Biology subjects

Plourde, M.

Publications and source records attributed to Plourde, M..

3 recordsLinked to original sources

bioRxiv2023

Impact of in vivo cyclic reprogramming on the choroid plexus

In vivo reprogramming using the transient expression of Oct3/4, Sox2, Klf4 and c{square}Myc (OSKM) transcription factors can be used to induce tissue regeneration. A cyclic regime for short{square}term OSKM expression has been shown to promote regeneration of several organs however its impact on the brain remains largely unknown. We investigated the effects of a cyclic short-term OSKM expression on the choroid plexus (CP), a highly vascularized tissue found within the brain ventricles which is responsible for producing the cerebrospinal fluid (CSF). Transient reprogramming was done on 8-week-old mice carrying the polycistronic OSKM cassette under tetracycline operator (tetO) and confirmed the successful transient reprogramming. We then performed the analysis of the CP at cellular and molecular levels. The CP tissue exhibited minor morphological changes in height and area of epithelial cells. We did not observe any significant differences in the integrity of the brain-CSF barrier but noticed an increase of NKCC1 expression, a protein involved in CSF production. A whole transcriptome analysis (RNA-seq) was also carried on the tissue and showed no difference in gene expression after the transient reprogramming, at the exception of blood-related genes. Our results indicate that surprisingly the CP mainly remains insensible to in vivo transient reprogramming as only morphological and protein changes were observed in the tissue, suggesting that translational changes might be at stake during the reprogramming process but are not present at the transcriptomic level. Our results also highlight that more tailored strategies need to be developed for exploring the potential of CP reprogramming in regenerative medicine.

neuroscience↗

bioRxiv2022

Genetic inactivation of the USP19 deubiquitinase regulates a-synuclein ubiquitination and inhibits accumulation of Lewy body like aggregates in mice

The USP19 deubiquitinase is found in a locus associated with Parkinsons Disease (PD), interacts with heat shock proteins and promotes secretion of a-synuclein (a-syn) through the misfolding associated protein secretion (MAPS) pathway. Since these processes might modulate the processing of a-syn aggregates during the progression of PD, we tested the effect of USP19 knockout (KO) in mice expressing the A53T mutation of a-syn and in whom a-syn preformed fibrils (PFF) had been injected in the striatum. Compared to WT, KO brains showed decreased accumulation of phospho-synuclein (pSyn) positive aggregates. The improved pathology was associated with less activation of microglia, higher levels of synaptic marker proteins and improved performance in a tail suspension test. Exposure of primary neurons from WT and KO mice to PFF in vitro also led to decreased accumulation of pSyn aggregates. KO did not affect uptake of PFF in the cultured neurons. It also did not affect the propagation of aggregates as assessed by exposing WT or KO neurons to PFF and measuring pSyn positive aggregates in non-exposed adjacent neurons separated using a microfluidics device. We conclude that USP19 instead modulates intracellular dynamics of aggregates. Indeed, at the early time following PFF injection when the number of pSyn positive neurons were similar in WT and KO brains, the KO neurons contained less aggregates. KO brain aggregates stained more intensely with anti-ubiquitin antibodies. Immunoprecipitation of soluble proteins from primary neurons exposed to PFF with antibodies to ubiquitin or pSyn showed higher levels of ubiquitinated a-syn oligomeric species in the KO neurons. We propose that the improved pathology in USP19 KO brains may arise from decreased formation or enhanced clearance of the more ubiquitinated aggregates and/or enhanced disassembly towards more soluble oligomeric species. USP19 inhibition may represent a novel therapeutic approach that targets the intracellular dynamics of a-syn complexes.

neuroscience↗

bioRxiv2022

Decoupling of mRNA and protein expression in aging brains reveals the age-dependent adaptation of specific gene subsets

During aging, changes in gene expression are associated with decline in physical and cognitive abilities. Here, we investigated the connection between changes of mRNA and protein expression in the brain by comparing the transcriptome and proteome of the mouse cortex during aging. Our transcriptomic analysis revealed that aging mainly triggers gene activation in the cortex. We showed that increase of mRNA expression correlates with protein expression, specifically in the anterior cingulate cortex where we also observed an increase of cortical thickness during aging. Genes exhibiting an aging-dependent increase of mRNA and protein levels are involved in sensory perception and immune functions. Our proteomic analysis also identified changes in protein abundance in the aging cortex and highlighted a subset of proteins that were differentially enriched but exhibited stable mRNA levels during aging, implying the contribution of aging-related post transcriptional and post-translational mechanisms. These specific genes were associated with general biological processes such as translation, ribosome assembly and protein degradation, but also important brain functions related to neuroplasticity. By decoupling mRNA and protein expression, we have thus characterized distinct subsets of genes that differentially adjust to cellular aging in the cerebral cortex.

biochemistry↗