Lead poisoning could reduce gene expression in humans

Date:
August 7, 2020
Source:
Hokkaido University
Summary:
Scientists have unveiled a correlation between high blood lead
levels in children and methylation of genes involved in haem
synthesis and carcinogenesis, indicating a previously unknown
mechanism for lead poisoning.



FULL STORY ========================================================================== Scientists have unveiled a correlation between high blood lead levels
in children and methylation of genes involved in haem synthesis and carcinogenesis, indicating a previously unknown mechanism for lead
poisoning.


==========================================================================
Lead poisoning is a well-documented disease, the incidence
of which has drastically reduced since the use of lead has been
curtailed. Nevertheless, many areas across the world still have unsafe
levels of lead in the environment. Lead poisoning causes symptoms such
as abdominal pain, kidney failure and infertility, among others, but the
most damaging effects are seen in children, where it causes neurological
and developmental deterioration; however, a number of mechanisms behind
it have been elusive.

In the current work, published in the journal Environmental Research, scientists at Hokkaido University collaborated with colleagues at the University of Zambia to investigate blood lead levels in 140 children aged
2 to 10 years in Kabwe, Zambia. Children were chosen from townships close
to and distant from an old, highly polluted lead-zinc mine. According to
a survey conducted by the Blacksmith Institute (now, Pure Earth), due
to this mine, Kabwe was considered one of the 10 most polluted places
on Earth in 2013.

Blood lead levels were measured in all children. The scientists discovered
that children living closer to the mine had blood levels that were three
times higher than that of children living further away. They then used
a technique called methylation-specific polymerase chain reaction (MSP)
to determine the methylation of the DNA sequences. Methylation is a
process by which methyl (CH3) groups are added to DNA; this modification generally causes the activity of genes to reduce.

Increased blood lead levels correlated positively with aberrant, increased methylation of DNA responsible for the expression of genes. The genes
affected were ALAD, which synthesizes a key compound in the development
of red blood cells; and p16, a tumour suppressor gene, which is frequently inactivated in different types of cancer.

This study has established the correlation between blood lead levels
and aberrant methylation of DNA. It has also revealed a major healthcare
issue in children in the region. Future work in this area would involve large-scale studies to determine the true extent of lead poisoning, as
well as setting up an effort to provide children in the region with the necessary care and treatment. "The ultimate goal is," Dr. Yohannes says,
"to achieve a lead-free population to ensure a healthy future." Dr. Yared
B. Yohannes, Assistant Professor Shouta Nakayama, and Professor Mayumi
Ishizuka from the Laboratory of Toxicology were the key contributors to
this research. The laboratory has been studying lead poisoning in Kabwe
for over half a decade. Their research is part of ongoing collaborations
with eight African countries on the project Clarification of the Effect
of Continued Environmental Contamination in Africa on Humans and Animals.


========================================================================== Story Source: Materials provided by Hokkaido_University. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Yared B. Yohannes, Shouta MM. Nakayama, John Yabe, Hokuto Nakata,
Haruya
Toyomaki, Andrew Kataba, Kaampwe Muzandu, Yoshinori Ikenaka,
Kennedy Choongo, Mayumi Ishizuka. Blood lead levels and aberrant
DNA methylation of the ALAD and p16 gene promoters in children
exposed to environmental- lead. Environmental Research, 2020; 188:
109759 DOI: 10.1016/ j.envres.2020.109759 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200807102334.htm

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