Muscle S13 Flashcards
(27 cards)
exercise physiology
exercise can transform skeletal muscle myofibrils to alter its metabolism
altering fiber type oxidative metabolism
- transforming from type II to type I means for efficient at using oxygen and higher endurance level
- upon cessation, metabolic changes are REVERSIBLE
marathon runner =
endurance; type I
sprint runner =
speed; type IIb
remodelling in skeletal muscles involve activation of..
intracellular singling pathways
activation of intracellular signalling pathways cause alteration in..
- muscle mass
- contractile properties
- metabolic states (modify myofibrils function lead to changes in muscle performance)
Signalling pathway for muscle remodelling
- stress signal (calcium influx)
- receptor receives signal
- activating factors
- change
calcium
primarily used as a second messenger for gene expression in myofibre
HDAC (histone deacetylases) kinases
activates and phosphorylate HDAC in response to increase in intensity of activity (increase cytosolic Ca2+)
phosphorylate of HDAC
create a docking site for chaperone protein 14-3-3 to bind to HDAC
binding of chaperone protein to HDAC
induces a conformational change in HDAC causing it to exit from nucleus and promoting MEF2 activation and leading to remodelling
HDAC
a class of enzymes that cause histones to wrap the DNA tightly
myocyte enhancer factor-2 (MEF2)
a protein/transcription factor that control gene expression and is important regulator of cellular differentiation
-addition of various stimuli enhance DNA binding and promoting muscle transcription
calcineurin
a calcium and calmodulin dependent phosphatase
-activated by sustained, low-amplitude calcium waves and is a sensor of contractile activity by sensing calcium fluctuations
calcineurin signaling initiated by..
sustained, low-amplitude calcium waves - allowing calcium to bind to calmodulin, activating calcineurin
activated calcineurin
dephosphorylates NFAT, resulting in translocation of NFAT from cytoplasm to nucleus where it associated with other transcription factors to activate specific sets of calcium-dependent target genes
NFAT activity found higher in .. compared to .. muscles.
slow; fast
NFAT activity required for maintenance of ..
slow myosin heavy chain gene expression and potentially in repression of fast myosin heavy chain IIb gene
peroxisome-proliferator-activated receptor gamma coactivator-1 (PGC-1)
a transcriptional coactivator that regulates the genes involving in energy metabolism
- considered master of mitochondrial gene expression
- shown to activate mitochondrial biogenesis and oxidative metabolism
- enriched in type I and induced by endurance exercise
peroxisome-proliferator-activated (PPAR)
major transcriptional regulator of fat burning in adipose tissue
-increase specifically in type I fibres
Exercise induction of PGC1 may … PPAR and induce..
activate; myofiber remodeling
in response to increase in workload which causes ATP depletion..
AMPK is activated
AMP-activated protein kinase (AMPK)
activates both the uptake and oxidation of glucose and fatty acid
-inhibits synthesis of fatty acids, cholesterol, and triglycerides
PI3K/Akt/mTOR
shown to be activated during hypertrophy (of cultured myoblasts in response to IGF-1
