a r t i c l e i n f o a b s t r a c t
Article history:
Received 1 September 2009
Revised 9 November 2009
Accepted 13 November 2009
Available online 27 November 2009
Keywords:
Epigenetic
DNA methylation
Transmission
Nutrition
Chemical toxicants
Postnatal environment
The epigenome is the overall epigenetic state of a cell and represents the ensemble of chromatin
modifications. It is an essential mechanism for the regulation of the genome that depends on modifications of
DNA and histones but does not involve any change of the DNA sequence. It was previously assumed that in
order for appropriate cellular development and differentiation to occur in mammals, the epigenome was
fully erased and reestablished between generations. However, several examples of incomplete erasure at
specific genes have been reported, and this is suggested to be associated with the epigenetic inheritance of
gene profiles. Although the existence of such a mode of inheritance has been controversial, there is
increasing evidence that it does occur in rodents and humans. In this review, we discuss the evidence that
adverse environmental factors can affect not only the individuals directly exposed to these factors but also
their offspring. Because the epigenome is sensitive to environmental influence and, in some cases, can, in
part, be transmitted across generations, it provides a potential mechanism for the transgenerational
transmission of the impact of environmental factors. Environmental factors examined include exposure to
toxicants, diet, and postnatal care, and DNA methylation is the main mechanism discussed in this review.
© 2009 Elsevier Inc. All rights reserved.
a r t i c l e i n f o a b s t r a c t
Article history:
Received 1 September 2009
Revised 9 November 2009
Accepted 13 November 2009
Available online 27 November 2009
Keywords:
Epigenetic
DNA methylation
Transmission
Nutrition
Chemical toxicants
Postnatal environment
The epigenome is the overall epigenetic state of a cell and represents the ensemble of chromatin
modifications. It is an essential mechanism for the regulation of the genome that depends on modifications of
DNA and histones but does not involve any change of the DNA sequence. It was previously assumed that in
order for appropriate cellular development and differentiation to occur in mammals, the epigenome was
fully erased and reestablished between generations. However, several examples of incomplete erasure at
specific genes have been reported, and this is suggested to be associated with the epigenetic inheritance of
gene profiles. Although the existence of such a mode of inheritance has been controversial, there is
increasing evidence that it does occur in rodents and humans. In this review, we discuss the evidence that
adverse environmental factors can affect not only the individuals directly exposed to these factors but also
their offspring. Because the epigenome is sensitive to environmental influence and, in some cases, can, in
part, be transmitted across generations, it provides a potential mechanism for the transgenerational
transmission of the impact of environmental factors. Environmental factors examined include exposure to
toxicants, diet, and postnatal care, and DNA methylation is the main mechanism discussed in this review.
© 2009 Elsevier Inc. All rights reserved.
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