Biology subjects

Conlon, D. M.

Publications and source records attributed to Conlon, D. M..

3 recordsLinked to original sources

bioRxiv2026

Linking coronary microvascular structure and function in preclinical models of coronary microvascular disease

Despite growing awareness of the importance of the coronary microvasculature in cardiac health and disease, Coronary Microvascular Disease (CMVD) remains poorly understood, underdiagnosed, and without targeted therapies. Preclinical models and quantitative tools to measure CMVD are needed. Here, we use two novel quantitative methods to assess coronary microvascular structure (multi-fractal spectrum analysis) and function (Single Photon Emission Computed Tomography (SPECT)-based intramyocardial blood volume (IMBV) imaging) in mouse models of CMVD. Change in IMBV ({bigtriangleup}IMBV), which serves as a quantitative measure of vasodilatory capacity or microvascular function, was reduced with aging, driven by a significant decrease in female mice. Male mice on ApoE-/- background, fed a high-fat diet (HFD) for 6 months, or both had significantly reduced {bigtriangleup}IMBV. We used immunofluorescence to assess both traditional capillary density and global branching structure and vessel heterogeneity using multifractal spectrum analysis. Both were significantly reduced in all groups, and linear regression modeling showed that they were independently associated with {bigtriangleup}IMBV. Finally, we used {bigtriangleup}IMBV to assess the effects of widely used control Adeno-associated viral (AAV) vectors on coronary microvascular function. AAV-overexpression of GFP did not affect function, but Cre-recombinase compromised coronary microvascular structure and function by 16 weeks. In summary, quantitative assessments of coronary microvascular structure and function highlight changes consistent with CMVD seen with aging, female sex, and metabolic insults. Functional changes are partially driven, but not fully defined, by changes in the underlying structure, highlighting the important and incomplete link between structure and function.

physiology↗

bioRxiv2019

NASH patient liver derived organoids exhibit patient specific NASH phenotypes and drug responses.

To determine if patient liver derived organoids can in principle be a useful experimental model for non alcoholic staetohepatitis (NASH), we derived to our knowledge for the first time bipotent ductal organoids from endstage NASH patient livers, and for comparison from normal donor livers. We found that all tested NASH liver derived organoids exhibited a profound failure to dedifferentiate from the hepatic state back to the biliary state, consistent with the known poor regenerative capacity of NASH livers. Indeed, RNAseq on all tested NASH organoid populations confirmed down regulation of multiple cell cycle pathways. NASH liver derived hepatically differentiated organoids can slowly expand as monolayers, significantly simplifying microscopic quantitation: The monolayers show variable, but overall significantly increased lipid droplet accumulation in response to free fatty acids. Transcriptome analysis of NASH organoids reveals strong upregulation of a wide variety of pro inflammatory pathways in a NASH patient specific manner. Surprisingly, NASH liver derived organoids are highly diverse not only regarding their cytochrome cytochrome p450 metabolism and inflammatory response, but also react differentially to known antisteatotic, anti inflammatory and antifibrotic drugs, raising the possibility of using NASH patient liver biopsy derived organoids for personalized drug screening and therapy.\n\nOne Sentence SummaryNASH patient liver derived organoids replicate NASH liver phenotypes in a patient specific manner and exhibit profound differences in their response to drugs that are currently used in NASH clinical trials.

cell biology↗

bioRxiv2018

RNA-binding protein A1CF modulates plasma triglyceride levels through posttranscriptional regulation of stress-induced VLDL secretion

BackgroundA recent human exome-chip study on plasma lipids identified a missense mutation in the A1CF (APOBEC1 complementation factor) gene that is associated with elevated triglyceride (TG) levels, but how A1CF, an RNA binding protein, influences plasma TG is unknown.\n\nMethodsWe generated A1cf knockout (A1cf -/-) mice and knock-in mice homozygous for the TG-associated Gly398Ser mutation (A1cfGS/GS), determined lipid phenotypes, and assessed TG physiology through measurements of clearance and secretion. We further identified A1CFs RNA binding targets using enhanced cross-linking and immunoprecipitation sequencing of cultured HepG2 cells and investigated pathways enriched for these targets. Transcriptomic effects of A1CF deficiency were evaluated through RNA sequencing and analyses for differential expression, alternative splicing, and RNA editing.\n\nResultsBoth A1cf -/-and A1cfGS/GS mice exhibited increased fasting plasma TG, establishing that the TG phenotype is due to A1CF loss of function. In vivo TG secretion and clearance studies revealed increased TG secretion without changes in clearance in A1cf -/-mice. Increased VLDL-apoB secretion was also seen in A1cf -/-rat hepatoma cells, but no increase in apoB synthesis was observed. This phenotype was seen without significant shifts in apoB-100/apoB-48 in A1CF deficiency. To discover novel pathways for A1CFs role in TG metabolism, we identified A1CFs RNA binding targets, which were enriched for pathways related to proteasomal catabolism and endoplasmic reticulum (ER) stress. Indeed, proteasomal inhibition led to increased cellular stress in A1cf -/-cells, and higher expression of ER-stress protein GRP78 was observed in resting A1cf -/-cells. RNA-seq of whole livers from wild-type and A1cf -/-mice revealed that pro-inflammatory, not lipogenesis, genes were upregulated as a secondary effect of A1CF deficiency. Differential alternative splicing (AS) analysis and RNA editing analysis revealed that genes involved in cellular stress and metabolism underwent differential changes in A1CF deficiency, and top A1CF binding target proteins with relevance to intracellular stress were differentially expressed on the protein but not mRNA level, implicating multiple mechanisms by which A1CF influences TG secretion.\n\nConclusionsThese data suggest an important role for A1CF in mediating VLDL-TG secretion through regulating intracellular stress.

genomics↗