Fig. 9: Schematic diagram of a working model of the inhibition of tumor growth by Tmprss6 overexpression.
From: Transmembrane serine protease 6, a novel target for inhibition of neuronal tumor growth
The overexpression of Tmprss6 reduces HJV levels by cleaving HJV, thereby inhibiting the phosphorylation of Smad1/5/8 and retention of the latter in the cytoplasm. Due to the decreased P-Smad1/5/8 levels, the transport of P-Smad1/5/8 to the nucleus by Smad4 is reduced. Decreased P-Smad1/5/8 in the nucleus inhibits pro-hepcidin expression. The decreased pro-hepcidin levels block the internalization and degradation of FPN1. The increased FPN1 level leads to the export of cellular Fe2+, limiting the activity of RNR, ultimately arresting the cell cycle before the S phase. Additionally, the decreased amount of P-Smad1/5/8 frees up Smad4 to bind to ATF3 and translocate it to the nucleus, thus activating p38 signaling and the expression of Bnip3, leading to apoptosis.
