Pomegranate and green tea extracts protect against ER stress induced by a high-fat diet in skeletal muscle of mice.
OBJECTIVE
We tested the hypothesis that polyphenol-rich extracts can reduce endoplasmic reticulum (ER) stress induced by a high-fat diet (HFD) in skeletal muscle of mice.


METHODS
Mice were randomly assigned to four groups receiving during 20 weeks either a standard chow control (CTRL), or a HFD supplemented, or not, with pomegranate (HFD + P) or green tea (HFD + GT) extracts. After the nutritional intervention, mice were killed and gastrocnemius muscles were taken. Proteins and mRNA were measured by Western blot and RT-qPCR, respectively.


RESULTS
Body weight gain and visceral fat were higher in HFD, HFD + P and HFD + GT than in CTRL. The markers of the unfolded protein response BiP, XBP1u, XBP1s and ATF4 were higher only in HFD. In HFD + P and HFD + GT, this increase was not observed except for CHOP, which was elevated in all HFD groups. HFD increased also markers of ubiquitin-proteasome pathway, autophagy and oxidative stress, which were kept low in HFD + P and HFD + GT groups.


CONCLUSIONS
Our data provide evidence for a protective effect of pomegranate and green tea extracts against ER stress, oxidative stress and protein degradation induced by HFD in skeletal muscle. They give arguments for a usefulness of these natural nutritional compounds to fight against cellular dysfunctions related to fat excess.
Institute of Neuroscience, Université catholique de Louvain, Place Pierre de Coubertin-1, bte L8.10.01, 1348, Louvain-la-Neuve, Belgium.
Julie
J
Rodriguez
Hélène
H
Gilson
Cécile
C
Jamart
Damien
D
Naslain
Nicolas
N
Pierre
Louise
L
Deldicque
Marc
M
Francaux
D051701:Activating Transcription Factor 4 / Q000378:metabolism; D000818:Animals; D004268:DNA-Binding Proteins / Q000378:metabolism; D059305:Diet, High-Fat / Q000009:adverse effects*; D000091342:Endoplasmic Reticulum Chaperone BiP; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects*; D005260:Female; D006360:Heat-Shock Proteins / Q000378:metabolism; D029561:Lythraceae / Q000737:chemistry*; D051379:Mice; D008810:Mice, Inbred C57BL; D018482:Muscle, Skeletal / Q000187:drug effects*; D009765:Obesity / Q000188:drug therapy; D018384:Oxidative Stress / Q000187:drug effects; D010936:Plant Extracts / Q000494:pharmacology*; D059808:Polyphenols / Q000494:pharmacology; D000071701:Regulatory Factor X Transcription Factors; D015398:Signal Transduction; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism; D013662:Tea / Q000737:chemistry*; D014157:Transcription Factors / Q000378:metabolism; D056811:Unfolded Protein Response; D015430:Weight Gain / Q000187:drug effects; D000071717:X-Box Binding Protein 1
C081452:Atf4 protein, mouse; D004268:DNA-Binding Proteins; D000091342:Endoplasmic Reticulum Chaperone BiP; D006360:Heat-Shock Proteins; D010936:Plant Extracts; D059808:Polyphenols; D000071701:Regulatory Factor X Transcription Factors; D013662:Tea; D014157:Transcription Factors; D000071717:X-Box Binding Protein 1; C000605544:Xbp1 protein, mouse; D051701:Activating Transcription Factor 4; C546843:mTOR protein, mouse; D058570:TOR Serine-Threonine Kinases