The yeast protein kinase Sch9 adjusts V-ATPase assembly/disassembly to control pH homeostasis and longevity in response to glucose availability

The evolutionary conserved TOR complex 1 controls growth in response to the quality and quantity of nutrients such as carbon and amino acids. The protein kinase Sch9 is the main TORC1 effector in yeast. However, only few of its direct targets are known. In this study, we performed a genome-wide screening looking for mutants which require Sch9 function for their survival and growth. In this way, we identified multiple components of the highly conserved vacuolar proton pump (V-ATPase) which mediates the luminal acidification of multiple biosynthetic and endocytic organelles. Besides a genetic interaction, we found Sch9 also physically interacts with the V- ATPase to regulate its assembly state in response to glucose availability and TORC1 activity. Moreover, the interaction with the V-ATPase has consequences for ageing as it allowed Sch9 to control vacuolar pH and thereby trigger either lifespan extension or lifespan shortening. Hence, our results provide insights into the signaling mechanism coupling glucose availability, TORC1 signaling, pH homeostasis and longevity. As both Sch9 and the V-ATPase are highly conserved and implicated in various pathologies, these results offer fertile ground for further research in higher eukaryotes

A global review on short peptides: frontiers and perspectives

Peptides are fragments of proteins that carry out biological functions. They act as signaling entities via all domains of life and interfere with protein-protein interactions, which are indispensable in bio-processes. Short peptides include fundamental molecular information for a prelude to the symphony of life. They have aroused considerable interest due to their unique features and great promise in innovative bio-therapies. This work focusing on the current state-of-the-art short peptide-based therapeutical developments is the first global review written by researchers from all continents, as a celebration of 100 years of peptide therapeutics since the commencement of insulin therapy in the 1920s. Peptide “drugs” initially played only the role of hormone analogs to balance disorders. Nowadays, they achieve numerous biomedical tasks, can cross membranes, or reach intracellular targets. The role of peptides in bio-processes can hardly be mimicked by other chemical substances. The article is divided into independent sections, which are related to either the progress in short peptide-based theranostics or the problems posing challenge to bio-medicine. In particular, the SWOT analysis of short peptides, their relevance in therapies of diverse diseases, improvements in (bio)synthesis platforms, advanced nano-supramolecular technologies, aptamers, altered peptide ligands and in silico methodologies to overcome peptide limitations, modern smart bio-functional materials, vaccines, and drug/gene-targeted delivery systems are discussed

Phosphorylation, lipid raft interaction and traffic of α-synuclein in a yeast model for Parkinson

Parkinson's disease is a neurodegenerative disorder characterized by the formation of Lewy bodies containing aggregated α-synuclein. We used a yeast model to screen for deletion mutants with mislocalization and enhanced inclusion formation of α-synuclein. Many of the mutants were affected in functions related to vesicular traffic but especially mutants in endocytosis and vacuolar degradation combined inclusion formation with enhanced α-synuclein-mediated toxicity. The screening also allowed for identification of casein kinases responsible for α-synuclein phosphorylation at the plasma membrane as well as transacetylases that modulate the α-synuclein membrane interaction. In addition, α-synuclein was found to associate with lipid rafts, a phenomenon dependent on the ergosterol content. Together, our data suggest that toxicity of α-synuclein in yeast is at least in part associated with endocytosis of the protein, vesicular recycling back to the plasma membrane and vacuolar fusion defects, each contributing to the obstruction of different vesicular trafficking routes

FLT1 kinase is a mediator of radioresistance and survival in head and neck squamous cell carcinoma

<div><p></p><p>Head and neck squamous cell carcinoma (HNSCC) is the fifth most common malignancy worldwide, responsible for approximately half a million new cases every year. The treatment of this disease is challenging and characterised by high rates of therapy failure and toxicity, stressing the need for new innovative treatment strategies. <i>Material and methods.</i> In this study we performed a shRNAmir-based screen on HNSCC cells with the aim to identify tyrosine kinases that are mediating radiotherapy resistance. <i>Results.</i> The receptor tyrosine kinase FLT1 (VEGFR1) was identified as an important driver of cell survival and radioresistance. We show that FLT1 is phosphorylated in HNSCC cells, and document autocrine production of FLT1 ligands VEGFA and VEGFB, leading to receptor activation. Immunohistochemistry on HNSCC patient samples demonstrated FLT1 and VEGFA to be uniformly expressed. Interestingly, FLT1 was selectively overexpressed in tumour tissue as compared to non-cancerous epithelium. Remarkably, we found only membrane permeable FLT1 kinase inhibitors to be effective, which was in agreement with the intracellular localisation of FLT1. <i>Discussion and conclusion.</i> Taken together, we document expression of FLT1 in HNSCC and demonstrate this kinase to modulate radioresistance and cancer cell survival. Given the fact that FLT1 kinase is selectively upregulated in tumour tissue and that its kinase function seems expendable for normal life and development, this kinase holds great promise as a new potential therapeutic target.</p></div

The yeast protein kinase Sch9 adjusts V-ATPase assembly/disassembly to control pH homeostasis and longevity in response to glucose availability

The conserved protein kinase Sch9 is a central player in the nutrient-induced signaling network in yeast, although only few of its direct substrates are known. We now provide evidence that Sch9 controls the vacuolar proton pump (V-ATPase) to maintain cellular pH homeostasis and ageing. A synthetic sick phenotype arises when deletion of SCH9 is combined with a dysfunctional V-ATPase, and the lack of Sch9 has a significant impact on cytosolic pH (pHc) homeostasis. Sch9 physically interacts with, and influences glucose-dependent assembly/disassembly of the V-ATPase, thereby integrating input from TORC1. Moreover, we show that the role of Sch9 in regulating ageing is tightly connected with V-ATPase activity and vacuolar acidity. As both Sch9 and the V-ATPase are highly conserved in higher eukaryotes, it will be interesting to further clarify their cooperative action on the cellular processes that influence growth and ageing.status: publishe

Characterization of ALK driven molecular networks identifies perturbed RET and cholinergic signaling in neuroblastoma

Purpose: Activating ALK mutations are present in nearly 10% of primary neuroblastomas and mark patients for treatment with ALK inhibitors. Clinical trials for small molecule ALK inhibitors have been initiated for neuroblastoma and other ALK-driven tumor entities. Recent studies have shown that multiple mechanisms drive resistance to molecular therapies targeting receptor tyrosine kinases including oncogene switching and modulation of various regulatory loops. We anticipated that detailed mapping of the oncogenic ALK-driven signaling in neuroblastoma can pave the way to identify fragile nodes that may serve as additional targets for combination therapies. Experimental design: To achieve this aim, we analysed the transcriptional consequences of mutant ALK signaling in neuroblastoma. As such, we established a 79-gene signature recapitulating the transcriptional response upon ALK inhibition based on transcriptome profiling of ALKwt, ALKF1174L and ALKR1275Q mutant, as well as ALKamplified NB cell lines following ALK inhibition by either NVP-TAE-684, LDK-378, X-396 or Crizotinib. Further, the 79-gene signature was validated in an ALK-inducible NB cell line and primary tumor samples. Results: We established a 79-gene signature marking ALK activity in neuroblastoma cells, which was also preserved to a large extent in other ALK driven tumor entities and across ALKF1174L- and MYCN-driven human and murine NB tumors. Further data mining confirmed that MEK/MAPK, AKT/mTOR and MYC/MYCN pathways are important downstream branches of ALK signaling and highlight a disabled MAPK negative feedback loop. Moreover, using cross-species genomics analysis we show that mutant ALK induces RET and RET driven cholinergic sympathetic neuronal markers such as VIP, VGF, ChAT and VAChT, pointing out to a perturbed RET and cholinergic signaling in neuroblastoma. Conclusions: These novel insights are important leads for further studies exploring novel combination therapy strategies in ALK mutant neuroblastomas and can also pave the way for deeper understanding of the role of ALK signaling in normal sympathetic nervous system development. Moreover, our data emphasize RET as a target for further molecular combination therapies