Altered succinylation of mitochondrial proteins, APP and tau in Alzheimer’s disease

Abnormalities in brain glucose metabolism and accumulation of abnormal protein deposits called plaques and tangles are neuropathological hallmarks of Alzheimer’s disease (AD), but their relationship to disease pathogenesis and to each other remains unclear. Here we show that succinylation, a metabolism-associated post-translational protein modification (PTM), provides a potential link between abnormal metabolism and AD pathology. We quantified the lysine succinylomes and proteomes from brains of individuals with AD, and healthy controls. In AD, succinylation of multiple mitochondrial proteins declined, and succinylation of small number of cytosolic proteins increased. The largest increases occurred at critical sites of amyloid precursor protein (APP) and microtubule-associated tau. We show that in vitro, succinylation of APP disrupted its normal proteolytic processing thereby promoting Aβ accumulation and plaque formation and that succinylation of tau promoted its aggregation to tangles and impaired microtubule assembly. In transgenic mouse models of AD, elevated succinylation associated with soluble and insoluble APP derivatives and tau. These findings indicate that a metabolism-linked PTM may be associated with AD.

Method for milk whey microfiltration with filtrate pulsed backpressure and installation for its implementation

During deep processing of whey using microfiltration, the loss of membrane efficiency can take place. In this work, an installation for microfiltration of milk whey has been developed. It includes pumps, containers with liquids, throttling valves, a pressure gauge, and a microfiltration cell with a tubular ceramic membrane. A thin titanium oxide layer was deposited on the inner surface of the porous alumina tube. The outer diameter of the tubes is 10 mm, the wall thickness is 2 mm, the length of the tubes is 45 cm. A homogenized aqueous dispersion of sugar beet fiber was used as an agent that improves the performance of the installation by creating a pulsed backpressure of the filtrate. It is shown that the use of a finely ground suspension of dietary fiber during microfiltration of milk whey through a tubular ceramic membrane prevents the formation of protein deposits on the membrane and in its pores. The installation allows obtaining a suspension of dietary fiber, enriched with milk protein, as an additional product. The protein-enriched fiber suspension left over after microfiltration can be used in food production, for example, as a thickening agent in the production of yogurts.

Deletion of Mocos induces xanthinuria with obstructive nephropathy and major metabolic disorders in mice

Background: Xanthinuria type II is a rare autosomal purine disorder. This recessive defect of purine metabolism remains an underrecognized disorder. Methods: Mice with targeted disruption of the molybdenum cofactor sulfurase (Mocos) gene were generated to enable an integrated understanding of purine disorders and evaluate pathophysiological functions of this gene found in large number of pathways and known to be associated with autism. Results: Mocos deficient mice die with 4 weeks of age due to renal failure of distinct obstructive nephropathy with xanthinuria, xanthine deposits, cystic tublular dilatation, Tamm Horsfall (uromodulin) protein deposits, tubular cell necrosis with neutrophils and occasionally hypdronephrosis with urolithiasis. Obstructive nephropathy is associated with moderate interstitial inflammatory and fibrotic responses, anemia, reduced detoxification systems and important alterations of the metabolism of purines, amino acids and phospholipids.Conversely, heterozygous mice expressing reduced MOCOS protein are healthy with no apparent pathology. Conclusions: Mocos deficient mice develop a lethal obstructive nephropathy associated with profound metabolic changes. Studying MOCOS functions may provide important clues about the underlying pathogenesis of xanthinuria and other diseases requiring early diagnosis

Silver Nanoparticles as a Tool for the Study of Spontaneous Aggregation of Immunoglobulin Monoclonal Free Light Chains

Some misfolded proteins, e.g., immunoglobulin monoclonal free light chains (FLC), tend to form fibrils. Protein deposits in tissue may lead to amyloidosis and dysfunction of different organs. There is currently no technique allowing for the identification of FLC that are prone to aggregate. The development of such a method would enable the early selection of patients at high risk of developing amyloidosis. The aim of this study was to investigate whether silver nanoparticles (AgNPs) could be a useful tool to study the process of aggregation of FLC and their susceptibility to form the protein deposits. Mixtures of AgNPs and urine samples from patients with multiple myeloma were prepared. To evaluate the aggregation process of nanoparticles coated with proteins, UV-visible spectroscopy, transmission electron microscopy, and the original laser light scattering method were used. It has been shown that some clones of FLC spontaneously triggered aggregation of the nanoparticles, while in the presence of others, the nanoparticle solution became hyperstable. This is probably due to the structure of the chains themselves, unique protein-AgNPs interactions and perhaps correlates with the tendency of some FLC clones to form deposits. Nanoparticle technology has proven to be helpful in identifying clones of immunoglobulin FLC that tend to aggregate.

Sequence grammar underlying unfolding and phase separation of globular proteins

Protein homeostasis involves regulation of the concentrations of unfolded states of globular proteins. Dysregulation can cause phase separation leading to protein-rich deposits. Here, we uncover the sequence-grammar that influences the triad of folding, binding, and phase equilibria of unfolded proteins in cells. We find that the interactions that drive deposit formation of ALS-associated superoxide dismutase 1 mutations are akin to those that drive phase separation and deposit formation in variants of a model protein, barnase. We examined a set of barnase variants to uncover the molecular interactions that drive phase separation of unfolded proteins and formation of unfolded protein deposits (UPODs). The formation of UPODs requires protein destabilization, to increase the concentration of unfolded states, and a requisite sequence grammar to enable cohesive interactions among unfolded proteins. We further find that molecular chaperones, Hsp40 and Hsp70, destabilize UPODs by binding preferentially to and processing unfolded proteins in the dilute phase.

Complex Protein Astrogliopathy in an Octogenarian

Combination of multiple neurodegenerative proteinopathies is frequent in the elderly. We report the case of an octogenarian who attempted suicide and deceased after hospital admission. Anatomical mapping was performed in several cortical and subcortical brain regions using antibodies against phospho-tau, 4R tau, 3R tau, phospho-TDP-43, ubiquitin, α-synuclein, Aβ and p62. Unexpectedly, histopathologic examination showed prominent subpial, subependymal, grey and white matter, and perivascular aging-related tau astrogliopathy (ARTAG) affecting cortical and subcortical brain regions. This pathology was associated with intermediate Alzheimer’s disease neuropathologic change, cerebral amyloid angiopathy, Lewy-body-type and astroglial synuclein proteinopathy and a multiple system TDP-43 proteinopathy involving also the astroglia. This unusual case of extensive and widespread ARTAG with a complex multiproteinopathy may represent an independent disease entity in the elderly with tau astrogliopathy as the leading force.Learning ObjectiveRecognize astroglial protein deposits in neurodegeneration

Olfactory Bulb Proteomics Reveals Widespread Proteostatic Disturbances in Mixed Dementia and Guides for Potential Serum Biomarkers to Discriminate Alzheimer Disease and Mixed Dementia Phenotypes

The most common form of mixed dementia (MixD) is constituted by abnormal protein deposits associated with Alzheimer’s disease (AD) that coexist with vascular disease. Although olfactory dysfunction is considered a clinical sign of AD-related dementias, little is known about the impact of this sensorial impairment in MixD at the molecular level. To address this gap in knowledge, we assessed olfactory bulb (OB) proteome-wide expression in MixD subjects (n = 6) respect to neurologically intact controls (n = 7). Around 9% of the quantified proteins were differentially expressed, pinpointing aberrant proteostasis involved in synaptic transmission, nucleoside monophosphate and carbohydrate metabolism, and neuron projection regeneration. In addition, network-driven proteomics revealed a modulation in cell-survival related pathways such as ERK, AKT, and the PDK1-PKC axis. Part of the differential OB protein set was not specific of MixD, also being deregulated across different tauopathies, synucleinopathies, and tardopathies. However, the comparative functional analysis of OB proteome data between MixD and pure AD pathologies deciphered commonalities and differences between both related phenotypes. Finally, olfactory proteomics allowed to propose serum Prolow-density lipoprotein receptor-related protein 1 (LRP1) as a candidate marker to differentiate AD from MixD phenotypes.

Human kidney is a target for novel severe acute respiratory syndrome coronavirus 2 infection

It is unclear whether severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can directly infect human kidney, thus leading to acute kidney injury (AKI). Here, we perform a retrospective analysis of clinical parameters from 85 patients with laboratory-confirmed coronavirus disease 2019 (COVID-19); moreover, kidney histopathology from six additional COVID-19 patients with post-mortem examinations was performed. We find that 27% (23/85) of patients exhibited AKI. The elderly patients and cases with comorbidities (hypertension and heart failure) are more prone to develop AKI. Haematoxylin & eosin staining shows that the kidneys from COVID-19 autopsies have moderate to severe tubular damage. In situ hybridization assays illustrate that viral RNA accumulates in tubules. Immunohistochemistry shows nucleocapsid and spike protein deposits in the tubules, and immunofluorescence double staining shows that both antigens are restricted to the angiotensin converting enzyme-II-positive tubules. SARS-CoV-2 infection triggers the expression of hypoxic damage-associated molecules, including DP2 and prostaglandin D synthase in infected tubules. Moreover, it enhances CD68+ macrophages infiltration into the tubulointerstitium, and complement C5b-9 deposition on tubules is also observed. These results suggest that SARS-CoV-2 directly infects human kidney to mediate tubular pathogenesis and AKI.