Photo-induced Proton Transfers of Microbial Rhodopsins

Molecular Photochemistry - Various Aspect

First-line axitinib therapy is less effective in metastatic renal cell carcinoma with spindle histology

Axitinib, a vascular endothelial growth factor receptor-tyrosine kinase inhibitor, will be used in combination first-line therapies against metastatic renal cell carcinoma (mRCC), but its effects as a first-line monotherapy are unclear. Thus, we aimed to elucidate pretreatment clinical factors that predict the prognosis of patients with mRCC receiving first-line axitinib therapy. We enrolled 63 patients with mRCC treated with axitinib as first-line therapy between Nov. 2003 and Jul. 2018. Progression-free survival (PFS) and overall survival (OS) were assessed using the Wald chi (2) statistic in Cox proportional hazards regression. Median patient age was 67 (range: 25-85) years. Seven (11.1%) patients were classified as being at favorable risk, 33 (52.4%) at intermediate risk, and 23 (36.5%) at poor risk according to the International Metastatic Renal Cell Carcinoma Database Consortium (IMDC) risk classification system. Median follow-up duration after axitinib initiation was 14 (range: 1-72) months. Median PFS and OS were 18 months and 65 months, respectively. Cox regression analyses of clinical predictors revealed that high C-reactive protein (CRP) levels were significantly correlated with shorter PFS [hazard ratio (HR), 1.63; 95% confidence interval (CI) 1.7-4.0)], whereas spindle cells and poor IMDC risk scores were related to worse OS (HR, 2.87 and 2.88, respectively; 95% CI 1.4-11.0 and 1.1-8.5, respectively). Thus, patients with mRCC and spindle histology or poor IMDC risk scores had worse OS, and those with high CRP levels had shorter PFS in first-line axitinib treatment. Other therapies might be more suitable for initial management of such patients

Interhelical interactions between D92 and C218 in the cytoplasmic domain regulate proton uptake upon N-decay in the proton transport of Acetabularia rhodopsin II

Acetabularia rhodopsin II (ARII or Ace2), an outward light-driven algal proton pump found in the giant unicellular marine alga Acetabularia acetabulum, has a unique property in the cytoplasmic (CP) side of its channel. The X-ray crystal structure of ARII in a dark state suggested the formation of an interhelical hydrogen bond between C218(ARII) and D92(ARII), an internal proton donor to the Schiff base (Wada et al., 2011). In this report, we investigated the photocycles of two mutants at position C218(ARII): C218(AAII) which disrupts the interaction with D92(ARII), and C218S(ARII) which potentially forms a stronger hydrogen bond. Both mutants exhibited slower photocycles compared to the wild-type pump. Together with several kinetic changes of the photoproducts in the first half of the photocycle, these replacements led to specific retardation of the N-to-O transition in the second half of the photocycle. In addition, measurements of the flash-induced proton uptake and release using a pH sensitive indium-tin oxide electrode revealed a concomitant delay in the proton uptake. These observations strongly suggest the importance of a native weak hydrogen bond between C218(ARII) and D92(ARII) for proper proton translocation in the CP channel during N-decay. A putative role for the D92(ARII)-C218(ARII) interhelical hydrogen bond in the function of ARII is discussed