Biology subjects

Outeiro, T.

Publications and source records attributed to Outeiro, T..

4 recordsLinked to original sources

bioRxiv2026

LRRK2/LRRK1 interactions modulate Rab7 activity and inhibit lysosomal exocytosis

Mutations in the LRRK2 gene are the most common genetic cause of both familial and sporadic Parkinsons disease (PD). LRRK2 belongs to the leucine-rich repeat kinase (LRRK) family. Two members of the LRRK family exist in humans (LRRK1 and LRRK2). Although there is strong structural similarity between the two proteins, they have attracted very different levels of attention by the scientific community owing to the strong association between LRRK2 and PD. In contrast, the role of LRRK1 is relatively unexplored. LRRK2 is also known to regulate endolysosomal function, but its precise role in this process remains incompletely understood. Our study investigated the interaction between LRRK1 and LRRK2 under different cellular conditions, uncovering their role in modulating the endolysosomal system. We found that LRRK1 and LRRK2 interact and modulate each others activity, and that this interaction is reduced under starvation conditions. We also found that LRRK1 and LRRK2 have contrasting effects on lysosomal size, impacting on lysosomal exocytosis. Together, our findings suggest that LRRK2 regulates endolysosomal homeostasis, at least in part, by modulating LRRK1. Our findings offer new insight into the molecular mechanisms associated with lysosomal function and, ultimately, we anticipate this knowledge will help us better understand the molecular crosstalk between LRRK kinases and their contribution to PD pathogenesis. Graphical abstractStarvation reduces the interaction between LRRK2 and LRRK1 due to a conformational change in LRRK2. Under normal conditions, LRRK2/LRRK1 interaction enhances LRRK1 activity, leading to increased phosphorylation of Rab7. Disruption of the Rab7 cycle impairs lysosomal homeostasis, leading to lysosomal accumulation and an increase in lysosomal diameter. This enlargement negatively impacts lysosomal exocytosis. Created with BioRender.com. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=176 SRC="FIGDIR/small/731951v1_ufig1.gif" ALT="Figure 1"> View larger version (34K): org.highwire.dtl.DTLVardef@13ce58forg.highwire.dtl.DTLVardef@1034543org.highwire.dtl.DTLVardef@1b84096org.highwire.dtl.DTLVardef@198598f_HPS_FORMAT_FIGEXP M_FIG C_FIG

Cell Biology↗

bioRxiv2024

Glycation of alpha-synuclein enhances aggregation and neuroinflammatory responses

The risk of developing Parkinsons disease (PD) is elevated in people with type 2 diabetes, but the precise molecular pathways underlying this connection are still unclear. One hypothesis is that glycation, a non-enzymatic family of reactions between glycating agents, such as reducing sugars or reactive dicarbonyls, and specific amino acids, such as lysines and arginines, may alter proteostasis and trigger pathological alterations. Glycation of alpha-synuclein (aSyn), a central player in PD pathology, causes profound changes in the aggregation process of aSyn. Methylglyoxal (MGO), a strong glycating agent, induces the formation of pathological inclusions enriched in phosphorylated aSyn on serine 129 (pS129). In addition, we found that neuroinflammatory responses are enhanced by MGO-mediated aSyn glycation. Using novel polyclonal antibodies developed towards specific MGO-glycated aSyn residues, we confirmed the occurrence of glycated aSyn both in vitro as well as in animal and in human brain tissue. In total, our findings shed light into the interplay between glycation, PD, and type 2 diabetes, potentially paving the way for the development of novel therapeutic strategies targeting these intertwined conditions.

neuroscience↗

bioRxiv2024

Synphilin-1 as a modulator of aSyn assembly

Alpha-synuclein (aSyn) is an intrinsically disordered protein that undergoes phase-separation and is associated with several neurodegenerative conditions. However, the function and the pathological role of aSyn are still elusive. Here, we modeled different types of aSyn assemblies in living cells, and developed a model that reports on gel and solid-like inclusions based on the coexpression of aSyn and synphilin-1 (Sph1). We identified striking morphological differences between aSyn-aSyn and Sph1-aSyn assemblies, characterized by distinct antibody recognition patterns, resistance to Proteinase K treatment, and protein mobilities. Importantly, we showed that the interaction between Sph1-aSyn can be manipulated, altering inclusion size and number. Sph1-aSyn interactions were central for inclusion formation and localization, and that inclusions include lysosomes and AP-1 vesicles, consistent with previous studies in human brain tissue. In total, we provide novel insight into the biology of protein aggregation, shedding light on potential therapeutic strategies that extend beyond conventional targets. Deciphering the role of Sph1 and other aSyn-interacting proteins on aSyn biology and pathobiology will be essential for treating synucleinopathies.

molecular biology↗

bioRxiv2023

Post-mortem AT-8 reactive tau species correlate with non-plaque Aβ levels in the frontal cortex of non-AD and AD brains

The amyloid cascade hypothesis states that A{beta} and its aggregates induce pathological changes in tau, leading to formation of neurofibrillary tangles (NFTs) and cell death. A caveat with this hypothesis is the temporo-spatial divide between plaques and NFTs. This has been addressed by the inclusion of soluble species of A{beta} and tau in the revised amyloid cascade hypothesis, however, the demonstration of a correlative relationship between A{beta} and tau burden in post-mortem human tissue has remained elusive. Employing frozen and fixed frontal cortex grey and associated white matter tissue from non-AD controls (Con; n=39) and Alzheimers diseases (AD) cases (n=21), biochemical and immunohistochemical measures of A{beta} and AT-8 phosphorylated tau were assessed. Native-state dot-blot from crude tissue lysates demonstrated robust correlations between intraregional A{beta} and AT-8 tau, such increases in A{beta} immunoreactivity conferred increases in AT-8 immunoreactivity, both when considered across the entire cohort as well as separately in Con and AD cases. In contrast, no such association between A{beta} plaques and AT-8 were reported when using immunohistochemical measurements. However, when using the non-amyloid precursor protein cross reactive MOAB-2, antibody to measure intracellular A{beta} within a subset of cases, a similar correlative relationship with AT-8 tau as that observed in biochemical analysis was observed. Collectively our data suggests that accumulating intracellular A{beta} may influence AT-8 pathology. Despite the markedly lower levels of phospho-tau in non-AD controls correlative relationships between AT-8 phospho-tau and A{beta} as measured in both biochemical and immunohistochemical assays were more robust in non-AD controls, suggesting a physiological association of A{beta} production and tau phosphorylation, at least within the frontal cortex. Such interactions between regional A{beta} load and phospho-tau load may become modified with disease potentially, as a consequence of interregional tau seed propagation, and thus may diminish the linear relationship observed between A{beta} and phospho-tau in non-AD controls. This study provides evidence supportive of the revised amyloid cascade hypothesis, and demonstrates an associative relationship between AT-8 tau pathology and intracellular A{beta} but not extracellular A{beta} plaques.

neuroscience↗