Cell death, Cell tissue/survival assays, models of cell survival Flashcards
executioner caspases
Caspase-3, -6, -7
Senescence
Permanent arrest in G1
Cell aging, they lose the ability to divide. Can also be induced by radiation.
Extrinsic apoptotsis pathway Initiator
Caspase 8
Hallmark of apoptosis
Chromatin condensation, large nucleus, membrane blebbling
4 R’s
Repair
Redistribution
Repopulation
Reoxygenation (last step)
Quiescence
reversible, physiological, G0.
Terminal differentiation
Irreversible. Physiologically active process, less commonly induced by RT.
Time frame for Mitotic catastrophe
hours - days since cells have to go through the cycle
Necroptosis requires what protein?
Regulated necrosis. RIPk1/RIPk3, induced by cell death receptors. Lacks caspase activation.
Ferroptosis
iron-dependent non-apoptotic regulated cell death induced by lipid peroxidation.
PCR of apoptosis vs mitotic catastrophe
apoptosis is a ladder, mitotic catastrophe is a smear
Inhibitors of apoptosis
Survivin, XIAP
Role of SMAC/DIABLE in apoptosis
Downregulate apoptosis inhibitors
Assays for apoptosis
TUNEL (uses TdT to transfer biotin-dUTP to strand breaks of cleaved DNA)
DNA Ladder formation (gel electrophoresis)
Annexin V labeling (most common, flow cytometry, detects phosphatydyl serase on the membrane prior to DNA cleavage)
DAPI - DNA specific flourescent dye
What happens in the execution phase of apoptosis?
Nucleases cleave DNA into 180-200 base pair increments
TNFR protein family is involved with what?
The extrinsic apoptosis pathway
Bcl-xL inhibition of apoptosis takes place where?
mitochondrion
Beclin is involved with what cell death process?
Autophagy
What paracrine signal from apoptosis stimulates proliferation in other cells?
Caspase 3
In the jejunum, are crypt stem cells morphologically different from differentiated cells?
no, but they proliferate 3-4 days after RT so you can check regrowth
Till & McCulloch’s studies of RT response in murine heme colony forming units represent the first
demonstration of the presence of rare, pluripotent stem cells in normal tissue
D(0) is also called the
mean lethal dose
Equation relating mean lethal dose D(0), N, and Dq
ln(N) = Dq/D(0)
D(0) definition
dose required to reduce the population of cells by a factor of 0.37.
Sometimes it is easier to use the dose required to reduce the population by a factor of 10 (0.1 to 0.01 etc) instead of D(0). D10 = D(0) ln10
Tumor Control Equation
TCP = e ^(SF*M)
90% cure is _____ surviving cells
0.105 surviving cells
61% cure is _____ surviving cells
0.5
50% cure is _____ surviving cells
.693
37% cure is _____ surviving cells
1
10% cure is _____ surviving cells
2.3
Average number of surviving cells equation
N = SF * M
% cure equation
TCP = e ^n (n= number of surviving cells)
When given the D0 in a cell survival problem, what steps can you take to solve for total dose?
1) find number of log kills
2) find D10 of dose for 1 decade of log kills D10 = 2.3* D0
3) D10 * n log kills = total dose
SF2
surviving fraction after 2 Gy
e^(-1)
0.37
D0 of most mammalian cells
1-2 Gy
If N = 1 then the curve is
exponential (appears straight on the log graph)
B= 0 means that…
All sublethal damage has been repaired
Tumor regrowth assay
measures the time it takes for a tumor (in a mouse) to grow to a pre-determined size compared to controls
Ras-Raf Mek ERK/MAPK leads to
cell proliferation
Ras PI3K Akt mTOR pathway leads to
protein synthesis
Ras Raf Mek ERK Msk1
Chromatin modeling
Ras pathway with Jnk/Sek-1 leads to
Apoptosis
