Detailed search for protein kinase(s) involved in plasma membrane H+-ATPase activity regulation of yeast cells
FEMS YEAST RESEARCH
Authors: Pereira, Renata R.; Castanheira, Diogo; Teixeira, Janaina A.; Bouillet, Leoneide E. M.; Ribeiro, Erica M. C.; Tropia, Maria M. J.; Alvarez, Florencia; Correa, Lygia F. M.; Mota, Bruno E. F.; Conceicao, Luis Eduardo F. R.; Castro, Ieso M.; Brandao, Rogelio L.
Abstract
This study displays a screening using yeast strains deficient in protein kinases known to exist in Saccharomyces cerevisiae. From 95 viable single mutants, 20 mutants appear to be affected in the glucose-induced extracellular acidification. The mutants that are unaffected in calcium signaling were tested for their sensitivity to hygromycin B. Furthermore, we verified whether the remaining mutants produced enzymes that are appropriately incorporated at plasma membrane. Finally, we measure the kinetic properties of the enzyme in purified plasma membranes from glucose-starved as well as glucose-fermenting cells. We confirmed the kinase Ptk2 involvement in H+-ATPase regulation (increase of affinity for ATP). However, the identification of the kinase(s) responsible for phosphorylation that leads to an increase in V-max appears to be more complex. Complementary experiments were performed to check how those protein kinases could be related to the control of the plasma membrane H+-ATPase and/or the potential membrane. In summary, our results did not permit us to identify the protein kinase(s) involved in regulating the catalytic efficiency of the plasma membrane H+-ATPase. Therefore, our results indicate that the current regulatory model based on the phosphorylation of two different sites located in the C-terminus tail of the enzyme could be inappropriate.
Somatic copy number alterations by whole-exome sequencing implicates YWHAZ and PTK2 in castration-resistant prostate cancer
JOURNAL OF PATHOLOGY
Authors: Menon, Roopika; Deng, Mario; Rueenauver, Kerstin; Queisser, Angela; Pfeifer, Martin; Offermann, Anne; Boehm, Diana; Vogel, Wenzel; Scheble, Veit; Fend, Falko; Kristiansen, Glen; Wernert, Nicolas; Oberbeckmann, Nicole; Biskup, Saskia; Rubin, Mark A.; Shaikhibrahim, Zaki; Perner, Sven
Abstract
Castration-resistant prostate cancer (CRPC) is the most aggressive form of prostate cancer (PCa) and remains a significant therapeutic challenge. The key to the development of novel therapeutic targets for CRPC is to decipher the molecular alterations underlying this lethal disease. The aim of our study was to identify therapeutic targets for CRPC by assessing somatic copy number alterations (SCNAs) by whole-exome sequencing on five CRPC/normal paired formalin-fixed paraffin-embedded (FFPE) samples, using the SOLiD4 next-generation sequencing (NGS) platform. Data were validated using fluorescence in situ hybridization (FISH) on a PCa progression cohort. PTK2 and YWHAZ amplification, mRNA and protein expression were determined in selected PCa cell lines. Effects of PTK2 inhibition using TAE226 inhibitor and YWHAZ knock-down on cell proliferation and migration were tested in PC3 cells in vitro. In a larger validation cohort, the amplification frequency of YWHAZ was 3% in localized PCa and 48% in CRPC, whereas PTK2 was amplified in 1% of localized PCa and 35% in CRPC. YWHAZ knock-down and PTK2 inhibition significantly affected cell proliferation and migration in the PC3 cells. Our findings suggest that inhibition of YWHAZ and PTK2 could delay the progression of the disease in CRPC patients harbouring amplification of the latter genes. Furthermore, our validated whole-exome sequencing data show that FFPE tissue could be a promising alternative for SCNA screening using next-generation sequencing technologies. Copyright (c) 2013 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.