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result(s) for
"Overby, Peter"
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Skeletal muscle IL-6 regulates muscle substrate utilization and adipose tissue metabolism during recovery from an acute bout of exercise
by
Pilegaard, Henriette
,
Bertholdt, Lærke
,
Overby, Peter
in
Active control
,
Adaptation
,
Adipocytes
2017
An acute bout of exercise imposes a major challenge on whole-body metabolism and metabolic adjustments are needed in multiple tissues during recovery to reestablish metabolic homeostasis. It is currently unresolved how this regulation is orchestrated between tissues. This study was undertaken to clarify the role of skeletal muscle derived interleukin 6 (IL-6) in the coordination of the metabolic responses during recovery from acute exercise. Skeletal muscle specific IL-6 knockout (IL-6 MKO) and littermate Control mice were rested or ran on a treadmill for 2h. Plasma, skeletal muscle, liver and adipose tissue were obtained after 6 and 10h of recovery. Non-exercised IL-6 MKO mice had higher plasma lactate and lower plasma non-esterified fatty acids than Controls. The activity of pyruvate dehydrogenase in the active form was, in skeletal muscle, higher in IL-6 MKO mice than Controls in non-exercised mice and 6h after exercise. IL-6 MKO mice had lower glucose transporter 4 protein content in inguinal adipose tissue (WAT) than Control in non-exercised mice and 10h after treadmill running. Epididymal WAT hormone sensitive lipase phosphorylation and inguinal WAT mitogen activated kinase P38 phosphorylation were higher in IL-6 MKO than Control mice 6h after exercise. These findings indicate that skeletal muscle IL-6 may play an important role in the regulation of substrate utilization in skeletal muscle, basal and exercise-induced adaptations in adipose tissue glucose uptake and lipolysis during recovery from exercise. Together this indicates that skeletal muscle IL-6 contributes to reestablishing metabolic homeostasis during recovery from exercise by regulating WAT and skeletal muscle metabolism.
Journal Article
The Novel J-Domain Protein Mrj1 Is Required for Mitochondrial Respiration and Virulence in Cryptococcus neoformans
by
Hu, Guanggan
,
Johnson, James D.
,
Kronstad, James W.
in
Adaptation
,
Alternative oxidase
,
Amino acids
2020
Cryptococcus neoformans is the causative agent of cryptococcal meningitis, a disease responsible for ∼15% of all HIV-related deaths. Unfortunately, development of antifungal drugs is challenging because potential targets are conserved between humans and C. neoformans . In this context, we characterized a unique J-domain protein, Mrj1, which lacks orthologs in humans. We showed that Mrj1 was required for normal mitochondrial respiration and that mutants lacking Mrj1 were deficient in growth, capsule elaboration, and virulence. Furthermore, we were able to phenocopy the defects in growth and capsule elaboration by inhibiting respiration. This result suggests that the role of Mrj1 in mitochondrial function was responsible for the observed virulence defects and reinforces the importance of mitochondria to fungal pathogenesis. Mitochondria are difficult to target, as their function is also key to human cells; however, Mrj1 presents an opportunity to target a unique fungal protein required for mitochondrial function and virulence in C. neoformans . The opportunistic fungal pathogen Cryptococcus neoformans must adapt to the mammalian environment to establish an infection. Proteins facilitating adaptation to novel environments, such as chaperones, may be required for virulence. In this study, we identified a novel mitochondrial co-chaperone, Mrj1 ( m itochondrial r espiration J -domain protein 1 ), necessary for virulence in C. neoformans . The mrj1Δ and J-domain-inactivated mutants had general growth defects at both routine laboratory and human body temperatures and were deficient in the major virulence factor of capsule elaboration. The latter phenotype was associated with cell wall changes and increased capsular polysaccharide shedding. Accordingly, the mrj1Δ mutant was avirulent in a murine model of cryptococcosis. Mrj1 has a mitochondrial localization and co-immunoprecipitated with Qcr2, a core component of complex III of the electron transport chain. The mrj1 mutants were deficient in mitochondrial functions, including growth on alternative carbon sources, growth without iron, and mitochondrial polarization. They were also insensitive to complex III inhibitors and hypersensitive to an alternative oxidase (AOX) inhibitor, suggesting that Mrj1 functions in respiration. In support of this conclusion, mrj1 mutants also had elevated basal oxygen consumption rates which were completely abolished by the addition of the AOX inhibitor, confirming that Mrj1 is required for mitochondrial respiration through complexes III and IV. Furthermore, inhibition of complex III phenocopied the capsule and cell wall defects of the mrj1 mutants. Taken together, these results indicate that Mrj1 is required for normal mitochondrial respiration, a key aspect of adaptation to the host environment and virulence. IMPORTANCE Cryptococcus neoformans is the causative agent of cryptococcal meningitis, a disease responsible for ∼15% of all HIV-related deaths. Unfortunately, development of antifungal drugs is challenging because potential targets are conserved between humans and C. neoformans . In this context, we characterized a unique J-domain protein, Mrj1, which lacks orthologs in humans. We showed that Mrj1 was required for normal mitochondrial respiration and that mutants lacking Mrj1 were deficient in growth, capsule elaboration, and virulence. Furthermore, we were able to phenocopy the defects in growth and capsule elaboration by inhibiting respiration. This result suggests that the role of Mrj1 in mitochondrial function was responsible for the observed virulence defects and reinforces the importance of mitochondria to fungal pathogenesis. Mitochondria are difficult to target, as their function is also key to human cells; however, Mrj1 presents an opportunity to target a unique fungal protein required for mitochondrial function and virulence in C. neoformans .
Journal Article
Beta-cell specific Insr deletion promotes insulin hypersecretion and improves glucose tolerance prior to global insulin resistance
2022
Insulin receptor (Insr) protein is present at higher levels in pancreatic β-cells than in most other tissues, but the consequences of β-cell insulin resistance remain enigmatic. Here, we use an
Ins1
cre
knock-in allele to delete
Insr
specifically in β-cells of both female and male mice. We compare experimental mice to
Ins1
cre
-containing littermate controls at multiple ages and on multiple diets. RNA-seq of purified recombined β-cells reveals transcriptomic consequences of
Insr
loss, which differ between female and male mice. Action potential and calcium oscillation frequencies are increased in
Insr
knockout β-cells from female, but not male mice, whereas only male β
Insr
KO
islets have reduced ATP-coupled oxygen consumption rate and reduced expression of genes involved in ATP synthesis. Female β
Insr
KO
and β
Insr
HET
mice exhibit elevated insulin release in ex vivo perifusion experiments, during hyperglycemic clamps, and following
i.p
. glucose challenge. Deletion of
Insr
does not alter β-cell area up to 9 months of age, nor does it impair hyperglycemia-induced proliferation. Based on our data, we adapt a mathematical model to include β-cell insulin resistance, which predicts that β-cell
Insr
knockout improves glucose tolerance depending on the degree of whole-body insulin resistance. Indeed, glucose tolerance is significantly improved in female β
Insr
KO
and β
Insr
HET
mice compared to controls at 9, 21 and 39 weeks, and also in insulin-sensitive 4-week old males. We observe no improved glucose tolerance in older male mice or in high fat diet-fed mice, corroborating the prediction that global insulin resistance obscures the effects of β-cell specific insulin resistance. The propensity for hyperinsulinemia is associated with mildly reduced fasting glucose and increased body weight. We further validate our main in vivo findings using an
Ins1
-CreERT transgenic line and find that male mice have improved glucose tolerance 4 weeks after tamoxifen-mediated
Insr
deletion. Collectively, our data show that β-cell insulin resistance in the form of reduced β-cell
Insr
contributes to hyperinsulinemia in the context of glucose stimulation, thereby improving glucose homeostasis in otherwise insulin sensitive sex, dietary and age contexts.
Insulin receptor protein is present in pancreatic β-cells, but the consequences of β-cell insulin resistance are incompletely understood. Here the authors use a combination of mouse studies and mathematical modelling to show that loss of beta-cell insulin receptor affects male and female mice differently and can contribute to hyperinsulinemia in the context of glucose stimulation.
Journal Article
PGC‐1α promotes exercise‐induced autophagy in mouse skeletal muscle
by
Overby, Peter
,
Ringholm, Stine
,
Pilegaard, Henriette
in
Animals
,
Autophagy
,
Autophagy - physiology
2016
Recent evidence suggests that exercise stimulates the degradation of cellular components in skeletal muscle through activation of autophagy, but the time course of the autophagy response during recovery from exercise has not been determined. Furthermore, the regulatory mechanisms behind exercise‐induced autophagy remain unclear, although the muscle oxidative phenotype has been linked with basal autophagy levels. Therefore, the aim of this study was to investigate the role of the key regulator of muscle oxidative capacity, PGC‐1α, in exercise‐induced autophagy at several time points during recovery. Mice with transgenic muscle‐specific overexpression (TG) or knockout (MKO) of PGC‐1α and their respective littermate controls were subjected to a single 1 h bout of treadmill running and euthanized immediately (0 h), 2, 6, and 10 h after exercise. In the PGC‐1α MKO strain, quadriceps protein content of the autophagy marker LC3II was increased from 2 h into recovery in lox/lox control, but not in MKO mice. In the PGC‐1α TG strain, quadriceps protein content of LC3II was increased from 2 h after exercise in TG, but not in WT. Although AMPK and ACC phosphorylation was increased immediately following exercise, the observed exercise‐induced autophagy response was not associated with phosphorylation of the AMPK‐target ULK1. However, lower protein carbonyl content was observed in lox/lox and TG mice after exercise coinciding with the increased LC3 lipidation. In conclusion, the present results suggest a role of skeletal muscle PGC‐1α in coordinating several exercise‐induced adaptive responses including autophagic removal of damaged cellular components. Autophagy has been shown to be activated in skeletal muscle in response to a exercise and recent studies suggest a link between muscle oxidative phenotype and autophagy. We subjected mice with transgenic muscle‐specific overexpression or knockout of the regulator of muscle oxidative capacity, PGC‐1α to a single 1 h bout of treadmill running. Muscle‐specific knockout of PGC‐1α, abolished the elevation of the autophagy marker LC3II in skeletal muscle during recovery from exercise, while muscle‐specific overexpression of PGC‐1α promoted the exercise‐induced increase in LC3II content, together suggesting a role of PGC‐1α in coordinating exercise‐induced adaptive responses in skeletal muscle including autophagic removal of damaged cellular components.
Journal Article
Trump Wins First Round in Legal Battle Over Emoluments
2017
A federal district judge has dismissed a lawsuit alleging that President Trump is violating two anti-corruption provisions of the Constitution. [...]more than 200 House and Senate Democrats allege that Trump is violating the Foreign Emoluments Clause by failing to ask for congressional consent. Richard Blumenthal, D-Conn., and Rep. Jerrold Nadler, D-N.Y., said last night the judge's decision reinforces their argument that Congress ought to be involved.
Web Resource
Trump's Third Home Away From Home To Cost Taxpayers Millions
2017
With the official designation as a presidential residence, Congress appropriated up to $41 million to cover security costs incurred between the Jan. 20 inauguration and Oct. 1, which starts a new fiscal year. The costs are incurred by state, county and township law enforcement officers when Trump comes to town, as he did this month for the U.S. Women's Open golf tournament.
Web Resource
Ethics Agency Rejects White House Move To Block Ethics Waiver Disclosures
2017
The Office of Government Ethics has rejected a White House attempt to block the agency's compilation of federal ethics rules waivers granted to officials hired into the Trump administration from corporations and lobbying firms. The White House has raised a conflict-of-interest question to challenge newly appointed special counsel Robert Mueller, who will oversee the FBI's investigation of Russian interference in the 2016 election.
Web Resource
House Democrats Lose Another Bid To Investigate Trump, But Don't Plan To Quit
2017
The resolution, sponsored by Rep. Bill Pascrell, D-N.J., has already gone down on party-line votes in the Ways and Means Committee and on the House floor.
Web Resource
Progressives Push New York Attorney General To Investigate Trump
2017
New York State Attorney General Eric Schneiderman provided no specifics but told NPR a charter challenge is indeed part of a broader discussion among Democratic attorneys general about President Trump's business holdings. The coordinated legal strategy being developed by Schneiderman and other Democratic state attorneys general would be similar to what happened in the Obama era when Republican AGs banded together to challenge the Affordable Care Act and various environmental regulations.
Web Resource