GRIM-19 in Health and Disease.

GRIM-19, a gene associated with retinoid interferon-induced mortality, was originally identified as a critical regulatory protein for interferon-beta and retinoic acid-induced cell death. It was also demonstrated that GRIM-19 is involved in mitochondrial metabolism, as an integrant component of complex I of the mitochondrial respiratory chain. GRIM-19 appears, therefore, as a dual function protein involved in cell death and mitochondrial metabolism. GRIM-19 knock out leads to Complex I assembly disruption and embryonic lethality in mice, showing that it is a crucial component of the mitochondrial respiratory chain essential for early embryonic development. Recently, mutations in GRIM-19 were described in Hürthle cell (mitochondrion-rich) tumors of the thyroid and down-regulation or loss of its expression were found in renal cell carcinomas, suggesting a role for GRIM-19 in tumorigenesis. As GRIM-19 binds and inhibits the signal transducer and activator of transcription-3 (STAT3), which has been shown to be activated in several human tumors it is tempting to advance that GRIM-19 may function as a tumor suppressor gene in tumors in which STAT3 plays a major role.