title: Human membrane protein Tim-3 facilitates hepatitis A virus entry into target cells.
abstract: In this study, a cellular surface membrane protein of immunoglobulin (Ig) superfamily (IgSF) was identified from a human dendritic cell (DC) cDNA library by large-scale random sequencing, which is identical to previously reported Tim-3 (T-cell Ig- and mucin-domain-containing molecule 3). Recent data have suggested the association of the 281-residue mouse Tim-3 molecule with Th1-related T cell responses and disease in mice. Human Tim-3 is a 301-residue type I membrane protein whose extracellular region contains a Cys-rich Ig-like domain and a mucin domain, the characteristics of Tim proteins. It shows significant homology to human hepatitis A virus (HAV) cellular receptor-1 (HuHAVcr-1)/Tim-1. Human Tim-3 mRNA was highly expressed in monocytes or monocyte-derived cells, and the expression level decreased when DC underwent maturation and activation. There is no previous report on the biological functions of human Tim-3, especially the involvement in virus infection. We demonstrated that HeLa cells, which are refractory to HAV infection, acquired a limited susceptibility to HAV infection after stably overexpressing human Tim-3 as confirmed by Western blot analysis using anti-Tim-3 antibody, but Tim-3-Fc fusion protein had no direct HAV-binding activity. The results indicated that human Tim-3 can promote HAV entry into target cells but itself may not function as a cellular receptor of HAV.
authors: Institute of Immunology, Second Military Medical University, Shanghai, PR China.
authors: Lili
authors: L
authors: Sui
authors: Wenyuan
authors: W
authors: Zhang
authors: Yong
authors: Y
authors: Chen
authors: Yuanyuan
authors: Y
authors: Zheng
authors: Tao
authors: T
authors: Wan
authors: Weiping
authors: W
authors: Zhang
authors: Yadong
authors: Y
authors: Yang
authors: Guojian
authors: G
authors: Fang
authors: Jiangsen
authors: J
authors: Mao
authors: Xuetao
authors: X
authors: Cao