Epigenetics

Epigenetics

DNA Methylation
1. Transcription repressed
  1. no gene expression
Histone Modification
1. Transcription repressed
  1. No gene expression
heritable traits NOT caused by change in DNA sequence
Integrated with genes and environment
1. Ancestors' nutrition was indicated as the main influence on longevity through unspecified epigenetic mechanisms of inheritance.
2. Dutch famine example
  1. children of mothers exposed to famine before conception had lowest degree of methylation
3. Environmental factors such as socioeconomic status can raise stress levels
  1. being poor affects cortisol
  2. Low maternal warmth contributes to stress, but high levels of maternal warmth can be protective factors
4. Paternal obesity is associated with IGF2 hypomethylation in newborns
  1. heavier fathers--> percent methylation drops for children
    1. increased body weight in children
5. Common Disease Genetic and Epigenetic (CDGE) Hypothesis
  1. in addition to genetic variation, epigenetics provides an added layer of variation that might mediate the relationship between genotype and internal and external environmental factors
Match-mismatch paradigm of disease involves epigenetic mechanisms of gene regulation. Baby in utero receives cues from mother about its future environment, and modifies metabolism among other things. Mismatch occurs when the anticipated environment differs from reality
1. Permanent gene expression changes
  1. Phenotype affected later in life
    1. obesity, Type 2 Diabetes, psychiatric disorders, cancer, etc. consequences of match-mismatch
2. Example: stress of mother leads to increased insulin, cortisol, and higher blood pressure
DNA Acetylation
1. Transcription facilitated
  1. gene expressed

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