Allelic imbalance of tissue-type plasminogen activator (t-PA) gene expression in human brain tissue

Anna Tjärnlund-Wolf; Karin Hultman; Maurice A. Curtis; Richard L. M. Faull; Robert L. Medcalf; Christina Jern

doi:10.1160/TH10-10-0682

Thrombosis and Haemostasis, Table of Contents

Thromb Haemost 2011; 105(06): 945-953
DOI: 10.1160/TH10-10-0682

Blood Coagulation, Fibrinolysis and Cellular Haemostasis

Schattauer GmbH

Allelic imbalance of tissue-type plasminogen activator (t-PA) gene expression in human brain tissue

Anna Tjärnlund-Wolf

¹Institute of Neuroscience and Physiology, Section for Clinical Neuroscience and Rehabilitation, the Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden

,

Karin Hultman

¹Institute of Neuroscience and Physiology, Section for Clinical Neuroscience and Rehabilitation, the Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden

,

Maurice A. Curtis

²Department of Anatomy with Radiology, Centre for Brain Research, University of Auckland, Auckland, New Zealand

,

Richard L. M. Faull

²Department of Anatomy with Radiology, Centre for Brain Research, University of Auckland, Auckland, New Zealand

,

Robert L. Medcalf

³Australian Centre for Blood Diseases, Department of Clinical Haematology, Alfred Medical Research and Education Precinct, Monash University, Melbourne, Victoria, Australia

,

Christina Jern

¹Institute of Neuroscience and Physiology, Section for Clinical Neuroscience and Rehabilitation, the Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden

› Author Affiliations

Abstract

Summary

We have identified a single-nucleotide polymorphism (SNP) in the t-PA enhancer (-7351C>T), which is associated with endothelial t-PA release in vivo. In vitro studies demonstrated that this SNP is functional at the level of transcription. In the brain, t-PA has been implicated in both physiologic and pathophysiologic processes. The aim of the present study was to examine the effect of the t-PA –7351C>T SNP on t-PA gene expression in human brain tissue. Allelic mRNA expression was measured in heterozygous post-mortem brain tissues using quantitative TaqMan genotyping assay. Protein-DNA interactions were assessed using electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP). Significantly higher levels of t-PA mRNA were generated from chromosomes that harboured the wild-type –7351C allele, as compared to those generated from the mutant T allele (for the hippocampus, C to T allelic ratio of ~1.3, p=0.010, n=12; and for the cortex, C to T allelic ratio of ~1.2, p=0.017, n=12). EMSA showed reduced neuronal and astrocytic nuclear protein binding affinity to the T allele, and identified Sp1 and Sp3 as the major transcription factors that bound to the –7351 site. ChIP analyses confirmed that Sp1 recognises this site in intact cells. In conclusion, the t-PA –7351C>T SNP affects t-PA gene expression in human brain tissue. This finding might have clinical implications for neurological conditions associated with enhanced t-PA levels, such as in the acute phase of cerebral ischaemia, and also for stroke recovery.

Keywords

Allelic imbalance - gene expression - human brain tissue - polymorphism - tissue-type plasminogen activator

Full Text

References

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