April 28, 2014
So much about our own bodies and minds is unknown to us. For every new star discovered, every new piece of our world’s history unearthed, we are learning more and more about ourselves as well. Greater understanding regarding our own bodies and minds forwards our ability to treat various forms of biological defects and harmful abnormalities.
For example, the Cell Single Unit team of the Okinawa Institute of Science and Technology – OIST – led by Professor Tadashi Yamamoto has recently uncovered that a cause of hyperactivity – a behavioral disorder that has symptoms of restlessness, lack of coordination, and aggressive behavior – may be linked to lacking a specific intracellular trafficking protein called LMTK3. This protein is found in both the cerebral cortex, which his what coordinates our perception and movement, and the hippocampus, which controls our memory and ability to learn. They discovered that LMTK3 is essential for regulating the trafficking of neurotransmitter receptors at synapses, the connectors between the various neurons of our brains. In order for one part of our brain to send a message to another part, a nerve terminus in the pre-synapse releases a neurotransmitter that is then received by a post-synaptic receptor. In the neurons of lab mice that have a LMTK3 deficiency, the internalization of their receptors are augmented in the post-synapse, which suggests that their synaptic communication is impaired. These mice also show various hyperactive behaviors also found in humans such as restlessness and a hypersensitivity to sound. In addition, they also had elevated dopamine levels, which is a neurotransmitter known to be important to the regulation of movement and hormone levels, not to mention motivation, learning, and the ability to express emotion. Elevated levels such as these can result in things like schizophrenia and abnormal thoughts/emotion.
In studying LMTK3, Professor Yamamoto hopes to be able to identify the genetic factors that contribute to hyperactivity in order to explain the pathological mechanisms that can cause things like autism and ADHD – Attention Deficit Hyperactivity Disorder – in humans. According to Professor Yamamoto, “We hope to advance our research in order to elucidate genetic defects that result in behavioral abnormalities.”
Unfortunately, as with many new discoveries, we have also uncovered a number of new questions. We still do not understand the function of many of the proteins our bodies produce and the relationships between the regulation of neurotransmitter receptors expressions by the LMTK3 protein, dopamine turnover, and the various biochemical pathways that can induce hyperactivity remain a mystery. Even so, this discovery by the OIST Cell Single Unit team represents a great step forward in our understanding of the possible causes of hyperactivity. Although we have yet to uncover all of the answers, the road leading to our complete understanding has become a little more clear to us, and that in itself is a remarkable achievement.
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