9.B.312. The Cytokine Expression and Secretion Mediator, TMEM9 (TMEM9) Family
Human transmembrane protein 9 (TMEM9) is a protein of 183 amino acids with 2 TMSs, one N-terminal, and one about 2/3rds of the way from the N-terminus. The N-terminal region contains several important domains. Honologues are found in animals such as Caenorhabditis elegans and Drosophila melanogaster. In humans, the gene is expressed in many tissues and cells. TMEM9 may play a role in intracellular transport. Wei et al. 2018 studied the expression of the TMEM9 gene and its effect on cytokine secretion in tumor necrosis factor-alpha (TNF-α)-induced LX-2 cells. They showed that overexpression increased the expression of IL-6 and IL-1β. while knockdown decreased their secretion; this enhanced the expression levels of the canonical Wnt/β-catenin genes, accompanied by increased wnt2b, wnt3a and β-catenin protein levels treated with TNF-α. Thus, TMEM9 plays a role in the modulation of TNF-α-enhanced cytokine (IL-6 and IL-1β) secretion. The canonical Wnt/β-catenin signaling pathway is involved in the induction of the expression of the relevant gene (Wei et al. 2018).