Single-Cell Transcriptional Profiling Reveals Sex and Age Diversity of Gene Expression in Mouse Endothelial Cells

Xianxi Huang; Wenjun Shen; Stefan Veizades; Grace Liang; Nazish Sayed; Patricia K Nguyen

doi:10.3389/fgene.2021.590377

Single-Cell Transcriptional Profiling Reveals Sex and Age Diversity of Gene Expression in Mouse Endothelial Cells

Front Genet. 2021 Feb 17:12:590377. doi: 10.3389/fgene.2021.590377. eCollection 2021.

Authors

Xianxi Huang^{1

2

3}, Wenjun Shen^{4

5}, Stefan Veizades^{2

3

6}, Grace Liang^{2

3

7}, Nazish Sayed³, Patricia K Nguyen^{2

3

7}

Affiliations

¹ Department of Critical Care Medicine, The First Affiliated Hospital of Shantou University Medical College, Shantou, China.
² Division of Cardiovascular Medicine, Stanford University, Stanford, CA, United States.
³ Stanford Cardiovascular Institute, Stanford, CA, United States.
⁴ Department of Bioinformatics, Shantou University Medical College, Shantou, China.
⁵ Center for Biomedical Informatics Research, Stanford University, Stanford, CA, United States.
⁶ Edinburgh Medical School, College of Medicine and Veterinary Medicine, University of Edinburgh, Edinburgh, United Kingdom.
⁷ Cardiology Section, Department of Veteran Affairs, Palo Alto, CA, United States.

Abstract

Although it is well-known that sex and age are important factors regulating endothelial cell (EC) function, the impact of sex and age on the gene expression of ECs has not been systematically analyzed at the single cell level. In this study, we performed an integrated characterization of the EC transcriptome of five major organs (e.g., fat, heart-aorta, lung, limb muscle, and kidney) isolated from male and female C57BL/6 mice at 3 and 18 months of age. A total of 590 and 252 differentially expressed genes (DEGS) were identified between females and males in the 3- and 18-month subgroups, respectively. Within the younger and older group, there were 177 vs. 178 DEGS in fat, 305 vs. 469 DEGS in heart/aorta, 22 vs. 37 DEGS in kidney, 26 vs. 439 DEGS in limb muscle, and 880 vs. 274 DEGS in lung. Interestingly, LARS2, a mitochondrial leucyl tRNA synthase, involved in the translation of mitochondrially encoded genes was differentially expressed in all organs in males compared to females in the 3-month group while S100a8 and S100a9, which are calcium binding proteins that are increased in inflammatory and autoimmune states, were upregulated in all organs in males at 18 months. Importantly, findings from RNAseq were confirmed by qPCR and Western blot. Gene enrichment analysis found genes enriched in protein targeting, catabolism, mitochondrial electron transport, IL 1- and IL 2- signaling, and Wnt signaling in males vs. angiogenesis and chemotaxis in females at 3 months. In contrast, ECs from males and females at 18-months had up-regulation in similar pathways involved in inflammation and apoptosis. Taken together, our findings suggest that gene expression is largely similar between males and females in both age groups. Compared to younger mice, however, older mice have increased expression of genes involved in inflammation in endothelial cells, which may contribute to the development of chronic, non-communicable diseases like atherosclerosis, hypertension, and Alzheimer's disease with age.

Keywords: age; cardiovascular disease; endothelial cells; sex; single-cell sequencing.

Grants and funding

R01 HL134830/HL/NHLBI NIH HHS/United States