Transcript epigenetics_v3.1_-_MS_Format

Epigenetics:
”From Phenomenon to Field”
and
Impact on Plastic Surgery Research
Basic Science Seminar Series
University of Michigan
Department of Surgery
Section of Plastic Surgery
Brent M. Egeland, MD
October 13, 2007
Outline
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Importance

History
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Definitions
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Chemistry
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Laboratory Techniques
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Implications in Plastic Surgery
Why?
Definition: Epigenetics
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Waddington 1942
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Originally a combination of the
words "genetics" and "epigenesis"
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Epigenesis: differentiation of cells
from a totipotent state in embryonic
development (used in contrast to
"preformationism").
Definition: Epigenetics
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
69th CSH Symposia (2004):
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Conference Dedicated to Epigenetics
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No definition could be agreed upon
”An epigenetic phenomenon is a switch-like change in
phenotype that is heritable, but does not involve DNA
mutation.” C. David Allis
Why Epigenetics?
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Post-Genomic Era
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ENCODE
Genomics and proteomics is not enough
Contol of above beyond promoters and
regulators is of utmost importance in:
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Oncogenesis
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Stem Cell Biology
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Genetic therapy
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Aging
History
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Coalesced into field of study that affects
all areas of biology
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Collection of apparently disparate phenomena
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Over 1000 manuscripts on topic
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First observations dates to 1941
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HJ Mueller ”eversporting displacement”
McClintock noted that these positional effects were
the basis of ”mutible loci”
History
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X-Chromosome Inactivation
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Pre-32 cell stage
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mosaic cell population
History
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1980's: Molecular Biology and
Genetics
1990's: Genomics
2003: Human Genome
Complete
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2004: ENCODE
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2005: NCI announce:
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Human Epigenome Project
Definition: Epigenome
”Sum of genome-wide epigenetic patterns,
distinguishes and defines one tissue from
another, stem cells from somatic cells, and
aged from young cells.”
National Cancer Institute (NCI), Division of Cancer Biology (DCB)
Workshop on Defining the Epigenome: Addressing the Value and Scope of
a Human Epigenome Project
November 28–29, 2005
Andrew P. Feinberg and Peter A. Jones
Chromatin
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Euchromatin:
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Uncompacted
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Active
Heterochromatin:
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Compacted
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Untranscribed
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Changes with cell cycle
30nm Fiber
Beads on a String
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H1: Linker histone: contacts
the exit/entry of the DNA
strand on the nucleosome.
Linker DNA between Histones
Nucleosome
Histone
DNA Packaging
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Varys greatly with Cell Cycle
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DNA never completely ”naked”
Scaffold or Dynamic?
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Is chromatin simply a scaffold for packaging DNA?
Dynamic
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Histones are Modified
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DNA is Modified
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Heritable transcription states
Histone Modifications
K
K
Methylation
Acetylation == Transcriptional
Transcriptionally
Competence
Silenced
DNA Cellular Differentiation
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All cells inherit the same DNA sequences
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Cellular differentiation processes rely strongly on
epigenetic rather than genetic inheritance.
DNA Modification
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Chemical modification of DNA
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Can be inherited without sequence
change
Part of the epigenetic code
Methylation is most characterized
epigenetic mechanism
Commonly occurs at ”junk” DNA
DNA Methylation
DNA Methylation
CpG Islands
Laboratory Techniques
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Chromatin Immunoprecipitation
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Inhibition of Deacetylases (HDAC-I)
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Site-specific analysis of histone
methylation
Multigenerational assesment of above
Methylation-specific PCR in-situ
Hybridization
Q-PCR in Combination with ChIP
Consequences
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Genome is static
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Genotype
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Germ Cell Inheritance
Epigenome is dynamic
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Phenotype
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Somatic epigenetic inheritance
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Cellular "memory"
Most terminally (irreversibly)
differentiate
Morphogens activate/silence
genes – DNA is not altered
Consequences
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Mammals cannot respond to loss of some tissues
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Inability to regenerate limbs
Plant cells do not terminally differentiate
Evolution
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Short-term adaptation
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allowing for reversible phenotype
Allows multigenerational revisible
phenotypic switch to express and
repress that particular gene
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DNA message is unchanged
Differential mutation rates associated
with epigenetic features to control the
mutation rates of particular genes
Teratogens
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Exert effects on fetus by epigenetic means
Epigenetic effects may preserve effect of
teratogen throughout life of child
Can a teratogen exert influence offspring?
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Diethylstilbestrol: Second and possibly Third
generation effects
Research
Epigenetic Grants
140
130
120
110
100
Grants Awarded
90
80
70
60
50
40
30
20
10
0
2000
2001
2002
2003
Year
2004
2005
2006
2007
Why Do I Care?
?
Plastic Surgery
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Fundamentally involved in clinical epigenetics
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Aging
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Oncology
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Wound Healing
Basic Science in Plastic Surgery
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Regenerative medicine
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Stem Cell biology
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Organogenesis
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Neural plasticity
Oncology
Clin Cancer Res 2007;13(13) July 1, 2007
Aging
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Chronological or Epigenetically
Defined?
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Free-Radicals
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Oxidants
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Telomeres
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methylation
Aging
Change in phenotype with methylation of DNA.
Werner Syndrome
Breast Cancer
Stem Cells
Organogenesis
Neuroal Plasticity
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Why does the CNS
lack plasticity?
What are the
possibilitys of
increasing this
plasticity towards
regenerative capacity?
Hernia
Male Pattern Baldness
The list goes on....
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Are there differing methylation signatures of
fibroblasts in normal, hypertrophic, keloid
scarring.
Can fibrotic tissue (fibroblasts) be reversed to
form skin, bone, muscle?
Is cleft lip epigenetically inhereited?
Can we Modify Epigenetics?
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Can methylation be reversed?
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Rate decreased?
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Environment?
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Diet?
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Pharmacologically?
Diet
Agouti Gene: Yellow fur, obesity, diabetes, tumorogenesis
No Supplements
.
Methyl Donor Diet:
(onions, garlic,
beets, folic acid,
B12,
genestein)
HCC: Histone deacetylase inhibitors
(HDAC-I) & Demethylating agents
Journal of Clinical Oncology, 2006 ASCO Annual Meeting Proceedings Part I. Vol 24, No. 18S (June 20 Supplement), 2006: 10066
Decitabine & Azacitidine
5-aza-2'-deoxycytidine
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Mechanism of action:
aza
Phosphorylation and direct insertion into
DNA
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Blocks effects of DNA methyltransferase
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Causing hypomethylation fo DNA.
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Azacitidine
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May reverse inactivation of supressor
genes
Can lead to cytotoxicity, bone marrow
suppression
References
Age-related DNA methylation changes in normal huma...[Clin Cancer Res. 2007] - PubMed Result
A method to study the expression of DNA methyltran...[Methods Mol Biol. 2007] - PubMed Result
Clinical Trial: Epigenetics in the Aging Process
Decreased androgen receptor gene methylation in pr...[J Clin Endocrinol Metab. 2006] - PubMed Result
EMF Award: Epigenetic Control of Senescence and Aging
Entirely new approach to the treatment of aging
Epidermal stem cells are defined by global histone...[PLoS ONE. 2007] - PubMed Result
Epigenetic inactivation of the premature aging Werner syndrome gene in human cancer -- Agrelo et al. 103 (23): 8822 -- Proceedings of the National Academy of Sciences
From The Cover: Epigenetic differences arise during the lifetime of monozygotic twins -- Fraga et al. 102 (30): 10604 -- Proceedings of the National Academy of Sciences
Google Image Result for http://edoc.hu-berlin.de/dissertationen/seitz-stefanie-2004-10-20/HTML/seitz_html_21996ee1.png
Google Image Result for http://www.biophysik.uni-bremen.de/radmacher/gallery/osteoblast_b.gif
Google Image Result for http://www.med.ufl.edu/biochem/keithr/fig2pt2_flowchart-sm.gif
Google Image Result for http://www.mun.ca/biology/desmid/brian/BIOL2250/Week_Two/bead2sol.jpg
Human hair genealogies and stem cell latency. [BMC Biol. 2006] - PubMed Result
IngentaConnect Techniques Used in Studies of Age-Related DNA Methylation Changes
It Is Time for a Human Epigenome Project -- Rauscher 65 (24): 11229 -- Cancer Research
Leukemia - Abstract of article: Age-related differences in leukemia biology and prognosis: the paradigm of MLL-AF4-positive acute lymphoblastic leukemia
Mitochondria, oxidants, and aging. [Cell. 2005] - PubMed Result
Modern Pathology - Abstract of article: DNA methylation in breast and colorectal cancers
NOVA | Ghost in Your Genes | Epigenetic Therapy | PBS
NOVA: Epigenetic Therapy
http://www.bio.sci.osaka-u.ac.jp/bio_web/lab_page/ogura/photo-neuron.jpg
PLoS Biology - DNA Methylation Profiling of the Human Major Histocompatibility Complex: A Pilot Study for the Human Epigenome Project
Program | The First Annual Iberian Congress on Anti-Aging Medicine and Biomedical Technologies
Proteome analysis of human hair shaft: from protei...[Mol Cell Proteomics. 2006] - PubMed Result
Reversal of Maternal Programming of Stress Responses ... Altering Epigenetic Marking Later in Life -- Weaver et al. 25 (47): 11045 -- Journal of Neuroscience
Title: Epigenetics and aging: the targets and the marks. Source: Trends in genetics [0168-9525] Fraga yr:2007 vol:23 iss:8 pg:413 -8
The DNA methyltransferases of mammals. [Hum Mol Genet. 2000] - PubMed Result
The emerging role of epigenetics in cellular and o...[Exp Gerontol. 2003 Nov-Dec] - PubMed Result
Transposable Elements: Targets for Early Nutritional Effects on Epigenetic Gene Regulation -- Waterland and Jirtle 23 (15): 5293 -- Molecular and Cellular Biology
Transposable Elements: Targets for Early Nutritional Effects on Epigenetic Gene Regulation -- Waterland and Jirtle 23 (15): 5293 -- Molecular and Cellular Biology