Genome-wide Transcriptome Study in Skin Biopsies Reveals an Association of E2F4 With Cadasil and Cognitive Impairment

Abstract

Background:CADASIL is a small vessel disease caused by mutations in NOTCH3 that lead to an odd number of cysteines in the receptor, causing protein misfolding and aggregation. The main symptoms are migraine, psychiatric disturbances, recurrent strokes and dementia, as executive function is characteristically impaired. The molecular pathways altered by this receptor aggregation need to be studied further.Methods:Agenome-wide transcriptome study(four casespaired with three healthysiblings)was carried out,in addition toa qRT-PCR for validation purposes(ten new cases and eight new controls).Neuropsychological tests were performedto evaluateverbal memory, attention and information processing speed (IPS), motor speed and dexterity, executive function and visuoconstructional skills. The Single-nuclei Brain RNA-seq expression browser (SNBREB) and the GTExPortalwere used to study brain expressionof the significant mRNAs found.Results: The two most significant differentially expressed mRNAs (BANP,p-value=7.23x10-4 and PDCD6IP, p-value=8.36x10-4) were selected for the validation study by qRT-PCR. Additionally, we selectedtwo more mRNAs(CAMK2G,p-value=4.52x10-3 and E2F4, p-value=4.77x10-3) due to their association with ischemic neuronal death. E2F4showed differential expression in the genome-wide transcriptome study and in the qRT-PCR (p=1.23x10-3), and it was upregulated in CADASIL cases. Furthermore, higher E2F4 expressionwas associated with worseexecutive function (p=2.04x10-2) and attention and IPS (p=8.73x10-2).In silico studies indicated that E2F4 is expressed in brain endothelial cells. Conclusions:Skin biopsies of CADASIL patients presented higher mRNA levels of E2F4and these higher levels have a significant correlation with worseexecutive function and IPS.

Technical aspects and current clinical applications of the skin and skeletal muscle biopsy in neurological diagnostics: an overview

“…Skin biopsy is also used in diagnostics of sensory ganglionopathies, vasculitides and cerebral microangiopathies of generalized character such us CADASIL (cerebral autosomal dominant arteriopathy with ischemic stroke and leukoencephalopathy), CARASIL (cerebral recessive dominant arteriopathy with ischemic stroke and leukoencephalopathy), CARASAL (cathepsin A-related arteriopathy with strokes and leukoencephalopathy), and others. Tissue samples obtained from a skin biopsy may also be subjected to further molecular tests allowing, among others, to identify mRNA differentially expressed in various neurological disorders [14].…”