JNK activation in TA and EDL muscle is load-dependent in rats receiving identical excitation patterns

AbstractAs the excitation–contraction coupling is inseparable during voluntary exercise, the relative contribution of the mechanical and neural input on hypertrophy-related molecular signalling is still poorly understood. Herein, we use a rat in-vivo strength exercise model with an electrically-induced standardized excitation pattern, previously shown to induce a load-dependent increase in myonuclear number and hypertrophy, to study acute effects of load on molecular signalling. We assessed protein abundance and specific phosphorylation of the four protein kinases FAK, mTOR, p70S6K and JNK after 2, 10 and 28 min of a low- or high-load contraction, in order to assess the effects of load, exercise duration and muscle-type on their response to exercise. Specific phosphorylation of mTOR, p70S6K and JNK was increased after 28 min of exercise under the low- and high-load protocol. Elevated phosphorylation of mTOR and JNK was detectable already after 2 and 10 min of exercise, respectively, but greatest after 28 min of exercise, and JNK phosphorylation was highly load-dependent. The abundance of all four kinases was higher in TA compared to EDL muscle, p70S6K abundance was increased after exercise in a load-independent manner, and FAK and JNK abundance was reduced after 28 min of exercise in both the exercised and control muscles. In conclusion, the current study shows that JNK activation after a single resistance exercise is load-specific, resembling the previously reported degree of myonuclear accrual and muscle hypertrophy with repetition of the exercise stimulus.

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JNK activation in TA and EDL muscle is load-dependent in rats receiving identical excitation patterns

10.1101/2021.02.04.429746 ◽

2021 ◽

Author(s):

Einar Eftestøl ◽

Martino V. Franchi ◽

Stephanie Kasper ◽

Martin Flück

Keyword(s):

Exercise Duration ◽

Voluntary Exercise ◽

Muscle Type ◽

Exercise Load ◽

Relative Contribution ◽

Low Load ◽

Anaesthetized Rats ◽

Excitation Pattern ◽

Edl Muscle

ABSTACTAimAs the excitation-contraction coupling is inseparable during voluntary exercise, the relative contribution of the mechanical and neural input is poorly understood. Herein, we use a rat in-vivo strength training setup with an electrically induced standardized excitation pattern previously shown to lead to a load-dependent increase in myonuclear number and hypertrophy, to study acute effects of load per se on molecular signalling.MethodsAnaesthetized rats were subjected to unliteral identical electrically-paced contractions of the TA and EDL muscles under a high or low load for a duration of 2, 10 or 28-minutes. Muscle soluble proteins were extracted, and abundance and specific phosphorylations of FAK, mTOR, p70S6K and JNK were measured. Effects of exercise, load, muscle and exercise duration were assessed.ResultsSpecific phosphorylation of S2448-mTOR, T421/S424-p70S6K and T183/Y185-JNK was increased after 28-minutes of exercise under the high- and low-load protocol. Elevated phosphorylation of mTOR and JNK was detectable already after 2 and 10 minutes of exercise, respectively, but greatest after 28-minutes of exercise. T183/Y185-JNK and S2448-mTOR demonstrated a load-dependent increase in phosphorylation in the exercised muscles that for mTOR depended on muscle type. The abundance of all four kinases was higher in TA compared to EDL muscle. FAK and JNK abundance was reduced after 28 minutes of exercise in both the exercised and control muscle.ConclusionThe current study shows that JNK and mTOR activation is load-driven, and together with muscle-type specific mTOR and p70S6K effects it may drive muscle-type specific exercise and load-responses.

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Effects of voluntary exercise duration on myocardial ischaemic tolerance, kinase signaling and gene expression

Life Sciences ◽

10.1016/j.lfs.2021.119253 ◽

2021 ◽

pp. 119253

Author(s):

Boris P. Budiono ◽

Louise E. See Hoe ◽

Jason N. Peart ◽

Jelena Vider ◽

Kevin J. Ashton ◽

...

Keyword(s):

Gene Expression ◽

Exercise Duration ◽

Voluntary Exercise ◽

Kinase Signaling

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Blocking Migration of Polymorphonuclear Myeloid-Derived Suppressor Cells Inhibits Mouse Melanoma Progression

Cancers ◽

10.3390/cancers13040726 ◽

2021 ◽

Vol 13 (4) ◽

pp. 726

Author(s):

Christopher Groth ◽

Ludovica Arpinati ◽

Merav E. Shaul ◽

Nina Winkler ◽

Klara Diester ◽

...

Keyword(s):

Tumor Progression ◽

Checkpoint Inhibitors ◽

Suppressor Cells ◽

Receptor Expression ◽

Myeloid Derived Suppressor Cells ◽

Melanoma Progression ◽

Relative Contribution ◽

Immunosuppressive Tumor Microenvironment ◽

Metastatic Sites

Background: Despite recent improvement in the treatment of malignant melanoma by immune-checkpoint inhibitors, the disease can progress due to an immunosuppressive tumor microenvironment (TME) mainly represented by myeloid-derived suppressor cells (MDSC). However, the relative contribution of the polymorphonuclear (PMN) and monocytic (M) MDSC subsets to melanoma progression is not clear. Here, we compared both subsets regarding their immunosuppressive capacity and recruitment mechanisms. Furthermore, we inhibited PMN-MDSC migration in vivo to determine its effect on tumor progression. Methods: Using the RET transgenic melanoma mouse model, we investigated the immunosuppressive function of MDSC subsets and chemokine receptor expression on these cells. The effect of CXCR2 inhibition on PMN-MDSC migration and tumor progression was studied in RET transgenic mice and in C57BL/6 mice after surgical resection of primary melanomas. Results: Immunosuppressive capacity of intratumoral M- and PMN-MDSC was comparable in melanoma bearing mice. Anti-CXCR2 therapy prolonged survival of these mice and decreased the occurrence of distant metastasis. Furthermore, this therapy reduced the infiltration of melanoma lesions and pre-metastatic sites with PMN-MDSC that was associated with the accumulation of natural killer (NK) cells. Conclusions: We provide evidence for the tumor−promoting properties of PMN-MDSC as well as for the anti-tumor effects upon their targeting in melanoma bearing mice.

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Metformin induces Ferroptosis by inhibiting UFMylation of SLC7A11 in breast cancer

Journal of Experimental & Clinical Cancer Research ◽

10.1186/s13046-021-02012-7 ◽

2021 ◽

Vol 40 (1) ◽

Author(s):

Jingjing Yang ◽

Yulu Zhou ◽

Shuduo Xie ◽

Ji Wang ◽

Zhaoqing Li ◽

...

Keyword(s):

Breast Cancer ◽

Cancer Treatment ◽

Morphological Changes ◽

Tumor Model ◽

Independent Manner ◽

Regulated Cell Death ◽

Anti Cancer ◽

Cancer Agent ◽

Approved Drugs

Abstract Background Ferroptosis is a newly defined form of regulated cell death characterized by the iron-dependent accumulation of lipid peroxidation and is involved in various pathophysiological conditions, including cancer. Targeting ferroptosis is considered to be a novel anti-cancer strategy. The identification of FDA-approved drugs as ferroptosis inducers is proposed to be a new promising approach for cancer treatment. Despite a growing body of evidence indicating the potential efficacy of the anti-diabetic metformin as an anti-cancer agent, the exact mechanism underlying this efficacy has not yet been fully elucidated. Methods The UFMylation of SLC7A11 is detected by immunoprecipitation and the expression of UFM1 and SLC7A11 in tumor tissues was detected by immunohistochemical staining. The level of ferroptosis is determined by the level of free iron, total/lipid Ros and GSH in the cells and the morphological changes of mitochondria are observed by transmission electron microscope. The mechanism in vivo was verified by in situ implantation tumor model in nude mice. Results Metformin induces ferroptosis in an AMPK-independent manner to suppress tumor growth. Mechanistically, we demonstrate that metformin increases the intracellular Fe2+ and lipid ROS levels. Specifically, metformin reduces the protein stability of SLC7A11, which is a critical ferroptosis regulator, by inhibiting its UFMylation process. Furthermore, metformin combined with sulfasalazine, the system xc− inhibitor, can work in a synergistic manner to induce ferroptosis and inhibit the proliferation of breast cancer cells. Conclusions This study is the first to demonstrate that the ability of metformin to induce ferroptosis may be a novel mechanism underlying its anti-cancer effect. In addition, we identified SLC7A11 as a new UFMylation substrate and found that targeting the UFM1/SLC7A11 pathway could be a promising cancer treatment strategy.

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Hypoxia promotes the metastasis of pancreatic cancer through regulating NOX4/KDM5A-mediated histone methylation modification changes in a HIF1A-independent manner

Clinical Epigenetics ◽

10.1186/s13148-021-01016-6 ◽

2021 ◽

Vol 13 (1) ◽

Author(s):

Hongzhen Li ◽

Chunyan Peng ◽

Chenhui Zhu ◽

Shuang Nie ◽

Xuetian Qian ◽

...

Keyword(s):

Pancreatic Cancer ◽

Nadph Oxidase ◽

Western Blot ◽

Cancer Progression ◽

Histone Methylation ◽

Invasion And Metastasis ◽

Independent Manner ◽

Nadph Oxidase 4

Abstract Background Hypoxia is a characteristic of the tumor microenvironments within pancreatic cancer (PC), which has been linked to its malignancy. Recently, hypoxia has been reported to regulate the activity of important carcinogenic pathways by changing the status of histone modification. NOX4, a member of NADPH oxidase (NOX), has been found to be activated by hypoxia and promote cancer progression in several cancers. But whether it is involved in the epigenetic changes of tumor cells induced by hypoxia is still unclear, and its biological roles in PC also need to be explored. Methods A hypoxic-related gene signature and its associated pathways in PC were identified by analyzing the pancreatic cancer gene expression data from GEO and TCGA database. Candidate downstream gene (NOX4), responding to hypoxia, was validated by RT-PCR and western blot. Then, we evaluated the relationship between NOX4 expression and clinicopathologic parameters in 56 PC patients from our center. In vitro and in vivo assays were preformed to explore the phenotype of NOX4 in PC. Immunofluorescence, western blot and chromatin immunoprecipitation assays were further applied to search for a detailed mechanism. Results We quantified hypoxia and developed a hypoxia signature, which was associated with worse prognosis and elevated malignant potential in PC. Furthermore, we found that NADPH oxidase 4 (NOX4), which was induced by hypoxia and upregulated in PC in a HIF1A-independent manner, caused inactivation of lysine demethylase 5A (KDM5A), increased the methylation modification of histone H3 and regulated the transcription of EMT-associated gene_ snail family transcriptional repressor 1 (SNAIL1). This served to promote the invasion and metastasis of PC. NOX4 deficiency repressed hypoxia-induced EMT, reduced expression of H3K4ME3 and impaired the invasion and metastasis of PC cells; however, knockdown of KDM5A reversed the poor expression of H3KEME3 induced by NOX4 deficiency, thereby promoting EMT. Conclusions This study highlights the prognostic role of hypoxia-related genes in PC and strong correlation with EMT pathway. Our results also creatively discovered that NOX4 was an essential mediator for hypoxia-induced histone methylation modification and EMT in PC cells.

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WASP confers selective advantage for specific hematopoietic cell populations and serves a unique role in marginal zone B-cell homeostasis and function

Blood ◽

10.1182/blood-2008-02-140715 ◽

2008 ◽

Vol 112 (10) ◽

pp. 4139-4147 ◽

Cited By ~ 71

Author(s):

Lisa S. Westerberg ◽

Miguel A. de la Fuente ◽

Fredrik Wermeling ◽

Hans D. Ochs ◽

Mikael C. I. Karlsson ◽

...

Keyword(s):

T Cells ◽

B Cells ◽

B Cell ◽

Marginal Zone ◽

Hematopoietic Cells ◽

Selective Advantage ◽

Relative Contribution ◽

B Cell Homeostasis ◽

And Function

Abstract Development of hematopoietic cells depends on a dynamic actin cytoskeleton. Here we demonstrate that expression of the cytoskeletal regulator WASP, mutated in the Wiskott-Aldrich syndrome, provides selective advantage for the development of naturally occurring regulatory T cells, natural killer T cells, CD4+ and CD8+ T lymphocytes, marginal zone (MZ) B cells, MZ macrophages, and platelets. To define the relative contribution of MZ B cells and MZ macrophages for MZ development, we generated wild-type and WASP-deficient bone marrow chimeric mice, with full restoration of the MZ. However, even in the presence of MZ macrophages, only 10% of MZ B cells were of WASP-deficient origin. We show that WASP-deficient MZ B cells hyperproliferate in vivo and fail to respond to sphingosine-1-phosphate, a crucial chemoattractant for MZ B-cell positioning. Abnormalities of the MZ compartment in WASP−/− mice lead to aberrant uptake of Staphylococcus aureus and to a reduced immune response to TNP-Ficoll. Moreover, WASP-deficient mice have increased levels of “natural” IgM antibodies. Our findings reveal that WASP regulates both development and function of hematopoietic cells. We demonstrate that WASP deficiency leads to an aberrant MZ that may affect responses to blood-borne pathogens and peripheral B-cell tolerance.

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Telomere Formation by Rap1p Binding Site Arrays Reveals End-Specific Length Regulation Requirements and Active Telomeric Recombination

Molecular and Cellular Biology ◽

10.1128/mcb.21.23.8117-8128.2001 ◽

2001 ◽

Vol 21 (23) ◽

pp. 8117-8128 ◽

Cited By ~ 28

Author(s):

Simona Grossi ◽

Alessandro Bianchi ◽

Pascal Damay ◽

David Shore

Keyword(s):

Binding Sites ◽

De Novo ◽

Repeat Sequence ◽

Independent Manner ◽

Telomere Repeat ◽

Length Regulation ◽

End Capping ◽

Original Array

ABSTRACT Rap1p, the major telomere repeat binding protein in yeast, has been implicated in both de novo telomere formation and telomere length regulation. To characterize the role of Rap1p in these processes in more detail, we studied the generation of telomeres in vivo from linear DNA substrates containing defined arrays of Rap1p binding sites. Consistent with previous work, our results indicate that synthetic Rap1p binding sites within the internal half of a telomeric array are recognized as an integral part of the telomere complex in an orientation-independent manner that is largely insensitive to the precise spacing between adjacent sites. By extending the lengths of these constructs, we found that several different Rap1p site arrays could never be found at the very distal end of a telomere, even when correctly oriented. Instead, these synthetic arrays were always followed by a short (≈100-bp) “cap” of genuine TG repeat sequence, indicating a remarkably strict sequence requirement for an end-specific function(s) of the telomere. Despite this fact, even misoriented Rap1p site arrays promote telomere formation when they are placed at the distal end of a telomere-healing substrate, provided that at least a single correctly oriented site is present within the array. Surprisingly, these heterogeneous arrays of Rap1p binding sites generate telomeres through a RAD52-dependent fusion resolution reaction that results in an inversion of the original array. Our results provide new insights into the nature of telomere end capping and reveal one way by which recombination can resolve a defect in this process.

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Angiotensin II stimulates calcium-dependent activation of c-Jun N-terminal kinase.

Molecular and Cellular Biology ◽

10.1128/mcb.15.11.6160 ◽

1995 ◽

Vol 15 (11) ◽

pp. 6160-6168 ◽

Cited By ~ 117

Author(s):

I E Zohn ◽

H Yu ◽

X Li ◽

A D Cox ◽

H S Earp

Keyword(s):

Epithelial Cells ◽

Rat Liver ◽

Ang Ii ◽

Tetraacetic Acid ◽

Independent Manner ◽

Calcium Dependent ◽

Liver Epithelial Cells ◽

Intracellular Ca ◽

Rat Liver Epithelial Cells ◽

Jnk Activation

In GN4 rat liver epithelial cells, angiotensin II (Ang II) and other agonists which activate phospholipase C stimulate tyrosine kinase activity in a calcium-dependent, protein kinase C (PKC)-independent manner. Since Ang II also produces a proliferative response in these cells, we investigated downstream signaling elements traditionally linked to growth control by tyrosine kinases. First, Ang II, like epidermal growth factor (EGF), stimulated AP-1 binding activity in a PKC-independent manner. Because increases in AP-1 can reflect induction of c-Jun and c-Fos, we examined the activity of the mitogen-activated protein (MAP) kinase family members Erk-1 and -2 and the c-Jun N-terminal kinase (JNK), which are known to influence c-Jun and c-Fos transcription. Ang II stimulated MAP kinase (MAPK) activity but only approximately 50% as effectively as EGF; again, these effects were independent of PKC. Ang II also produced a 50- to 200-fold activation of JNK in a PKC-independent manner. Unlike its smaller effect on MAPK, Ang II was approximately four- to sixfold more potent in activating JNK than EGF was. Although others had reported a lack of calcium ionophore-stimulated JNK activity in lymphocytes and several other cell lines, we examined the role of calcium in GN4 cells. The following results suggest that JNK activation in rat liver epithelial cells is at least partially Ca(2+) dependent: (i) norepinephrine and vasopressin hormones that increase inositol 1,4,5-triphosphate stimulated JNK; (ii) both thapsigargin, a compound that produces an intracellular Ca(2+) signal, and Ca(2+) ionophores stimulated a dramatic increase in JNK activity (up to 200-fold); (iii) extracellular Ca(2+) chelation with ethylene glycol tetraacetic acid (EGTA) inhibited JNK activation by ionophore and intracellular chelation with 1,2-bis-(o-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid tetraacetoxymethyl-ester (BAPTA-AM) partially inhibited JNK activation by Ang II or thapsigargin; and (iv) JNK activation by Ang II was inhibited by pretreatment of cells with thapsigargin and EGTA, a procedure which depletes intracellular Ca(2+) stores. JNK activation following Ang II stimulation did not involve calmodulin; either W-7 nor calmidizolium, in concentrations sufficient to inhibit Ca(2+)/calmodulin-dependent kinase II, blocked JNK activation by Ang II. In contrast, genistein, in concentrations sufficient to inhibit Ca(2+)-dependent tyrosine phosphorylation, prevented Ang II and thapsigargin-induced JNK activation. In summary, in GN4 rat liver epithelial cells, Ang II stimulates JNK via a novel Ca(2+)-dependent pathway. The inhibition by genistein suggest that Ca(2+)-dependent tyrosine phosphorylation may modulate the JNK pathway in a cell type-specific manner, particularly in cells with a readily detectable Ca(2+)-regulated tyrosine kinase.

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Maximal rate of blood lactate accumulation during exercise at altitude in humans

Journal of Applied Physiology ◽

10.1152/jappl.1995.79.1.331 ◽

1995 ◽

Vol 79 (1) ◽

pp. 331-339 ◽

Cited By ~ 18

Author(s):

B. Grassi ◽

G. Ferretti ◽

B. Kayser ◽

M. Marzorati ◽

A. Colombini ◽

...

Keyword(s):

Sea Level ◽

Exercise Bout ◽

Exercise Duration ◽

Bicycle Ergometer ◽

Glycolytic Flux ◽

Maximal Rate ◽

Lactate Accumulation ◽

Blood Lactate Accumulation ◽

The Individual

The lower peak lactate accumulation in blood ([La(b)]p) at altitude may be associated with a reduced maximal glycolytic flux. Based on certain assumptions, the latter can be indirectly evaluated in vivo, during short supramaximal exercises, by measuring the maximal rate of lactate accumulation in blood (delta [La(b)]max). delta [La(b)]max was determined on six white subjects at sea level (SL1), after approximately 1 wk (Alt1) and 4 wk (Alt2) of a 35-day sojourn at 5,050 m, and 1 wk after return to sea level (SL2). The subjects performed exercises of increasing duration (5, 15, 25, 35, 45 s or until exhaustion) on a bicycle ergometer at loads = 200% of the individual Wmax. The latter was previously determined in each condition as the greatest work rate that could be sustained for 2–4 min during an incremental exercise. Net [La(b)] accumulation (delta [La(b)]) was measured after each exercise bout. delta [La(b)] resulted to be linearly related to exercise duration. The slopes of the individual delta [La(b)] vs. exercise duration lines were taken as delta [La(b)]max. Exhaustion times were approximately 30–45 s in all conditions. [La(b)]p (in mM) during recovery after the exhaustive load was higher at SL1 (10.22 +/- 1.09; means +/- SD) than at Alt1 (5.08 +/- 0.82), Alt2 (8.13 +/- 2.67), and SL2 (8.18 +/- 1.43). delta [La(b)]max was lower at Alt1 (0.09 +/- 0.02) and at Alt2 (0.17 +/- 0.05) than at SL1 (0.25 +/- 0.05) and SL2 (0.23 +/- 0.06). Both [La(b)]p and delta [La(b)]max increased during acclimatization.

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