G protein-coupled receptor class C group 5 member B (GPRC5B) is involved in extracellular glucose sensing, glucose metabolism, and insulin resistance. Many cancers require glucose at high concentratio Show more
G protein-coupled receptor class C group 5 member B (GPRC5B) is involved in extracellular glucose sensing, glucose metabolism, and insulin resistance. Many cancers require glucose at high concentrations to survive and grow. We have investigated the association between tumour GPRC5B expression and the prognosis for patients with cancer, including head-and-neck squamous cell carcinoma (HNSCC), using data from The Human Protein Atlas. The 5-year survival rate was significantly reduced in patients with HNSCC, gastric, pancreatic, colorectal, and breast cancers if their tumours exhibited high levels of GPRC5B expression. The role of GPRC5B in glucose metabolism was assessed using six HNSCC cell lines with varying levels of GPRC5B expression. High levels of GPRC5B expression were found to favour rapid cell growth. The viability of an HNSCC cell line with normal and transfected GPRC5B expression was also assessed and no differences were observed under standard culture conditions. However, under glucose-deficient culture conditions, GPRC5B-overexpressing cells exhibited increased viability and reduced apoptosis. The results highlight the association between high GPRC5B expression and poor 5-year survival rates in patients with various cancers, including HNSCC. Furthermore, we have demonstrated that GPRC5B supports cancer cell survival under glucose-depleted conditions and could be a target molecule for cancer therapy. Show less
RIG-I is a DExD/H-box RNA helicase and functions as a critical cytoplasmic sensor for RNA viruses to initiate antiviral interferon (IFN) responses. Here we demonstrate that another DExD/H-box RNA heli Show more
RIG-I is a DExD/H-box RNA helicase and functions as a critical cytoplasmic sensor for RNA viruses to initiate antiviral interferon (IFN) responses. Here we demonstrate that another DExD/H-box RNA helicase DHX36 is a key molecule for RIG-I signaling by regulating double-stranded RNA (dsRNA)-dependent protein kinase (PKR) activation, which has been shown to be essential for the formation of antiviral stress granule (avSG). We found that DHX36 and PKR form a complex in a dsRNA-dependent manner. By forming this complex, DHX36 facilitates dsRNA binding and phosphorylation of PKR through its ATPase/helicase activity. Using DHX36 KO-inducible MEF cells, we demonstrated that DHX36 deficient cells showed defect in IFN production and higher susceptibility in RNA virus infection, indicating the physiological importance of this complex in host defense. In summary, we identify a novel function of DHX36 as a critical regulator of PKR-dependent avSG to facilitate viral RNA recognition by RIG-I-like receptor (RLR). Show less