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Yilmaz, S.

Publications and source records attributed to Yilmaz, S..

22 records · Page 2Linked to original sources

Robust Inference of Kinase Activity using Functional Networks

Mass spectrometry enables high-throughput screening of phospho-proteins across a broad range of biological contexts. When complemented by computational algorithms, phospho-proteomic data allows the inference of kinase activity, facilitating the identification of dysregulated kinases in various diseases including cancer, Alzheimers disease and Parkinsons disease. To enhance the reliability of kinase activity inference, we present a network-based framework, RoKAI, that integrates various sources of functional information to capture coordinated changes in signaling. Through computational experiments, we show that phosphorylation of sites in the functional neighborhood of a kinase are significantly predictive of its activity. The incorporation of this knowledge in RoKAI consistently enhances the accuracy of kinase activity inference methods while making them more robust to missing annotations and quantifications. This enables the identification of understudied kinases and will likely lead to the development of novel kinase inhibitors for targeted therapy of many diseases. RoKAI is available as web-based tool at http://rokai.io.

systems biology↗

Replacing the Calvin cycle with the reductive glycine pathway in Cupriavidus necator

Formate can be directly produced from CO2 and renewable electricity, making it a promising microbial feedstock for sustainable bioproduction. Cupriavidus necator is one of the few biotechnologically-relevant hosts that can grow on formate, but it uses the inefficient Calvin cycle. Here, we redesign C. necator metabolism for formate assimilation via the highly efficient synthetic reductive glycine pathway. First, we demonstrate that the upper pathway segment supports glycine biosynthesis from formate. Next, we explore the endogenous route for glycine assimilation and discover a wasteful oxidation-dependent pathway. By integrating glycine biosynthesis and assimilation we are able to replace C. necators Calvin cycle with the synthetic pathway and achieve formatotrophic growth. We then engineer more efficient glycine metabolism and use short-term evolution to optimize pathway activity, doubling the growth yield on formate and quadrupling the growth rate. This study thus paves the way towards an ideal microbial platform for realizing the formate bioeconomy.

synthetic biology↗

Neuron-glia interaction through Serotonin-BDNF-NGFR axis enables regenerative neurogenesis in Alzheimer’s model of adult zebrafish brain

It was recently suggested that supplying the brain with new neurons could counteract Alzheimers disease. This provocative idea requires further testing in experimental models where the molecular basis of disease-induced neuronal regeneration could be investigated. We previously found that zebrafish stimulates neural stem cell (NSC) plasticity and neurogenesis in Alzheimers disease and could help to understand the mechanisms to be harnessed for develop new neurons in diseased mammalian brains. Here, by performing single-cell transcriptomics, we found that Amyloid toxicity-induced Interleukin-4 induces NSC proliferation and neurogenesis by suppressing the tryptophan metabolism and reducing the production of Serotonin. NSC proliferation was suppressed by Serotonin via downregulation of BDNF-expression in Serotonin-responsive periventricular neurons. BDNF enhances NSC plasticity and neurogenesis via NGFRA/NFkB signaling in zebrafish but not in rodents. Collectively, our results suggest a complex neuron-glia interaction that regulates regenerative neurogenesis after Alzheimers disease conditions in zebrafish.\n\nKey findings- Amyloid-induced Interleukin-4 suppresses Serotonin (5-HT) production in adult zebrafish brain\n- 5-HT affects htr1-expresing neurons and suppresses bdnf expression\n- BDNF enhances plasticity in neural stem cells via NGFRA/NFkB signaling\n- BDNF/NGFRA signaling is a neuro-regenerative mechanism in zebrafish but not in mammals.

neuroscience↗

SPADIS: An Algorithm for Selecting Predictive and Diverse SNPs in GWAS

Phenotypic heritability of complex traits and diseases is seldom explained by individual genetic variants. Algorithms that select SNPs which are close and connected on a biological network have been successful in finding biologically-interpretable and predictive loci. However, we argue that the connectedness constraint favors selecting redundant features that affect similar biological processes and therefore does not necessarily yield better predictive performance. In this paper, we propose a novel method called SPADIS that selects SNPs that cover diverse regions in the underlying SNP-SNP network. SPADIS favors the selection of remotely located SNPs in order to account for the complementary additive effects of SNPs that are associated with the phenotype. This is achieved by maximizing a submodular set function with a greedy algorithm that ensures a constant factor (1-1/e) approximation. We compare SPADIS to the state-of-the-art method SConES, on a dataset of Arabidopsis Thaliana genotype and continuous flowering time phenotypes. SPADIS has better regression performance in 12 out of 17 phenotypes on average, it identifies more candidate genes and runs faster. We also investigate the use of Hi-C data to construct SNP-SNP network in the context of SNP selection problem for the first time, which yields slight but consistent improvements in regression performance. SPADIS is available at http://ciceklab.cs.bilkent.edu.tr/spadis

bioinformatics↗