Systemic analysis of tissue cells potentially vulnerable to SARS-CoV-2 infection by the protein-proofed single-cell RNA profiling of ACE2, TMPRSS2 and Furin proteases

Lulin Zhou; Zubiao Niu; Xiaoyi Jiang; Zhengrong Zhang; You Zheng; Zhongyi Wang; Yichao Zhu; Lihua Gao; Xiaoning Wang; Qiang Sun

Based on the expression analysis across 36 human tissues, ACE2 displays a tissue-specific expression at both mRNA and protein levels. And 10 tissues express relatively higher level of ACE2 mRNA, including small intestine, colon, esophagus, thyroid gland, kidney, testis, ovary, breast, heart muscle and adipose tissue. Meanwhile, the majority of the other tissues, such as lung, liver, pancreas, spleen, prostate, urinary bladder, skin and neuronal tissues, give marginal expression of ACE2 mRNA ( Figure 1A -B, S1A). The protein expression score, though also displaying a tissue-specific pattern, only reports 6 tissues expressing ACE2 protein, with 5 of them matching the mRNA expression, including small intestine, colon, thyroid gland, kidney and testis. Interestingly, adrenal gland expresses, though little mRNA, median level of ACE2 protein. The inconsistency is actually also applied for ACE2 to other tissues such as breast, heart muscle and adipose tissue, which express high level of mRNA but undetectable protein.