scholarly journals Long-Term Exercise Reduces Formation of Tubular Aggregates and Promotes Maintenance of Ca2+ Entry Units in Aged Muscle

2021 ◽  
Vol 11 ◽  
Author(s):  
Simona Boncompagni ◽  
Claudia Pecorai ◽  
Antonio Michelucci ◽  
Laura Pietrangelo ◽  
Feliciano Protasi
Keyword(s):  
Ex Vivo ◽  
Wild Type ◽  
Tubular Aggregates ◽  
Male Adult ◽  
Muscular Disease ◽  
Wild Type Male ◽  
Intracellular Ca ◽  
Fast Twitch ◽  
Old Mice

Tubular aggregates (TAs) in skeletal muscle fibers are unusual accumulation of sarcoplasmic reticulum (SR) tubes that are found in different disorders including TA myopathy (TAM). TAM is a muscular disease characterized by muscle pain, cramping, and weakness that has been recently linked to mutations in STIM1 and ORAI1. STIM1 and ORAI1 are the two main proteins mediating store-operated Ca2+ entry (SOCE), a mechanism activated by depletion of intracellular Ca2+ stores (e.g., SR) that allows recovery of Ca2+ from the extracellular space during repetitive muscle activity. We have recently shown that exercise triggers the formation of unique intracellular junctions between SR and transverse tubules named Ca2+entry units (CEUs). CEUs promote colocalization of STIM1 with ORAI1 and improve muscle function in presence of external Ca2+. TAs virtually identical to those of TAM patients are also found in fast-twitch fibers of aging male mice. Here, we used a combination of electron and confocal microscopy, Western blotting, and ex vivo stimulation protocols (in presence or absence of external Ca2+) to evaluate the presence of TAs, STIM1-ORAI1 localization and expression and fatigue resistance of intact extensor digitorum longus (EDL) muscles in wild-type male adult (4-month-old) and aged (24-month-old) mice and in mice trained in wheel cages for 15 months (from 9 to 24 months of age). The results collected indicate that (i) aging causes STIM1 and ORAI1 to accumulate in TAs and (ii) long-term exercise significantly reduced formation of TAs. In addition, (iii) EDL muscles from aged mice exhibited a faster decay of contractile force than adult muscles, likely caused by their inability to refill intracellular Ca2+ stores, and (iv) exercise in wheel cages restored the capability of aged EDL muscles to use external Ca2+ by promoting maintenance of CEUs. In conclusion, exercise prevented improper accumulation of STIM1 and ORAI1 in TAs during aging, maintaining the capability of aged muscle to refill intracellular Ca2+ stores via SOCE.

Increased susceptibility to fatigue of slow- and fast-twitch muscles from mice lacking the MG29 gene

2000 ◽  
Vol 4 (1) ◽  
pp. 43-49 ◽  
Author(s):  
RAMAKRISHNAN Y. NAGARAJ ◽  
CHRISTOPHER M. NOSEK ◽  
MARCO A. P. BROTTO ◽  
MIYUKI NISHI ◽  
HIROSHI TAKESHIMA ◽  
...  
Keyword(s):  
Major Protein ◽  
Force Frequency ◽  
Wild Type ◽  
Membrane Structures ◽  
Intracellular Ca ◽  
Slow Twitch Muscle ◽  
Fast Twitch Muscle ◽  
Frequency Relationship ◽  
Fast Twitch

Mitsugumin 29 (MG29), a major protein component of the triad junction in skeletal muscle, has been identified to play roles in the formation of precise junctional membrane structures important for efficient signal conversion in excitation-contraction (E-C) coupling. We carried out several experiments to not only study the role of MG29 in normal muscle contraction but also to determine its role in muscle fatigue. We compared the in vitro contractile properties of three muscles types, extensor digitorum longus (EDL) (fast-twitch muscle), soleus (SOL) (slow-twitch muscle), and diaphragm (DPH) (mixed-fiber muscle), isolated from mice lacking the MG29 gene and wild-type mice prior to and after fatigue. Our results indicate that the mutant EDL and SOL muscles, but not DPH, are more susceptible to fatigue than the wild-type muscles. The mutant muscles not only fatigued to a greater extent but also recovered significantly less than the wild-type muscles. Following fatigue, the mutant EDL and SOL muscles produced lower twitch forces than the wild-type muscles; in addition, fatiguing produced a downward shift in the force-frequency relationship in the mutant mice compared with the wild-type controls. Our results indicate that fatiguing affects the E-C components of the mutant EDL and SOL muscles, and the effect of fatigue in these mutant muscles could be primarily due to an alteration in the intracellular Ca homeostasis.

scholarly journals Long-term blood pressure lowering and cGMP-activating actions of the novel ANP analog MANP

2020 ◽  
Vol 318 (4) ◽  
pp. R669-R676 ◽  
Author(s):  
Yang Chen ◽  
Jacob J. Schaefer ◽  
Seethalakshmi R. Iyer ◽  
Gerald E. Harders ◽  
Shuchong Pan ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Subcutaneous Injection ◽  
Ex Vivo ◽  
Subcutaneous Administration ◽  
Therapeutic Drug ◽  
Hypertensive Rats ◽  
Pressure Lowering ◽  
Intracellular Ca ◽  
Isolated Arteries

Based on the cardiac hormone atrial natriuretic peptide (ANP) and its seminal role in blood pressure (BP) homeostasis, we investigated the chronic BP lowering actions of a novel ANP analog currently entering clinical trials for hypertension. Previous reports demonstrate that this analog MANP activates the guanylyl cyclase A receptor (GC-A) and results in more potent biological actions compared with ANP; thus, it may represent a new therapeutic drug for hypertension. A major goal of this study was to establish that chronic subcutaneous delivery of MANP is feasible and hypotensive together with cGMP effects. We investigated the BP-lowering and cGMP-activating actions of acute and chronic subcutaneous delivery in normal and hypertensive rats. Furthermore, we explored vascular mechanisms of MANP in human aortic smooth muscle cells (HASMC) and ex vivo in isolated arteries. In normal rats with a single subcutaneous injection, MANP promoted robust dose-dependent BP-lowering actions and natriuresis, together with cGMP activation. Most importantly in hypertensive rats, once-a-day subcutaneous injection of MANP for 7 days induced cGMP elevation and long-term BP reduction compared with vehicle. Mechanistically, in HASMC, MANP activated cGMP and attenuated angiotensin II-mediated increases in intracellular Ca2+ levels while directly vasorelaxing arterial rings. Our study demonstrates for the first time the effectiveness of subcutaneous administration of MANP for 7 days and provides innovative, vascular mechanisms of BP regulation supporting its continued development as a novel therapeutic for hypertension.

scholarly journals Protective effect of extracellular superoxide dismutase on endothelial function during aging

2009 ◽  
Vol 296 (6) ◽  
pp. H1920-H1925 ◽  
Author(s):  
Donald D. Lund ◽  
Yi Chu ◽  
Jordan D. Miller ◽  
Donald D. Heistad
Keyword(s):  
Superoxide Dismutase ◽  
Endothelial Dysfunction ◽  
Endothelial Function ◽  
Ex Vivo ◽  
Vascular Dysfunction ◽  
Extracellular Superoxide Dismutase ◽  
Mrna Levels ◽  
Wild Type ◽  
Vasomotor Function ◽  
Old Mice

Endothelial vasomotor function decreases with increasing age. Extracellular superoxide dismutase (ecSOD) protects against vascular dysfunction in several disease states. The purpose of this study was to determine whether endogenous ecSOD protects against endothelial dysfunction in old mice. Vasomotor function of the aorta was studied ex vivo in wild-type (ecSOD+/+) and ecSOD-deficient (ecSOD−/−) mice at 11 (adult) and 29 (old) mo of age. Maximal relaxation to acetylcholine (10−4 M) was impaired in vessels from adult ecSOD−/− mice [75 ± 3% (mean ± SE)] compared with wild-type mice (89 ± 2%, P < 0.05). Maximal relaxation to acetylcholine (10−4 M) was profoundly impaired in aorta from old ecSOD−/− mice (45 ± 5%) compared with wild-type mice (75 ± 4%, P < 0.05). There was a significant correlation between expression of ecSOD and maximal relaxation to acetylcholine in adult and old mice. Tempol (1 mM), a scavenger of superoxide, improved relaxation in response to acetylcholine (63 ± 8%) in old ecSOD−/− mice ( P < 0.05), but not wild-type mice (75 ± 4%). Maximal relaxation to sodium nitroprusside was similar in aorta from adult and old wild-type and ecSOD−/− mice. Quantitative RT-PCR showed a decrease in mRNA levels of ecSOD and catalase in aorta of old mice and an increase in levels of TNFα and Nox-4 in aorta of old mice compared with adult mice. The findings support the hypothesis that impaired antioxidant mechanisms may contribute to cumulative increases in oxidative stress and impaired endothelial function in old mice. In conclusion, endogenous ecSOD plays an important role in protection against endothelial dysfunction during aging.

scholarly journals Peri-adolescent THC exposure does not lead to anxiety-like behavior in adult mice

2020 ◽  
Author(s):  
Matija Sestan-Pesa ◽  
Marya Shanabrough ◽  
Tamas L. Horvath ◽  
Maria Consolata Miletta
Keyword(s):  
Anxiety And Depression ◽  
Depression And Anxiety ◽  
Wild Type ◽  
Growth Hormone Secretagogue Receptor ◽  
Male Adult ◽  
Growth Hormone Secretagogue ◽  
Adult Mice ◽  
Marijuana Consumption ◽  
Long Term Impact

AbstractAs marijuana use during adolescence has been increasing, the need to understand the effects of its long-term use becomes crucial. Previous research suggested that marijuana consumption during adolescence increases the risk of developing mental illness, such as schizophrenia, depression, and anxiety. Ghrelin is a peptide produced primarily in the gut and is important for feeding behavior. Recent studies have shown that ghrelin and its receptor, the growth hormone secretagogue receptor (GHSR) play important roles in mediating stress, as well as anxiety and, depression-like behaviors in animal models. Here, we investigated the effects of chronic Tetrahydrocannabinol (THC) administration during adolescence (P42-55), in GHSR (GHSR-/-) knockout mice and their wild type littermates in relation to anxiety-like behaviors. We found that continuous THC exposure during peri-adolescence did not lead to any significant alterations in anxiety-like behavior of male adult mice, regardless of genotype. These data indicate that in the presence of intact GHSR signaling, THC exposure during peri-adolescence has limited if any long term impact on anxiety-like behaviors in mice.

scholarly journals Nfe2 is dispensable for early but required for adult thrombocyte formation and function in zebrafish

2018 ◽  
Vol 2 (23) ◽  
pp. 3418-3427 ◽  
Author(s):  
Megan S. Rost ◽  
Ilya Shestopalov ◽  
Yang Liu ◽  
Andy H. Vo ◽  
Catherine E. Richter ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Severe Thrombocytopenia ◽  
Wild Type ◽  
Transcription Activator ◽  
Platelet Production ◽  
Adult Kidney ◽  
Depth Study ◽  
And Function

AbstractThe NFE2 transcription factor is expressed in multiple hematopoietic lineages with a well-defined role in regulating megakaryocyte biogenesis and platelet production in mammals. Mice deficient in NFE2 develop severe thrombocytopenia with lethality resulting from neonatal hemorrhage. Recent data in mammals reveal potential differences in embryonic and adult thrombopoiesis. Multiple studies in zebrafish have revealed mechanistic insights into hematopoiesis, although thrombopoiesis has been less studied. Rather than platelets, zebrafish possess thrombocytes, which are nucleated cells with similar functional properties. Using transcription activator-like effector nucleases to generate mutations in nfe2, we show that unlike mammals, zebrafish survive to adulthood in the absence of Nfe2. Despite developing severe thrombocytopenia, homozygous mutants do not display overt hemorrhage or reduced survival. Surprisingly, quantification of circulating thrombocytes in mutant 6-day-old larvae revealed no significant differences from wild-type siblings. Both wild-type and nfe2 null larvae formed thrombocyte-rich clots in response to endothelial injury. In addition, ex vivo thrombocytic colony formation was intact in nfe2 mutants, and adult kidney marrow displayed expansion of hematopoietic progenitors. These data suggest that loss of Nfe2 results in a late block in adult thrombopoiesis, with secondary expansion of precursors: features consistent with mammals. Overall, our data suggest parallels with erythropoiesis, including distinct primitive and definitive pathways of development and potential for a previously unknown Nfe2-independent pathway of embryonic thrombopoiesis. Long-term homozygous mutant survival will facilitate in-depth study of Nfe2 deficiency in vivo, and further investigation could lead to alternative methodologies for the enhancement of platelet production.

scholarly journals Genetic Analysis of Cytoprotective Functions Supported by Graded Expression of Keap1

2010 ◽  
Vol 30 (12) ◽  
pp. 3016-3026 ◽  
Author(s):  
Keiko Taguchi ◽  
Jonathan M. Maher ◽  
Takafumi Suzuki ◽  
Yukie Kawatani ◽  
Hozumi Motohashi ◽  
...  
Keyword(s):  
Acute Toxicity ◽  
Wild Type ◽  
Term Survival ◽  
Constitutive Activation ◽  
Oxidative Stresses ◽  
Adult Mice ◽  
Nrf2 Activation ◽  
Weaning Age ◽  
Old Mice

ABSTRACT Keap1 regulates Nrf2 activity in response to xenobiotic and oxidative stresses. Nrf2 is an essential regulator of cytoprotective genes. Keap1-null mice are lethal by weaning age due to malnutrition caused by severe hyperkeratosis of the upper digestive tract. Analysis of Keap1::Nrf2 double mutant mice revealed that currently recognizable phenotypes of Keap1-null mice are all attributable to constitutive activation of Nrf2. We previously reported that hepatocyte-specific Keap1 knockout (Keap1 flox/ −::Albumin-Cre) mice are viable and more resistant to acute toxicity of acetaminophen (APAP). In the current study, we found that the floxed Keap1 allele is hypomorphic and that Keap1 expression was decreased in all examined tissues of Keap1 flox/ − mice. Taking advantage of the hypomorphic phenotype of Keap1 flox/ − mice, we examined the effects of graded reduction of Keap1 expression in adult mice. When challenged with APAP, Keap1 flox/ − mice were more protected from mortality than wild-type and even Keap1 flox/ −::Albumin-Cre mice. In contrast, a decrease in Keap1 levels to less than 50% resulted in increased mortality in a study of 2-year-old mice. These results support our contention that the benefits of Nrf2 activation in acute toxicity are hormetic and that constitutive Nrf2 activation beyond a certain threshold is rather disadvantageous to long-term survival.

scholarly journals Antibody targeting KIT as pretransplantation conditioning in immunocompetent mice

Blood ◽  
2010 ◽  
Vol 116 (24) ◽  
pp. 5419-5422 ◽  
Author(s):  
Xingkui Xue ◽  
Nancy K. Pech ◽  
W. Christopher Shelley ◽  
Edward F. Srour ◽  
Mervin C. Yoder ◽  
...  
Keyword(s):  
Low Dose ◽  
Lentiviral Vector ◽  
Ex Vivo ◽  
Selective Advantage ◽  
Wild Type ◽  
Gene Correction ◽  
Hematopoietic Stem ◽  
Immunocompetent Mice

Abstract Inherited hematologic defects that lack an in vivo selective advantage following gene correction may benefit from effective yet minimally toxic cytoreduction of endogenous hematopoietic stem cells (HSCs) prior to transplantation of gene-modified HSCs. We studied the efficacy of administering a novel sequential treatment of parenteral ACK2, an antibody that blocks KIT, followed by low-dose irradiation (LD-IR) for conditioning of wild-type and X-linked chronic granulomatous disease (X-CGD) mice. In wild-type mice, combining ACK2 and LD-IR profoundly decreased endogenous competitive long-term HSC repopulating activity, and permitted efficient and durable donor-derived HSC engraftment after congenic transplantation. ACK2 alone was ineffective. The combination of ACK2 and LD-IR was also effective conditioning in X-CGD mice for engraftment of X-CGD donor HSCs transduced ex vivo with a lentiviral vector. We conclude that combining ACK2 with LD-IR is a promising approach to effectively deplete endogenous HSCs and facilitate engraftment of transplanted donor HSCs.

Differential Outcomes for Long Term ex vivo Lung Perfusion in a Porcine Model - With or without Red Cells?

2015 ◽  
Vol 63 (S 01) ◽  
Author(s):  
W. Sommer ◽  
M. Avsar ◽  
J. Salman ◽  
C. Kühn ◽  
I. Tudorache ◽  
...  
Keyword(s):  
Porcine Model ◽  
Ex Vivo ◽  
Lung Perfusion ◽  
Red Cells ◽  
Ex Vivo Lung Perfusion ◽  
Differential Outcomes

Strategies to Protect Hematopoietic Stem Cells from Culture-Induced Stress Conditions

2020 ◽  
Vol 15 ◽  
Author(s):  
Fatima Aerts-Kaya
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Ex Vivo ◽  
Stress Conditions ◽  
Stress Factors ◽  
Hematopoietic Stem ◽  
Induced Stress

: In contrast to their almost unlimited potential for expansion in vivo and despite years of dedicated research and optimization of expansion protocols, the expansion of Hematopoietic Stem Cells (HSCs) in vitro remains remarkably limited. Increased understanding of the mechanisms that are involved in maintenance, expansion and differentiation of HSCs will enable the development of better protocols for expansion of HSCs. This will allow procurement of HSCs with long-term engraftment potential and a better understanding of the effects of the external influences in and on the hematopoietic niche that may affect HSC function. During collection and culture of HSCs, the cells are exposed to suboptimal conditions that may induce different levels of stress and ultimately affect their self-renewal, differentiation and long-term engraftment potential. Some of these stress factors include normoxia, oxidative stress, extra-physiologic oxygen shock/stress (EPHOSS), endoplasmic reticulum (ER) stress, replicative stress, and stress related to DNA damage. Coping with these stress factors may help reduce the negative effects of cell culture on HSC potential, provide a better understanding of the true impact of certain treatments in the absence of confounding stress factors. This may facilitate the development of better ex vivo expansion protocols of HSCs with long-term engraftment potential without induction of stem cell exhaustion by cellular senescence or loss of cell viability. This review summarizes some of available strategies that may be used to protect HSCs from culture-induced stress conditions.

scholarly journals Protein recycling and limb muscle recovery after critical illness in slow- and fast-twitch limb muscle

2019 ◽  
Vol 316 (5) ◽  
pp. R584-R593 ◽  
Author(s):  
Sebastien Preau ◽  
Michael Ambler ◽  
Anna Sigurta ◽  
Anna Kleyman ◽  
Alex Dyson ◽  
...  
Keyword(s):  
Critical Illness ◽  
Functional Disability ◽  
Ex Vivo ◽  
Therapeutic Option ◽  
Limb Muscle ◽  
Fungal Cell ◽  
Hindlimb Muscles ◽  
Initial Reduction ◽  
Male Wistar Rats

An impaired capacity of muscle to regenerate after critical illness results in long-term functional disability. We previously described in a long-term rat peritonitis model that gastrocnemius displays near-normal histology whereas soleus demonstrates a necrotizing phenotype. We thus investigated the link between the necrotizing phenotype of critical illness myopathy and proteasome activity in these two limb muscles. We studied male Wistar rats that underwent an intraperitoneal injection of the fungal cell wall constituent zymosan or n-saline as a sham-treated control. Rats ( n = 74) were killed at 2, 7, and 14 days postintervention with gastrocnemius and soleus muscle removed and studied ex vivo. Zymosan-treated animals displayed an initial reduction of body weight but a persistent decrease in mass of both lower hindlimb muscles. Zymosan increased chymotrypsin- and trypsin-like proteasome activities in gastrocnemius at days 2 and 7 but in soleus at day 2 only. Activated caspases-3 and -9, polyubiquitin proteins, and 14-kDa fragments of myofibrillar actin (proteasome substrates) remained persistently increased from day 2 to day 14 in soleus but not in gastrocnemius. These results suggest that a relative proteasome deficiency in soleus is associated with a necrotizing phenotype during long-term critical illness. Rescuing proteasome clearance may offer a potential therapeutic option to prevent long-term functional disability in critically ill patients.

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