Adipogenesis from MSCs

Question 1

Give me 3 reagents that induce adipogenesis of MSCs

Answer 1

Insulin
Idomethacin
IBMX

Question 2

How do these regents induce adipogenesis?

Answer 2

increase PPAR(gamma) expression either directly or indirectly

Question 3

What is PPAR(gamma)?

Answer 3

Nuclear hormone receptor believed to be the master receptor of adipogenesis

Question 4

What is the difference in expression pattern of the two PPAR-gamma isoforms?

Answer 4

PPAR-g1 = ubiquitously expressed
PPAR-g2 = Adipose tissue only, appearing to be a more potent stimulator of adipogenesis

Question 5

What does PPAR-g2 bind to?

Answer 5

the 5’ flanking region of adipocyte P2 gene, one capable of inducing adipo-specific gene expression

Question 6

When is PPAR-g2 expresses?

Answer 6

Early adipo differentiation

Question 7

What is a unique ability of OE PPAR-g2?

Answer 7

Can induce TD of fibroblasts and myoblasitc cells into adipocytes

Question 8

What are the 3 C/EBPs that play roles in adipogenesis and which is most prominent?

Answer 8

alpha (most prominent)
beta
sigma

Question 9

When are the 3 C/EBPs expressed in adipogenesis?

Answer 9

a = late differentiation, immediately prior to activation of adipo-specific genes
B and s = early stages then diminish prior to terminal differentiation

Question 10

How to C/EBP b and s function in adipogenesis?

Answer 10

They relay hormone signals to activate alpha:
B and S induce PPAR-g via C/EBP binding sites int he PPAR promotor
PPAR-g activates C/EBPa
C/EBPa activates PPARg (+ve feedback loop)

Question 11

Give me 3 TF’s involved in the inducement of adipogenesis

Answer 11

PPAR-gamma2
C/EBP alpha, beta, sigma
SREBPI/Add-1

Question 12

How does TF SREBP1/Add-1 induce adipogenesis?

Answer 12

Interacts with E-box domain in PPAR-g promotor region
ALlows further regulation of PPAR-g to induce adipogenesis

Question 13

Give me 3 TF’s involved in the down regulation of adipogenesis

Answer 13

CHOPs
IDs
GATAs

Question 14

what does CHOP10 do and why is it important?

Answer 14

binds to C/EBP beta in early differentiation
Prevents it from binding to PPARg
therefore delays terminal differentiation of adipocytes
This is crucial in the initial clonal expansion step in vitro

Question 15

What do inhibitors of DNA binding (IDs) interact with in adipogenesis?

Answer 15

Prevent SREBPI/Add-1 from binding to E-box DNA regulatory signals
therefore cant upregulate PPARg

Question 16

What do GATA 2 and 3 do in adipogenesis and when/where are they expressed?

Answer 16

Seen in pre-adipocytes
Directly bind to PPAR-gs and forms complexes with C/EBP a or B
Prevents maturation from pre -> mature adipocytes