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SCD final Flashcards

1
Q

MSCS properties

A

Non immunogenic due to ability to secrete immunosuppressive substances
Multipotent cells that can give rise to three main lineages - adipose, chondro and osteo

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2
Q

Normal function of mesenchymal SC

A

Structural support for parenchyma cells

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3
Q

Where do MSC reside

A

In the BOne marrow stroma and perivascular space

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4
Q

What is the morphology of MSCS in invitro culture

A

Spindle shape (fibroblast like morphology) and will adhere to the plastic in the dish

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5
Q

Why is MSC used/research in regenerative medicine ? What properties and how

A

MSCS are found to be immunogenic and hence there is a possibility that allograft transplant can be used.
It’s ability to home to injury site via blood stream injection
They can differentiate into different types of cell lineage
They are thought to regenerate via direct or indirect means

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6
Q

Indirect and direct means of MSC repair

A

Direct - directly contributing to tissue reconstitution

Indirect - secrete substances that influence the microenvronment and promote healing

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7
Q

What cells do MSCS influence to achieve immunosuppressive effect and what do they secrete

A

They suppress NK, T and DCs by producing factors such as NO and IDO

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8
Q

NSCS neuronal stem cells are multipotent stem cells that reside in the neural Epithelia

A

True

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9
Q

Process of neurogenesis

A
  1. The neural epithelial will proliferate and form radial glial cells
  2. Radial glial cell further proliferate and delaminates from the neuronal epithelia
  3. As the radial glial cell go through cell division, then uneven protein distribution at the surface of the cells due to mitotic spindle rotation results in asymmetric cell division, forming a ganglion mother cell and a neuroblast (radial glial cell)
  4. The GMC further differentiate into neurones
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10
Q

What one type of cell is a neuroblast

A

Multipotent stem cell

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11
Q

The uneven distribution of proteins in the neuroblast results in differentiation of what type of cell

A

GMC

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12
Q

What are the factors that determines multipotency of a NB and differentiation of GMC

A

NB- inscutable and Ba2

GMC - numb and Miranda

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13
Q

What is the function of numb protein?

A

Numb is a protein that promotes differentiation by inhibiting Notch. Notch normally promote pluripotency by activating the Jak stat pathway and inhibiting mapk

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14
Q

Direction of NSC differentiation

A

Towards the basal side of the brain

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15
Q

Where does neurogenesis occur in adults and is it common

A

It is rare but occurs in olfactory bulb and hippocampus (dentate gyrus). In olfactory built because the sensory neurones for smelling needs replacement every 6-7 weeks and memory formation requires neuronoplasticity

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16
Q

How does neuronal blasts generate large variety of other cell types

A

Due to the different types of NB produced and Via temporal TF codes they receive. The inheritance of TF determines cell fate and instructs lineage differentiation
Type I and type II NB (type 2 provide greater variety due to formation of intermediate NB that can further proliferate and renew thereby increasing complexity)

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17
Q

Older cells migrate more superficially in the brain

A

True

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18
Q

Extracting NSC

A

Extraction from inner cellular mass
Pluripotent ESC differentiate into NSCS
Tissue dissection from brain
Somatic cell de-differentiation from fibroblast directly back to NSC or induced back to pluripotent stem cells and then differentiate into NSC

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19
Q

Notch signalling pathway process

A

2 subsequent cleavage event upon ligand binding
ECD cleaved by TACE , TMD cleaved by gamma secretase which liberates ICD
ICD translocate into nucleus binding to CSL TF (cbf2 Su(H) Lag2) and displace NCoR also recruit coactivators
Transcription occurs

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20
Q

Genes transcribed after notch activation

A

Promote pluripotency

  • drive somatogenesis
  • HES gene
  • p21
  • cMyc
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21
Q

Notch is a cell surface protein that contains

And what does it bind to

A

Contains 36 EGF like repeats
Binds to EGF11/12 repeats - ligand often delta or serrate
Delta 1/3/4
Seerate 1/2

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22
Q

Juxtacrine explain

A

E.g. Notch
Juxtacrine is a signalling means whereby the ligand is attached to a cell surface of another cell and its rapid, close proximity signalling means

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23
Q

Notch in neuronal patterning

A
  1. Expression of proneuronsl genes is broad initially
  2. Expression will be restricted to a single cell cluster via lateral inhibition of notch
  3. Competition amongst cells to maintain delta expression will differentiate
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24
Q

Glycosylation of notch regulates interaction with ligand (t/f)

A

T

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25
How does glycosylation of notch interefeore with ligand interaction
Enhance binding to delta and inhibit serrate interaction | Important in d/v boundary formation
26
What is fringe
Fringe is prevalent in Cells around the boundary | It promotes glycosylation of notch which allows it to enhance its binding to delta and inhibit serrate
27
What is wingless/Wnt
WnT is a morphogen that can stimulate cell pluripotency and differentiation. High concentration of wnt promotes differentiation. It follows a French flag model. 350-400 a that is cysteine rich Adhere to ECM Paracrind action
28
What is the French flag model
French flag model depicts that the cells have the different threshold response to the same signalling molecule This is important in morphogenic cell differentiation
29
What is the wingless pathway
Wingless will bind to frizzle, a core receptor that is also formed with LRP. This then activate dishevelled which will inhibit the action of the GSK3/APC/axin complex whose function is to tag beta catenin for degradation. This causes beta catenin to be released and translocate to the nucleus, displace Groucho , a corepressor, on the TCF toprmote transcription
30
What genes are transcribed after wingless signalling
HOX, cMyc, cyclin D, MMP, VEGF | Things that are related to differentiation
31
# Define sc term - fate - specialise - determine
Fate - is what the cell will develop into Specialise - is what a cell will develop into when grown in an neutral and isolated environment Determine - is what a cell will develop into regardless of the environmental signals (doesn't respond to other influences) and is a consequence of induction
32
What does induction mean in SC term
Induction is the synchronise change that occurs as a result of interaction between two or more cells with distinct cell histories One group act as inducer and the other as responder. Which can further influence one another to increase cell complexity
33
Types of induction
Permissive - aka all or nothing. Cells only produce one kind of response until the threshold is reached Instructive - different response is produced in response to different concentration of signals
34
Somatic cell nuclear transfer (SCNT) definition
Aka. Cloning | Is the production of a genetically identical copy of a or part of an organism
35
Types of SCNTs
Embryonic Reproductive Therapeutic
36
``` Difference between the three types of SCNT in terms of Genomic sequence Epigenetics Mitochondria Appearance ```
Embryonic - all four will be the same (derive from the same embryo and mother - naturally it would have been twins) Reproductive - the underlying DNA and appearance willl be the same. But the mitochondria will be the same as the surrogate and the epigentics will be different as it respond to external stress conditions Therapeutic - similar to reproductive. But normally used to clone tissues or an organ, rather than an entire organism
37
SC niche is important for maintaining differentiation and quiescence of stem cells (t/f)
T
38
Communication between cells are
Clear and rapid (right time right pace) and determine - rate of differentiation - sensitivity of SC
39
SC regulation can be extrinsic and intrinsic and the boundary of this is
The ECM
40
Extrinsic regulation of sc
Defined by the orientation (position of the sc). If the sc is further away from the blood flow and receive low morphogen - tends to be quiescent
41
What cell secretes morphogen
mesenchymal cells
42
High morphogen levels normally indicates
Quiescent cell Pluripotency Close to niche
43
Intrinsic regulation of stem cells
Cell cycle regulators TF availability GF and cytokines
44
What's different about sc cell cycle ?
Abnormally short They don't have R checkpoint or other cell cycle check points and hence go straight to S phase It takes about 9-12 hrs to divide
45
What are the key factors that regulate pluripotency in an ESC
OCT4 SOX2 Nanog
46
OCT4 is
Pou5f1 domain TF Master regulator of pluripotency Coregulate with sox 2 and nanog Communicate and decide cell fate
47
SOX2 is
An SRY box2 TF Cooperates with OCT4 to maintain gene pluripotency Important in development in embryo Absolutely important in cell fate determination Important in activating pluripotency markers
48
Nanog is
A unique homeobox TF that also regulates pluripotency Downstream of OCT4 and SOX2 Very sensitive to downstream effect signals (LIF, BMP) LIF helps maintain Nanog expression Aids in activation transcription of pluripotency marketers and maintains stemness
49
LIF (leukaemic inhibitory factor
Can bind to receptor and activate jak stat pathway and inhibit mapk to prevent differentiation. Closely affect Nanog levels
50
How does a pluripotent SC maintain identity and differentiate into lineage
ESC sir pluripotent and can dif into three germ layers. For that, they just be poised and remain silent. BIVALENT modification allows them to do so. So they have both active and repressive markers. (H3K4/27) which are marked by TrxG and PcG respectively One will remain and the other is loss when dif occurs
51
DNA methylation occurs on the 1 st base (t/f
False | On the 5th pair
52
Where does DNA methylation occur
On. The 5th base of DNA and on cytosine residue
53
What are CpG islands
They are methylated DNA on cytosine residues and it is a way to silence a gene permanently Often in conserved area
54
Will there be more CpG islands in a cell that has yet to differentiate ?
No, those cells will be the least methylated and hence don't have many CpG islands
55
Is there a known DNA demethylase ?
Not in adult cells hence if DNA is met it is permanently silenced However in fertilisation, the spermatozoa and oocyte. Pronucleus needs to fuse to form a zygote. The heavily packaged DNA will rapidly demethylte during then.
56
What is the epigrnetic landscape
It is a concept representing representing stem cell development. It depicts the flexibility of a cell lineage differentiation decreases as they become more specified
57
Where do HSC originate from
Generated from blood islands formed by angiobkasr of mesodermal origin in the yolk sac . These cells will migrate to the AGM and form the first HSC
58
Process of frost HSC formation
Migration of angioblast to dorsal wall of Aorta where the endothelium cells will undergo EHT (endothelial haematopoietic transition) to produce haematopoietic progenitors which will later travel to the foetal liver
59
How do cells know what they are going to become?
Epigenetic markers and sequence specific transcription factors will instruct cell differentiation - dif TF is inherited throughout time
60
Master blood cell development regulator
Runx1
61
LT HSC V. ST HSC
LT HSC - great capacity in self renewal Mostly quiescent and can expand pool of HSC in the long run ST HSC- also multipotent but have insufficient renewal properties-differentiation will outcomepete self renewal
62
Where do the HSC reside
80% in endosteal of BM
63
Treatment for APML t(15;17)
ATRA to promote differentiation of WBC | Will bind to RAR which is bound to PML which is normally inhibited by HDAC
64
Faggot cells are expressed in what type of leukaemia
APML - contain crystallised granules
65
TF for RBC and Meg
EKLF and FLI1
66
TF for granulocyte
PU1
67
HSC transplant method
- CD34+ selection of LT HSCs from BM - Mobilise cells to peripheral by giving stimulating agents (Recombinant EPO, G-CSF for NP, TPO for platelet)
68
What is induction
Induction is the synchronised changes that occurs as a result of interaction between two one more cells with distinct cell history which results in cell determination
69
What is the concept of inducer and responder?
It is how cells influence one another and that results in the increase in complexity
70
Types of induction
Permissive - cells only produce 1 type of response after a certain threshold of signal is reached Instructive - cells respond to different concentrations of signals and repond in accordance to it
71
Juxtacrine signalling is
Rapid means of signalling whereby the ligand is bound to the receptor with direct cell cell contact
72
Notch activation results in transcription of what genes
CMYC HES p21
73
Fringe is what and what does it do
Fringe is a N'acetylglycosaminyltransferase that adds a sugar group onto notch in the ER lumen This allow notch to bind to delta better and inhibit serrated binding thereby facilitating D/V boundary formation
74
Fringe is expressed in which part of the wing
Dorsal compartment
75
VEntral area of the wing has high delta and weak sewerage expreesion and vice Versa for the dorsal compartment
Yes
76
Notch consist of how many EGF repeats to which does it's ligand bind to
EGF11/12
77
Low WnT signalling results in differentiation or pluripotency maintanence
Pluripotency maintenance
78
Notch pathway activates/inhibits what pathways
Activate JAK STAT | Inhibits MAPK
79
2 proteolytic event occurs when notch is bound to the ligand. What are they?
1) TACE cleaves ECD domain upon ligand binding | 2) gamma secretase cleaves TMD (S3 domain) to allow liberation of intercellular NOTCH (NICD)
80
Transcription of NOTCH genes
CMYC, HES, p21
81
HES GEnes recognise what type of promotors sequence
E box (CANNTG)
82
Activation of HES results in recruitment of what
Groucho, corepressor complex to repress transcription
83
Lateral inhibiton
The last cell that express active delta expression will differentiate Create neural pattern (by competition against each other)
84
Morphogen provide special information by forming concentration gradient that subdivides a field of cell by inducing or maintaining expression of target genes Is the concept of
French flag model
85
WnT is (characteristics)
A morphogen containing 350-400aa (cysteine rich glycoproteins) that adhere to ECM the action of which is graded

SCD (1 decks)

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