Biology subjects

Ouellette, A.

Publications and source records attributed to Ouellette, A..

6 recordsLinked to original sources

bioRxiv2026

Validation of tissue-specific RNAi systems in C. elegans reveals a converging role for polyubiquitin UBQ-1/UBC in vitellogenin metabolism and lifespan

Numerous studies in C. elegans have taken advantage of gene silencing RNAi libraries and tissue-specific RNAi systems to temporally and spatially understand gene function. Tissue-specific RNAi strains were created via tissue-specific functional expression of a key gene in the RNAi system in a presumably RNAi insensitive correspondingly mutated background. Here, we tested the level of RNAi insensitivity across different commonly used RNAi-defective mutants (rde-1 and sid-1) using lifespan analyses. Remarkably, while we found similarly important lifespan shortening in wild-type animals by silencing the polyubiquitin gene ubq-1 (UBC) at both 20{degrees}C and 25{degrees}C, we found wide and temperature-sensitive variations in RNAi sensitivity across different rde-1 and sid-1 strains from substantial sensitivity to complete insensitivity. This riveting finding warrants a re-evaluation of the tissue-specific interpretations in numerous tissue-specific RNAi studies in C. elegans. Using validated tissue-specific RNAi systems, we determined that proteasomal burden largely differs between the germline and the soma. Notably, gonadally accumulating vitellogenin proteins substantially contributed to the total polyubiquitinated proteins observed during aging. Interestingly, we found that UBQ-1 was essential to maintain the transcription of highly expressed genes, including vitellogenins, supporting a broad and key role for polyubiquitin beyond proteostasis. Altogether, we authenticated commonly used tissue-specific RNAi systems and uncovered a new approach to improve RNAi insensitivity in RNAi-defective strains. With validated tissue-specific RNAi strains, we spatially analyzed proteasomal function and age-related polyubiquitinated protein accumulation and revealed a converging regulatory link between UBQ-1, vitellogenin metabolism and lifespan in C. elegans.

genetics↗

bioRxiv2024

Spatial memory in Alzheimer's disease 5XFAD mice is enhanced by XPO1 inhibitor KPT-330

The proteostatic decline in Alzheimers disease is well established and improvement in proteostasis could potentially delay cognitive impairment. One emerging entry point to modulate proteostasis is the regulation of nucleo-cytoplasmic partitioning of proteins across the nuclear pore via karyopherins. The nuclear exportin XPO1 is a key regulator of proteostasis by driving the assembly of ribosomes and by modulating the process of autophagy. We recently found that XPO1 inhibitor KPT-330 (Selinexor), an FDA approved drug against multiple myelomas, enhances proteostasis, leading to benefits in models of neurodegenerative diseases in C. elegans and Drosophila. Here, we find that KPT-330 increases autophagy in murine neuronal cells and improves spatial memory performance in a murine model of Alzheimers disease (5XFAD). Unexpectedly, general amyloid deposition in several brain regions was significantly increased by KPT-330, but specific regions, especially the thalamus, displayed significantly lower deposition, suggesting that XPO1 inhibition has regional-specific effects on proteostasis and amyloid plaque formation. Altogether, we conclude that XPO1 inhibition can improve cognition via spatially-specific reductions in amyloid deposition.

neuroscience↗

bioRxiv2024

Lysyl Oxidases are Necessary for Myometrial Contractility and On-Time Parturition in Mice

The extracellular matrix (ECM) plays a pivotal role in the maintenance of tissue mechanical homeostasis. Collagens and elastic fibers are the most predominant fibrous ECM proteins providing tissue mechanical function through covalent cross-linking which is mediated by the lysyl oxidase family of enzymes. In this study, the function of lysyl oxidases in maintaining the integrity of the extracellular matrix in the myometrium and its impact on parturition-timing was investigated. Gene and protein expression analyses demonstrate that a sub-set of the lysyl oxidase family of enzymes are highly induced in pregnant myometrium. Inhibition of the activity of the lysyl oxidase family of enzymes through {beta}-aminopropionitrile (BAPN) delays parturition in mice, in part, due to myometrial dysfunction. In BAPN treated mice, the expression of genes encoding contraction associated proteins such as connexin 43, oxytocin receptor and prostaglandin synthase 2 is significantly reduced in the myometrium compared to the untreated control mice. Proteomic analysis revealed that the composition of the ECM is altered in response to BAPN treatment which demonstrates that the inhibition of the activity of lysyl oxidases disrupted the integrity of the myometrial ECM. Our findings demonstrate that the lysyl oxidases-mediated ECM function is necessary for the myometrium to transition from a quiescent to a contractile phenotype at term for on-time parturition.

physiology↗

bioRxiv2023

Detecting the effect of genetic diversity on brain composition in an Alzheimer's disease mouse model

Alzheimers disease (AD) is characterized by neurodegeneration, pathology accumulation, and progressive cognitive decline. There is significant variation in age at onset and severity of symptoms highlighting the importance of genetic diversity in the study of AD. To address this, we analyzed cell and pathology composition of 6- and 14-month-old AD-BXD mouse brains using the semi-automated workflow (QUINT); which we expanded to allow for nonlinear refinement of brain atlas-registration, and quality control assessment of atlas-registration and brain section integrity. Near global age-related increases in microglia, astrocyte, and amyloid-beta accumulation were measured, while regional variation in neuron load existed among strains. Furthermore, hippocampal immunohistochemistry analyses were combined with bulk RNA- sequencing results to demonstrate the relationship between cell composition and gene expression. Overall, the additional functionality of the QUINT workflow delivers a highly effective method for registering and quantifying cell and pathology changes in diverse disease models.

neuroscience↗

bioRxiv2022

Experimental Diets Dictate the Metabolic Benefits of Lactobacillus Strains in Obesity

BackgroundGrowing evidence supports the use of probiotics to prevent or mitigate obesity-related dysmetabolism and non-alcoholic fatty liver disease (NAFLD). However, frequent reports of responders versus non-responders to probiotic treatment warrant a better understanding of key modifiers of host-microbe interactions. The influence of host diet on probiotic efficacy, in particular against metabolic diseases, remains elusive. MethodWe fed C57BL6/J mice a low fat reference diet or one of two energy-matched high fat and high sucrose diets for 12 weeks; a classical high fat diet (HFD) and a customized fast food-mimicking diet (FFMD). During the studies, mice fed either obesogenic diet were gavaged daily with one of two probiotic lactic acid bacteria (LAB) strains previously classified as Lactobaccillus, namely Limosilactobacillus reuteri (L. reuteri) or Lacticaseibacillus paracasei subsp. paracasei (L. paracasei), or vehicle. ResultsThe tested probiotics exhibited a reproducible efficacy but dichotomous response according to the obesogenic diets used. Indeed, L. paracasei prevented weight gain, improved insulin sensitivity, and protected against NAFLD development in mice fed HFD, but not FFMD. Conversely, L. reuteri improved glucoregulatory capacity, reduced NAFLD development, and increased distal gut bile acid levels associated with changes in predicted functions of the gut microbiota exclusively in the context of FFMD-feeding. ConclusionWe found that the probiotic efficacy of two LAB strains is highly dependent on experimental obesogenic diets. These findings highlight the need to carefully consider the confounding impact of diet in order to improve both the reproducibility of preclinical probiotic studies and their clinical research translatability. Graphical abstract O_FIG_DISPLAY_L [Figure 1] M_FIG_DISPLAY C_FIG_DISPLAY

microbiology↗

bioRxiv2019

Rapamycin rejuvenates oral health in aging mice

Periodontal disease is an age-associated disorder clinically defined by periodontal bone loss, inflammation of the specialized tissues that surround and support the tooth, and microbiome dysbiosis. Currently, there is no therapy for reversing periodontal disease, and treatment is generally restricted to preventive measures or tooth extraction. The FDA-approved drug rapamycin slows aging and extends lifespan in multiple organisms, including mice. Here we demonstrate that short-term treatment with rapamycin rejuvenates the aged oral cavity of elderly mice, including regeneration of periodontal bone, attenuation of gingival and periodontal bone inflammation, and revertive shift of the oral microbiome toward a more youthful composition. This provides a geroscience strategy to potentially rejuvenate oral health and reverse periodontal disease in the elderly. Single Sentence SummaryShort-term treatment with rapamycin reverses periodontal bone loss, attenuates inflammation, and remodels the oral microbiome toward a more youthful state.

pathology↗