cell cycle i molecular cell biology november 6, 2014

Cell Cycle I

Molecular Cell BiologyNovember 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

Figure 17-3. Molecular Biology of the Cell, 4th Edition

• 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

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

• 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

Figure 17-13 Molecular Biology of the Cell, 4th Edition

What critical features are needed for proper guidance through the cell cycle?

The cell cycle is primarily regulated by cyclically activated protein kinases

Figure 17-15, 17-16 Molecular Biology of the Cell, 4th Edition

Malumbres M, Nature Reviews Cancer 2009

Evolution of cell cycle control: from yeast to humans

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

Overview of major cyclins and Cdks of vertebrates and yeast

Cdk activity is regulated by inhibitory phosphorylation and inhibitory proteins

Figure 17-18, 17-19. Molecular Biology of the Cell, 4th Edition

Why is cell cycle progression governed primarily by inhibitory regulation?

Figure 17-20. Molecular Biology of the Cell, 4th Edition

Cell cycle control depends on cyclical proteolysis

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

Figure 17-34. Molecular Biology of the Cell, 4th Edition

Overview of the cell cycle control system

Table 17-2. Molecular Biology of the Cell, 4th Edition

Summary of major cell cycle regulatory proteins

Figure 17-41. Molecular Biology of the Cell, 4th Edition

Mitogens stimulate cell division

Figure 17-42. Molecular Biology of the Cell, 4th Edition

Excessive stimulation of mitogenic pathways can lead to cell cycle arrest or cell death

Figure 17-44. Molecular Biology of the Cell, 4th Edition

Extracellular Growth Factors Stimulate Cell Growth

Figure 17-47. Molecular Biology of the Cell, 4th Edition

Extracellular Survival Factors Suppress Apoptosis

Intracellular signaling networks related to cell proliferation and cancer

Hanahan and Weinberg, Cell 2011

Primary myelofibrosis

Essential thrombocythemia

Polycythemia vera

JAK2 V617F

Myeloproliferative neoplasms are clonal disorders derived from hematopoietic stem/progenitor cells

Proliferation/Survival

JAK2JAK2

STAT3/5P P

STAT3/5 STAT3/5P P

P P

STAT3/5

TPOG-CSF

JAK2V617F

STAT3/5 STAT3/5P P

JAK-STAT activation is a hallmark of myeloproliferative neoplasms

Proliferation/SurvivalTNFαPIM1

JAK2JAK2

STAT3/5P P

STAT3/5 STAT3/5P P

P P

STAT3/5

TPOG-CSF

JAK2V617F

Rux

STAT3/5 STAT3/5P P

PI3K

AKT

S6K

S6

P P

SCFFLT-3L

LNK LNKSOCS

CBL

P PNFkB

Proliferation/SurvivalTNFα, GM-CSFIkBα

IkB degradation

IKKε

IKKγ P

P P

IkBαNFkB

TLRs

TBK1P

IKKα IKKβ

IkBαP

NFkBP P

PIM1BAD

CREB

RAS

RAF

MEK

ERK

Dysregulated signaling networks in myeloproliferative neoplasms

Cell cycle inhibition/Apoptosis

STAT1P

STAT3/5

JAK1JAK1

STAT1 STAT1P P

P P

Ifna

STAT1STAT1P P

STAT1STAT1P P

P

Spectral limitations of flow cytometry can be overcome with elemental mass cytometry

>30 parameters with single cell

resolution

Labeled cells

Metal conjugatedantibodies

CyTOF2mass cytometer

Mass channel readout

SPADE links related cell types in a multidimensional continuum of marker expression

Bendall et al Science 2011

How can we visualize data in 30+ dimensions?

SPADE identifies relevant cell subsets including HSPC

CD34 median expression:

Low High

HSPC

Cell cycle analysis via mass cytometry

Behbehani et al, Cytometry 2012

Cell cycle analysis via mass cytometry

Behbehani et al, Cytometry 2012

Malumbres M, Nature Reviews Cancer 2001

Cell cycle regulators are frequently disrupted in cancer

Malumbres M, Nature Reviews Cancer 2009

Overview of CDK inhibitors in clinical development for cancer therapy

Results thus far have been somewhat disappointing – why?

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