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Nutrigenetics & Nutrigenomics - Coggle Diagram
Nutrigenetics
&
Nutrigenomics
Mechanisms of epigenetic
gene expression
Histone modification
defined as a
post-translational modification
to one of
the a
mino acid side chains
in a
histone protein
The main modifications are:
lysine and arginine methylation,
phosphorylation, acetylation
ubiquitination
2 main effects
binding or prevention of binding of effector molecules
e.g. for DNA repair or transcription
disruption of contacts
between nucleosomes which
‘‘unravels’’ chromatin
modifies a transcription factor’s ability to access DNA -
Epigenetic regulation of chromatin structure through histone modifications enables cells to alter gene expression
RNA associated silencing
three classes of small, noncoding RNAs
regulate gene expression post-transcriptionally
by targeting messenger RNAs
endogenous small-interfering RNA [endo-siRNA]
piwi-interacting RNA [piRNA])
microRNA [miRNA]
associated with
oncogenesis and human disease
play critical roles in the
development of the
organism
and in
cell differentiation
DNA methylation
adds a methyl group to a cytosine
residue
immediately preceding a guanine
enables cells to
downgrade and maintain lineage
by either
down-regulating or turning off
promoters for genes
that are
not to be expressed by tissues
What role does it play?
play a no. of roles in
promoting gene stability
& maintenance
X-chromosome inactivation
suppression of repetitive elements
genomic imprinting
Changes in the methylation patterns of DNA during a cell’s lifetime
provide an adaptive ability for the organism to adjust to changes in the environment
associated with repression of
gene transcription
DNA methylation i
nfluences the ability of transcription factors
and other DNA-binding proteins to
recognise a nucleotide sequence that regulates gene expression.
Lack of methylation
deficiency of dietary methyl donors
such as folate, vitamin B12, choline, betaine,
and methionine
Methylation
occurs on CpG sites,
which are common in gene promoter regions
Inheritance
Imprinting
1% of genes imprinted
causes genes to be expressed in a
parent-of-origin-specific manner
particular diseases will develop depending on whether the mutation is inherited from the child's mother or father
gene expression occurs from only one allele
How does imprinting happen?
happens during ova and sperm formation,
when
epigenetic tags are added to silence specific genes
via DNA methylation or histone modification
The repressed allele is methylated, while the active allele is unmethylated.
Barker Hypothesis
Prenatal events
establish
lifelong physiological patterns
that may manifest as disease processes in later life
Improving the nutritional status of a foetus will improve health
throughout its life
Nutritional status at birth
will
determine susceptibility
to disease in later life
'Omics'
Proteomics
Protein structure, function and expression
Metabolomics
Metabolites -
suggestive of phenotypes
Transcriptomics
RNA expression
Genomics
study of whole genome,
not individual genes
Single gene disorders
caused by mutations in a single gene e.g. cystic fibrosis, sickle cell anaemia
Complex disorders
no single genetic cause –
effect of multiples genes in combination with environment factors e.g. heart disease, diabetes, psychiatric disorders
Collective characterization and quantification of genes
structure
function
evolution
mapping & sequencing of genome
Genome-wide association studies (GWAS)
Identify the
functional genetic variants
Allow elucidation of the
biological processes underlying the disease
pathogenesis
Association between
human traits and genetic variants
Aid development of
new treatments
for common complex disease
Gene mapping:
identify genes which cause susceptibility to complex disorders
Identify
single nucleotide polymorphisms
(SNPs)
that are associated with
disorders
from across the whole genome