Objective: Shear forces play a key role in the maintenance of vessel wall integrity. Current understanding regarding shear-dependent gene expression is mainly based on in vitro or in vivo observations with experimentally deranged shear, hence reflecting acute molecular events in relation to flow. Our objective was to combine computational fluid dynamic (CFD) simulations with global microarray analysis to study flow-dependent vessel wall biology in portions of the entire aorta under physiological conditions. Methods and Results: Animal-specific WSS magnitude and vector direction were estimated using CFD based on aortic geometry and flow information acquired by MRI. Two distinct flow pattern regions were identified in the normal rat aorta; the distal part of the inner curvature being exposed to low WSS and a non-uniform vector direction, and a region along the outer curvature being subjected to markedly higher levels of WSS and a uniform vector direction. Microarray analysis identified numerous novel mechanosensitive genes, including Hand2, trpc4 and slain2, and confirmed well-known ones, such as klf2 and BMP4. Three genes were further validated for protein , including Hand2, which showed higher expression in the endothelium in regions exposed to disturbed flow. Gene ontology analysis revealed an over-representation of genes involved in transcriptional regulation.
Characterization of shear-sensitive genes in the normal rat aorta identifies Hand2 as a major flow-responsive transcription factor.
Specimen part
View SamplesIncreasing evidence suggests that defective RNA processing contributes to the development of amyotrophic lateral sclerosis (ALS). This may be especially true for ALS caused by a repeat expansion in C9orf72 (c9ALS), in which the accumulation of RNA foci and dipeptide-repeat proteins are expected to modify RNA metabolism. We report extensive alternative splicing (AS) and alternative polyadenylation (APA) defects in the cerebellum of c9ALS cases (8,224 AS, 1,437 APA), including changes in ALS-associated genes (e.g. ATXN2 and FUS), and cases of sporadic ALS (sALS; 2,229 AS, 716 APA). Furthermore, hnRNPH and other RNA-binding proteins are predicted as potential regulators of cassette exon AS events for both c9ALS and sALS. Co-expression and gene-association network analyses of gene expression and AS data revealed divergent pathways associated with c9ALS and sALS. Overall design: Examination transcriptiome profiles in c9orf72-associated ALS, sporadic ALS and healthy control
Repetitive element transcripts are elevated in the brain of C9orf72 ALS/FTLD patients.
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View SamplesPancreatic cancers (PCs) are highly metastatic with poor prognosis, mainly due to delayed detection. We hypothesized that intercellular communication is critical for metastatic progression. Here, we show that PC-derived exosomes induce liver pre-metastatic niche formation in naïve mice and consequently increase liver metastatic burden. Uptake of PC-derived exosomes by Kupffer cells caused transforming growth factor ß secretion and upregulation of fibronectin production by hepatic stellate cells. This fibrotic microenvironment enhanced recruitment of bone marrow-derived macrophages. We found that macrophage migration inhibitory factor (MIF) was highly expressed in PC-derived exosomes, and its blockade prevented liver pre-metastatic niche formation and metastasis. Compared to patients whose pancreatic tumors did not progress, MIF was markedly higher in exosomes from stage I PC patients who later developed liver metastasis. These findings suggest that exosomal MIF primes the liver for metastasis and may be a prognostic marker for the development of PC liver metastasis. Overall design: Normal pancreas and Pancreatic cancer exosomes education of human von Kupffer cells in vitro
Pancreatic cancer exosomes initiate pre-metastatic niche formation in the liver.
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