Biology subjects

Matthiesen, R.

Publications and source records attributed to Matthiesen, R..

4 recordsLinked to original sources

bioRxiv2021

Glycation modulates glutamatergic signalling and exacerbates Parkinson's disease-like phenotypes

Alpha-synuclein (aSyn) is assumed to be a central player in the pathogenesis of synucleinopathies due to its accumulation in typical protein aggregates in the brain. However, it is still unclear how it contributes to neurodegeneration. Type-2 diabetes mellitus is a risk factor for Parkinsons disease and, one common molecular alteration among these disorders is an age-associated increase in protein glycation. Thus, we hypothesized that glycation-induced dysfunction of neuronal pathways might be an underlying molecular cause of synucleinopathies. Here, we evaluated if increased brain glycation modulated motor and/or non-motor phenotypes in a mouse model of synucleinopathies. In addition, we dissected the specific impact of methylglyoxal (MGO, a glycating agent) in mice overexpressing aSyn in the brain, and unveiled the major molecular pathways altered. Age-matched (16 weeks old) male aSyn transgenic (Thy1-aSyn) or WT mice received a single dose of MGO or vehicle via intracerebroventricular (ICV) injection. Behavioural phenotypes were analysed 4 weeks post-treatment, and, at the end of the tests, biochemical and histological studies were conducted on brain tissue. We found that glycation potentiates motor dysfunction, assessed by vertical pole, rotarod and hindlimb clasping tests in Thy1-aSyn mice. In addition, it induces cognitive impairment (Y maze test), olfactory disturbances (block test), and colonic dysfunction. These behavioural changes were accompanied by the accumulation of aSyn in the midbrain, striatum, and prefrontal cortex, and by an overall increase in glycation in the midbrain and cerebellum. Furthermore, MGO induced neuronal and dopaminergic cell loss in the midbrain of Thy1-aSyn mice. Quantitative proteomic analysis revealed that, in Thy1-aSyn mice, MGO mainly impacts on glutamatergic proteins in the midbrain, but not in the prefrontal cortex, where it mainly affects the electron transport chain. Among the altered proteins in the midbrain, we found an upregulation of N-Methyl-D-Aspartate (NMDA) and -amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) glutamate receptors levels, glutaminase, vesicle glutamate transporter (VGLUT), and the excitatory amino acid transporter (EAAT1), suggesting potentiation of glutamatergic signalling. Overall, we demonstrated that MGO-induced glycation accelerates Parkinsonian-like sensorimotor and cognitive alterations. The increase in glutamatergic-related proteins in the midbrain may represent a compensatory mechanism to the MGO-induced dopaminergic neurodegeneration. Our study sheds light into the enhanced vulnerability of the midbrain in Parkinsons disease-related synaptic dysfunction that, ultimately leads to cell loss, and provides molecular insight into the observation that glycation suppressors and anti-glutamatergic drugs hold promise as disease-modifying therapies for synucleinopathies.

neuroscience↗

bioRxiv2021

LAMP2A regulates the loading of proteins into exosomes.

Exosomes are extracellular vesicles of endosomal origin released by virtually all cell types across metazoans. Exosomes are active vehicles of intercellular communication and can transfer lipids, RNAs and proteins between different cells, tissues or organs. However, the mechanisms that regulate the selective loading of cytosolic proteins into these vesicles are still largely unknow. Here we describe a mechanism whereby proteins containing a pentapeptide sequence, biochemically related to the KFERQ-motif, are loaded into a subpopulation of exosomes in a process that is dependent on the membrane protein LAMP2A. Moreover, this mechanism is independent of the ESCRT machinery components TSG101 and VPS4b and dependent on HSC70, CD63, Alix, Syntenin-1, Rab31 and ceramides. The transcription factor and master regulator of hypoxia HIF1A is loaded into exosomes by this mechanism to transport hypoxia signaling to normoxic cells. Additionally, by tagging fluorescent proteins with KFERQ-like sequences we were able to follow inter-organ transfer of exosomes in zebrafish larvae. Our findings identify LAMP2A as a key component in exosome biogenesis while opening new avenues for exosome engineering by allowing the loading of bioactive proteins by tagging them with KFERQ-like motifs.

cell biology↗

bioRxiv2021

Messages From the Small Intestine Carried by Extracellular Vesicles in Prediabetes: a Proteomic Portrait

Extracellular vesicles (EVs) mediate communication in physiological and pathological conditions. In the pathogenesis of type 2 diabetes, inter-organ communication plays an important role in its progress and metabolic surgery leads to its remission. Moreover, gut dysbiosis is emerging as a diabetogenic factor. However, it remains unclear how gut senses metabolic alterations and whether this is transmitted to other tissues via EVs. Using a diet induced-prediabetic mouse model, we observed that protein packaging in gut derived EVs (GDE), specifically small intestine, is increased in prediabetes. Proteins related to lipid metabolism and to oxidative stress management were more abundant in prediabetic GDE compared to healthy controls. On the other hand, proteins related to glycolytic activity, as well as those responsible for the degradation of polyubiquitinated composites, were depleted in prediabetic GDE. Together, our findings show that protein packaging in GDE is markedly modified during prediabetes pathogenesis. Thus, suggesting that prediabetic alterations in small intestine are translated into modified GDE proteome, which are dispersed into the circulation where they can interact with and influence the metabolic status of other tissues. This study highlights the importance of the small intestine as a tissue that propagates prediabetic metabolic dysfunction throughout the body and the importance of GDE as the messenger.

pathology↗

bioRxiv2021

Cholesteryl Hemiazelate Induces Lysosome Dysfunction and Exocytosis in Macrophages

OBJECTIVEA key event in atherogenesis is the formation of lipid-loaded macrophages, lipidotic cells, which exhibit irreversible accumulation of undigested modified low-density lipoproteins in lysosomes. This event culminates with the loss of cell homeostasis, inflammation and cell death. In this study we propose to identify the chemical etiological factors and understanding the molecular and cellular mechanisms responsible for the impairment of lysosome function in macrophages. APPROACH AND RESULTSUsing shotgun lipidomics we have discovered that a family of oxidized lipids (cholesteryl hemiesters, ChE), end products of oxidation of polyunsaturated cholesteryl esters, occurs at higher concentrations in the plasma of two cohorts of cardiovascular disease patients than in the plasma of a control cohort. Macrophages exposed to the most prevalent ChE, cholesteryl hemiazelate (ChA) exhibit lysosome enlargement, peripheral lysosomal positioning, lysosome dysfunction and lipidosis which are irreversible. The transcriptomic profile of macrophages exposed to ChA indicates that the lysosome pathway is deeply affected and is well correlated with lysosome phenotypic and functional changes. Interestingly, the dysfunctional peripheral lysosomes are more prone to fuse with the plasma membrane, secreting their undigested luminal content into the extracellular milieu with potential consequences to the pathology. CONCLUSIONWe identify ChA not only as one of the molecules involved in the etiology of irreversible lysosome dysfunction culminating with lipidosis but also as a promoter of exocytosis of the dysfunctional lysosomes. The latter event is a new mechanism that may be important in the pathogenesis of atherosclerosis.

cell biology↗