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Rinsho Shinkeigaku. 2014;54(12):1151-4. doi: 10.5692/clinicalneurol.54.1151.

[Calpain plays a crucial role in TDP-43 pathology].

[Article in Japanese]

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Division of Clinical Biotechnology, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo.


Amyotrophic lateral sclerosis (ALS) is the most common adult-onset motor neuron disease affecting healthy middle-aged individuals. Mislocalization of TAR DNA binding protein of 43 kDa (TDP-43) or TDP-43 pathology observed in the spinal motor neurons is the pathological hallmark of ALS. The mechanism generating TDP-43 pathology remained uncertain. Several reports suggested that cleavage of TDP-43 into aggregation-prone fragments might be the earliest event. Therefore, elucidation of the protease(s) that is responsible for TDP-43 cleavage in the motor neurons is awaited. ALS-specific molecular abnormalities other than TDP-43 pathology in the motor neurons of sporadic ALS patients include inefficient RNA editing at the GluA2 glutamine/arginine (Q/R) site, which is specifically catalyzed by adenosine deaminase acting on RNA 2 (ADAR2). We have developed the conditional ADAR2 knockout (AR2) mice, in which the ADAR2 gene is targeted in motor neurons. We found that Ca(2+)-dependent cysteine protease calpain cleaved TDP-43 into aggregation-prone fragments, which initiated TDP-43 mislocalization in the motor neurons expressing abnormally abundant Ca(2+)-permeable AMPA receptors. Here we summarized the molecular cascade leading to TDP-43 pathology observed in the motor neurons of AR2 mice and discussed possible roles of dysregulation of calpain-dependent cleavage of TDP-43 in TDP-43 pathology observed in neurological diseases in general.

[Indexed for MEDLINE]

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