Joe Quadrilatero

University of Waterloo, Ватерлоо, Ontario, Canada

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Publications (55)196.17 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Previous research suggests that when the magnitude of peak compressive force applied during cyclic loading exceeds 30% of a functional spinal unit's estimated ultimate compressive tolerance, fatigue failure of the cartilaginous endplate or vertebra will occur before intervertebral disc herniation. Three levels of peak compressive force, three cycle rates and two dynamic postural conditions were examined using a full-factorial design. Cyclic compressive force was applied using a modified material testing apparatus, in accordance with a biofidelic time-varying waveform with synchronous flexion/extension rotation for 5000 cycles. Annulus fibrosus tissue from 36 "survivor" FSUs was excised for histological analysis. 80% of specimens survived 5000 cycles of cyclic loading. A marked difference of the magnitude of peak compressive force was noted in the Kaplan-Meier survival function of experimental conditions that induced fatigue injury. Overall, in the 40% ultimate compressive tolerance load condition, the probability of survival was less than 67%. The micro-structural damage detected in excised samples of annulus fibrosus tissue consisted of clefts and fissures within the intra-lamellar matrix, as well as delamination within the inter-lamellar matrix. Consistent with previous research, our findings support a threshold of peak compressive force of 30% ultimate compressive tolerance, where cyclic loading above this level will likely result in fatigue injury in less than 5000 cycles of in vitro mechanical loading. However, findings from our histological analyses demonstrate that considerable micro-structural damage occurred in specimens that "survived" the cyclic loading exposure. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Clinical biomechanics (Bristol, Avon) 07/2015; DOI:10.1016/j.clinbiomech.2015.07.003 · 1.88 Impact Factor
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    ABSTRACT: Reactive oxygen species (ROS) have been linked to a wide variety of pathologies, including obesity and diabetes, but ROS also act as endogenous signalling molecules, regulating numerous biological processes. DJ-1 is one of the most evolutionarily conserved proteins across species, and mutations in DJ-1 have been linked to some cases of Parkinson's disease. Here we show that DJ-1 maintains cellular metabolic homeostasis via modulating ROS levels in murine skeletal muscles, revealing a role of DJ-1 in maintaining efficient fuel utilization. We demonstrate that, in the absence of DJ-1, ROS uncouple mitochondrial respiration and activate AMP-activated protein kinase, which triggers Warburg-like metabolic reprogramming in muscle cells. Accordingly, DJ-1 knockout mice exhibit higher energy expenditure and are protected from obesity, insulin resistance and diabetes in the setting of fuel surplus. Our data suggest that promoting mitochondrial uncoupling may be a potential strategy for the treatment of obesity-associated metabolic disorders.
    Nature Communications 06/2015; 6:7415. DOI:10.1038/ncomms8415 · 10.74 Impact Factor
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    ABSTRACT: Treatment regimens for acute myeloid leukemia (AML) continue to offer weak clinical outcomes. Through a high-throughput cell-based screen, we identified avocatin B, a lipid derived from avocado fruit, as a novel compound with cytotoxic activity in AML. Avocatin B reduced human primary AML cell viability without effect on normal peripheral blood stem cells. Functional stem cell assays demonstrated selectivity toward AML progenitor and stem cells without effects on normal hematopoietic stem cells. Mechanistic investigations indicated that cytotoxicity relied on mitochondrial localization, as cells lacking functional mitochondria or CPT1, the enzyme that facilitates mitochondria lipid transport, were insensitive to avocatin B. Furthermore, avocatin B inhibited fatty acid oxidation and decreased NADPH levels, resulting in ROS-dependent leukemia cell death characterized by the release of mitochondrial proteins, apoptosis-inducing factor, and cytochrome c. This study reveals a novel strategy for selective leukemia cell eradication based on a specific difference in mitochondrial function. Cancer Res; 75(12); 2478-88. ©2015 AACR. ©2015 American Association for Cancer Research.
    Cancer Research 06/2015; 75(12):2478-88. DOI:10.1158/0008-5472.CAN-14-2676 · 9.28 Impact Factor
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    ABSTRACT: Centronuclear myopathy (CNM) is a congenital myopathy that is histopathologically characterized by centrally located nuclei, central aggregation of oxidative activity, and type I fibre predominance and hypotrophy. Here, we obtained commercially available mice overexpressing phospholamban (Pln(OE)), a well-known inhibitor of sarco(endo)plasmic reticulum Ca(2+)-ATPases (SERCAs), in their slow-twitch type I skeletal muscle fibres to determine the effects on SERCA function. As expected with a 6-7-fold overexpression of PLN, SERCA dysfunction was evident in Pln(OE) muscles with marked reductions in rates of Ca(2+) uptake, maximal ATPase activity and the apparent affinity of SERCA for Ca(2+). However, our most significant discovery was that the soleus and gluteus minimus muscles from the Pln(OE) mice displayed overt signs of myopathy histopathologically resembling human CNM with centrally located nuclei, central aggregation of oxidative activity, type I fibre predominance and hypotrophy, progressive fibrosis, and muscle weakness, a phenotype that is associated with significant up-regulation of muscle sarcolipin and dynamin 2 content, increased Ca(2+)-activated proteolysis, oxidative stress, and protein nitrosylation. Moreover, in our assessment of muscle biopsies from three human CNM patients, we found a significant 53% reduction in SERCA activity and trending increases in both total and monomeric PLN content compared to five healthy subjects, thereby justifying future studies with more CNM patients. Altogether our results suggest that the commercially available Pln(OE) mouse represents a novel mouse model phenotypically resembling human CNM and may be used to test potential mechanisms and therapeutic strategies. To date there is no cure for CNM and our results suggest that targeting SERCA function, which has already been shown to be an effective therapeutic target for murine muscular dystrophy and human cardiomyopathy, may represent a novel therapeutic strategy to combat CNM. © 2015. Published by The Company of Biologists Ltd.
    Disease Models and Mechanisms 05/2015; DOI:10.1242/dmm.020859 · 5.54 Impact Factor
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    ABSTRACT: Skeletal muscle is extremely adaptable to a variety of metabolic challenges, as both traditional moderate intensity endurance (ET) and high intensity interval training (HIIT) increase oxidative potential in a coordinated manner. While these responses have been clearly demonstrated in healthy individuals, it remains to be determined if both produce similar responses in the context of hypertension, one of the most prevalent and costly diseases worldwide. Therefore, in the current study we utilized the Dahl sodium sensitive rat, a model of hypertension, to determine the molecular responses to 4 weeks of either ET or HIIT in the red (RG) and white gastrocnemius (WG) muscles. In the RG, both ET and HIIT increased the content of electron transport chain proteins and increased succinate dehydrogenase (SDH) content in type I fibres. While both intensities of exercise shifted fibre type in RG (increased IIA, decreased IIX), only HIIT was associated with a reduction in eNOS and an increase in HIF1α proteins. In the WG, both ET and HIIT increased markers of the electron transport chain, however, HIIT decreased SDH content in a fibre-specific manner. ET increased type IIA, decreased IIB fibres and increased capillarization, in contrast HIIT increased the percentage of IIB fibres, decreased capillary to fibre ratios, decreased eNOS, and increased HIF1α protein. Altogether, these data show that unlike in healthy animals, ET and HIIT have divergent effects in the skeletal muscle of hypertensive rats. This suggests ET may be optimal at improving the oxidative capacity of skeletal muscle in animals with hypertension. Copyright © 2015, American Journal of Physiology - Regulatory, Integrative and Comparative Physiology.
    AJP Regulatory Integrative and Comparative Physiology 04/2015; 308(11):ajpregu.00048.2015. DOI:10.1152/ajpregu.00048.2015 · 3.53 Impact Factor
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    ABSTRACT: There has been re-emerging interest and significant work dedicated to investigating the metabolic effects of high intensity interval training (HIIT) in recent years. HIIT is considered to be a time efficient alternative to classic endurance training (ET) that elicits similar metabolic responses in skeletal muscle. However, there is a lack of information on the impact of HIIT on cardiac muscle in disease. Therefore, we determined the efficacy of ET and HIIT to alter cardiac muscle characteristics involved in the development of diastolic dysfunction, such as ventricular hypertrophy, fibrosis and angiogenesis, in a well-established rodent model of hypertension-induced heart failure before the development of overt heart failure. ET decreased left ventricle fibrosis by ~40% (P < 0.05), and promoted a 20% (P<0.05) increase in the left ventricular capillary/fibre ratio, an increase in endothelial nitric oxide synthase protein (P<0.05), and a decrease in hypoxia inducible factor 1 alpha protein content (P<0.05). In contrast, HIIT did not decrease existing fibrosis, and HIIT animals displayed a 20% increase in left ventricular mass (P<0.05) and a 20% decrease in cross sectional area (P<0.05). HIIT also increased brain natriuretic peptide by 50% (P<0.05), in the absence of concomitant angiogenesis, strongly suggesting pathological cardiac remodeling. The current data support the longstanding belief in the effectiveness of ET in hypertension. However, HIIT promoted a pathological adaptation in the left ventricle in the presence of hypertension, highlighting the need for further research on the widespread effects of HIIT in the presence of disease.
    PLoS ONE 03/2015; 10(3):e0121138. DOI:10.1371/journal.pone.0121138 · 3.23 Impact Factor
  • PLoS ONE 03/2015; 10(3):e0119382. DOI:10.1371/journal.pone.0119382 · 3.23 Impact Factor
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    ABSTRACT: Apoptotic signaling plays an important role in the development and maintenance of healthy skeletal muscle. However, dysregulation of apoptotic signals in skeletal muscle is associated with atrophy and loss of function. Apoptosis repressor with caspase recruitment domain (ARC) is a potent anti-apoptotic protein that is highly expressed in skeletal muscle; however, its role in this tissue has yet to be elucidated. To investigate whether ARC deficiency has morphological, functional, and apoptotic consequences, skeletal muscle from 18 week-old wild-type and ARC knockout (KO) mice was studied. In red muscle (soleus), we found lower maximum tetanic force, as well as a shift towards a greater proportion of type II fibers in ARC KO mice. Furthermore, the soleus of ARC KO mice exhibited lower total, as well as fiber type-specific cross sectional area in type I and IIA fibers. Interestingly, these changes in ARC KO mice corresponded with increased DNA fragmentation, albeit independent of caspase or calpain activation. However, cytosolic fractions of red muscle from ARC KO mice had higher apoptosis inducing factor content, suggesting increased mitochondrial-mediated, caspase-independent apoptotic signaling. This was confirmed in isolated mitochondrial preparations, as mitochondria from skeletal muscle of ARC KO mice were more susceptible to calcium stress. Interestingly, white muscle from ARC KO mice showed no signs of altered apoptotic signaling or detrimental morphological differences. Results from this study suggest that even under basal conditions ARC influences muscle apoptotic signaling, phenotype, and function, particularly in slow and/or oxidative muscle.
    APOPTOSIS 01/2015; 20(3). DOI:10.1007/s10495-014-1078-9 · 3.61 Impact Factor
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    ABSTRACT: Apoptosis and autophagy are critical in normal skeletal muscle homeostasis; however, dysregulation can lead to muscle atrophy and dysfunction. Lipotoxicity and/or lipid accumulation may promote apoptosis, as well as directly or indirectly influence autophagic signaling. Therefore, the purpose of this study was to examine the effect of a 16-week high-fat diet on morphological, apoptotic, and autophagic indices in oxidative and glycolytic skeletal muscle of female rats. High-fat feeding resulted in increased fat pad mass, altered glucose tolerance, and lower muscle pAKT levels, as well as lipid accumulation and reactive oxygen species generation in soleus muscle; however, muscle weights, fiber type-specific cross-sectional area, and fiber type distribution were not affected. Moreover, DNA fragmentation and LC3 lipidation as well as several apoptotic (ARC, Bax, Bid, tBid, Hsp70, pBcl-2) and autophagic (ATG7, ATG4B, Beclin 1, BNIP3, p70 s6k, cathepsin activity) indices were not altered in soleus or plantaris following high-fat diet. Interestingly, soleus muscle displayed small increases in caspase-3, caspase-8, and caspase-9 activity, as well as higher ATG12-5 and p62 protein, while both soleus and plantaris muscle showed dramatically reduced Bcl-2 and X-linked inhibitor of apoptosis protein (XIAP) levels. In conclusion, this work demonstrates that 16 weeks of high-fat feeding does not affect tissue morphology or induce a global autophagic or apoptotic phenotype in skeletal muscle of female rats. However, high-fat feeding selectively influenced a number of apoptotic and autophagic indices which could have implications during periods of enhanced muscle stress.
    Experimental Biology and Medicine 10/2014; 240(5). DOI:10.1177/1535370214557223 · 2.23 Impact Factor
  • Darin Bloemberg · Joe Quadrilatero
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    ABSTRACT: Skeletal muscle differentiation requires activity of the apoptotic protease caspase-3. We attempted to identify the source of caspase activation in differentiating C2C12 skeletal myoblasts. In addition to caspase-3, caspase-2 was transiently activated during differentiation; however, no changes were observed in caspase-8 or -9 activity. Although mitochondrial Bax increased, this was matched by Bcl-2, resulting in no change to the mitochondrial Bax:Bcl-2 ratio early during differentiation. Interestingly, mitochondrial membrane potential increased on a timeline similar to caspase activation and was accompanied by an immediate, temporary reduction in cytosolic Smac and cytochrome c. Since XIAP protein expression dramatically declined during myogenesis, we investigated whether this contributes to caspase-3 activation. Despite reducing caspase-3 activity by up to 57%, differentiation was unaffected in cells overexpressing normal or E3-mutant XIAP. Furthermore, a XIAP mutant which can inhibit caspase-9 but not caspase-3 did not reduce caspase-3 activity or affect differentiation. Administering a chemical caspase-3 inhibitor demonstrated that complete enzyme inhibition was required to impair myogenesis. These results suggest neither mitochondrial apoptotic signaling nor XIAP degradation is responsible for transient caspase-3 activation during C2C12 differentiation.
    Biochimica et Biophysica Acta (BBA) - Molecular Cell Research 09/2014; 1843(12). DOI:10.1016/j.bbamcr.2014.09.002 · 5.30 Impact Factor
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    ABSTRACT: The present study examined the effect of concurrent exercise training and daily resveratrol (RSV) supplementation (150 mg) on training-induced adaptations following low-dose high-intensity interval training (HIIT). Sixteen recreationally active (∼22 years, ∼51 mL·kg(-1)·min(-1)) men were randomly assigned in a double-blind fashion to either the RSV or placebo group with both groups performing 4 weeks of HIIT 3 days per week. Before and after training, participants had a resting muscle biopsy taken, completed a peak oxygen uptake test, a Wingate test, and a submaximal exercise test. A main effect of training (p < 0.05) and interaction effect (p < 0.05) on peak aerobic power was observed; post hoc pairwise comparisons revealed that a significant (p < 0.05) increase occurred in the placebo group only. Main effects of training (p < 0.05) were observed for both peak oxygen uptake (placebo - pretraining: 51.3 ± 1.8, post-training: 54.5 ± 1.5 mL·kg(-1)·min(-1), effect size (ES) = 0.93; RSV - pretraining: 49.6 ± 2.2, post-training: 52.3 ± 2.5 mL·kg(-1)·min(-1), ES = 0.50) and Wingate peak power (placebo: pretraining: 747 ± 39, post-training: 809 ± 31 W, ES = 0.84; RSV - pretraining: 679 ± 39, post-training: 691 ± 43 W, ES = 0.12). Fibre-type distribution was unchanged, while a main effect of training (p < 0.05) was observed for succinate dehydrogenase activity and glycogen content, but not α-glycerophosphate dehydrogenase activity or intramuscular lipids in type I and IIA fibres. The fold change in PGC-1α, SIRT1, and SOD2 gene expression following training was significantly (p < 0.05) lower in the RSV group than placebo. These results suggest that concurrent exercise training and RSV supplementation may alter the normal training response induced by low-volume HIIT.
    Applied Physiology Nutrition and Metabolism 07/2014; 39(11):1-9. DOI:10.1139/apnm-2014-0070 · 2.23 Impact Factor
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    ABSTRACT: The current study involved the completion of two distinct experiments. Experiment 1 compared fibre specific and whole muscle responses to acute bouts of either low-volume high-intensity interval training (LV-HIT) or moderate-intensity continuous endurance exercise (END) in a randomized crossover design. Experiment 2 examined the impact of a six-week training intervention (END or LV-HIT; 4 days/week), on whole body and skeletal muscle fibre specific markers of aerobic and anaerobic capacity. Six recreationally active men (Age: 20.7±3.8 yrs; VO2peak: 51.9±5.1 mL/kg/min) reported to the lab on two separate occasions for experiment 1. Following a muscle biopsy taken in a fasted state, participants completed an acute bout of each exercise protocol (LV-HIT: 8, 20-second intervals at ∼170% of VO2peak separated by 10 seconds of rest; END: 30 minutes at ∼65% of VO2peak), immediately followed by a muscle biopsy. Glycogen content of type I and IIA fibres was significantly (p<0.05) reduced, while p-ACC was significantly increased (p<0.05) following both protocols. Nineteen recreationally active males (n = 16) and females (n = 3) were VO2peak-matched and assigned to either the LV-HIT (n = 10; 21±2 yrs) or END (n = 9; 20.7±3.8 yrs) group for experiment 2. After 6 weeks, both training protocols induced comparable increases in aerobic capacity (END: Pre: 48.3±6.0, Mid: 51.8±6.0, Post: 55.0±6.3 mL/kg/min LV-HIT: Pre: 47.9±8.1, Mid: 50.4±7.4, Post: 54.7±7.6 mL/kg/min), fibre-type specific oxidative and glycolytic capacity, glycogen and IMTG stores, and whole-muscle capillary density. Interestingly, only LV-HIT induced greater improvements in anaerobic performance and estimated whole-muscle glycolytic capacity. These results suggest that 30 minutes of END exercise at ∼65% VO2peak or 4 minutes of LV-HIT at ∼170% VO2peak induce comparable changes in the intra-myocellular environment (glycogen content and signaling activation); correspondingly, training-induced adaptations resulting for these protocols, and other HIT and END protocols are strikingly similar.
    PLoS ONE 06/2014; 9(6):e98119. DOI:10.1371/journal.pone.0098119 · 3.23 Impact Factor
  • Elliott M McMillan · Joe Quadrilatero
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    ABSTRACT: Several degradative systems assist in formation of multinucleated, terminally differentiated myotubes. However, the role of autophagy in this process has not been examined. GFP-LC3B puncta, LC3B-II protein, and LysoTracker fluorescence increased during C2C12 differentiation. Importantly, accumulation of LC3B-II protein occurred in chloroquine (CQ) treated cells throughout differentiation. Furthermore, BECN1, ATG7, and ATG12-5 protein increased, while SQSTM1/p62 protein was rapidly reduced during differentiation. A transient decrease in BECN1:BCL2 association was observed from D0.5 to D2 of differentiation. Chemical inhibition of JNK during differentiation reduced LC3B-II protein and GFP-LC3B puncta, and maintained BECN1:BCL2 association. Inhibition of autophagy by 3MA or shRNA against Atg7 (shAtg7) resulted in lower myosin heavy chain expression, as well as impaired myoblast fusion and differentiation. Interestingly, 3MA treatment during differentiation increased transient CASP3 activation, DNA fragmentation, and the percentage of apoptotic nuclei. Similarly, shAtg7 cells had increased DNA fragmentation during differentiation compared to controls. Collectively, these data demonstrate that autophagy increases and is required during myoblast differentiation. Moreover, autophagy protects differentiating myoblast from apoptotic cell death.
    Biochemical Journal 05/2014; 462(2). DOI:10.1042/BJ20140312 · 4.78 Impact Factor
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    ABSTRACT: AimThe purpose of this study was to determine whether 17β-Estradiol (E2) enhances the activation, proliferation and differentiation of muscle satellite cells (SC) following eccentric exercise either via Insulin-like Growth Factor-1 (IGF-1) or through phosphatidylinositol 3-kinase (PI3K) signaling.Methods This study used 64, nine-week old, ovariectomized Sprague-Dawley rats that were divided into eight treatments groups based on: estrogen status (0.25 mg estrogen pellet or sham), exercise status (90 min run @ 17 m/min, -13.5° or unexercised), PI3K signaling inhibition (0.7 mg Wortmannin·kg−1 Body Weight or DMSO control).ResultsSignificant increases in total SCs were found in both soleus and white gastrocnemius muscles (immunofluorescent co-localization of Pax7+ nuclei) 72 hr following eccentric exercise (p < 0.05). Estrogen-supplementation caused a further enhancement in total SCs in exercised rats (p < 0.05). In animals where the PI3K pathway was inhibited, regardless of estrogen or exercise status, there was no significant enhancement of SC number in both the soleus or white gastrocnemius muscles. Interestingly, estrogen-supplementation lowered muscle levels of IGF-1 with this effect being most prominent in the soleus muscle. While IGF-1 was increased following exercise (p < 0.05), estrogen-supplementation abrogated this increase back to sedentary levels.Conclusion This data suggests that the increase in SC population following exercise in estrogen-supplemented females may be mediated via PI3K pathway signaling and not IGF-1.This article is protected by copyright. All rights reserved.
    Acta Physiologica 05/2014; 212(1). DOI:10.1111/apha.12317 · 4.25 Impact Factor
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    ABSTRACT: To identify novel anti-cancer agents, we created and screened a unique nutraceutical library for activity against acute myeloid leukemia (AML) cells. From this screen, we determined that glucopsychosine was selectively toxic toward AML cell lines and primary AML patient samples with no effect toward normal hematopoietic cells. It delayed tumor growth and reduced tumor weights in mouse xenografts models without imparting toxicity. Glucopsychosine increased cytosolic calcium and induced apoptosis through calpain enzymes. Extracellular calcium was functionally important for glucopsychosine-induced AML cell death and surface calcium channel expression is altered in AML cells highlighting a unique mechanism of glucopsychosine's selectivity.
    Cancer letters 03/2014; 348(1-2). DOI:10.1016/j.canlet.2014.03.003 · 5.62 Impact Factor
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    ABSTRACT: Neuroinflammation is a component of age-related neurodegenerative diseases and cognitive decline. Saturated (SFA) and monounsaturated (MUFA) fatty acids are bioactive molecules that may play different extrinsic and intrinsic roles in neuroinflammation, serving as exogenous ligands for cellular receptors, or endogenous components of cell structural, energetic and signaling pathways. We determined the fatty acyl profile of BV2 microglial cells before and after acute activation with lipopolysaccharide (LPS). We also investigated the effect of SFA and MUFA pretreatment on the production of an invasive, neurotoxic phenotype in BV2 cells. Acute activation of BV2 microglia resulted in an increase in the relative content of SFA (12:0, 16:0, 18:0, 20:0, 22:0, and 24:0 increased significantly), and a relative decrease in the content of MUFA (16:1n7, 18:1n7, 18:1n9, 20:1n9, 24:1n9 decreased significantly). In agreement, the major stearoyl-CoA desaturase (SCD) isoform in BV2 cells, SCD2, was significantly down-regulated by LPS. We next treated cells with SFA (16:0 or 18:0) or MUFA (16:1n7 or 18:1n9), and found that levels of secreted IL6 were increased, as was secreted MMP9-mediated proteolytic activity. To test the functional significance, we treated SH-SY5Y neuronal cells with conditioned medium from BV2 cells pretreated with fatty acids, and found a small but significant induction of cell death. Our findings suggest differential intrinsic roles for SFA and MUFA in activated microglial cells, but similar extrinsic roles for these fatty acid species in inducing activation. Expansion of SFA is important during microglial cell activation, but either supplemental SFA or MUFA may contribute to chronic low-grade neuroinflammation.
    Lipids 01/2014; DOI:10.1007/s11745-014-3882-y · 2.35 Impact Factor
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    ABSTRACT: Sarcolipin (SLN) and phospholamban (PLN) inhibit the activity of sarco(endo)plasmic reticulum Ca(2+)-ATPases (SERCAs) by reducing their apparent affinity for Ca(2+). A ternary complex between SLN, PLN, and SERCAs results in super-inhibition of SERCA activity. Analysis of skeletal muscle homogenate has limited our current understanding of whether SLN and PLN regulate SERCA1a, SERCA2a, or both in skeletal muscle and whether SLN and PLN are co-expressed in skeletal muscle fibers. Biopsies from human vastus lateralis were analyzed through single fiber Western blotting and immunohisto/fluorescence staining to circumvent this limitation. With a newly generated SLN antibody, we report for the first time that SLN protein is present in human skeletal muscle. Addition of the SLN antibody (50 µg) to vastus lateralis homogenates increased the apparent Ca(2+) affinity of SERCA (K Ca, pCa units) (-Ab, 5.85 ± 0.02 vs. +Ab, 5.95 ± 0.02) and maximal SERCA activity (μmol/g protein/min) (-Ab, 122 ± 6.4 vs. +Ab, 159 ± 11) demonstrating a functional interaction between SLN and SERCAs in human vastus lateralis. Specifically, our results suggest that although SLN and PLN may preferentially regulate SERCA1a, and SERCA2a, respectively, physiologically they both may regulate either SERCA isoform. Furthermore, we show that SLN and PLN co-immunoprecipitate in human vastus lateralis homogenate and are simultaneously expressed in 81% of the fibers analyzed with Western blotting which implies that super-inhibition of SERCA may exist in human skeletal muscle. Finally, we demonstrate unequivocally that mouse soleus contains PLN protein suggesting that super-inhibition of SERCA may also be important physiologically in rodent skeletal muscle.
    PLoS ONE 12/2013; 8(12):e84304. DOI:10.1371/journal.pone.0084304 · 3.23 Impact Factor
  • 2013 CSEP Extreme Human Physiology: Pathology to Performance; 10/2013
  • Darin Bloemberg · Evan McDonald · Dhanbir Dulay · Joe Quadrilatero
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    ABSTRACT: Autophagy is a subcellular degradation mechanism important for muscle maintenance. Hypertension induces well-characterized pathological changes to the heart and is associated with impaired function and increased apoptotic signalling in skeletal muscle. We examined whether essential hypertension affects several autophagy markers in skeletal and cardiac muscle. Immunoblotting and qRT-PCR were used to measure autophagy-related proteins/mRNA in multiple skeletal muscles as well as left ventricle (LV) of spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY). SHR skeletal muscles had decreased (p<0.01) cross sectional area of type I fibers (e.g., soleus WKY: 2952.9±64.4μm(2) vs SHR: 2579.9±85.8μm(2) ) and a fiber redistribution towards a "fast" phenotype. Immunoblot analysis revealed some SHR skeletal muscles displayed a decreased LC3II/I ratio (p<0.05), but none showed differences in p62 protein. LC3 and LAMP2 mRNA levels were increased approximately 2-3-fold in all skeletal muscles (p<0.05), while cathepsin activity, cathepsin L mRNA, and Atg7 protein were increased 16-17% (p<0.01), 2-3-fold (p<0.05), and 29-49% (p<0.01), respectively, in fast muscles of hypertensive animals. Finally, protein levels of BAG3, a marker of chaperone-assisted selective autophagy, were 18-25% lower (p<0.05) in SHR skeletal muscles. In the LV of SHR, LC3I and p62 protein were elevated 34% (p<0.05) and 47% (p<0.01), respectively. Furthermore, p62 mRNA was 68% higher (p<0.05) while LAMP2 mRNA was 45% lower (p<0.05) in SHR cardiac muscle. There was no difference in Beclin1, Atg7, Bnip3, or BAG3 protein in the LV between strains. These results suggest autophagy is altered in skeletal and cardiac muscle during hypertension. This article is protected by copyright. All rights reserved.
    Acta Physiologica 10/2013; 210(2). DOI:10.1111/apha.12178 · 4.25 Impact Factor
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    ABSTRACT: We examined the influence of estrogen receptor-alpha (ERα) activation on estrogen-mediated regulation of heat shock proteins 70 (Hsp70) and 27 (Hsp27) in soleus. Ovariectomized rats received estrogen (EST), an ERα agonist (propyl pyrazole triol, PPT), both (EST+PPT), or a sham, and they served as either unexercised controls or were subjected to exercise by having to run downhill (17 m/min, -13.5° grade) for 90 min. At 72 h postexercise, soleus muscles were removed and either immunohistochemically stained for Hsp70 and myosin heavy chain or homogenized for Western blotting for Hsp70 and Hsp27. Elevated (p < 0.05) basal Hsp70 in both type I and II fibres in the unexercised EST, PPT, and EST+PPT groups relative to unexercised sham animals was noted. Compared with Hsp70 levels in the unexercised animals, that in exercised animals was elevated (p < 0.05) in both sham and PPT groups but not in EST and EST+PPT groups. Western blot determined that Hsp27 levels were not significantly different between groups. Hence, the ability of estrogen to augment resting type I and type II muscle fibre Hsp70 content is primarily mediated via muscle ERα. However, the blunted Hsp70 response following damaging exercise in estrogen-supplemented animals does not appear to be fully accounted for by ERα-mediated effects.
    Canadian Journal of Physiology and Pharmacology 10/2013; 91(10):823-29. DOI:10.1139/cjpp-2013-0037 · 1.55 Impact Factor