Aggregation of TAR-DNA-binding protein 43 (TDP-43) and of its fragments TDP-25 and TDP-35 occurs in amyotrophic lateral sclerosis (ALS). TDP-25 and TDP-35 act as seeds for TDP-43 aggregation, altering its function and exerting toxicity. Thus, inhibition of TDP-25 and TDP-35 aggregation and promotion of their degradation may protect against cellular damage. Upregulation of HSPB8 is one possible approach for this purpose, since this chaperone promotes the clearance of an ALS associated fragments of TDP-43 and is upregulated in the surviving motor neurones of transgenic ALS mice and human patients. We report that overexpression of HSPB8 in immortalized motor neurones decreased the accumulation of TDP-25 and TDP-35 and that protection against mislocalized/truncated TDP-43 was observed for HSPB8 in Drosophila melanogaster. Overexpression of HSP67Bc, the functional ortholog of human HSPB8, suppressed the eye degeneration caused by the cytoplasmic accumulation of a TDP-43 variant with a mutation in the nuclear localization signal (TDP-43-NLS). TDP-43-NLS accumulation in retinal cells was counteracted by HSP67Bc overexpression. According with this finding, downregulation of HSP67Bc increased eye degeneration, an effect that is consistent with the accumulation of high molecular weight TDP-43 species and ubiquitinated proteins. Moreover, we report a novel Drosophila model expressing TDP-35, and show that while TDP-43 and TDP-25 expression in the fly eyes causes a mild degeneration, TDP-35 expression leads to severe neurodegeneration as revealed by pupae lethality; the latter effect could be rescued by HSP67Bc overexpression. Collectively, our data demonstrate that HSPB8 upregulation mitigates TDP-43 fragment mediated toxicity, in mammalian neuronal cells and flies.
Biosensors based on organic electrochemical transistors (OECT) are attractive devices for real‐time monitoring of biological processes. The direct coupling between the channel of the OECT and the electrolyte enables intimate interfacing with biological environments at the same time bringing signal amplification and fast sensor response times. So far, these devices are mainly applied to mammalian systems; cells or body fluids for the development of diagnostics and various health status monitoring technology. Yet, no direct detection of biomolecules from cells or organelles is reported. Here, an OECT glucose sensor applied to chloroplasts, which are the plant organelles responsible for the light‐to‐chemical energy conversion of the photosynthesis, is reported. Real‐time monitoring of glucose export from chloroplasts in two distinct metabolic phases is demonstrated and the transfer dynamics with a time resolution of 1 min is quantified, thus reaching monitoring dynamics being an order of magnitude better than conventional methods.
Organic electronic transistors are rapidly emerging as ultra-high sensitive label-free biosensors suited for point of care or in-field deployed applications. Most organic biosensors reported to date are based on immunorecognition between the relevant biomarkers and the immobilized antibodies, whose use is hindered by large dimensions, poor control of sequence and relative instability. Here, we report an Electrolyte Gated Organic Field Effect Transistor (EGOFET) biosensor where the recognition units are surface immobilized peptide aptamers (Affimerä proteins) instead of antibodies. We demonstrate our peptide aptasensor for the detection of the pro-inflammatory cytokine Tumor Necrosis Factor alpha (TNFa) with a 1pM limit of detection. Ultra-low sensitivity is met even in complex solutions such as cell culture media containing 10 % serum, demonstrating the remarkable ligand specificity of our device. The device performances, together with the simple one-step immobilization strategy of the recognition moieties and the low operational voltages, all prompt EGOFET peptide aptasensors as candidates for early diagnostics and monitoring at the point-of-care.
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