Sunday, July 30, 2017
Schizophrenia could largely be the result of defective cells
"It was through studies of mice with human glial cells that we succeeded in testing how dysfunctional glial cells may cause abnormalities in the formation of the brain's neural networks, which may in turn cause severe anxiety, anti-social behaviour and severe sleep problems," says lead researcher Steven Goldman
Glial cells come in a variety of forms and can be found throughout the nervous system, taking on a bunch of supportive tasks to allow the nerve cells do what they do... best – pass on messages. This could be in the form of support, wrapping themselves around the nerves, or by surrounding the nerves to clean up stray chemical messages.
While dysfunctional helper cells have been associated with schizophrenia before, it's been assumed to be less important than abnormalities in the neurons themselves.
In this research the scientists took glial progenitor cells from patients diagnosed with schizophrenia and transplanted them into the brains of young mice. They then compared them with the same kinds of cells taken from subjects without schizophrenia.
That way they could be confident that similar behaviours in the mice were the product of the same pathology in humans.
Sure enough, the stem cells derived from the subjects with schizophrenia showed an unusual pattern of migration as they spread through the mice brains, leading to lower numbers of a type of glial cell that was responsible for mopping up neurotransmitter chemicals in the gaps between neurons.
The research hints at a faulty mechanism telling the glial cells where to stop and change into cells that perform their jobs.
When the mice were observed for behavioural differences, they showed clear signs of anxiety, sleep disruption, and anhedonia.
The Minding Brain
Mother's epigenetic memory is essential for the development and survival of the new generation.
The Minding Brain
Epigenetic mechanisms modulated by envir...onmental cues such as diet, disease or our lifestyle take a major role in regulating the DNA by switching genes on and off. Epigenetic marks transmitted from the mother are a fine-tuned mechanism to control gene activation during the complex process of early embryogenesis
It has long been thought that these epigenetic modifications never cross the border of generations. Scientists assumed that epigenetic memory accumulated throughout life is entirely cleared during the development of sperms and egg cells.
Just recently a handful of studies stirred the scientific community by showing that epigenetic marks indeed can be transmitted over generations, but exactly how, and what effects these genetic modifications have in the offspring is not yet understood.
It has been long debated if epigenetic modifications accumulated throughout the entire life can cross the border of generations and be inherited to children or even grand children.
Now researchers from the Max Planck Institute of Immunobiology and Epigenetics in Freiburg show robust evidence that not only the inherited DNA itself but also the inherited epigenetic instructions contribute in regulating gene expression in the offspring.
They discovered that embryos lacking H3K27me3 during early development could not develop to the end of embryogenesis. "It turned out that, in reproduction, epigenetic information is not only inherited from one generation to another but also important for the development of the embryo itself,"
It seems, virtually, that inherited epigenetic information is needed to process and correctly transcribe the genetic code of the embryo," explains Fides Zenk.
In our body we find more than 250 different cell types. They all contain the exact same DNA bases in exactly the same order; however, liver or nerve cells look very different and have different skills. What makes the difference is a process called epigenetics.
Epigenetic modifications label specific regions of the DNA to attract or keep away proteins that activate genes. Thus, these modifications create, step by step, the typical patterns of active and inactive DNA sequences for each cell type.
Moreover, contrary to the fixed sequence of 'letters' in our DNA, epigenetic marks can also change throughout our life and in response to our environment or lifestyle. For example, smoking changes the epigenetic makeup of lung cells, eventually leading to cancer. Other influences of external stimuli like stress, disease or diet are also supposed to be stored in the epigenetic memory of cells.
At the Max Planck Institute of Immunobiology and Epigenetics in Freiburg, Germany used fruit flies to explore how epigenetic modifications are transmitted from the mother to the embryo
The Max Planck researchers found that H3K27me3 modifications labeling chromatin DNA in the mother's egg cells were still present in the embryo after fertilization, even though other epigenetic marks are erased. "This indicates that the mother passes on her epigenetic marks to her offspring. But we were also interested, if those marks are doing something important in the embryo,"
Our study indicates that we inherit more than just genes from our parents. It seems to be that we also get a fine-tuned as well as important gene regulation machinery that can be influenced by our environment and individual lifestyle
Subscribe to:
Posts (Atom)