Volume 99 Issue 7, July 2019

Brain inclusions of the microtubule-associated protein tau are prominent pathological features in a spectrum of neurodegenerative diseases. MAPT gene mutations that encodes tau can directly cause neurodegeneration. Herein, the authors review what is known about MAPT mutations dysfunctions with a focus on the prion-like properties of tau protein.

More than 40 different neurological diseases are caused by microsatellite repeat expansions. Repeat-associated non-AUG (RAN) proteins are translated from different types of nucleotide repeat expansions. The authors review the pathological and molecular aspects of RAN protein accumulation for each RAN translation disorder, the correlation between disease pathology, the available in vivo models and the common features shared by some of the newly discovered RAN proteins.

Increasing lines of evidence have shown beneficial effects of physical exercise against or delay neurodegeneration. However, the mechanisms of their beneficial effects are confusing because it involves the connection between the brain and muscles. This review summarizes these findings and discusses the differential and common effects of aerobic versus resistance exercises.

In this review, the amyloid cascade is summarized along with the results of major clinical trials that have sought to target the amyloid cascade for therapeutic intervention. The distinction between theory, largely unaltered, and proof of concept that might temper the theory, is highlighted.

This review discusses the templated spread of α-synuclein (α-syn) pathology in neurodegenerative disease from the perspective of proteopathic α-syn seeds. Recent discoveries concerning the structure and cell biology of pathological α-syn aggregates are highlighted.

Leveraging an extensive panel of α-synuclein antibodies that targets a wide range of epitopes, the authors provide evidence that multiple system atrophy α-synuclein inclusions display distinct misfolded strain-like characteristics divergent from Lewy body diseases. The findings also indicate that in multiple system atrophy α-synuclein prion-like strains are likely inherently mutable.

Neurodegenerative diseases evolve in multi-factorial manners, yet coherent paradigms are emerging. Both Tau and TDP-43 proteinopathies are linked to multiple upstream influences, and both are connected with numerous deleterious downstream endpoints. Gene variants can be either disease-specific, or, exert influence on the misfolding pathology itself rather than the upstream cause.

In this paper the authors outline the known neuropathology of mild traumatic brain injury (mTBI). They employed immunohistochemistry and gene expression profiling techniques in two post-mortem cases in order to propose markers of DNA damage as the driver of pathology and symptoms after mTBI.

In this study, the authors show that machine learning is a useful tool for complex pathological assessment of Alzheimer disease and other tauopathies. Using deep learning classifiers, we now have the potential to integrate cell- and region-specific annotations with clinical, genetic, and molecular data, providing unbiased data for clinicopathological correlations that will enhance our knowledge of the neurodegeneration.

RNA binding proteins associated with amyotrophic lateral sclerosis and muscle myopathy possess sequence elements that bear resemblance to yeast prion domains. Fusion proteins of the nuclear matrix protein matrin 3 (MATR3), transactive response DNA binding proteinTARDBP43 (TDP43) or the RNA binding protein FUS with yellow fluorescent protein or mCherry were used to examine phase separation and protein interaction in mouse C2C12 myoblast cells. The authors show that N-terminal sequences in MATR3 can mediate phase separation into intranuclear droplet-like structures, which recruit TDP43 variants lacking RNA binding elements.

The authors report that pathogenic TDP-43 is increased and closely associated with mitochondria in degenerating skeletal muscles of patients with inclusion body myositis, while key subunits of mitochondrial oxidative phosphorylation complexes I and III are reduced, implying a potential role of mitochondria and associated TDP-43 for disease pathogenesis.

The authors identified and compared the primary and contributing diagnoses for people with primary age-related tauopathy (PART) to those with Alzheimer’s disease neuropathologic change (ADNP). Clinicians diagnose AD less frequently in those with PART, recognizing a distinction in the clinical presentation between PART and ADNP.

In a series of Huntington’s disease (HD) brains, the authors identified phospho-tau aggregation in all cases. In contrast to recent observations suggesting a new role for tau in HD pathogenesis, the tau pathology in our cases was classifiable into known diagnostic entities and most likely represents non-specific age- or perhaps trauma-related changes.