Dao-Fu Dai

University of Iowa | UI · Department of Pathology

Human pluripotent stem cells (PSCs) represent an attractive source of cardiomyocytes with potential applications including disease modeling, drug discovery and safety screening, and novel cell-based cardiac therapies. Insights from embryology have contributed to the development of efficient, reliable methods capable of generating large quantities o...

Chronic caloric restriction (CR) and rapamycin inhibit the mechanistic target of rapamycin (mTOR) signaling, thereby regulating metabolism and suppressing protein synthesis. Caloric restriction or rapamycin extends murine lifespan and ameliorates many aging-associated disorders; however, the beneficial effects of shorter treatment on cardiac aging...

Mitochondrial dysfunction has been implicated in several cardiovascular diseases; however, the roles of mitochondrial oxidative stress and DNA damage in hypertensive cardiomyopathy are not well understood. We evaluated the contribution of mitochondrial reactive oxygen species (ROS) to cardiac hypertrophy and failure by using genetic mouse models ov...

Age is a major risk for cardiovascular diseases. Although mitochondrial reactive oxygen species have been proposed as one of the causes of aging, their role in cardiac aging remains unclear. We have previously shown that overexpression of catalase targeted to mitochondria (mCAT) prolongs murine median lifespan by 17% to 21%. We used echocardiograph...

We investigated the effect of reducing mitochondrial oxidative stress by the mitochondrial-targeted antioxidant peptide SS-31 in hypertensive cardiomyopathy. Oxidative stress has been implicated in hypertensive cardiovascular diseases. Mitochondria and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase have been proposed as primary sites o...

Background: Type 2 diabetes (T2D) is associated with a strongly increased risk for restenosis after angioplasty driven by proliferation of vascular smooth muscle cells (VSMCs). Here, we sought to determine whether and how mitochondrial dysfunction in T2D drives VSMC proliferation with a focus on ROS and intracellular [Ca2+] that both drive cell pro...

Neuroinflammation is one of the main mechanisms leading to neuronal death and dysfunction in neurodegenerative diseases. The role of microglia as primary mediators of inflammation is unclear in Leigh syndrome (LS) patients. This study aims to elucidate the role of microglia in LS progression by a detailed multipronged analysis of LS neuropathology,...

Introduction Renal intravascular large B-cell lymphoma (IVLBCL) is a rare, aggressive B-cell lymphoma with neoplastic cells occupying the vascular lumina with only 53 patients reported to date. Here, we present the largest case series to characterize this rare disease. Methods We performed a multi-institutional, retrospective review of kidney biop...

In spite of its central role in biology and disease, protein turnover is a largely understudied aspect of most proteomic studies due to the complexity of computational workflows that analyze in vivo turnover rates. To address this need, we developed a new computational tool, TurnoveR, to accurately calculate protein turnover rates from mass spectro...

Many studies in mice have demonstrated that cardiac-specific innate immune signaling pathways can be reprogrammed to modulate inflammation in response to myocardial injury and improve outcomes. In these studies, however, the standard parameters of left ventricular (LV) ejection fraction, fractional shortening, and end-diastolic diameter, among othe...

Background: Mice with deletion of complex I subunit Ndufs4 develop mitochondrial encephalomyopathy resembling Leigh syndrome (LS). The metabolic derangement and underlying mechanisms of cardio-encephalomyopathy in LS remains incompletely understood. Methods: We performed echocardiography, electrophysiology, confocal microscopy, metabolic and mol...

Coronavirus disease 2019 (COVID-19) may cause a wide spectrum of kidney pathologies. The impact of COVID-19 is unclear in the context of the complement system abnormalities, including C3 glomerulopathy (C3G). In this report, we describe a young adult receiving a kidney transplant for C3 glomerulopathy (C3G), a disorder of the alternative complement...

Mice with deletion of complex I subunit Ndufs4 develop mitochondrial encephalomyopathy resembling Leigh syndrome (LS). We report that LS mice also develop severe cardiac bradyarrhythmia and diastolic dysfunction. Human induced pluripotent stem cell-derived cardiomyocytes (iPS-CMs) with Ndufs4 deletion recapitulate LS cardiomyopathy. Mechanistically...

The roles of free radicals in aging have a long, complicated, and controversial history. The free radical hypothesis of aging was first proposed by Denham Harman (1956), in which he proposed that free radical-induced macromolecular damage accumulated with age and was the primary factor in aging as well as an essential determinant of life expectancy...

Mitochondrial dysfunction is well documented in experimental models of cardiac aging, ischemia reperfusion injury, hypertensive cardiomyopathy and heart failure. The dysfunction includes increased mitochondrial oxidative stress, mitochondrial DNA depletion and increased mitochondrial DNA mutation or deletion frequency, impaired mitochondrial respir...

Pregnancy is proposed to aggravate cyst progression in autosomal dominant polycystic kidney disease (ADPKD) but Tolvaptan, the only FDA-approved drug for adult ADPKD, is not recommended for pregnant ADPKD patients because of potential fetal harm. Since pregnancy itself may increase the risk for ADPKD progression, we investigated the safety and effi...

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by progressively enlarging cysts. Here we elucidate the interplay between oxidative stress, mitochondrial dysfunction, and metabolic derangement using two mouse models of PKD1 mutation, PKD1RC/null and PKD1RC/RC. Mouse kidneys with PKD1 mutation have decreased mitochondrial compl...

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by progressively enlarging cysts. Here we elucidate the interplay between oxidative stress, mitochondrial dysfunction, and metabolic derangement using two mouse models of PKD1 mutation, PKD1RC/null and PKD1RC/RC. Mouse kidneys with PKD1 mutation have decreased mitochondrial compl...

Background: Cardiac manifestations of cystic fibrosis are classically accepted as cor pulmonale, yet emerging evidence supports that cardiac abnormalities can develop early when respiratory function is preserved. Myocardial cystic fibrosis transmembrane regulator (CFTR) channels, inactive in normal conditions, are activated in response to catechola...

Loss of function of the lipid kinase diacylglycerol kinase ε (DGKε), encoded by the gene DGKE, causes a form of atypical hemolytic uremic syndrome that is not related to abnormalities of the alternative pathway of the complement, by mechanisms that are not understood. By generating a potentially novel endothelial specific Dgke-knockout mouse, we de...

Sphingosine-1-phosphate (S1P), is a signaling sphingolipid which acts as a bioactive lipid mediator. We assessed whether S1P had multiplex effects in regulating the large-conductance Ca2+-activated K+ channel (BKCa) in catecholamine-secreting chromaffin cells. Using multiple patch-clamp modes, Ca2+ imaging, and computational modeling, we evaluated...

TFEB promotes lysosomal biogenesis, autophagy, and lysosomal exocytosis. The present study characterized the consequence of inducible TFEB overexpression in cardiomyocytes in vivo. We generated cardiomyocyte-specific doxycycline inducible (Tet off) mice to achieve spatial and temporal control of TFEB overexpression, by crossing TFEB transgenic mice...

mechanistic Target of Rapamycin (mTOR) signaling is a key regulator of cellular metabolism, integrating nutrient sensing with cell growth. Over the past two decades, studies on the mTOR pathway have revealed that mTOR complex 1 controls life span, health span, and aging by modulating key cellular processes such as protein synthesis, autophagy, and...

Aging results in structural deteriorations and functional decline of the heart and is a major risk factor for cardiovascular disease, the leading cause of death in the United States and other Western populations. As the elderly population is continuously growing, the prevalence and economic burden of age-related cardiovascular disabilities continue...

Background: Mice with germline mutation of the mitochondrial respiratory complex I subunit Ndufs4 exhibit progressive neurodegenerative phenotypes resembling Leigh syndrome (LS). Cardiomyocyte-specific Ndufs4 -/- mice demonstrate protein hyperacetylation and accelerated heart failure in response to pressure overload. Methods and Results: LS mice de...

This study investigated the direct roles of hydrogen peroxide (H2O2) in kidney aging using transgenic mice overexpressing glutathione peroxidase‐1 (GPX1 TG). We demonstrated that kidneys in old mice recapitulated kidneys in elderly humans and were characterized by glomerulosclerosis, tubular atrophy, interstitial fibrosis, and loss of cortical mass...

Therapeutic complement inhibition is a major focus for novel drug development. Of upstream targets, factor D (FD) is appealing because it circulates in plasma at low concentrations and has a single function: to cleave factor B to generate C3 convertase of the alternative pathway (AP). Mice with a targeted deletion of factor H (FH; Cfh-/- mice) deve...

Inhibition of mammalian target of rapamycin complex I (mTORC1) by rapamycin improves cardiac function in both aging and heart failure. While the protective mechanisms are not fully understood in mammals, they are presumably mediated through metabolic regulation and suppression of protein translation by reduced phosphorylation of 4EBP1, a target of...

Mitotic catastrophe (MC) is a major cause of podocyte loss in vitro and in vivo. We evaluated urine samples (n = 184 urine samples from diabetic patients; n = 41 patients) from diabetic patients and determined the presence of podocytes in the urine and studied their characteristics, specifically asking whether apoptosis versus MC is present. We als...

Fibrillary GN is a rare form of GN of uncertain pathogenesis that is characterized by the glomerular accumulation of randomly arranged, nonbranching fibrils (12-24 nm) composed of Ig and complement proteins. In this study, we used mass spectrometry to comprehensively define the glomerular proteome in fibrillary GN compared with that in controls and...

Accumulation of protein aggregates with age was first described in aged human tissue over 150 years ago and has since been described in virtually every human tissue. Ubiquitin modifications are a canonical marker of insoluble protein aggregates; however, the composition of most age-related inclusions remains relatively unknown. To examine the lands...

Human pluripotent stem cells derived cardiomyocytes (PSC-CMs) have been widely used for disease modeling, drug safety screening, and preclinical cell therapy to regenerate myocardium. Most studies have utilized PSC-CM grown in vitro for a relatively short period after differentiation. These PSC-CMs demonstrated structural, electrophysiological, and...

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...

Significance Calcium entry initiates contraction in cardiac myocytes, and altered expression of voltage-gated calcium channel 1.2 (Ca V 1.2) causes heart failure in mice. Here we show that reducing β-adrenergic regulation of Ca V 1.2 by mutation of a PKA site in the C-terminal domain causes age-related heart failure. Dual mutation of a nearby casei...

Fig. S2 Histograms of changes in peptide abundance during 17‐days of Heavy Leucine diet.

Data S1 Spreadsheets relative abundance statistics and turnover statistics in the cardiac proteome.

Fig. S3 Density plot of half‐life (in days) in heart and liver tissue.

Fig. S4 Heatmap containing hepatic protein abundance changes.

Fig. S5 Western blotting and qPCR of mCAT expression in hearts and livers.

Fig. S7 Western blotting of mitochondrial proteins and markers of mitochondrial biogenesis.

Fig. S1 Experimental workflow for metabolic labeling and proteomic analysis.

Fig. S6 Earlier studies of proteomic abundance independently confirm a pattern of antagonistic pleiotropy.

Fig. S8 Western blotting of markers of protein synthesis and degradation.

Data S2 Spreadsheets relative abundance statistics and turnover statistics in the hepatic proteome.

Reactive oxygen species (ROS) are highly reactive oxygen-containing molecules associated with aging and a broad spectrum of pathologies. We have previously shown that transgenic expression of the antioxidant enzyme catalase targeted to the mitochondria (mCAT) in mice reduces ROS, attenuates age-related disease, and increases lifespan. However, it h...

Cardiovascular diseases are the leading cause of death for population over 65 years of age. With the progressive increase of population in this age group, it is crucial to understand the interaction between aging and cardiovascular diseases. Aging results in structural changes and functional decline of the cardiovascular system and is a major risk...

The mitochondrial respiratory chain (RC) produces most of the cellular ATP and requires strict quality-control mechanisms. To examine RC subunit proteostasis in vivo, we measured RC protein half-lives (HLs) in mice by liquid chromatography-tandem mass spectrometry with metabolic [(2)H3]-leucine heavy isotope labeling under divergent conditions. We...

Interstitial eosinophilic aggregates (IEA) in renal biopsies often suggest allergic tubulointerstitial nephritis, yet clear associations with drug reactions are often difficult to establish. IEA are also encountered in diabetic nephropathy (DN) and thought to be attributed to medication exposure. Native medical kidney biopsies performed at the Univ...

Calorie restriction (CR) and rapamycin (RP) extend lifespan and improve health across model organisms. Both treatments inhibit mammalian target of rapamycin (mTOR) signaling, a conserved longevity pathway and a key regulator of protein homeostasis, yet their effects on proteome homeostasis are relatively unknown. To comprehensively study the effect...

Cardiac aging is an intrinsic process that results in impaired cardiac function, along with cellular and molecular changes. These degenerative changes are intimately associated with quality control mechanisms. This review provides a general overview of the clinical and cellular changes which manifest in cardiac aging, and the quality control mechan...

Cardiovascular diseases are the leading causes of death in the western hemisphere. The exponential increases in the incidence and mortality rate of cardiovascular diseases in the elderly suggest that age per se is a major risk factor for cardiovascular diseases. The Framingham Heart Study and the Baltimore Longitudinal Study on Aging demonstrated t...

Background: We reported that inhibition of mechanistic target of rapamycin (mTOR) by short-term rapamycin or caloric restriction ameliorates age-dependent cardiac hypertrophy and diastolic dysfunction. Although inhibition of mTOR signaling is well known to regulate metabolism and suppress protein synthesis, the mechanisms of beneficial effect of mT...

Chronic right heart failure predisposes to hepatic passive congestion and centrizonal necrosis that may lead to hepatic fibrosis (cardiac sclerosis). Although there have been several studies on the histologic features of congestive hepatopathy, there is no available grading system. In this study we developed a novel grading system for congestive he...

The free radical theory of aging proposes that reactive oxygen species (ROS)-induced accumulation of damage to cellular macromolecules is a primary driving force of aging and a major determinant of lifespan. Although this theory is one of the most popular explanations for the cause of aging, several experimental rodent models of antioxidant manipul...

Fig. S1 Body weights of mice over the course of the experiment. Fig. S2 Topograph plot for turnover analysis. Fig. S3 mTOR Western. Fig. S4 Mitochondrial copy number and mitochondrial biogenesis markers did not increase with CR or RP. Fig. S5 Precursor pool increased over time in all experimental group. Fig. S6 Distribution of relative standard err...

Table S1 Slope of proteome dynamics (turnover) Table S2 (A) Pathway analysis of YCL versus OCL. (B) Pathway analysis of OCR versus OCL. (C) Pathway analysis of ORP versus OCL. Table S3 Protein abundance ratio (log2 of fold change) Table S4 Top pathway abundance ratio (for heat map) Table S5 Top pathway half-life ratios (for heat map) Table S6 Metab...

Method S1 Altered proteome turnover and remodeling by subacute caloric restriction and rapamycin rejuvenate the aging heart

-We investigated the protective effects of mitochondrial-targeted antioxidant and protective peptides, SS31 and SS20, on cardiac function, proteomic remodeling and signaling pathways. -We applied an improved label-free shotgun proteomics approach to evaluate the global proteomics changes in transverse aortic constriction (TAC) induced heart failure...

Lmna(-/-) mice display multiple tissue defects and die by 6-8 weeks of age reportedly from dilated cardiomyopathy with associated conduction defects. We sought to determine whether restoration of lamin A in cardiomyocytes improves cardiac function and extends the survival of Lmna(-/-) mice. We observed increased total desmin protein levels and diso...

Lmna+/+ and Lmna+/+; Tg hearts show no significant difference in cardiac function. (A & B) No significant difference is noted in (A) fractional shortening, (B) myocardial performance index (MPI), or (C) left ventricular mass index (LVMI) of Lmna+/+ and Lmna+/+; Tg hearts at 4–8 weeks of age as measured by echocardiography. Two-tailed unpaired t-tes...

Lmna−/− hearts are enlarged relative to control littermates and Lmna−/−; Tg hearts are not significantly improved. Left ventricular mass of 4–8 week old mice was measured and normalized to body weight to resolve the LVMI. One-way ANOVA was performed and significant genotype differences are listed for each panel. Bonferonni post-tests were performed...

Additional information and specifics on methods with supporting references. Further details include genotyping primers, qPCR primers, specific antibodies used for both immunofluorescence and Western blotting, details on image analysis, and animal techniques. (DOC)

mRNA levels of global remodeling markers, ANF and BNP, are enriched in Lmna−/− and Lmna−/−; Tg mice. qPCR of cardiac remodeling mRNA's for Lmna−/− and Lmna−/−; Tg hearts. Data are presented as fold-increase over Lmna+/+ hearts. Global cardiac remodeling mRNA's, ANF and BNP, are all increased in Lmna−/− hearts and are not significantly changed in Lm...

Dropped beat in Lmna+/+; Tg heart. An isolated case of a dropped heartbeat was noted in a single Lmna+/+; Tg heart during ECG recording which could reflect either a sinus pause or sino-atrial block. (TIF)

Average ECG parameters from 5–7 week old mice. ECG parameters of individual mice from Lmna+/+ and Lmna−/− mice either expressing or not expressing FLAG-lamin A in cardiomyocytes. Similar mouse genotypes are grouped together with mouse ID displayed and parameters are averaged. Each parameter from an individual mouse represents an averaged value from...

Defects in protein turnover have been implicated in a broad range of diseases, but current proteomics methods of measuring protein turnover are limited by the software tools available. Conventional methods require indirect approaches to differentiate newly synthesized protein when synthesized from partially labeled precursor pools. To address this,...

Mutations in LMNA, the gene that encodes A-type lamins, cause multiple diseases including dystrophies of the skeletal muscle and fat, dilated cardiomyopathy, and progeria-like syndromes (collectively termed laminopathies). Reduced A-type lamin function, however, is most commonly associated with skeletal muscle dystrophy and dilated cardiomyopathy r...

Old age is a major risk factor for cardiovascular diseases. Several lines of evidence in experimental animal models have indicated the central role of mitochondria both in lifespan determination and in cardiovascular aging. In this article we review the evidence supporting the role of mitochondrial oxidative stress, mitochondrial damage and biogene...