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Abnormalities of AMPK activation and glucose uptake in cultured skeletal muscle cells from individuals with chronic fatigue syndrome.

Brown AE, Jones DE, Walker M, Newton JL - PLoS ONE (2015)

Bottom Line: Control cultures subjected to 16 h EPS showed a significant increase in both AMPK phosphorylation and glucose uptake compared with unstimulated cells.IL6 secretion in response to EPS was significantly reduced in CFS compared with control cultures at all time points measured.We found four main differences in cultured skeletal muscle cells from subjects with CFS; increased myogenin expression in the basal state, impaired activation of AMPK, impaired stimulation of glucose uptake and diminished release of IL6.

View Article: PubMed Central - PubMed

Affiliation: Institute of Cellular Medicine, William Leech Building, Medical School, Newcastle University, Newcastle upon Tyne, United Kingdom.

ABSTRACT

Background: Post exertional muscle fatigue is a key feature in Chronic Fatigue Syndrome (CFS). Abnormalities of skeletal muscle function have been identified in some but not all patients with CFS. To try to limit potential confounders that might contribute to this clinical heterogeneity, we developed a novel in vitro system that allows comparison of AMP kinase (AMPK) activation and metabolic responses to exercise in cultured skeletal muscle cells from CFS patients and control subjects.

Methods: Skeletal muscle cell cultures were established from 10 subjects with CFS and 7 age-matched controls, subjected to electrical pulse stimulation (EPS) for up to 24h and examined for changes associated with exercise.

Results: In the basal state, CFS cultures showed increased myogenin expression but decreased IL6 secretion during differentiation compared with control cultures. Control cultures subjected to 16 h EPS showed a significant increase in both AMPK phosphorylation and glucose uptake compared with unstimulated cells. In contrast, CFS cultures showed no increase in AMPK phosphorylation or glucose uptake after 16 h EPS. However, glucose uptake remained responsive to insulin in the CFS cells pointing to an exercise-related defect. IL6 secretion in response to EPS was significantly reduced in CFS compared with control cultures at all time points measured.

Conclusion: EPS is an effective model for eliciting muscle contraction and the metabolic changes associated with exercise in cultured skeletal muscle cells. We found four main differences in cultured skeletal muscle cells from subjects with CFS; increased myogenin expression in the basal state, impaired activation of AMPK, impaired stimulation of glucose uptake and diminished release of IL6. The retention of these differences in cultured muscle cells from CFS subjects points to a genetic/epigenetic mechanism, and provides a system to identify novel therapeutic targets.

No MeSH data available.


Related in: MedlinePlus

Analysis of the differentiation capacity of control vs CFS cultures.Representative light microscope images of 2 control (top panels) and 2 CFS (bottom panels) cultures taken 7 days after initiation of differentiation. Images were taken at a 10x magnification (A). MYOG expression at 24h, 72h and 7 days after initiation of differentiation from control and CFS cultures was measured by QPCR (B). Data were normalised to the reference gene, β2-microglobulin and are presented as the mean±SEM from 5 controls and 8 CFS subjects analysed in triplicate. ***p<0.0001. IL6 release into the media was measured at 24h, 72h and 7 days after initiation of differentiation from control and CFS cultures by ELISA (C). Data are expressed as the mean±SEM from 5 controls and 8 CFS subjects in duplicate. *p<0.05.
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pone.0122982.g001: Analysis of the differentiation capacity of control vs CFS cultures.Representative light microscope images of 2 control (top panels) and 2 CFS (bottom panels) cultures taken 7 days after initiation of differentiation. Images were taken at a 10x magnification (A). MYOG expression at 24h, 72h and 7 days after initiation of differentiation from control and CFS cultures was measured by QPCR (B). Data were normalised to the reference gene, β2-microglobulin and are presented as the mean±SEM from 5 controls and 8 CFS subjects analysed in triplicate. ***p<0.0001. IL6 release into the media was measured at 24h, 72h and 7 days after initiation of differentiation from control and CFS cultures by ELISA (C). Data are expressed as the mean±SEM from 5 controls and 8 CFS subjects in duplicate. *p<0.05.

Mentions: Fig 1A shows representative light microscope images of both control and CFS cultures taken 7 days after initiation of differentiation. Morphological measurements were made from 5 fields of view for each cell culture (Table 1). While there were no statistical differences between control and CFS cultures in terms of length and equidiameter, area was significantly reduced in CFS compared to control (P<0.0001). There was no difference in myotube number between control and CFS cultures at this time point (p = 0.1761). At the 72h time point, while myotube number tended to be higher in the CFS compared with control cultures, this difference was not statistically significant. There were no significant differences in length, area or equidiameter at the 72h time point (S1 Table).


Abnormalities of AMPK activation and glucose uptake in cultured skeletal muscle cells from individuals with chronic fatigue syndrome.

Brown AE, Jones DE, Walker M, Newton JL - PLoS ONE (2015)

Analysis of the differentiation capacity of control vs CFS cultures.Representative light microscope images of 2 control (top panels) and 2 CFS (bottom panels) cultures taken 7 days after initiation of differentiation. Images were taken at a 10x magnification (A). MYOG expression at 24h, 72h and 7 days after initiation of differentiation from control and CFS cultures was measured by QPCR (B). Data were normalised to the reference gene, β2-microglobulin and are presented as the mean±SEM from 5 controls and 8 CFS subjects analysed in triplicate. ***p<0.0001. IL6 release into the media was measured at 24h, 72h and 7 days after initiation of differentiation from control and CFS cultures by ELISA (C). Data are expressed as the mean±SEM from 5 controls and 8 CFS subjects in duplicate. *p<0.05.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4383615&req=5

pone.0122982.g001: Analysis of the differentiation capacity of control vs CFS cultures.Representative light microscope images of 2 control (top panels) and 2 CFS (bottom panels) cultures taken 7 days after initiation of differentiation. Images were taken at a 10x magnification (A). MYOG expression at 24h, 72h and 7 days after initiation of differentiation from control and CFS cultures was measured by QPCR (B). Data were normalised to the reference gene, β2-microglobulin and are presented as the mean±SEM from 5 controls and 8 CFS subjects analysed in triplicate. ***p<0.0001. IL6 release into the media was measured at 24h, 72h and 7 days after initiation of differentiation from control and CFS cultures by ELISA (C). Data are expressed as the mean±SEM from 5 controls and 8 CFS subjects in duplicate. *p<0.05.
Mentions: Fig 1A shows representative light microscope images of both control and CFS cultures taken 7 days after initiation of differentiation. Morphological measurements were made from 5 fields of view for each cell culture (Table 1). While there were no statistical differences between control and CFS cultures in terms of length and equidiameter, area was significantly reduced in CFS compared to control (P<0.0001). There was no difference in myotube number between control and CFS cultures at this time point (p = 0.1761). At the 72h time point, while myotube number tended to be higher in the CFS compared with control cultures, this difference was not statistically significant. There were no significant differences in length, area or equidiameter at the 72h time point (S1 Table).

Bottom Line: Control cultures subjected to 16 h EPS showed a significant increase in both AMPK phosphorylation and glucose uptake compared with unstimulated cells.IL6 secretion in response to EPS was significantly reduced in CFS compared with control cultures at all time points measured.We found four main differences in cultured skeletal muscle cells from subjects with CFS; increased myogenin expression in the basal state, impaired activation of AMPK, impaired stimulation of glucose uptake and diminished release of IL6.

View Article: PubMed Central - PubMed

Affiliation: Institute of Cellular Medicine, William Leech Building, Medical School, Newcastle University, Newcastle upon Tyne, United Kingdom.

ABSTRACT

Background: Post exertional muscle fatigue is a key feature in Chronic Fatigue Syndrome (CFS). Abnormalities of skeletal muscle function have been identified in some but not all patients with CFS. To try to limit potential confounders that might contribute to this clinical heterogeneity, we developed a novel in vitro system that allows comparison of AMP kinase (AMPK) activation and metabolic responses to exercise in cultured skeletal muscle cells from CFS patients and control subjects.

Methods: Skeletal muscle cell cultures were established from 10 subjects with CFS and 7 age-matched controls, subjected to electrical pulse stimulation (EPS) for up to 24h and examined for changes associated with exercise.

Results: In the basal state, CFS cultures showed increased myogenin expression but decreased IL6 secretion during differentiation compared with control cultures. Control cultures subjected to 16 h EPS showed a significant increase in both AMPK phosphorylation and glucose uptake compared with unstimulated cells. In contrast, CFS cultures showed no increase in AMPK phosphorylation or glucose uptake after 16 h EPS. However, glucose uptake remained responsive to insulin in the CFS cells pointing to an exercise-related defect. IL6 secretion in response to EPS was significantly reduced in CFS compared with control cultures at all time points measured.

Conclusion: EPS is an effective model for eliciting muscle contraction and the metabolic changes associated with exercise in cultured skeletal muscle cells. We found four main differences in cultured skeletal muscle cells from subjects with CFS; increased myogenin expression in the basal state, impaired activation of AMPK, impaired stimulation of glucose uptake and diminished release of IL6. The retention of these differences in cultured muscle cells from CFS subjects points to a genetic/epigenetic mechanism, and provides a system to identify novel therapeutic targets.

No MeSH data available.


Related in: MedlinePlus