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Open Access Research article

A systems biology analysis of brain microvascular endothelial cell lipotoxicity

Hnin H Aung1, Athanasios Tsoukalas23, John C Rutledge1 and Ilias Tagkopoulos23*

Author Affiliations

1 Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, CA 95616, USA

2 UC Davis Genome Center, University of California, Davis, CA 95616, USA

3 Department of Computer Science, University of California, Davis, CA 95616, USA

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BMC Systems Biology 2014, 8:80  doi:10.1186/1752-0509-8-80

Published: 4 July 2014

Abstract

Background

Neurovascular inflammation is associated with a number of neurological diseases including vascular dementia and Alzheimer’s disease, which are increasingly important causes of morbidity and mortality around the world. Lipotoxicity is a metabolic disorder that results from accumulation of lipids, particularly fatty acids, in non-adipose tissue leading to cellular dysfunction, lipid droplet formation, and cell death.

Results

Our studies indicate for the first time that the neurovascular circulation also can manifest lipotoxicity, which could have major effects on cognitive function. The penetration of integrative systems biology approaches is limited in this area of research, which reduces our capacity to gain an objective insight into the signal transduction and regulation dynamics at a systems level. To address this question, we treated human microvascular endothelial cells with triglyceride-rich lipoprotein (TGRL) lipolysis products and then we used genome-wide transcriptional profiling to obtain transcript abundances over four conditions. We then identified regulatory genes and their targets that have been differentially expressed through analysis of the datasets with various statistical methods. We created a functional gene network by exploiting co-expression observations through a guilt-by-association assumption. Concomitantly, we used various network inference algorithms to identify putative regulatory interactions and we integrated all predictions to construct a consensus gene regulatory network that is TGRL lipolysis product specific.

Conclusion

System biology analysis has led to the validation of putative lipid-related targets and the discovery of several genes that may be implicated in lipotoxic-related brain microvascular endothelial cell responses. Here, we report that activating transcription factors 3 (ATF3) is a principal regulator of TGRL lipolysis products-induced gene expression in human brain microvascular endothelial cell.

Keywords:
Activating transcription factor 3; Microarray; Triglyceride-rich lipoprotein; Blood–brain barrier