For several years, scientists have known that a protein called activity-dependent neuroprotective protein, ADNP, is mutated in both autism and that ADNP gene activity increases could be used as a marker for Alzheimer's disease. A team of researchers has now revealed more about the function of NAP, an eight amino acid portion of the ADNP molecule. NAP is able to stop the buildup of pathogenic neurofibrillary tangles, a hallmark of Alzheimer's disease. NAP orchestrates the interaction of a cellular component called microtubules with a protein called Tau. Aggregates of Tau have been identified as a key player in disease; they are linked to cognitive defects and the death of neurons. This new work which used movies such as the one below to monitor cellular events over time, was conducted at Tel Aviv University and has been reported in Molecular Psychiatry.
"Abnormal Tau proteins form tangles that contribute to the progression of Alzheimer's disease," said the leader of this work, Professor Illana Gozes. "We showed here, for the first time, that the drug candidate NAP augmented microtubule movement in nerve cells. At the molecular level, NAP, a fragment of activity-dependent neuroprotective protein (ADNP), enhanced Tau-microtubule interactions that block the recruitment of Tau to the tangles observed in Alzheimer's disease and related disorders." Gozes is the incumbent of the Lily and Avraham Gildor Chair for the Investigation of Growth Factors, as well as Head of the Elton Laboratory for Molecular Neuroendocrinology at TAU's Sackler Faculty of Medicine and a member of TAU's Adams Super Center for Brain Studies and the Sagol School of Neuroscience.
"ADNP and NAP operate through the stabilization of microtubules -- tubes within the cell that maintain cellular shape," Prof. Gozes said. "They transport biological material. These microtubules break down in in Alzheimer's disease and may be dysfunctional in autism. NAP works to protect the microtubules, thereby protecting the cell."
"We now discovered that ADNP dramatically enhances Tau binding to the microtubules, protecting them against destruction and against Tau pathology. We further discovered that this action of ADNP is through its NAP fragment, which is now intended for further clinical development."
"Knowing the precise mechanism of its action, it will be much easier to bring NAP to the clinic and to patients," said Professor Gozes. "Furthermore, the precise mechanism defines a new drug target for autism spectrum disorders, Alzheimer's disease and many other neurodegenerative and neuropsychiatric diseases."
It's known that carriers of mutations in the ADNP gene are at risk for developing autism with intellectual disability. Future studies are planned to evaluate NAP as a treatment for patients suffering from autism, especially those that have ADNP-related syndrome.
Check out a lecture from Professor Gozes on ADNP, NAP and how these molecules relate to Autism, Schizophrenia and Alzheimer's disease in the above video.
Sources: AAAS/Eurekalert! via Tel Aviv University, Nature Genetics, PLOS One, Molecular Psychiatry