David J Marcinek

University of Washington Seattle | UW · Department of Radiology

Genomic, transcriptomic and proteomic approaches have been used to gain insight into molecular underpinnings of aging in laboratory animals and in humans. However, protein function in biological systems is under complex regulation and includes factors besides abundance levels, such as modifications, localization, conformation and protein–protein in...

The pathology of aging impacts multiple organ systems, including the kidney and skeletal and cardiac muscles. Long-term treatment with the mitochondrial-targeted peptide elamipretide has previously been shown to improve in vivo mitochondrial function in aged mice, which is associated with increased fatigue resistance and treadmill performance, impr...

Accumulation of somatic mutations in the mitochondrial genome (mtDNA) has long been proposed as a possible mechanism of mitochondrial and tissue dysfunction that occurs during aging. A thorough characterization of age-associated mtDNA somatic mutations has been hampered by the limited ability to detect low frequency mutations. Here, we used Duplex...

The goal of this study is to identify a signature of bioenergetic and functional markers in the muscles of individuals with Parkinson’s disease (PD). Quantitative physiological properties of in vivo hand muscle (FDI, first dorsal interosseus) and leg muscle (TA, Tibialis Anterior) of older individuals with PD were compared to historical age/gender-...

Background: The Study of Muscle, Mobility and Aging (SOMMA) aims to understand the biological basis of many facets of human aging, with a focus on mobility decline, by creating a unique platform of data, tissues, and images. Methods: The multidisciplinary SOMMA team includes two clinical centers (University of Pittsburgh and Wake Forest Universi...

Aging muscle experiences functional decline in part mediated by impaired mitochondrial ADP sensitivity. Elamipretide (ELAM) rapidly improves physiological and mitochondrial function in aging and binds directly to the mitochondrial ADP transporter ANT. We hypothesized that ELAM improves ADP sensitivity in aging leading to rescued physiological funct...

In vivo control over metabolism is at the cutting edge of biomedical research. The particulars of mitochondrial function are especially important to understand in vivo to progress metabolic therapies that will be relevant for diseases of aging. Understanding the differences between how mitochondria function in vitro versus in vivo will be a necessa...

Background: Mitochondrial energetics are an important property of aging muscle, as generation of energy is pivotal to the execution of muscle contraction. However, its association with functional outcomes, including leg power and cardiorespiratory fitness is largely understudied. Methods: In the Study of Muscle, Mobility, and Aging (SOMMA), we c...

The use of permeabilized muscle fibers (PMF) has emerged as a gold standard for assessing skeletal muscle mitochondrial function. PMF provide an intermediate approach between in vivo strategies and isolated mitochondria that allows the mitochondria to be maintained in close to their native morphology in the myofiber while allowing greater control o...

Hallmark features of systolic heart failure are reduced contractility and impaired metabolic flexibility of the myocardium. Cardiomyocytes (CMs) with elevated deoxy ATP (dATP) via overexpression of ribonucleotide reductase (RNR) enzyme robustly improve contractility. However, the effect of dATP elevation on cardiac metabolism is unknown. Here, we d...

Hallmark features of systolic heart failure are reduced contractility and impaired metabolic flexibility of the myocardium. Cardiomyocytes (CMs) with elevated deoxy ATP (dATP) via overexpression of ribonucleotide reductase (RNR) enzyme robustly improve contractility. However, the effect of dATP elevation on cardiac metabolism is unknown. Here, we d...

Aging and poor diet are independent risk factors for heart disease, but the impact of high-sucrose (HS) consumption in the aging heart is understudied. Aging leads to impairments in mitochondrial function that result in muscle dysfunction (e.g., cardiac remodeling and sarcopenia). We tested whether HS diet (60%kcal sucrose) would accelerate muscle...

Accumulation of somatic mutations in the mitochondrial genome (mtDNA) during aging has long been proposed as a possible mechanism of mitochondrial and tissue dysfunction. A thorough characterization of age-associated mtDNA somatic mutations has been hampered by the limited ability to detect low frequency mutations. Here, we used Duplex Sequencing o...

Genomic, transcriptomic, and proteomic approaches have been employed to gain insight into molecular underpinnings of aging in laboratory animals and in humans. However, protein function in biological systems is under complex regulation and includes factors in addition to abundance levels, such as modifications, localization, conformation, and prote...

Importance: Aging is associated with a decline in mitochondrial function and reduced exercise capacity. Urolithin A is a natural gut microbiome-derived food metabolite that has been shown to stimulate mitophagy and improve muscle function in older animals and to induce mitochondrial gene expression in older humans. Objective: To investigate whet...

Purpose: The purpose of this study was to present our hypothesis that aging alters metabolic function in ocular tissues. We tested the hypothesis by measuring metabolism in aged murine tissues alongside retinal responses to light. Methods: Scotopic and photopic electroretinogram (ERG) responses in young (3-6 months) and aged (23-26 months) C57Bl...

Mutations in mitochondrial DNA (mtDNA) cause maternally inherited diseases, while somatic mutations are linked to common diseases of aging. Although mtDNA mutations impact health, the processes that give rise to them are under considerable debate. To investigate the mechanism by which de novo mutations arise, we analyzed the distribution of natural...

It has been demonstrated that elamipretide (SS-31) rescues age-related functional deficits in the heart but the full set of mechanisms behind this have yet to be determined. We investigated the hypothesis that elamipretide influences post-translational modifications to heart proteins. The S-glutathionylation and phosphorylation proteomes of mouse h...

It has been demonstrated that elamipretide (SS-31) rescues age-related functional deficits in the heart but the full set of mechanisms behind this have yet to be determined. We investigated the hypothesis that elamipretide influences post-translational modifications to heart proteins. The S-glutathionylation and phosphorylation proteomes of mouse h...

Background Loss of mitochondrial function contributes to fatigue, exercise intolerance and muscle weakness, and is a key factor in the disability that develops with age and a wide variety of chronic disorders. Here, we describe the impact of a first-in-class cardiolipin-binding compound that is targeted to mitochondria and improves oxidative phosph...

Background: Mutations in the mitochondrial genome (mtDNA) can cause devastating maternally inherited diseases, while the accumulation of somatic mtDNA mutations is linked to common diseases of aging. Although mtDNA mutations impact human health, the process(es) that give rise to these mutations are unclear and are under considerable debate. We anal...

Aging and poor nutrition are independent risk factors for the development of chronic disease. When young animals are given diets high in fat or sugar, they exhibit hallmarks of aging like mitochondrial dysfunction and inflammation, and also develop a greater risk for age-related disease. The same mitochondrial dysfunction and inflammation that prog...

Abstract Background Eccentric contractions induce muscle damage (EIMD) that compromises muscle function. Poor recovery from EIMD has been suggested to be a contributor to the decline in muscle function evident in sarcopenia, but it is unclear which aspects of muscle function are more susceptible to disruption by EIMD in old versus young muscle. The...

High intensity exercise is a popular mode of exercise to elicit similar or greater adaptive responses compared to traditional moderate intensity continuous exercise. However, the molecular mechanisms underlying these adaptive responses are still unclear. The purpose of this pilot study was to compare high and low intensity contractile stimulus on t...

Endurance training (ET) is recommended for the elderly to improve metabolic health and aerobic capacity. However, ET‐induced adaptations may be suboptimal due to oxidative stress and exaggerated inflammatory response to ET. The natural antioxidant and anti‐inflammatory dietary supplement astaxanthin (AX) has been found to increase endurance perform...

Domoic acid (DA) and saxitoxin (STX)‐producing algae are present in Alaskan seas, presenting exposure risks to marine mammals that may be increasing due to climate change. To investigate potential increases in exposure risks to four pagophilic ice seal species (Erignathus barbatus, bearded seals; Pusa hispida, ringed seals; Phoca largha, spotted se...

Introduction High intensity exercise is an increasingly popular mode of exercise to elicit similar or greater adaptive responses compared to traditional moderate intensity continuous exercise. However, the molecular mechanisms underlying these adaptive responses are still unclear. The purpose of this pilot study was to compare high and low intensit...

Purpose Characterize how metabolic function in the murine retina and retinal pigment epithelium-choroid-sclera (eyecup) complex is impacted by natural aging. Methods We examined scotopic and photopic visual function of young (3-6 months) and aged (23-26 months) C57Bl/6J mice using electroretinograms (ERGs). Metabolic changes in retina and eyecup e...

Aging-associated diseases, including cardiac dysfunction, are increasingly common in the population. However, the mechanisms of physiologic aging in general, and cardiac aging in particular, remain poorly understood. Age-related heart impairment is lacking a clinically effective treatment. Using the model of naturally aging mice and rats, we show d...

Background Loss of mitochondrial function contributes to fatigue, exercise intolerance and muscle weakness, and is a key factor in the disability that develops with age and a wide variety of chronic disorders. Here, we describe the impact of a first-in-class cardiolipin-binding compound that is targeted to mitochondria and improves oxidative phosph...

The effects of two different mitochondrial‐targeted drugs, SS‐31 and NMN, were tested on Old mouse hearts. After treatment with the drugs, individually or Combined, heart function was examined by echocardiography. SS‐31 partially reversed an age‐related decline in diastolic function while NMN fully reversed an age‐related deficiency in systolic fun...

Mitochondrial dysfunction underlies the etiology of a broad spectrum of diseases including heart disease, cancer, neurodegenerative diseases, and the general aging process. Therapeutics that restore healthy mitochondrial function hold promise for treatment of these conditions. The synthetic tetrapeptide, elamipretide (SS-31), improves mitochondrial...

Background Cancer cachexia is a multifactorial wasting syndrome that is characterized by the loss of skeletal muscle mass and weakness, which compromises physical function, reduces quality of life, and ultimately can lead to mortality. Experimental models of cancer cachexia have recapitulated this skeletal muscle atrophy and consequent decline in m...

Aging-associated diseases, including cardiac dysfunction, are increasingly common in the population. However, the mechanisms of physiologic aging in general, and cardiac aging in particular, remain poorly understood. While effective medical interventions are available for some kinds of heart failure, one age-related impairment, diastolic dysfunctio...

Mitochondrial dysfunction underlies the etiology of a broad spectrum of diseases including heart disease, cancer, neurodegenerative diseases, and the general aging process. Therapeutics that restore healthy mitochondrial function hold promise for treatment of these conditions. The synthetic tetrapeptide, elamipretide (SS-31), improves mitochondrial...

Domoic acid (DA)-producing harmful algal blooms (HABs) have been present at unprecedented geographic extent and duration in recent years causing an increase in contamination of seafood by this common environmental neurotoxin. The toxin is responsible for the neurotoxic illness, amnesic shellfish poisoning (ASP), that is characterized by gastro-inte...

Sarcopenia and exercise intolerance are major contributors to reduced quality of life in the elderly for which there are few effective treatments. We tested whether enhancing mitochondrial function and reducing mitochondrial oxidant production with SS-31 (elamipretide) could restore redox balance and improve skeletal muscle function in aged mice. Y...

Muscle redox status and post-translational modifications (PTMs) regulate diverse aspects of skeletal muscle function, including mitochondrial energetics and contractile performance. In aging skeletal muscle mitochondrial oxidative stress contributes to altered redox homeostasis. We have previously demonstrated that reducing mitochondrial oxidant pr...

Table S1. Exclusion Criteria Table S2. Treadmill time (min) and incline grade (%) during training at baseline (Pre), at the end (Post) and the change (∆Post‐Pre) with the study. Table S3. Walking distance at baseline (Pre), at the end (Post) and the change (∆Post‐Pre) with the study in the placebo (PL) and astaxanthin formulation (AX) fed groups....

Background Building both strength and endurance has been a challenge in exercise training in the elderly, but dietary supplements hold promise as agents for improving muscle adaptation. Here, we test a formulation of natural products (AX: astaxanthin, 12 mg and tocotrienol, 10 mg and zinc, 6 mg) with both anti‐inflammatory and antioxidant propertie...

Domoic acid (DA) is a neuroexcitotoxic amino acid that is naturally produced by some species of marine diatoms during harmful algal blooms (HABs). The toxin is transferred through the food web from plantivorous fish and shellfish to marine mammals resulting in significant morbidity and mortality. Due to the timing and location of DA producing HABs,...

Protein S-glutathionylation is an important reversible post-translational modification implicated in redox signaling. Oxidative modifications to protein thiols can alter the activity of metabolic enzymes, transcription factors, kinases, phosphatases, and the function of contractile proteins. However, the extent to which muscle contraction induces o...

Protein S-glutathionylation (P-SSG) is a reversible redox modification known to alter the activity of transcription factors, kinases, and contractile proteins as well as protect critical cysteine residues from irreversible oxidation. Exercise elicits an acute oxidative stress that is reported to result in beneficial adaptive responses, a process kn...

Fatigue is the symptom most commonly reported by long-term cancer survivors and is increasingly recognized as related to skeletal muscle dysfunction. Traditional chemotherapeutic agents can cause acute toxicities including cardiac and skeletal myopathies. To investigate the mechanism by which chemotherapy may lead to persistent skeletal muscle dysf...

Representative immunoblots for oxidative stress related antibodies and actin control. Cyclophosphamide (Cy) and Saline (S) gastrocnemius muscle protein homogenates were prepared as described in Materials and methods. Samples were loaded onto each gel randomly and are representative of signals detected for each antibody. (TIF)

mtDNA mutation frequency in EDL muscles is similar between saline and Cy groups 6 weeks after drug administration. Data presented as box plot showing min, median, and max data point. N = 5 per group. (TIF)

No differences in respiration rate after exposure to Cy compared to saline only. State 3 respiration with complex I+II substrates at (A) 1 day, (N = 4 for each group). (B) 1 week (N = 4 for each group). (C) 6 weeks (N = 8 for each group). Data presented as box plot showing min, median, and max data point. P>0.05 for all. (TIF)

Metabolites, Hb and Mb concentrations in distal hindlimb muscles from Cy treated mice. (DOCX)

Select antioxidant enzymes remain unchanged after exposure to Cy. SDS-PAGE separation of homogenized EDL muscle followed by immunobloting with antibody specific for A) SOD1, B) SOD2, and C) catalase. Luminescent signal for each was normalized to actin signal. Data presented as box plot showing min, median, and max data point. N = 4 (1 day and 1 wee...

Levels of NF-ĸB p65 increase shortly after Cy exposure but not at 1 or 6 weeks. NF-ĸB p65 signal was normalized to actin. Data presented as box plot showing min, median, and max data point. N = 4 (1 day and 1 week), N = 8 (6 weeks). (TIF)

We previously reported the bioaccumulation of contaminants of emerging concern (CECs), including pharmaceuticals and personal care products (PPCPs) and perfluorinated compounds, in field-collected juvenile Chinook salmon from urban estuaries of Puget Sound, WA (Meador et al., 2016). Although the toxicological impacts of CECs on salmon are poorly un...

The consumption of one meal of seafood containing domoic acid (DA) at levels high enough to induce seizures can cause gross histopathological lesions in hippocampal regions of the brain and permanent memory loss in humans and marine mammals. Seafood regulatory limits have been set at 20 mg DA/kg shellfish to protect human consumers from symptomatic...

Changes in mitochondrial capacity and quality play a critical role in skeletal and cardiac muscle dysfunction. In vivo measurements of mitochondrial capacity provide a clear link between physical activity and mitochondrial function in aging and heart failure, although the cause and effect relationship remains unclear. Age-related decline in mitocho...

Significance Mitochondria meet the majority of living cells’ demand for ATP and, as important regulators of redox homeostasis, metabolite levels, and calcium buffering, are a critical link between cell energetics and signaling. Disruption of these processes can induce adaptive or pathological signaling responses to stress and under severe stress pr...

Domoic acid (DA) is a neurotoxin that is naturally produced by phytoplankton and accumulates in seafood during harmful algal blooms. As the prevalence of DA increases in the marine environment, there is a critical need to identify seafood consumers at risk of DA poisoning. DA exposure was estimated in recreational razor clam (Siliqua patula) harves...

Although age-associated changes in kidney glomerular architecture have been described in mice and man, the mechanisms are unknown. It is unclear if these changes can be prevented or even reversed by systemic therapies administered at advanced age. Using light microscopy and transmission electron microscopy, our results showed glomerulosclerosis wit...

The free-radical theory of aging was proposed more than 50 years ago. As one of the most popular mechanisms explaining the aging process, it has been extensively studied in several model organisms. However, the results remain controversial. The mitochondrial version of free-radical theory of aging proposes that mitochondria are both the primary sou...

Exercise is the most effective treatment for sarcopenia, the age-related loss of muscle mass and function. Despite its positive effects, many studies indicate that adaptive signaling with exercise is altered or attenuated with age. We and others have found that aging muscle presents with increased mitochondrial reactive oxygen species (ROS) generat...

Muscle redox status regulates diverse aspects of skeletal muscle function, including mitochondrial energetics and contractile performance. In aging skeletal muscle mitochondrial dysfunction contributes to altered redox homeostasis creating a feedforward cycle. Despite this, the role of redox status and its dynamic nature has not been adequately exp...

Neuromuscular diseases are often caused by inherited mutations that lead to progressive skeletal muscle weakness and degeneration. In diverse populations of normal healthy mice, we observed correlations between the abundance of mRNA transcripts related to mitochondrial biogenesis, the dystrophin-sarcoglycan complex, and nicotinamide adenine dinucle...

Aim: Skeletal muscle nitric oxide-cyclic guanosine monophosphate (NO-cGMP) pathways are impaired in Duchenne and Becker muscular dystrophy partly because of reduced nNOSμ and soluble guanylate cyclase (GC) activity. However, GC function and the consequences of reduced GC activity in skeletal muscle are unknown. Here we explore the functions of GC...

Heart disease is already the leading cause of death in the United States. People over 65 years of age are the fastest growing age group, and the incidence of heart failure is expected to increase further in the coming decades. We have previously demonstrated that upregulation of ribonucleotide reductase (RNR) in cardiomyocytes results in an elevati...

Fig. S1 Protein half‐life is modified with age and is dependent on muscle type (B). Fig. S2 EDL and SOL Tissue Weights. Fig. S3 Minimal Inverse Correlation between Protein Abundance and Half‐life. Fig. S4 Oxidative State of Skeletal Muscle: Muscle Fiber H2O2 Production, Protein Carbonyl content and GSH‐modified Proteins. Table S1 Ingenuity Path...

It is now clear that mitochondria are involved as either a cause or consequence of many chronic diseases. This central role of mitochondria is due to their position in the cell as important integrators of cellular energetics and signaling. Mitochondrial function affects many aspects of the cellular environment such as redox homeostasis and calcium...

Mitochondrial oxidative stress is a common feature of skeletal myopathies across multiple conditions; however, the mechanism by which it contributes to skeletal muscle dysfunction remains controversial. Oxidative damage to proteins, lipids, and DNA has received the most attention, yet an important role for reversible redox post-translational modifi...

Changes in mitochondrial function with age vary between different muscle types, and mechanisms underlying this variation remain poorly defined. We examined whether the rate of mitochondrial protein turnover contributes to this variation. Using heavy label proteomics, we measured mitochondrial protein turnover and abundance in slow-twitch soleus (SO...

Pacific salmon exposed to sublethal concentrations of organophosphate pesticides (OP) have impaired olfactory function that can lead to loss of behaviors that are essential for survival. These exposures often involve mixtures and can occur at levels below those which inhibit acetylcholinesterase (AChE). In the current study, juvenile Coho salmon we...