lipids synth- pt2 Flashcards
what is elevated haptic SCD1 associated with
increased VLDL synthesis (and
subsequently increased LDL)
what is Whole-body SCD1 activity is directly
proportional to
degree of obseity
excess SCD1 activity and tumors
Several tumours have excessive oleate
levels due to excess SCD1 activity
Excessive SCD1 activity in skin leads to
scaly lesions (combated by dietary 18:2)
SCD1 and production of linoleate and linolenate
SCD1 is essential toward the production of
precursors for the synthesis of the
essential fatty acids linoleate and
linolenate, and ultimately arachidonate
and eicosanoid synthesis
how is oleate related to SCD1
SCD1 is essential for providing oleate in
myelin synthesis
B and T lymphocytes and SCD1
SCD1 is necessary for regulating B- and
T-lymphocyte functions (by modulating
stearate levels)
omega 3 FA examples
ALA
EPA
DHA
omega 3 and 6 FA benificial or detrimental?
Evidence to date suggests that omega-3 fatty acids are more beneficial than detrimental
omega-6 fatty acids are more detrimental than beneficial
examples of omega 6 FA
LA and arachidonate
Omega-3 and -6 fatty acids
influence gene transcription
Liver-X-receptor / retinoic acid-X-receptor heterodimer:
– Increase expression of cholesterol efflux
transporters (beneficial), but increases
expression of FAS and SCD1 (detrimentally
leading to hypertriglyceridemia and hepatic
steatosis)
– Oxysterols (derived from cholesterol) activate
LXR/RXR activity
– Omega-3 and -6 fatty acids inhibit oxysterol
activation of LXR/RXR
Omega-3 and -6 fatty acids
influence gene transcription
Sterol regulatory element binding protein
(SREBP):
– Increases expression of several elongases
and desaturases, synthesis of FAS, and
synthesis of cholesterol
– SREBP resides on the ER membrane, then is
cleaved, resulting in activation and transport
to the nucleus
– Omega-3 and -6 fatty acids inhibit the
cleavage of SREBP
Omega-3 and -6 fatty acids
influence gene transcription
Carbohydrate response element binding
protein (ChREBP):
– Increases expression of FAS
– ChREBP is phosphorylated and needs to be
dephosphorylated to be active
– Omega-3 and -6 fatty acids inhibit the
dephosphorylation of ChREBP
Omega-3 and -6 fatty acids
influence gene transcription
Peroxisome proliferator activated receptor
(PPAR) / RXR heterodimer:
– Increases expression of Δ5 and Δ6
desaturases, lipoprotein lipase, proteins
associated with β-oxidation, and improves
insulin sensitivity
– Omega-3 and -6 fatty acids activate the
PPAR/RXR heterodimer
what do omega 3 fatty acids do to CVD risk
decrease CVD risk
n the nervous system, omega-3 fatty acids:
– Are essential for learning and memory (based
on in vivo studies);
– Increase cellular energy to improve
neurotransmission;
– Stimulates neuronal growth
the brain and DHA
The brain loses DHA with age, resulting in increased lipid oxidation, ischemia, inflammation, and amyloid burden
Omega 3 and omega 6 FA and eicosanoids
Both omega-3 and omega-6 fatty acids are
used for the synthesis of eicosanoids:
– a class of very potent short-range lipid
signalling molecules involved in pain,
inflammation, regulation of blood pressure,
blood clotting, reproduction, etc.
effect of the amount of omega 3 and 6 derived eicosanoids on health
Omega-3 and -6 derived eicosanoids are
important, but excess omega-6
eicosanoids result in excess inflammation
and detrimental outcomes (such as utirine
contraction and premature birth)
