Adipocytes

Question 1

What is adipose tissue?

Answer 1

Fat

More than just an energy store, also an endocrine organ

Question 2

Adipose tissue mass =?

Answer 2

Adipocytes (number and volume)

Question 3

How do you calculate BMI?

Answer 3

weight kg/ height m^2

Question 4

What is a healthy BMI?

Answer 4

18.5 to 24.9

Question 5

What are the different fat depots?

Answer 5

Subcutaneous depot

Visceral depot

Question 6

What are visceral fat pads?

Answer 6

Epicardial
Mesenteric
Omental
Retroperitoneal
Gonadal

Question 7

What are subcutaneous fat pads?

Answer 7

Abdominal
Gluteal
Femoral

Question 8

Body fat distribution is an independent determinant of?

Answer 8

Health

Question 9

Describe white adipose tissue morphology

Answer 9

Uniocular adipocytes
Preadipocytes
Stromal cells
Blood vessels

Question 10

How is adipose tissue mass regulated?

Answer 10

Pluripotent stem cell
Preadipocyte
Many preadipocytes
Differentiation
Adipocytes

Question 11

How does adipose tissue differentiate?

Answer 11

Pluripotent stem cells

Mesenchymal precursors

Question 12

What mesenchymal precursors form which adipose tissue?

Answer 12

MYF5- produced white adipose tissue

MYF+ produce both, but predominantly brown

Question 13

What can muscle satellite cells form?

Answer 13

Brown adipose tissue

Question 14

What can endothelial precursors form?

Answer 14

Both adipose tissue types

Question 15

What are the three types of adipose tissue?

Answer 15

Brown
Beige
White

Question 16

What are transcriptional regulators of adipogenesis?

Answer 16

Different transcriptional factors
Tightly controlled
Time dependent expression
Transcription factors interact with each other, co-activators and miRNA

Question 17

Name some typical white adipose tissue genes?

Answer 17

Fatty acid synthase
Fatty acid binding protein
Hormone sensitive lipase
Glut4
Acetyl coA carboxylase
Adipokines: adiponectin, leptin

Question 18

Models for adipose tissue

Answer 18

3T3 L1 rodent fibroblasts
SGBS human cells
Human primary pre-adipocytes

Question 19

What are the functions for white adipose tissue?

Answer 19

Energy storage
Physical protection
Cold protection
Endocrine organ

Question 20

How is energy best stored in the body?

Answer 20

Short term - glycogen

Long term - triglycerides

Question 21

How is dietary lipid uptake facilitated?

Answer 21

A challenge because they’re hydrophobic
Absorbed into the lymphatics
By lipoproteins

Question 22

How are lipids digested?

Answer 22

Triglycerides gut lumen are broken down to glycerol and fatty acids by pancreatic lipase
Fatty acids mix with bile acids and salts. Form water soluble micelle

Question 23

How are lipids absorbed?

Answer 23

Absorbed by enterocytes
Dissociate from bile acids and salts
Return to triglyceride
Packaged into a chylomicron and enters the lymphatics

Question 24

What are the major lipoproteins?

Answer 24

Chylomicrons
VLDL
LDL
HDL

Question 25

What is the role of chylomicrons?

Answer 25

Transport of triglycerides into the body | Made of triglycerides

Question 26

What is the role of VLDL?

Answer 26

Transport of triglycerides from the liver to the tissues | Made of cholesterol and triglycerides

Question 27

What is the role of LDL and HDL?

Answer 27

Mechanisms of moving cholesterol | Made of cholesterol and little triglyceride

Question 28

How are fatty acids deposited in tissues?

Answer 28

Chylomicrons in the blood stream Some triglyceride used immediately for energy The rest is deposited in adipose tissue

Question 29

How is fatty acid transported into adipose tissue?

Answer 29

Chylomicrons in adipose tissue capillaries Come in contact with lipoprotein lipase LPL hydrolyses the triglycerideand frees the fatty acid in the lumen Taken up into adipocytes by transporters

Question 30

What is the effect of insulin on adipose tissue?

Answer 30

Insulin release increases lipoprotein lipase expression and translocation Takes 2-3 hours

Question 31

What happens to the remnant of the chylomicron?

Answer 31

Returns to the liver Any triglyceride is packaged into VLDL None wasted

Question 32

Describe the process of de novo lipogenesis

Answer 32

The synthesis of lipids from glucose | Glucose + acetyl coA to malonyl coA to free fatty acids + glycerol to triglyceride

Question 33

What enzymes are involved in de novo lipogenesis?

Answer 33

Acetyl coA carboxylase Fatty acid synthase Esterification

Question 34

What is lipolysis?

Answer 34

Release of fatty acids stored in lipid droplets Driven by catecholamines or absence of insulin Catalysed by lipases

Question 35

How is the lipid droplet maintained?

Answer 35

Perilipin in the phospholipid layer protects from lipases | When phosphorylated, folds back, unprotected

Question 36

What lipases are involved in lipolysis?

Answer 36

Adipose triglyceride lipase Hormone sensitive lipase Monogylglycerol lipase

Question 37

Triglyceride to diaglyceride to monoglyceride to glycerol requires which enzymes?

Answer 37

ATGL HSL MGL

Question 38

What is NEFA?

Answer 38

Non-esterified fatty acid Enters the blood stream and binds to albumin Goes to tissues that need energy Glucose also enters blood

Question 39

How is lipolysis regulated?

Answer 39

``` Hormone sensitive lipase controlled by hormones Promoted by adrenaline and noradrenaline Inhibited by insulin Always a basal level by ATGL Catecholamines increase rate ```

Question 40

What does adipose tissue secrete?

Answer 40

``` Resistin TNFalpha IL-6 RBP4 Leptin Adiponectin Visfatin Omentin ```

Question 41

What is leptin?

Answer 41

Appetite regulator | When leptin levels decrease, the brain increases food intake

Question 42

What is adiponectin?

Answer 42

Widespread effects on liver, skeletal muscle, heart and vasculature, monocytes and macrophages Improves metabolism when secreted

Question 43

What is brown adipose tissue?

Answer 43

High thermogenic capacity Main function is heat production Multiple small lipid droplets Stain brown because many mitochondria

Question 44

What is thermogenesis?

Answer 44

Driven by catecholamines Beta3-AR is activated by (nor)adrenaline Signals via adenylyl cyclase, oAMP and PKA Triggers lipolysis Majority of fatty acids travel to the mitochondria

Question 45

What is UCP1?

Answer 45

Uncoupling protein Transports H+ from the inter membrane space into the matrix Produces heat

Question 46

What is the role of brown adipose tissue in infants?

Answer 46

``` Maintaining constant body temperature Mass declines with age Is present in adults Activated by the cold Beta adrenergic stimulation increases temperatures Could be an obesity treatment ```