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Regulation of Gene Expression > Broccoli: Lecture XVII > Flashcards

Broccoli: Lecture XVII Flashcards

Human Embryo Development

1
Q

What is a zygote?

A

the cell we derive from

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2
Q

How does the zygote form?

A

fusion of the sperm and ovum along the oviducts

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3
Q

What kind of single cell forms after the fusion of the sperm and ovum?

A

diploid cell

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4
Q

What is the membrane of the diploid cell?

A

membrane pellucida

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5
Q

What doe the membrane pellucida protecting the embryo from?

A

maternal tissue

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6
Q

When does the embryo break maternal tissue?

A

when it arrive in the uterus, it breaks the maternal tissue to attach to the maternal endometrium

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7
Q

How long does it take an embryo to travel from the oviduct to a uterus?

A

5 day in humans

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8
Q

How many times does the embryo divide during its journey to the uterus?

A

into 32 blastomeres

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9
Q

When does the morula stage of the embryo occur?

A

when it has divided into 32 blastomeres

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10
Q

What kind of cells are the 32 embryonic cells called?

A

totipotent cells

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11
Q

What happens when the embryo forms an internal cavity?

A

it becomes a blastocyst

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12
Q

What are the “flat cells” of the blastocyst?

A

trophoblast cells that generate the walls of the blastocyte

they protect a mass of 50 internal cells called inner cell mass (ICM)

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13
Q

What does the ICM do?

A

give rise to an entire individual

pluripotent stem cells that form organs

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14
Q

What do the trophoblast cells do?

A

give rise to the embryonic part of the placenta

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15
Q

What is the Leukemia Inhibitor Factor (LIF)?

A

molecule that maintains pluripotency

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16
Q

What is pluropotency a unique property of?

A

ICM at the blastocyst stage

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17
Q

When do adult stem cells form?

A

once the embryo forms the fetus

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18
Q

What are adult stem cells?

A

organ-specific stem cells, which are organ specific meaning they cannot be differentiated

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19
Q

Where are totipotent stem cells found?

A

only in the zygote in the morula stage (1-5 days)

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20
Q

When are pluripotent stem cells found?

A

when blastocyst is formed (5-10 days)

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21
Q

Adult stem cells are ___.

A

multipotent

22
Q

What does it mean is adult stem cells are multipotent?

A

they can differentiate into some cell types, but very few

23
Q

How are neuronal cells created?

A

ectoderm → neural plate (brain, spinal cord, and neural projections) & epidermal tissue (epidermis and epidermis sheets) → neural progenitors → neural tube

24
Q

What are BMP factors?

A

bone morphogenetic factors, which are expressed by the epidermis and specify the epidermal tissue

25
Q

What are fibroblast growth factors (FGF-2)?

A

the signal of BMPs protect neural progenitors by the FGF-2

FGF-2 are proteins that block the action of BMPs and specify the ectodermal cell to become neural progenitors

26
Q

How can we be use that the cultured cells are pluripotent?

A

we inject them into a blastocyst host in the blastocele cavity, which can the be replanted into a surogate mother

27
Q

What is a chimeric animal?

A

when an inoculated blastocyst attaches tot he endometrium and generates an embryo or fetus

they are animals that are generated by 2 different cell types (1 with an ICM of the host blastocyst and the other from ESCs cultured in vitro and injected in the blastocyst)

28
Q

If ESCs are injected, as they are in vitro, into an adult animal, what would they give rise to?

A

tumor of embryonic origin because the cells will not have a signal to be able to differentiate and cause them to stop proliferating

29
Q

What is the tumor called that is produced when ESC are implanted into adult tissue?

A

teratoma

30
Q

What is a hypotoxic environment?

A

environment that does not have much metabolic supprt

31
Q

What are the minimal molecular signals that are sufficient to maintain cells in a pluripotent state?

A

culture condition in which there are fibroblasts and animal serum

the 2 molecules found in these that are necessary for the pluropotency of the cells are PD0325901 and CHIR99021

32
Q

What is PD0325901?

A

small inhibitor of the FGF pathway

33
Q

What is CHIR99021?

A

inhibits the GSK3 pathway

34
Q

What do pluripotent cells express?

A

FGF4 receptor

35
Q

If FGF4 is expressed, what is caused?

A

iPS cells start to differentiate

36
Q

What are the 2 signals that activate the network of TFs that stimulate pluripotency?

A

β-catenin and STAT1/3

37
Q

What are the 3 pluripotency TFs?

A

Oct4
Sox2
Nanog

38
Q

What happens if Oct4, Sox2, and Nanog are not activated?

A

they do not specify inner cell mass and they lose their pluripotency

39
Q

Why is the ICM important in vivo and in vitro?

A

it creates a feed forward-loop that is essential to maintain the stable expression of proteins, which is required for the pluripotency state of the ESCs

40
Q

What is required to culture human embryonic stem cells?

A

FGF2 and activin without serum

41
Q

Describe the difference between human ESC and mouse ESC:

A

mice colonies have a dome shape, and human colonies are flat

trypsin is used for mice for single cell suspension and humans cannot grow from a single cell

42
Q

What are epiblast stem cells?

A

made from the epiblast, which is a late stage where the blastocyst starts to generate an ectoderm and are found in mice

43
Q

In the 1st experiment, what were the 4 factors found to be necessary to start the conversion of adult fibroblasts into mouse embryonic stem cells?

A

Oct4
Sox2
Klf4
c-Myc

44
Q

In the 2nd experiment, what was found?

A

fully mature hepatocyte can be reprogrammed into iPScell through the TFs Oct4, Sox2, Klf4, and c-Myc

45
Q

What is cell reprogramming?

A

the idea that we can reprogram the identity of cells altogether

46
Q

What is a limitation in cell reprogramming?

A

it is not very efficient: the pluripotency switch occurs in 1 of 100,000 cells

47
Q

Why is efficiency so low?

A

it is not known

48
Q

What are the Yamanaka factors?

A

Oct4
Sox2
Klf4
c-Myc

they can reprogram iPS cells into any type of cell

49
Q

What cells have a higher percentage of reprogramming?

A

progenitors of mature T & B cells

50
Q

Fibroblast-derived iPS cells have a ___ percentage to differentiate in blood stem cells compared to blood-derived iPS cells.

A

low

this infers the cells have memory

Regulation of Gene Expression (28 decks)

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