Lipids as signals Flashcards
Hormone is
any biochemical that can act as a signal
Three types of hormones
Paracrine - any hormone or signal that acts on the same tissue or nearby cells
Autocrine- influcnes itself, targets the cell that produces the signal
Juxtacrine- that requires close contact to produce an effect
Three types of lipids
Structural( membrane ) and bioactive lipids
Storage
Eight major categories of biological lipids
Fatty acids Glycerolipids Glycerophospholipids( membrane lipids+ bioactive) Sphingolipids ( bioactive +membrane) Sterol lipids Prenol lipids( vitamin A, K,E, -> bioactive) Saccharolipids ( bioactive) Polyketidies
Glycerophospholipids are precursors of
Inositol phosphate (phosphotylinositol 4,5-biphosphate ->PIP2)
Types of phospholipases
Phospholipase A1- hydrolyses of first ester bond
A2- second ester bond
C- detaches the sugar and phosphate group from glycerol
D- detaches sugar
How do you get IP3 and PIP23
PIP2 with phospholipase C->IP3(second messenger) +DAG
PIP2 with PI3Kinase->PIP3( nucleation center )
What stimulates glycogen breakdown
IP3 opens Ca channels
Binding of Ca to calmodulin activates phosphorylase kinase
Glycogen ->(glycogen phosphorylase)->glucose
How do sphingolipids participate in signal regulators?
Ceramides stabalize “Lipid drafts”
Sphingomyelins insulate nerve axons-> they allow the signal propagate faster
What is a Lipid raft?
Raft - is like a boat in the ocean ( phospholipid), rafts move freely along the cytoplasm membrane, they can carry any signaling mechanism with them , localizing the signal
What is the marker of blood groups
Glycosphingolipids
What is the basic sequence of sugars attached to sphingolipids?
glucose+galactose+GLcNAc+galactose+fructose-> N-antigen
Why do we have different blood types?
regulated by glycosyltransferases, enzymes that are coded in your gene that attaches a sugar
According to what glycosyltransferase you have, you have a specific sugar attached. In O people, we can have any glycosyltransferase, but because One nucleotide deletion in O group, no sugar attached
How do you get blood type A and B
A: basic+GalNAc
B:galactose
How do we get arachidonate?
It is released from glycerophospholipids by phospholipase A2
Arachidonic acid is
An eicosanoid
What can you get from eicosanoid
Prostaglandins
Thromboxane
Leukotriens
Lipoxin
The function of prostaglandins
Smooth muscle contraction, regulate blood flow, regulate body temperature
When you have fever , you have high concentration of them , prostaglandins are involved in the reproductive cycle ( involved in ovalution), uterine contraction in labering( can be used as drug ) or mence
Function of thromboxanes
form platelets
form blood clot
reduce blood flow
What are NSAIDs ad what do they do
nonsteroidal anti-inflammatory drugs (aspirin, iboprufen)
that blocks early steps in arachidonic acids, that prevent formation ofthromboxanes and prostaglandins by inhibiting cycloxigenase enzymes -> reduce inflammation,
what do leukotriens do
Airway smooth muscle contraction,
What is done in Asthma, Arthritis, organ transportation ,etc.
Prednisone is given, it inhibits phospholipase A2
Eicosanoids function through which signaling pathway
GPCR
Molecules derived from cholesterol
Testosteron (AR) Estradiol (ER) Cortisol (GR) Aldosterone (MR) Vitamin D
How are steroids transported in the blood
By carrier proteins, because they are lipids in the aqueous solution
What do steroids do
Affect cellular transcription through nuclear receptors
How do we sunthesize vitamin D in the skin and how it gets activated
formed in the skin from 7-
dehydrocholesterol in a photochemical reaction driven by the UV component of sunlight
Vitamin D3(cholecalciferol) is not itself biologically active, but it is converted by enzymes in the liver and kidney to 1α,25-dihydroxyvitamin D3 (calcitriol),.
What are linear and ring eicosanoids
Ring->prostaglandinds,thromboxanes
Linear->Lipoxin, leukotriens
Functions of calcitriol
a hormone that regulates calcium uptake in the
intestine and calcium levels in kidney and bone
Vitamin D3 deficiency results in
Rickets
Vitamin D sugnals through
VDR- nuclear receptor
Prenol lipids examples
Carotenoids, vitamin A
Vitamin A deficiency leads to
Growth retardation, night blindness
Tretinoin ised to treat
Retin -A is used to treat acne and wrinkled skin
What receptors are involved with vitamin A
Retinoic acid receptor (RAR)
Retinoid X receptor (RXR)
How do we get viramin A and use it
Vitamin A1 or β-
carotene in the diet can be converted enzymatically to all-trans-retinal and then to all-trans-retinoic acid
Vitamin A functions
regulate gene expression
central to embryonic development, stem cell differentiation, and cell proliferation
Function of vitamin A in vision
From all trans-retinal-> all-trans-retinol or obtained directly through the diet, can
be converted to the cis-retinal . This product combines with the protein opsin to form rhodopsin. When a rhodopsin
molecule is excited by visible light, the 11-cis-retinal undergoes a series of photochemical reactions that convert it to alltrans-
retinal .This transformation in the rod cell of the
vertebrate retina sends an electrical signal to the brain that is the basis of visual transduction
Tocopherols acting as cofactors examples
Vitamin E and vitamin K
Ubiquinone
Plastoquinone
Vitamin E and vitamin K functions
Vitamin E->an antioxidant. reacts with O2 radicals
Vitamin K- a blood clotting cofactor to prothrombin
What medicine is prescribed to patients with strokes
Warfarin : a blood coagulant . It inhibits prothrombin
Tocopherol is the same as
Prenol lipids
Functions of ubiquinone and platoquinone
Electron transporters in mitochondria
Ubiquinone -> coenzyme A in electric transport chain
Plastoquinone: chloroplast electron carrier
How does tretinoin reduce acne acne and skin wrinkle?
Tretinoin is all-trans retinoic acid
Acne occurs due to increased cell-cycle and increased inflammation
Tretinoin normalizes cell cycle and reduces expression of enzymes that increases proinflammatory response
Tretinoin increases Type 1 collagen expression and reduces matrix metalloproteinase expression->reduced skin wrinkle
