Transcriptome Analysis Reveals Sexual Disparities in Differential Gene Expression Signature in Rat Brain Microvessels
Authors: Chandra Partha K. , Cikic Sinisa , Baddoo Melody C. , Rutkai Ibolya , Flemington Erik K. , Busija David W. 
Published: April 2020

Background

Sex appears to be an important determinant of brain microvessel (MV) function and susceptibility to cerebrovascular and neurological diseases. However, little is known about sex differences in brain MVs. The object of the current study was to examine differential gene expression in brain MVs of young male and female rats.

Methods

Microvessels (MVs) were isolated from the brains of age‐matched, male and female, Sprague‐Dawley rats (8–10 weeks old, n = 3/group). The quality of the isolated MVs were monitored under light microscopy, and the presence of end‐arterioles, capillaries, and venules in MVs were confirmed by alkaline phosphatase staining. Total RNA was isolated, and RNASeq analysis was performed by Illumina NextSeq 550 sequencing system. Banana SLUG analytics platform from UCSC was used for bioinformatics analysis of the 23,786 identified genes.

Results

A total of 298 (1.2%) significant (FDR < 0.05) differentially expressed (DE) genes were identified, of which 40% (119/298) and 60% (179/298) of DE genes were abundant in male and female MVs respectively. GO analysis categorized under biological process, cellular compartment and molecular functions to discover the most important putative functions of the target genes. Using PANTHER protein class, 23 most significant (FDR < 0.05) gene functions were higher in male than female MVs. Nucleic acid binding, enzyme modulator, and transcription factor were the top three gene functions, abundantly high in male MVs, in which more than 20 significant DE genes were involved in each class. Based on Reactome and KEGG enrichment analysis, 20 significantly (FDR<0.05) enriched canonical pathways were abundantly high in male rat MVs. Synthesis of glycosylphosphatidylinositol (GPI), post‐translational modification of GPI‐anchored proteins, and GPI‐anchor biosynthesis were the top three significantly enriched canonical pathways that were abundantly high in male rat MVs. Similarly, peptide chain elongation, ribosome, and 3′‐UTR‐mediated translational regulation were the top three significantly (FDR<0.05) enriched canonical pathways that were abundantly high in female rat MVs. Genes involved in different biological processes like vasodilation, mannosylation, mitochondria morphogenesis, anchor metabolic process, t‐RNA transport, DNA replication, and basal transcription factors were predominantly high in male rat MVs. Surprisingly and simultaneously, genes involved in mitochondrial apoptotic pathway, necroptotic processes, FAS, and caspase activation pathways were also abundantly higher in male than female MVs.

Conclusions

Several DE genes and signaling pathways were identified in the brain MVs of male and female rats. Our findings show major differences in gene expression of male and female rats and provide a foundation to study the role of brain MVs in the development of cerebrovascular and other neurological diseases.

Support or Funding Information

HL‐093554