Reichmann, H. | Search bioRxiv

bioRxiv2020

Physiological and pathological changes in the enteric nervous system of rotenone-exposed mice as potential early biomarkers for Parkinson's disease

Parkinsons disease (PD) is known to involve the peripheral nervous system (PNS) and the enteric nervous system (ENS). Functional changes in PNS and ENS appear early in the course of the disease and are responsible for some of the non-motor symptoms observed in PD patients like constipation, that can precede the appearance of motor symptoms by years. We have shown that environmental toxins can trigger the disease by acting on the ENS and on the autonomic nervous system. Oral exposure to the pesticide rotenone, a mitochondrial Complex I inhibitor, leads to decreased stool depositions in mice. Here we analyzed the effect of rotenone on the function and structure of the ENS by measuring intestinal contractility in a tissue bath and by analyzing related protein expression. Our results show that rotenone changes the normal physiological response of the intestine to carbachol, dopamine and electric field stimulation. The magnitude and direction of these alterations varies between intestinal regions and exposure times and is associated with an early up-regulation of dopaminergic, cholinergic and adrenergic receptors and an irregular reduction in the amount of enteric neurons in rotenone-exposed mice. The early appearance of these alterations makes them ideal candidates to be used as biomarkers for the detection of Parkinsons disease in its early stages.

neuroscience↗

bioRxiv2018

The unique nested gene ALZAS as a potential source of Aβ-peptides in Alzheimer’s disease

Amyloid-beta (A{beta}) peptides are considered to be the cause of neuronal and synaptic cell death in Alzheimers disease (AD) since approximately 100 years. To date, it is assumed that A{beta}-peptides arise from the proteolytic cleavage of the amyloid precursor protein (APP). However, within the APP gene, a nested gene called ALZheimer ASsociated (ALZAS) exists, which includes the entire A{beta}42-sequence and thus may also be the origin of various A{beta}-species. Here, we firstly confirmed expression and the postulated amino acid sequence of ALZAS and revealed the binding of selected monoclonal A{beta}-antibodies to A{beta}- and ALZAS protein. We confirmed the specificity of the anti-ALZAS antibody to ALZAS by protein sequence analysis. This anti-ALZAS antibody detects the same amino acid sequence as the autoantibody found in human blood of AD patients. Since no detailed data are currently available concerning ALZAS expression and the amount, localization and function of ALZAS protein in human cells and tissue, we performed gene (over)expression experiments on transcriptional and translational level. We verified a considerably lower mRNA amount of ALZAS compared to the host gene APP. Nevertheless, ALZAS transcription and translation seems to be heavily regulated in different human tissues and cells. Artificially increased mRNA levels of ALZAS did not led to an enhanced protein amount or considerable increase in cell death. Notably, cell localization of the ALZAS protein showed accordance to endosomes indicating that ALZAS, which contains the whole transmembrane domain of APP, might be a peripheral membrane protein. Since endosome dysfunctions are a characteristic event in early stages of AD and the highest ALZAS-autoantibody levels were already detected in early AD stages, ALZAS might play a crucial role in AD pathology and could possibly be a further diagnostic marker.

neuroscience↗