Cell Cycle I
Molecular Cell Biology
November 6, 2014
Stephen Oh, M.D., Ph.D.
Assistant Professor
Division of Hematology
Outline
• Overview of the cell cycle
• Cell cycle regulation – fundamental concepts
• Cancer as a fundamental disruption in cell
cycle regulation
What is the basic function of the cell cycle?
• Accurately duplicate the vast amount of DNA in
chromosomes
• Segregate the copies precisely into genetically
identical daughter cells
Figure 17-2 Molecular Biology of the Cell, 4th Edition
The phases of the cell cycle
•
•
•
•
G1 – gap between M and S phases
S – DNA replication
G2 – gap between S and M phases
M - mitosis
• Interphase ~23 hours
• M phase ~1 hour
Figure 17-3. Molecular Biology of the Cell, 4th Edition
Why are gap phases needed?
What critical features are needed for
proper guidance through the cell cycle?
Figure 17-13 Molecular Biology of the Cell, 4th Edition
What critical features are needed for
proper guidance through the cell cycle?
Figure 17-13 Molecular Biology of the Cell, 4th Edition
• A clock, or timer, that turns on each event
at a specific time
• A mechanism for initiating events in the
correct order
• A mechanism to ensure that each event is
triggered only once per cycle
• Binary (on/off) switches that trigger events
in a complete, irreversible fashion
• Backup mechanisms to ensure that the
cycle can work properly even when parts
of the system malfunction
• Adaptability so that the system's behavior
can be modified to suit specific cell types
or environmental conditions
The cell cycle is primarily regulated by
cyclically activated protein kinases
Figure 17-15, 17-16 Molecular Biology of the Cell, 4th Edition
Evolution of cell cycle control: from yeast to humans
Malumbres M, Nature Reviews Cancer 2009
Overview of major cyclins and Cdks of
vertebrates and yeast
Table 17-1. Molecular Biology of the Cell, 4th Edition
Overview of major cyclins and Cdks of
vertebrates and yeast
Bardin AJ, Nature Rev Mol Cell Biol 2001
Cdk activity is regulated by inhibitory
phosphorylation and inhibitory proteins
Why is cell cycle progression governed
primarily by inhibitory regulation?
Figure 17-18, 17-19. Molecular Biology of the Cell, 4th Edition
Cell cycle control depends on cyclical proteolysis
Figure 17-20. Molecular Biology of the Cell, 4th Edition
Mechanisms controlling S-phase initiation
Figure 17-30. Molecular Biology of the Cell, 4th Edition
DNA damage leads to cell cycle arrest in G1
Figure 17-33. Molecular Biology of the Cell, 4th Edition
Overview of the cell cycle control system
Figure 17-34. Molecular Biology of the Cell, 4th Edition
Summary of major cell cycle regulatory proteins
Table 17-2. Molecular Biology of the Cell, 4th Edition
Mitogens stimulate cell division
Figure 17-41. Molecular Biology of the Cell, 4th Edition
Excessive stimulation of mitogenic pathways
can lead to cell cycle arrest or cell death
Figure 17-42. Molecular Biology of the Cell, 4th Edition
Extracellular Growth Factors Stimulate Cell Growth
Figure 17-44. Molecular Biology of the Cell, 4th Edition
Extracellular Survival Factors Suppress Apoptosis
Figure 17-47. Molecular Biology of the Cell, 4th Edition
Intracellular signaling networks related
to cell proliferation and cancer
Hanahan and Weinberg, Cell 2011
Myeloproliferative neoplasms are clonal disorders derived
from hematopoietic stem/progenitor cells
JAK2 V617F
Primary
myelofibrosis
Essential
thrombocythemia
Polycythemia vera
JAK-STAT activation is a hallmark of myeloproliferative neoplasms
TPO
G-CSF
JAK2
V617F
P
P
P
P
JAK2
JAK2
STAT3/5
P
STAT3/5
P
STAT3/5
P
STAT3/5
STAT3/5
P
STAT3/5
Proliferation/Survival
Dysregulated signaling networks in myeloproliferative neoplasms
TPO
G-CSF
Ifna
P
JAK1
P
P
P
STAT1
LNK
LNK
JAK2
V617F
Rux
JAK1
SCF
FLT-3L
P
P
JAK2
JAK2
P
P
P
P
STAT3/5
STAT1
SOCS
TLRs
STAT3/5
CBL
RAS
PI3K
RAF
AKT
STAT1
P
STAT1
P
IKKγ
P
IKKα IKKβ
P
S6K
ERK
STAT3/5
P
P
MEK
P
TBK1
IKKε
TNFα
IkBα
NFkB
S6
P
P
STAT3/5
STAT1
P
CREB
P
STAT3/5
P
PIM1
BAD
NFkB
P
IkBα
IkB degradation
P
STAT3/5
P
STAT1
P
STAT1
P
STAT3/5
Proliferation/Survival
TNFα
PIM1
P
Cell cycle inhibition/Apoptosis
NFkB
P
Proliferation/Survival
TNFα, GM-CSF
IkBα
Spectral limitations of flow cytometry can be overcome
with elemental mass cytometry
Intensity
>30 parameters
with single cell
resolution
Metal
conjugated
antibodies
Mass
Labeled cells
CyTOF2
mass cytometer
Mass channel
readout
How can we visualize data in
30+ dimensions?
Bendall et al Science 2011
SPADE links related cell types in a multidimensional continuum
of marker expression
SPADE identifies relevant cell
subsets including HSPC
CD15
Gran
HSPC
CD61
Mega
CD71
CD34 median
expression:
Low
High
Ery
Cell cycle analysis via mass cytometry
Behbehani et al, Cytometry 2012
Cell cycle analysis via mass cytometry
Behbehani et al, Cytometry 2012
Cell cycle regulators are frequently disrupted in cancer
Malumbres M, Nature Reviews Cancer 2001
Overview of CDK inhibitors in clinical
development for cancer therapy
Results thus far have been somewhat disappointing – why?
Malumbres M, Nature Reviews Cancer 2009
Suggested reading
• Alberts et al., Molecular Biology of the Cell, 4th Edition, Garland.
Updated 2001. Chapter 17.
– http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=mboc4.TOC&depth=2
• Malumres M, Barbacid M. Cell cycle, CDKs and cancer: a changing
paradigm. Nat Rev Cancer. 2009 Mar;9(3):153-66.
– http://www.nature.com/nrc/journal/v9/n3/full/nrc2602.html
• Hanahan and Weinberg. Hallmarks of Cancer: The Next Generation.
Cell. 2011 Mar 4;144(5):646-74.
– http://www.sciencedirect.com/science/article/pii/S0092867411001279
• Anand S, Huntly BJ. Disordered signaling in myeloproliferative
neoplasms. Hematol Oncol Clin North Am. 2012 Oct;26(5):1017-35.
– http://www.sciencedirect.com/science/article/pii/S0889858812001281
Contact: stoh@dom.wustl.edu