scholarly journals The effects of chronic muscle use and disuse on cardiolipin metabolism

2013 ◽  
Vol 114 (4) ◽  
pp. 444-452 ◽  
Author(s):  
Olga Ostojić ◽  
Michael F. N. O'Leary ◽  
Kaustabh Singh ◽  
Keir J. Menzies ◽  
Anna Vainshtein ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Contractile Activity ◽  
Compensatory Mechanism ◽  
Mrna Levels ◽  
Mitochondrial Membranes ◽  
Phospholipid Scramblase ◽  
Metabolism Enzymes ◽  
Underlying Mechanisms ◽  
Knockout Animals ◽  
First Time

Cardiolipin (CL) is a phospholipid that maintains the integrity of mitochondrial membranes. We previously demonstrated that CL content increases with chronic muscle use, and decreases with denervation-induced disuse. To investigate the underlying mechanisms, we measured the mRNA expression of 1) CL synthesis enzymes cardiolipin synthase (CLS) and CTP:PA-cytidylyltransferase-1 (CDS-1); 2) remodeling enzymes tafazzin and acyl-CoA:lysocardiolipin acyltransferase-1 (ALCAT1); and 3) outer membrane CL enzymes, mitochondrial phospholipase D and phospholipid scramblase 3 (Plscr3), during chronic contractile activity (CCA)-induced mitochondrial biogenesis and denervation. With CCA, CDS-1 expression increased by 128%, parelleling CL levels. Surprisingly, denervation also led to large increases in CDS-1 and CLS, despite a decrease in mitochondria, possibly due to a compensatory mechanism to restore lost CL. ALCAT1 decreased by 32% with CCA, but increased by 290% following denervation, indicating that both CCA and denervation alter CL remodeling. CCA and denervation also elicited 60–90% increases in Plscr3, likely to facilitate CL movement to the outer membrane. The expression of these genes was not affected by aging, but changes due to CCA and denervation were attenuated compared with young animals. The absence of PPARγ coactivator-1α in knockout animals led to a decrease in CDS-1 and an increase in ALCAT1 mRNA levels, implicating PGC-1α in regulating both CL synthesis and remodeling. These data suggest that chronic muscle use and disuse modify the expression of mRNAs encoding CL metabolism enzymes. Our data also illustrate, for the first time, that PPARγ coactivator-1α regulates the CL metabolism pathway in muscle.

scholarly journals Biogenesis of the mitochondrial Tom40 channel in skeletal muscle from aged animals and its adaptability to chronic contractile activity

2010 ◽  
Vol 298 (6) ◽  
pp. C1308-C1314 ◽  
Author(s):  
Anna-Maria Joseph ◽  
Vladimir Ljubicic ◽  
Peter J. Adhihetty ◽  
David A. Hood
Keyword(s):  
Outer Membrane ◽  
Protein Import ◽  
Contractile Activity ◽  
Brown Norway ◽  
Compensatory Mechanism ◽  
Assembly Process ◽  
Mitochondrial Content ◽  
Fischer 344 ◽  
Assembly Pathway ◽  
Subsarcolemmal Mitochondria

Evidence exists that mitochondrial content and/or function is reduced in muscle of aging individuals. The purposes of this study were to investigate the contribution of outer membrane protein import and assembly processes to this decline and to determine whether the assembly process could adapt to chronic contractile activity (CCA). Tom40 assembly into the translocases of the outer membrane (TOM complex) was measured in subsarcolemmal mitochondria obtained from young (6 mo old) and aged (36 mo old) Fischer 344 × Brown Norway animals. While the initial import of Tom40 did not differ between young and aged animals, its subsequent assembly into the final ∼380 kDa complex was 2.2-fold higher ( P < 0.05) in mitochondria from aged compared with young animals. This was associated with a higher abundance of Tom22, a protein vital for the assembly process. CCA induced a greater initial import and subsequent assembly of Tom40 in mitochondria from young animals, resulting in a CCA-induced 75% increase ( P < 0.05) in Tom40 within mitochondria. This effect of CCA was attenuated in mitochondria from old animals. These data suggest that the import and assembly of proteins into the outer membrane do not contribute to reduced mitochondrial content or function in aged animals. Indeed, the greater assembly rate in mitochondria from aged animals may be a compensatory mechanism attempting to offset any decrements in mitochondrial content or function within aged muscle. Our data also indicate the potential of CCA to contribute to increased mitochondrial biogenesis in muscle through changes in the outer membrane import and assembly pathway.

scholarly journals Heparan Sulfate Deficiency in Cartilage: Enhanced BMP-Sensitivity, Proteoglycan Production and an Anti-Apoptotic Expression Signature after Loading

2021 ◽  
Vol 22 (7) ◽  
pp. 3726
Author(s):  
Matthias Gerstner ◽  
Ann-Christine Severmann ◽  
Safak Chasan ◽  
Andrea Vortkamp ◽  
Wiltrud Richter
Keyword(s):  
Heparan Sulfate ◽  
Pain Perception ◽  
Biological Process ◽  
Transcriptome Profiling ◽  
Mrna Levels ◽  
Unconfined Compression ◽  
Expression Signature ◽  
Hypomorphic Allele ◽  
Underlying Mechanisms ◽  
Engineered Cartilage

Osteoarthritis (OA) represents one major cause of disability worldwide still evading efficient pharmacological or cellular therapies. Severe degeneration of extracellular cartilage matrix precedes the loss of mobility and disabling pain perception in affected joints. Recent studies showed that a reduced heparan sulfate (HS) content protects cartilage from degradation in OA-animal models of joint destabilization but the underlying mechanisms remained unclear. We aimed to clarify whether low HS-content alters the mechano-response of chondrocytes and to uncover pathways relevant for HS-related chondro-protection in response to loading. Tissue-engineered cartilage with HS-deficiency was generated from rib chondrocytes of mice carrying a hypomorphic allele of Exostosin 1 (Ext1), one of the main HS-synthesizing enzymes, and wildtype (WT) littermate controls. Engineered cartilage matured for 2 weeks was exposed to cyclic unconfined compression in a bioreactor. The molecular loading response was determined by transcriptome profiling, bioinformatic data processing, and qPCR. HS-deficient chondrocytes expressed 3–6% of WT Ext1-mRNA levels. Both groups similarly raised Sox9, Col2a1, and Acan levels during maturation. However, HS-deficient chondrocytes synthesized and deposited 50% more GAG/DNA. TGFβ and FGF2-sensitivity of Ext1gt/gt chondrocytes was similar to WT cells but their response to BMP-stimulation was enhanced. Loading induced similar activation of mechano-sensitive ERK and P38-signaling in WT and HS-reduced chondrocytes. Transcriptome analysis reflected regulation of cell migration as major load-induced biological process with similar stimulation of common (Fosl1, Itgα5, Timp1, and Ngf) as well as novel mechano-regulated genes (Inhba and Dhrs9). Remarkably, only Ext1-hypomorphic cartilage responded to loading by an expression signature of negative regulation of apoptosis with pro-apoptotic Bnip3 being selectively down-regulated. HS-deficiency enhanced BMP-sensitivity, GAG-production and fostered an anti-apoptotic expression signature after loading, all of which may protect cartilage from load-induced erosion.

scholarly journals Maternal Neutrophil Depletion Fails to Avert Systemic Lipopolysaccharide-Induced Early Pregnancy Defects in Mice

2021 ◽  
Vol 22 (15) ◽  
pp. 7932
Author(s):  
Sourav Panja ◽  
John T. Benjamin ◽  
Bibhash C. Paria
Keyword(s):  
Early Pregnancy ◽  
Normal Pregnancy ◽  
Mrna Levels ◽  
Interesting Approach ◽  
Blastocyst Implantation ◽  
Neutrophil Depletion ◽  
Underlying Mechanisms ◽  
Myd88 Signaling ◽  
Induced Defects ◽  
Dose Dependent

Maternal infection-induced early pregnancy complications arise from perturbation of the immune environment at the uterine early blastocyst implantation site (EBIS), yet the underlying mechanisms remain unclear. Here, we demonstrated in a mouse model that the progression of normal pregnancy from days 4 to 6 induced steady migration of leukocytes away from the uterine decidual stromal zone (DSZ) that surrounds the implanted blastocyst. Uterine macrophages were found to be CD206+ M2-polarized. While monocytes were nearly absent in the DSZ, DSZ cells were found to express monocyte marker protein Ly6C. Systemic endotoxic lipopolysaccharide (LPS) exposure on day 5 of pregnancy led to: (1) rapid (at 2 h) induction of neutrophil chemoattractants that promoted huge neutrophil infiltrations at the EBISs by 24 h; (2) rapid (at 2 h) elevation of mRNA levels of MyD88, but not Trif, modulated cytokines at the EBISs; and (3) dose-dependent EBIS defects by day 7 of pregnancy. Yet, elimination of maternal neutrophils using anti-Ly6G antibody prior to LPS exposure failed to avert LPS-induced EBIS defects allowing us to suggest that activation of Tlr4-MyD88 dependent inflammatory pathway is involved in LPS-induced defects at EBISs. Thus, blocking the activation of the Tlr4-MyD88 signaling pathway may be an interesting approach to prevent infection-induced pathology at EBISs.

scholarly journals Shadowing the Actions of a Predator: Backlit Fluorescent Microscopy Reveals Synchronous Nonbinary Septation of Predatory Bdellovibrio inside Prey and Exit through Discrete Bdelloplast Pores

2010 ◽  
Vol 192 (24) ◽  
pp. 6329-6335 ◽  
Author(s):  
A. K. Fenton ◽  
M. Kanna ◽  
R. D. Woods ◽  
S.-I. Aizawa ◽  
R. E. Sockett
Keyword(s):  
Cell Division ◽  
Outer Membrane ◽  
Fluorescent Microscopy ◽  
Gram Negative Bacteria ◽  
Bacterial Cell Division ◽  
Prey Cell ◽  
Gram Negative ◽  
A Genome ◽  
Predatory Bacteria ◽  
First Time

ABSTRACT The Bdellovibrio are miniature “living antibiotic” predatory bacteria which invade, reseal, and digest other larger Gram-negative bacteria, including pathogens. Nutrients for the replication of Bdellovibrio bacteria come entirely from the digestion of the single invaded bacterium, now called a bdelloplast, which is bound by the original prey outer membrane. Bdellovibrio bacteria are efficient digesters of prey cells, yielding on average 4 to 6 progeny from digestion of a single prey cell of a genome size similar to that of the Bdellovibrio cell itself. The developmental intrabacterial cycle of Bdellovibrio is largely unknown and has never been visualized “live.” Using the latest motorized xy stage with a very defined z-axis control and engineered periplasmically fluorescent prey allows, for the first time, accurate return and visualization without prey bleaching of developing Bdellovibrio cells using solely the inner resources of a prey cell over several hours. We show that Bdellovibrio bacteria do not follow the familiar pattern of bacterial cell division by binary fission. Instead, they septate synchronously to produce both odd and even numbers of progeny, even when two separate Bdellovibrio cells have invaded and develop within a single prey bacterium, producing two different amounts of progeny. Evolution of this novel septation pattern, allowing odd progeny yields, allows optimal use of the finite prey cell resources to produce maximal replicated, predatory bacteria. When replication is complete, Bdellovibrio cells exit the exhausted prey and are seen leaving via discrete pores rather than by breakdown of the entire outer membrane of the prey.

Selected Contribution: Effects of contractile activity on mitochondrial transcription factor A expression in skeletal muscle

2001 ◽  
Vol 90 (1) ◽  
pp. 389-396 ◽  
Author(s):  
Joe W. Gordon ◽  
Arne A. Rungi ◽  
Hidetoshi Inagaki ◽  
David A. Hood
Keyword(s):  
Skeletal Muscle ◽  
Transcription Factor ◽  
Mitochondrial Biogenesis ◽  
Contractile Activity ◽  
Regulatory Protein ◽  
Mrna Levels ◽  
Mitochondrial Transcription ◽  
Mitochondrial Transcription Factor ◽  
Mitochondrial Transcription Factor A ◽  
Mitochondrial Transcript

Mitochondrial transcription factor A (Tfam) is a nuclear-encoded gene product that is imported into mitochondria and is required for the transcription of mitochondrial DNA (mtDNA). We hypothesized that conditions known to produce mitochondrial biogenesis in skeletal muscle would be preceded by an increase in Tfam expression. Therefore, rat muscle was stimulated (10 Hz, 3 h/day). Tfam mRNA levels were significantly elevated (by 55%) at 4 days and returned to control levels at 14 days. Tfam import into intermyofibrillar (IMF) mitochondria was increased by 52 and 61% ( P < 0.05) at 5 and 7 days, respectively. This corresponded to an increase in the level of import machinery components. Immunoblotting data indicated that IMF Tfam protein content was increased by 63% ( P < 0.05) at 7 days of stimulation. This was associated with a 49% ( P < 0.05) increase in complex formation at the mtDNA promoter and a 65% ( P< 0.05) increase in the levels of a mitochondrial transcript, cytochrome- c oxidase (COX) subunit III. Similarly, COX enzyme activity was elevated by 71% ( P < 0.05) after 7 days of contractile activity. These results indicate that early events in mitochondrial biogenesis include increases in Tfam mRNA, followed by accelerations in mitochondrial import and increased Tfam content, which correspond with increased binding to the mtDNA promoter region. This was accompanied by increased mitochondrial transcript levels and elevated COX activity. These data support the role of Tfam as a regulatory protein involved in contractile activity-induced mitochondrial biogenesis.

Fish embryo culture: cardiac monolayers and contractile activity in embryo explants from the zebrafish, Brachydanio rerio

1984 ◽  
Vol 62 (5) ◽  
pp. 878-885 ◽  
Author(s):  
Hans Willer Laale
Keyword(s):  
Embryo Culture ◽  
Nutrient Medium ◽  
Contractile Activity ◽  
Functional Differentiation ◽  
Brachydanio Rerio ◽  
Fish Embryo ◽  
Embryo Cultures ◽  
Culture Substrate ◽  
First Time ◽  
Cardiac Mesoderm

Stage 16+ axial isolates from embryos of the zebrafish, Brachydanio rerio (Hamilton-Buchanan), were separated from their yolk spheres and epidermis. Rhombencephalic level explants, with intact bilateral cardiac rudiments, were maintained in nutrient medium for 20 days at 24 ± 2 °C. All embryo cultures became attached to the culture substrate and underwent subsequent differentiation. Ten out of 25 explants showed bilateral migrations of determined but initially undifferentiated cardiac mesoderm. The progressive structural and functional differentiation of zebrafish cardiac monolayers and intact rudiments are described for the first time.

scholarly journals Lineage-specific selection and the evolution of virulence in the Candida clade

2021 ◽  
Vol 118 (12) ◽  
pp. e2016818118
Author(s):  
Sheena D. Singh-Babak ◽  
Tomas Babak ◽  
Hunter B. Fraser ◽  
Alexander D. Johnson
Keyword(s):  
Fungal Pathogens ◽  
Fungal Infections ◽  
Systemic Infection ◽  
Orthologous Gene ◽  
Regulatory Sequence ◽  
Mrna Levels ◽  
Evolutionary Changes ◽  
Interspecies Hybrids ◽  
Metabolism Enzymes ◽  
Evolution Of Virulence

Candida albicans is the most common cause of systemic fungal infections in humans and is considerably more virulent than its closest known relative, Candida dubliniensis. To investigate this difference, we constructed interspecies hybrids and quantified mRNA levels produced from each genome in the hybrid. This approach systematically identified expression differences in orthologous genes arising from cis-regulatory sequence changes that accumulated since the two species last shared a common ancestor, some 10 million y ago. We documented many orthologous gene-expression differences between the two species, and we pursued one striking observation: All 15 genes coding for the enzymes of glycolysis showed higher expression from the C. albicans genome than the C. dubliniensis genome in the interspecies hybrid. This pattern requires evolutionary changes to have occurred at each gene; the fact that they all act in the same direction strongly indicates lineage-specific natural selection as the underlying cause. To test whether these expression differences contribute to virulence, we created a C. dubliniensis strain in which all 15 glycolysis genes were produced at modestly elevated levels and found that this strain had significantly increased virulence in the standard mouse model of systemic infection. These results indicate that small expression differences across a deeply conserved set of metabolism enzymes can play a significant role in the evolution of virulence in fungal pathogens.

scholarly journals TheBDKRB2 +9/-9 Polymorphisms Influence Pro-Inflammatory Cytokine Levels in Knee Osteoarthritis by Altering TLR-2 Expression: Clinical and in Vitro Studies

2016 ◽  
Vol 38 (3) ◽  
pp. 1245-1256 ◽  
Author(s):  
Shuo Chen ◽  
Lei Zhang ◽  
Ruonan Xu ◽  
Yunfan Ti ◽  
Yunlong Zhao ◽  
...  
Keyword(s):  
Knee Osteoarthritis ◽  
Inflammatory Cytokine ◽  
Molecular Mechanisms ◽  
Enzyme Linked Immunosorbent Assay ◽  
Mrna Levels ◽  
Knee Oa ◽  
Tnf Α ◽  
Cytokine Levels ◽  
Underlying Mechanisms

Background/Aims: The bradykinin B2 receptor (BDKRB2) +9/-9 gene polymorphisms have been shown to be associated with the susceptibility and severity of osteoarthritis (OA); however, the underlying mechanisms are unclear. In this study, we investigated the correlation between the BDKRB2 +9/-9 polymorphisms and pro-inflammatory cytokine levels in OA and the molecular mechanisms involved. Methods: A total of 156 patients with primary knee OA and 121 healthy controls were enrolled. The BDKRB2 +9/-9 polymorphisms were genotyped. The tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, and IL-8 levels were determined using Enzyme-linked immunosorbent assay (ELISA). The toll-like receptor (TLR)-2 and TLR-4 mRNA levels were determined by quantitative real-time PCR. The basal and bradykinin-stimulated pro-inflammatory cytokine secretion in human OA synoviocytes and the involvement of TLR-2 and mitogen-activated protein kinases (MAPKs) were investigated. Results: The presence of -9 bp genotype is associated with higher TNF-α, IL-6, and IL-8 levels and higher TLR-2 expression in OA patients. The basal and bradykinin-induced TLR-2 expressions in human OA synoviocytes were significantly reduced by specific inhibitors of p38, JNK1/2, and ERK1/2. Both the B2 receptor antagonist MEN16132 and TLR-2 silencing inhibited IL-6 and IL-8 secretion in human OA synoviocytes. Conclusion: The data suggested that the BDKRB2 +9/-9 polymorphisms influence pro-inflammatory cytokine levels in knee osteoarthritis by altering TLR-2 expression.

scholarly journals A Three-Pool Model Dissecting Readily Releasable Pool Replenishment at the Calyx of Held

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Jun Guo ◽  
Jian-long Ge ◽  
Mei Hao ◽  
Zhi-cheng Sun ◽  
Xin-sheng Wu ◽  
...  
Keyword(s):  
Time Course ◽  
Current View ◽  
Vesicle Recycling ◽  
Releasable Pool ◽  
Readily Releasable Pool ◽  
Central Synapse ◽  
Pool Model ◽  
Underlying Mechanisms ◽  
First Time ◽  
Intense Stimulation

Abstract Although vesicle replenishment is critical in maintaining exo-endocytosis recycling, the underlying mechanisms are not well understood. Previous studies have shown that both rapid and slow endocytosis recycle into a very large recycling pool instead of within the readily releasable pool (RRP) and the time course of RRP replenishment is slowed down by more intense stimulation. This finding contradicts the calcium/calmodulin-dependence of RRP replenishment. Here we address this issue and report a three-pool model for RRP replenishment at a central synapse. Both rapid and slow endocytosis provide vesicles to a large reserve pool (RP) ~42.3 times the RRP size. When moving from the RP to the RRP, vesicles entered an intermediate pool (IP) ~2.7 times the RRP size with slow RP-IP kinetics and fast IP-RRP kinetics, which was responsible for the well-established slow and rapid components of RRP replenishment. Depletion of the IP caused the slower RRP replenishment observed after intense stimulation. These results establish, for the first time, a realistic cycling model with all parameters measured, revealing the contribution of each cycling step in synaptic transmission. The results call for modification of the current view of the vesicle recycling steps and their roles.

scholarly journals Weaning affects lipoprotein lipase activity and gene expression in adipose tissues and in masseter but not in other muscles of the calf

2001 ◽  
Vol 86 (4) ◽  
pp. 433-441 ◽  
Author(s):  
Jean-François Hocquette ◽  
Benoît Graulet ◽  
Michel Vermorel ◽  
Dominique Bauchart
Keyword(s):  
Gene Expression ◽  
Lipoprotein Lipase ◽  
Skeletal Muscles ◽  
Contractile Activity ◽  
Net Energy ◽  
Mrna Levels ◽  
Mammal Species ◽  
Adipose Tissues ◽  
Net Energy Intake ◽  
Rate Limiting

The nutritional and physiological modifications that occur during the weaning period induce adaptations of tissue metabolism in all mammal species. Among the adaptations due to weaning in ruminants, the regulation of lipoprotein lipase (LPL) activity, one of the rate-limiting steps of fatty acid utilization by tissues, was still unknown. The present study aimed at comparing LPL activity and gene expression in the heart, seven skeletal muscles and three adipose tissue sites between two groups of seven preruminant (PR) or ruminant (R) calves having a similar age (170 d), similar empty body weight (194 kg) at slaughter, and similar net energy intake from birth onwards. Triacylglycerol content of adipose tissues was 16 % lower in R than in PR calves, (P<0·01). This could be partly the result from a lower LPL activity (-57 %, P<0·01). LPL mRNA levels were also lower in R calves (-48 % to -68 %, P<0·01) suggesting a pretranslational regulation of LPL activity. Activity and mRNA levels of LPL did not differ significantly in the heart and skeletal muscles except in the masseter in which LPL activity and mRNA levels were higher (+50 % and +120 % respectively, P<0·01) in the R calves. Regulation of LPL in masseter could be explained by the high contractile activity of this muscle after weaning due to solid food chewing. In conclusion, weaning in the calf affects LPL activity and expression in adipose tissues, but not in skeletal muscles except the masseter.

Sign in / Sign up

Export Citation Format

Share Document