The RNA-Recognition Motifs of TAR DNA-Binding Protein 43 May Play a Role in the Aberrant Self-Assembly of the Protein

The TAR DNA-binding protein 43 (TDP-43) is a nucleic acid-binding protein implicated in gene regulation and RNA processing and shuffling. It is a ribonuclear protein that carries out most of its functions by binding specific nucleic acid sequences with its two RNA-recognition motifs, RRM1 and RRM2. TDP-43 has been identified in toxic cytosolic inclusions in neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration with ubiquitin-positive inclusions (FTLD-U). The unstructured C-terminus has prion-like behavior and has been considered the driver of the aberrant self-assembly of TDP-43. In this work, we set out to test the hypothesis that the RNA-binding domains could also play a role in protein aggregation. This knowledge could be of important value for understanding TDP-43 aberrant, disease-leading behavior and, in the future, inform the design of small molecules that could prevent or slow down protein aggregation by exploiting the RNA-binding properties of the protein. We investigated the behavior of the two tandem RRM domains separately and linked together and studied their self-assembly properties and RNA-binding ability with a number of biophysical techniques. The picture that emerges from our study suggests that this region of the protein plays an important and so far unexplored role in the aggregation of this protein

Heavy Metals in Soil and Salad in the Proximity of Historical Ferroalloy Emission

Emissions of manganese (Mn), lead (Pb), iron (Fe), zinc (Zn), copper (Cu) from ferro-alloy operations has taken place in Valcamonica, a pre-Alp valley in the province of Brescia, Italy, for about a century until 2001. Metal concentrations were measured in the soil of local home gardens and in the cultivated vegetables. Soil analysis was carried out using a portable X-Ray Fluorescence (XRF) spectrometer in both surface soil and at 10 cm depth. A subset of soil samples (n = 23) additionally was analysed using the modified BCR sequential extraction method and ICP-OES for intercalibration with XRF (XRF Mn = 1.33 * total OES Mn – 71.8; R = 0.830, p < 0.0001). Samples of salads (Lactuca sativa and Chichorium spp.) were analyzed with a Total Reflection X-Ray Fluorescence (TXRF) technique. Vegetable and soil metal measurements were performed in 59 home gardens of Valcamonica, and compared with 23 gardens from the Garda Lake reference area. Results indicate significantly higher levels of soil Mn (median 986 ppm vs 416 ppm), Pb (median 46.1 ppm vs 30.2 ppm), Fe (median 19,800 ppm vs 13,100 ppm) in the Valcamonica compared to the reference area. Surface soil levels of all metals were significantly higher in surface soil compared to deeper soil, consistent with atmospheric deposition. Significantly higher levels of metals were shown also in lettuce from Valcamonica for Mn (median 53.6 ppm vs 30.2) and Fe (median 153 vs 118). Metals in Chichorium spp. did not differ between the two areas. Surface soil metal levels declined with increasing distance from the closest ferroalloy plant, consistent with plant emis- sions as the source of elevated soil metal levels. A correlation between Mn concentrations in soil and lettuce was also observed. These data show that historic ferroalloy plant activity, which ended nearly a decade before this study, has contributed to the persistence of increased Mn levels in locally grown vegetables. Further research is needed to assess whether this increase can lead to adverse effects in humans and plants especially for Mn, an essential element that can be toxic in humans when exceeding the homeostatic ranges

RNA aptamer reveals nuclear TDP-43 pathology is an early aggregation event that coincides with STMN-2 cryptic splicing and precedes clinical manifestation in ALS

Open Access via the Springer Agreement The research leading to this manuscript has been supported by (i) a Target ALS foundation grant to JMG, MHH, GGT, EZ and NS and employing MG and FMW BB-2022-C4-L2; (ii) an NIH grant to JG and MHH, employing HS and FR R01NS127186; (iii) the European Research Council (RIBOMYLOME_309545 and ASTRA_855923) to GGT; and (iv) an MND Association Lady Edith Wolfson Junior Non-Clinical Fellowship to RS Saleeb/Oct22/980-799 (RSS). The authors would also like to thank the University of Aberdeen Microscopy and Histology Core Facility in the Institute of Medical Sciences.Peer reviewe

RRM adjacent TARDBP mutations disrupt RNA binding and enhance TDP-43 proteinopathy

Amyotrophic lateral sclerosis (ALS) presents with focal muscle weakness due to motor neuron degeneration that becomes generalized,leading to death from respiratory failure within 3–5 years from symptom onset. Despite the heterogeneity of aetiology, TDP- 43 proteinopathy is a common pathological feature that is observed in 495% of ALS and tau-negative frontotemporal dementia(FTD) cases. TDP-43 is a DNA/RNA-binding protein that in ALS and FTD translocates from being predominantly nuclear to formdetergent-resistant, hyperphosphorylated aggregates in the cytoplasm of affected neurons and glia. Mutations in TARDBP accountfor 1–4% of all ALS cases and almost all arise in the low complexity C-terminal domain that does not affect RNA binding andprocessing. Here we report an ALS/FTD kindred with a novel K181E TDP-43 mutation that is located in close proximity to the RRM1 domain. To offer predictive gene testing to at-risk family members, we undertook a series of functional studies to characterizethe properties of the mutation. Spectroscopy studies of the K181E protein revealed no evidence of significant misfolding.Although it is unable to bind to or splice RNA, it forms abundant aggregates in transfected cells. We extended our study to includeother ALS-linked mutations adjacent to the RRM domains that also disrupt RNA binding and greatly enhance TDP-43 aggregation,forming detergent-resistant and hyperphosphorylated inclusions. Lastly, we demonstrate that K181E binds to, and sequesters, wild-type TDP-43 within nuclear and cytoplasmic inclusions. Thus, we demonstrate that TDP-43 mutations that disrupt RNAbinding greatly enhance aggregation and are likely to be pathogenic as they promote wild-type TDP-43 to mislocalize andaggregate acting in a dominant-negative manner. This study highlights the importance of RNA binding to maintain TDP-43solubility and the role of TDP-43 aggregation in disease pathogenesis

The RNA-recognition motifs of TAR DNA-binding protein 43 may play a role in the aberrant self-assembly of the protein

The TAR DNA-binding protein 43 (TDP-43) is a nucleic acid-binding protein implicated in gene regulation and RNA processing and shuffling. It is a ribonuclear protein that carries out most of its functions by binding specific nucleic acid sequences with its two RNA-recognition motifs, RRM1 and RRM2. TDP-43 has been identified in toxic cytosolic inclusions in neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration with ubiquitin-positive inclusions (FTLD-U). The unstructured C-terminus has prion-like behavior and has been considered the driver of the aberrant self-assembly of TDP-43. In this work, we set out to test the hypothesis that the RNA-binding domains could also play a role in protein aggregation. This knowledge could be of important value for understanding TDP-43 aberrant, disease-leading behavior and, in the future, inform the design of small molecules that could prevent or slow down protein aggregation by exploiting the RNA-binding properties of the protein. We investigated the behavior of the two tandem RRM domains separately and linked together and studied their self-assembly properties and RNA-binding ability with a number of biophysical techniques. The picture that emerges from our study suggests that this region of the protein plays an important and so far unexplored role in the aggregation of this protein

Effect of heat treatment on microstructure and erosion resistance of white cast irons for slurry pumping applications

A series of commercial and non-conventional heat treatments was performed to modify the initial as-cast microstructure of two high-chromium (14 wt% and 18 wt% Cr) white cast irons and a low chromium nickel-bearing grade (Ni-Hard 2) for slurry pumping applications. The effect of each heat treatment on the microstructure of the alloys was carefully investigated by optical and scanning electron microscope and X-ray diffraction analysis. Samples were tested for impact erosion resistance in flowing slurry by using a modified-Coriolis apparatus and their weight losses were related to microstructure and hardness. The analysis showed that the erosion resistance of these alloys is related to the carbides volume fraction and hardness, in combination with the matrix microstructure. In case of high-chromium white irons, the destabilization heat treatment (950°C-2h) produced a hard martensitic matrix with secondary carbides that gave superior erosion resistance compared to all other conditions. Excellent performances were obtained also for Ni-Hard 2 in as-cast condition, indicating that this alloy could be an economic alternative to high chromium irons in applications where good erosion resistance is required