Showing papers by "Dorothea Fiedler published in 2014"
TL;DR: It is demonstrated that IP7, formed by IP6K2, binds CK2 to enhance its phosphorylation of the TTT complex, thereby stabilizing DNA-PKcs and ATM and stimulating p53 phosphorylated at serine 15 to activate the cell death program in human cancer cells and in murine B cells.
97 citations
TL;DR: The synthesis of PP-IP bisphosphonate analogues (PCP-IPs) are described, which are resistant to chemical and biochemical degradation and inhibit protein pyrophosphorylation because of their inability to transfer the β-phosphoryl group, and thus enable the distinction betweenPP-IP signaling mechanisms.
Abstract: The diphosphoinositol polyphosphates (PP-IPs) represent a novel class of high-energy phosphate-containing messengers which control a wide variety of cellular processes. It is thought that PP-IPs exert their pleiotropic effects as allosteric regulators and through pyrophosphorylation of protein substrates. However, most details of PP-IP signaling have remained elusive because of a paucity of suitable tools. We describe the synthesis of PP-IP bisphosphonate analogues (PCP-IPs), which are resistant to chemical and biochemical degradation. While the two regioisomers 1PCP-IP5 and 5PCP-IP5 inhibited Akt phosphorylation with similar potencies, 1PCP-IP5 was much more effective at inhibiting its cognate phosphatase hDIPP1. Furthermore, the PCP analogues inhibit protein pyrophosphorylation because of their inability to transfer the β-phosphoryl group, and thus enable the distinction between PP-IP signaling mechanisms. As such, the PCP analogues will find widespread applications for the structural and biochemical characterization of PP-IP signaling properties.
44 citations
TL;DR: A highly selective and convenient method for the synthesis of pyrophosphopeptides in solution suggests that the intrinsic nucleophilicity of the phosphoserine residue is much higher than previously appreciated.
Abstract: A highly selective and convenient method for the synthesis of pyrophosphopeptides in solution is reported. The remarkable compatibility with functional groups (alcohol, thiol, amine, carboxylic acid) in the peptide substrates suggests that the intrinsic nucleophilicity of the phosphoserine residue is much higher than previously appreciated. Because the methodology operates in polar solvents, including water, a broad range of pyrophosphopeptides can be accessed. We envision these peptides will find widespread applications in the development of mass spectrometry and antibody-based detection methods for pyrophosphoproteins.
32 citations
TL;DR: Changes observed in metabolism and cell behavior support the rationale that phosphate could indeed modulate the activity of cancer cells.
Abstract: Background Altered cell metabolism is regarded as a hallmark of cancer with numerous studies highlighting glucose and glutamine as critical nutrients for tumor proliferation. Rapidly dividing cells should also require a continuous supply of phosphate, an essential nutrient for the synthesis of nucleic acids, phospholipids and high energy metabolites such as ATP. In agreement with this, high serum phosphate has recently been associated with lung and skin tumorigenesis in mouse models [1]. Although this example seems striking, the influence of phosphate on cancer cell proliferation has not been characterized to date. Elucidating the role of phosphate in cancer metabolism will be fundamental in understanding the needs of tumor cells. This is particularly relevant in breast cancer and bone metastasis, as bone is the single largest source of stored phosphorus. Additionally, the high local phosphate concentration during osteolysis represents a potential factor contributing to the cell’s prolific microenvironment. Taking an interdisciplinary approach combining cell biology and metabolomics will help us understand how the metabolic network can be rewired in response to changes in phosphate availability. Materials and methods Global metabolome analysis was conducted on a panel of breast cancer cell lines including MDA-MB-231 and MDA-MB-468 cultured with increasing phosphate levels, ranging from 1mM to 20mM. Metabolite extraction was performed using cold methanol and samples were analyzed on an orbitrap based LC-MS. Metabolite levels were characterized using an established database. Results The relative abundance of numerous metabolites changed significantly. These include NADPH, which decreased by approximately 80-fold and FMN, which increased approximately 15-fold as phosphate was increased. Additionally, several glycolytic intermediates were observed to increase reproducibly in the presence of high phosphate. Currently, NADPH turnover is being further analyzed using stable isotope tracers. Furthermore, global metabolomics experiments under phosphate starvation conditions are being performed to identify additional metabolic changes and to corroborate if effects observed in a high phosphate context present a reciprocal effect in phosphate starvation. Taken together, changes observed in metabolism and cell behavior support the rationale that phosphate could indeed modulate the activity of cancer cells.
9 citations
TL;DR: This group has developed a robust method to incorporate pyrophosphate residues into peptide sequences, and highlights several examples from the literature that inspired this chemical approach and discusses future applications of the orthogonal pyroph phosphorylation strategy.
Abstract: The detection and annotation of posttranslationally modified proteins in complex samples has benefited greatly from the ability to chemically synthesize and characterize model compounds harboring the modification of interest. To explore the signaling role of protein pyrophosphorylation, a recently discovered modification mediated by the inositol pyrophosphate messengers, our group has developed a robust method to incorporate pyrophosphate residues into peptide sequences. We highlight several examples from the literature that inspired our chemical approach and discuss future applications of our orthogonal pyrophosphorylation strategy.
4 citations