Lipids as signals Flashcards by Valeriya Boyarkina

Hormone is

any biochemical that can act as a signal

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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

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Three types of lipids

Structural( membrane ) and bioactive lipids

Storage

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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

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Glycerophospholipids are precursors of

Inositol phosphate (phosphotylinositol 4,5-biphosphate ->PIP2)

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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

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How do you get IP3 and PIP23

PIP2 with phospholipase C->IP3(second messenger) +DAG

PIP2 with PI3Kinase->PIP3( nucleation center )

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What stimulates glycogen breakdown

IP3 opens Ca channels
Binding of Ca to calmodulin activates phosphorylase kinase
Glycogen ->(glycogen phosphorylase)->glucose

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How do sphingolipids participate in signal regulators?

Ceramides stabalize “Lipid drafts”

Sphingomyelins insulate nerve axons-> they allow the signal propagate faster

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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

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What is the marker of blood groups

Glycosphingolipids

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What is the basic sequence of sugars attached to sphingolipids?

glucose+galactose+GLcNAc+galactose+fructose-> N-antigen

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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

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How do you get blood type A and B

A: basic+GalNAc
B:galactose

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How do we get arachidonate?

It is released from glycerophospholipids by phospholipase A2

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Arachidonic acid is

An eicosanoid

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What can you get from eicosanoid

Prostaglandins
Thromboxane
Leukotriens
Lipoxin

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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