Aberrant regulation of retinoic acid signaling genes in cerebral arterio venous malformation nidus and neighboring astrocytes

Mathew Abraham,Sumi Surendran,Jaya Mary Thomas,Arumugam Rajavelu,Chandrasekharan C Kartha,Dhakshmi Sasankan

doi:10.1186/s12974-021-02094-2

Abstract

BackgroundCerebral arterio venous malformations (AVM) are a major causal factor for intracranial hemorrhage, which result in permanent disability or death. The molecular mechanisms of AVM are complex, and their pathogenesis remains an enigma. Current research on cerebral AVM is focused on characterizing the molecular features of AVM nidus to elucidate the aberrant signaling pathways. The initial stimuli that lead to the development of AVM nidus structures between a dilated artery and a vein are however not known.MethodsIn order to understand the molecular basis of development of cerebral AVM, we used in-depth RNA sequencing with the total RNA isolated from cerebral AVM nidus. Immunoblot and qRT-PCR assays were used to study the differential gene expression in AVM nidus, and immunofluorescence staining was used to study the expression pattern of aberrant proteins in AVM nidus and control tissues. Immunohistochemistry was used to study the expression pattern of aberrant proteins in AVM nidus and control tissues.ResultsThe transcriptome study has identified 38 differentially expressed genes in cerebral AVM nidus, of which 35 genes were upregulated and 3 genes were downregulated. A final modular analysis identified an upregulation of ALDH1A2, a key rate-limiting enzyme of retinoic acid signaling pathway. Further analysis revealed that CYR61, a regulator of angiogenesis, and the target gene for retinoic acid signaling is upregulated in AVM nidus. We observed that astrocytes associated with AVM nidus are abnormal with increased expression of GFAP and Vimentin. Triple immunofluorescence staining of the AVM nidus revealed that CYR61 was also overexpressed in the abnormal astrocytes associated with AVM tissue.ConclusionUsing high-throughput RNA sequencing analysis and immunostaining, we report deregulated expression of retinoic acid signaling genes in AVM nidus and its associated astrocytes and speculate that this might trigger the abnormal angiogenesis and the development of cerebral AVM in humans.

Highlights

Cerebral arterio venous malformations (AVMs) are an important cause for intracranial hemorrhage (ICH) and neurological morbidity in young adults [2]
Transcriptome profiling of cerebral AVM nidus identifies aberrant gene expression To identify the aberrant molecular signatures in the cerebral AVM nidus structures, we employed in-depth Ribonucleic acid (RNA) sequencing with RNA isolated from cerebral AVM nidus
The qualities of RNA sequencing reads were very good in both controls and test samples, and 97.54% of sequencing reads for AVM nidus tissues and 91% reads in control tissues were mapped to the human reference human genome

Summary

Introduction

Cerebral arterio venous malformations (AVMs) are an important cause for intracranial hemorrhage (ICH) and neurological morbidity in young adults [2]. The AVM nidus structures consist of abnormal blood vessels whose identity is distinct from normal vascular structures [15] These lesions can occur in any of the four lobes of the brain, and patients with cerebral AVM present symptoms such as headache, seizures, and hemorrhage [10, 13]. Deregulated genes in AVM are associated with various cellular pathways that include genes regulating endocrine hormones, cell adhesion molecules, inflammatory factors, matrix metalloproteinases, and angiogenic factors [22]. It is unclear whether these genetic defects represent a primary cause for the disease or are a secondary response to disease development. The initial stimuli that lead to the development of AVM nidus structures between a dilated artery and a vein are not known

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Conclusion