLA2 activation. METHODS: Effects of oxalate and various

lipids on mitochondrial membrane potential (DeltaPsim) were measured in

Madin-Darby canine kidney (MDCK) cell monolayers using

5,5',6,6'-tetrachloro 1,1',3,3'-tetraethylbenzimidazolylcarbocyanine iodide

(JC-1), a DeltaPsim-sensitive dye. Other studies assayed caspases, serine

proteases activated during apoptosis, in response to oxalate or lipid

signaling molecules. Additional studies asked whether oxalate or lipids

produced by PLA2 activation promoted ROS formation in isolated renal

mitochondria. RESULTS: Oxalate exposure decreased MDCK cell DeltaPsim

within 30 minutes, a response attenuated by arachidonyl trifluoromethyl

ketone (AACOCF3), an inhibitor of cytosolic PLA2 (cPLA2). Exposure to

arachidonic acid or to lysophosphatidylcholine (lyso-PC), lipid products of

PLA2 activation, or to ceramide, another lipid signal generated in MDCK

cells following oxalate exposure, also depolarized MDCK cell DeltaPsim and

increased the number of caspase-positive cells. Isolated renal mitochondria

responded to oxalate, arachidonic acid, lyso-PC, and ceramide by increasing

their accumulation of ROS, lipid peroxides, and oxidized thiol proteins.

CONCLUSION: These studies suggest that lipid signaling molecules released

after oxalate-induced PLA2 activation trigger marked, rapid changes in

mitochondrial function that may mediate toxicity in renal epithelial cells.

PMID: 15496160 [PubMed - indexed for MEDLINE]

Essays Biochem. 2010;47:85-98.

Mitochondrial fission and fusion.

I, Youle RJ.

*National Heart, Lung and Blood Institute, National Institutes of Health,

9000 Rockville Pike, Bethesda, MD 20892, U.S.A.

Abstract

Mitochondria are highly dynamic cellular organelles, with the ability to

change size, shape and position over the course of a few seconds. Many of

these changes are related to the ability of mitochondria to undergo the

highly co-ordinated processes of fission (division of a single organelle

into two or more independent structures) or fusion (the opposing reaction).

These actions occur simultaneously and continuously in many cell types, and

the balance between them regulates the overall morphology of mitochondria

within any given cell. Fission and fusion are active processes which

require many specialized proteins, including mechanical enzymes that

physically alter mitochondrial membranes, and adaptor proteins that

regulate the interaction of these mechanical proteins with organelles.

Although not fully understood, alterations in mitochondrial morphology

appear to be involved in several activities that are crucial to the health

of cells. In the present chapter we discuss the mechanisms behind

mitochondrial fission and fusion, and discuss the implications of changes

in organelle morphology during the life of a cell.

PMID: 20533902 [PubMed - in process]

Hum Mol Genet. 2009 Oct 15;18(R2):R169-76.

Mitochondrial dynamics--fusion, fission, movement, and mitophagy--in

neurodegenerative diseases.

Chen H, Chan DC.

Division of Biology and Medical Institute, California

Institute of Technology, Pasadena, CA 91125, USA.

Abstract

Neurons are metabolically active cells with high energy demands at

locations distant from the cell body. As a result, these cells are

particularly dependent on mitochondrial function, as reflected by the

observation that diseases of mitochondrial dysfunction often have a

neurodegenerative component. Recent discoveries have highlighted that

neurons are reliant particularly on the dynamic properties of mitochondria.

Mitochondria are dynamic organelles by several criteria. They engage in

repeated cycles of fusion and fission, which serve to intermix the lipids

and contents of a population of mitochondria. In addition, mitochondria are

actively recruited to subcellular sites, such as the axonal and dendritic

processes of neurons. Finally, the quality of a mitochondrial population is

maintained through mitophagy, a form of autophagy in which defective

mitochondria are selectively degraded. We review the general features of

mitochondrial dynamics, incorporating recent findings on mitochondrial

fusion, fission, transport and mitophagy. Defects in these key features are

associated with neurodegenerative disease. Charcot-Marie-Tooth type 2A, a

peripheral neuropathy, and dominant optic atrophy, an inherited optic

neuropathy, result from a primary deficiency of mitochondrial fusion.

Moreover, several major neurodegenerative diseases--including Parkinson's,

Alzheimer's and Huntington's disease--involve disruption of mitochondrial

dynamics. Remarkably, in several disease models, the manipulation of

mitochondrial fusion or fission can partially rescue disease phenotypes. We

review how mitochondrial dynamics is altered in these neurodegenerative

diseases and discuss the reciprocal interactions between mitochondrial

fusion, fission, transport and mitophagy.

PMID: 19808793 [PubMed - indexed for MEDLINE]

Biogerontology. 2010 Mar 18. [Epub ahead of print]

Mitochondrial dysfunction in some oxidative stress-related genetic

diseases: Ataxia-Telangiectasia, Down Syndrome, Fanconi Anaemia and Werner

Syndrome.

Pallardó FV, Lloret A, Lebel M, d'Ischia M, Cogger VC, Le Couteur DG,

Gadaleta MN, Castello G, Pagano G.

Department of Physiology, University of Valencia, CIBERER, 46010, Valencia,

Spain.

Abstract

Oxidative stress is a phenotypic hallmark in several genetic disorders

characterized by cancer predisposition and/or propensity to premature

ageing. Here we review the published evidence for the involvement of

oxidative stress in the phenotypes of Ataxia-Telangiectasia (A-T), Down

Syndrome (DS), Fanconi Anaemia (FA), and Werner Syndrome (WS), from the

viewpoint of mitochondrial dysfunction. Mitochondria are recognized as both

the cell compartment where energetic metabolism occurs and as the first and

most susceptible target of reactive oxygen species (ROS) formation. Thus, a

critical evaluation of the basic mechanisms leading to an in vivo

pro-oxidant state relies on elucidating the features of mitochondrial

impairment in each disorder. The evidence for different mitochondrial

dysfunctions reported in A-T, DS, and FA is reviewed. In the case of WS,

clear-cut evidence linking human WS phenotype to mitochondrial

abnormalities is lacking so far in the literature. Nevertheless, evidence

relating mitochondrial dysfunctions to normal ageing suggests that WS, as a

progeroid syndrome, is likely to feature mitochondrial abnormalities.

Hence, ad hoc research focused on elucidating the nature of mitochondrial

dysfunction in WS pathogenesis is required. Based on the recognized, or

reasonably suspected, role of mitochondrial abnormalities in the

pathogenesis of these disorders, studies of chemoprevention with

mitochondria-targeted supplements are warranted.

PMID: 20237955 [PubMed - as supplied by publisher]

Nat Genet. 2008 Dec;40(12):1484-8.

The mitochondrial DNA genetic bottleneck results from replication of a

subpopulation of genomes.

Wai T, Teoli D, Shoubridge EA.

Montreal Neurological Institute and Department of Human Genetics, McGill

University, Montreal, Canada.

Comment in:

Nat Genet. 2010 Jun;42(6):471-2; author reply 472-3.

Abstract

In mammals, mitochondrial DNA (mtDNA) sequence variants are observed to

segregate rapidly between generations despite the high mtDNA copy number in

the oocyte. This has led to the concept of a genetic bottleneck for the

transmission of mtDNA, but the mechanism remains contentious. Several

studies have suggested that the bottleneck occurs during embryonic

development, as a result of a marked reduction in germline mtDNA copy

number. Mitotic segregation of mtDNAs during preimplantation, or during the

expansion of primordial germ cells (PGCs) before they colonize the gonad,

is thought to account for the increase in genotypic variance observed among

mature oocytes from heteroplasmic mothers. This view has, however, been

challenged by studies suggesting that the bottleneck occurs without a

reduction in germline mtDNA content. To resolve this controversy, we

measured mtDNA heteroplasmy and copy number in single germ cells isolated

from heteroplasmic mice. By directly tracking the evolution of mtDNA

genotypic variance during oogenesis, we show that the genetic bottleneck

occurs during postnatal folliculogenesis and not during embryonic oogenesis.

PMID: 19029901 [PubMed - indexed for MEDLINE]

J Med Genet. 2010 Apr;47(4):257-61. Epub 2009 Nov 12.

Information for genetic management of mtDNA disease: sampling pathogenic

mtDNA mutants in the human germline and in placenta.

Marchington D, Malik S, Banerjee A, K, s D, Macaulay V,

Oakeshott P, Fratter C, Kennedy S, Poulton J.

Nuffield Department of Obstetrics, University of Oxford, The Women's

Centre, UK.

Abstract

BACKGROUND: Families with a child who died of severe, maternally inherited

mitochondrial DNA (mtDNA) disease need information on recurrence risk.

Estimating this risk is difficult because of (a) heteroplasmy-the

coexistence of mutant and normal mtDNA in the same person-and ( the

so-called mitochondrial bottleneck, whereby the small number of mtDNAs that

become the founders for the offspring cause variation in dose of mutant

mtDNA. The timing of the bottleneck and of segregation of mtDNA during

foetal life determines the management options. Therefore, mtDNA

heteroplasmy was studied in oocytes and placenta of women in affected

families. RESULTS: One mother of a child dying from Leigh syndrome due to

the 9176T-->C mtDNA mutation transmitted various loads of mutant mtDNA to <

or =3 of 20 oocytes. This was used to estimate recurrence as < or =5%. She

subsequently conceived a healthy son naturally. Analysis of the placenta

showed that some segregation also occurred during placental development,

with the mutant mtDNA load varying by >10% in a placenta carrying 65%

3243A-->G mutant mtDNA. DISCUSSION: This is the first report of (a) an

oocyte analysis for preconception counselling, specifically, refining

recurrence risks of rare mutations and ( a widely different load of a

pathogenic mtDNA mutation in multiple oocytes, apparently confined to the

germline, in an asymptomatic carrier of an mtDNA disease. This suggests

that a major component of the bottleneck occurs during oogenesis, probably

early in the foetal life of the mother. The variable mutant load in

placenta implies that estimates based on a single sample in prenatal

diagnosis of mtDNA disorders have limited accuracy.

PMID: 19914907

Arthritis Res Ther. 2010;12(1):R17. Epub 2010 Jan 28.

Mitochondrial dysfunction and mitophagy activation in blood mononuclear

cells of fibromyalgia patients: implications in the pathogenesis of the

disease.

Cordero MD, De M, Moreno Fernández AM, Carmona López IM, Garrido

Maraver J, Cotán D, Gómez Izquierdo L, Bonal P, Campa F, Bullon P, Navas P,

Sánchez Alcázar JA.

Centro Andaluz de Biología del Desarrollo (CABD), Universidad Pablo de

Olavide-CSIC, Ctra, de Utrera, km, 1, ISCIII, Sevilla 41013, Spain.

mdcormor@...

Abstract

INTRODUCTION: Fibromyalgia is a chronic pain syndrome with unknown

etiology. Recent studies have shown some evidence demonstrating that

oxidative stress may have a role in the pathophysiology of fibromyalgia.

However, it is still not clear whether oxidative stress is the cause or the

effect of the abnormalities documented in fibromyalgia. Furthermore, the

role of mitochondria in the redox imbalance reported in fibromyalgia also

is controversial. We undertook this study to investigate the role of

mitochondrial dysfunction, oxidative stress, and mitophagy in fibromyalgia.

METHODS: We studied 20 patients (2 male, 18 female patients) from the

database of the Sevillian Fibromyalgia Association and 10 healthy controls.

We evaluated mitochondrial function in blood mononuclear cells from

fibromyalgia patients measuring, coenzyme Q10 levels with high-performance

liquid chromatography (HPLC), and mitochondrial membrane potential with

flow cytometry. Oxidative stress was determined by measuring mitochondrial

superoxide production with MitoSOX and lipid peroxidation in blood

mononuclear cells and plasma from fibromyalgia patients. Autophagy

activation was evaluated by quantifying the fluorescence intensity of

LysoTracker Red staining of blood mononuclear cells. Mitophagy was

confirmed by measuring citrate synthase activity and electron microscopy

examination of blood mononuclear cells. RESULTS: We found reduced levels of

coenzyme Q10, decreased mitochondrial membrane potential, increased levels

of mitochondrial superoxide in blood mononuclear cells, and increased

levels of lipid peroxidation in both blood mononuclear cells and plasma

from fibromyalgia patients. Mitochondrial dysfunction was also associated

with increased expression of autophagic genes and the elimination of

dysfunctional mitochondria with mitophagy. CONCLUSIONS: These findings may

support the role of oxidative stress and mitophagy in the pathophysiology

of fibromyalgia.

PMID: 20109177 [PubMed - in process]

Neurology 1999;52:854

© 1999 American Academy of Neurology

Brief Communications

Creatine monohydrate increases strength in patients with neuromuscular disease

Mark Tarnopolsky, MD, PhD and Joan , MSc

From the Department of Neurology/Neurological Rehabilitation and

Kinesiology, McMaster University Medical Center, Hamilton, Ontario, Canada.

Address correspondence and reprint requests to Dr. Mark Tarnopolsky, Room

4U4, Department of Neurology, McMaster University Medical Center, Hamilton,

Ontario, Canada, L8N 3Z5; e-mail: tarnopol@...

Creatine monohydrate has been shown to increase strength in studies of

young healthy subjects and in a few studies with patients. Creatine

monohydrate (10 g daily for 5 days to 5 g daily for 5 days) was

administered to patients with neuromuscular disease in a pilot study (Study

1; n = 81), followed by a single-blinded study (Study 2; n = 21). Body

weight, handgrip, dorsiflexion, and knee extensor strength were measured

before and after treatment. Creatine administration increased all measured

indices in both studies. Short-term creatine monohydrate increased

high-intensity strength significantly in patients with neuromuscular disease.