Kinesin light chain 1 suppression impairs human embryonic stem cell neural differentiation and amyloid precursor protein metabolism.

Five and a half million people in the U.S. alone have the disease. It is the sixth leading cause of death in the U.S. Care for the afflicted costs $200 billion annually. A staggering 1 in 8 older Americans U.S. have it. It is Alzheimer Disease, a devastating disease with no cure and no known cause. Scientists suspect the disease is exasperated by abnormal brain deposits of two proteins known as amyloid-beta and tau, but it is not known what causes these proteins to behave aberrantly. Since both of these proteins have uniquely human compositions, their behavior has been challenging to address fully in animal models, although recent work suggests that faulty transport of proteins and other cargos within nerve cells can lead to altered behavior of amyloid beta and tau. Therefore, we used a human model system based on human pluripotent stem cells –cells capable of giving rise to any cell type in the body – to test the notion that impaired transport of materials within nerve cells can lead to abnormal levels of amyloid beta and tau. We generated human pluripotent cells with reduced levels of a protein essential for the transport of many cargos within nerve cells and tested how this affected the production of the nerve cell cultures as well as the levels of amyloid beta and tau. Our results indicate that perturbing transport in this way can impair the production of nerve cells. Further, these nerve cell cultures contain less amyloid beta and tau proteins. Thus we have created a human model system with which to test the role of intracellular transport in any human cell type and have demonstrated that altering intracellular transport can alter levels of amyloid beta and tau in human nerve cells. This human model system will be useful for future studies addressing the possible causes and potential treatments of Alzheimer Disease.