25 Apr 2021
In amyotrophic lateral sclerosis and frontotemporal dementia, loss of the RNA-binding protein TDP-43 from the nucleus creates a surge of mis-spliced mRNAs in neurons. So far, only one of these errant transcripts, stathmin-2, has been tied to disease pathology. Now, two preprints uploaded to bioRXiv on April 4 detail another—UNC13A. Variants in this gene increase risk for ALS/FTD.
Neurons lacking nuclear TDP-43 mis-splice UNC13A, make less of the protein.
UNC13A risk variants incorporate cryptic exons.
This only occurs in brain and spinal cord tissue harboring TDP-43 deposits.
One paper was penned by researchers led by Pietro Fratta, University College London, and Michael Ward, National Institute of Neurological Disorders and Stroke, Bethesda, Maryland. The second is from the labs of Aaron Gitler, Stanford University, California, and Leonard Petrucelli, Mayo Clinic, Jacksonville, Florida. Both papers report that if TDP-43 binding to UNC13A falters, the transcript is mis-spliced and less Unc13A protein is made. In frontal cortex neurons from people who had ALS/FTD with TDP-43 deposits, mis-splicing was highest in cells carrying the UNC13A risk variants. The studies support the idea that sequestering TDP-43 in the cytosol may unleash aberrant splicing events that contribute to neurodegenerative disease pathology.