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Aktay, S.

Publications and source records attributed to Aktay, S..

3 recordsLinked to original sources

Transcriptional responses to proteotoxic stressors are profoundly diverse and tissue-specific

Cells counteract proteotoxic conditions by launching transcriptional stress responses. While synthesis of Heat shock proteins (HSPs) upon acute stress is well-characterized, how distinct proteotoxic conditions reshape the transcriptome remains poorly understood. Here, we analyse polyA+ RNA expression under heat shock, HSP90 inhibition, and polyglutamine (polyQ) aggregation. We find fundamentally distinct transcriptional responses to proteotoxic stressors, and a systemic deficiency of mice under chronic stress to launch acute responses. While heat shock and HSP90 inhibition induce chaperones, polyQ aggregation increases RNAs linked to transcription repression, chromatin remodeling, and autophagy. Analysing wildtype and Huntingtons Disease (HD) mice reveals tissue-specific transcriptional adaptations to polyQ, including repressed cell-type specific functions and altered energy metabolism. Despite profound reprogramming, remarkably few RNAs are consistently induced (Acy3, Abdh1, Tmc3) or reduced (Fos) across HD brain regions. These results emphasize cellular background in disease manifestation, and support energy metabolism and detoxifying enzymes as therapeutic targets in late-stage HD. Moreover, the systemic deficiency of chronically stressed mice to launch responses challenges strategies that rely on induced transcription. Altogether, we characterize transcription signatures to proteotoxic stresses, identify key trans-activators driving proteotoxic stress responses, provide an interactive gene-by-gene viewer of global changes, and delineate tissue-specific transcription programs in HD mice.

cell biology↗

Transcriptional architecture and Pol II regulation at promoters, enhancers, and enhancer clusters in Canis lupus familiaris

Domestic dog exhibits remarkable phenotypic diversity and provides versatile models for genomics, evolution, and complex traits. DNA sequences and stable RNAs have revealed regulatory regions in the dog genome. However, transcriptional activity, regulatory architecture, and control of RNA Polymerase II (Pol II) across genes and enhancers remain uncharacterized. Here, we track transcription at nucleotide-resolution, measure RNA expression and stability, and analyse mechanisms of Pol II regulation in golden retriever macrophages. We report the precise architectures of promoters, enhancers, and enhancer clusters, and quantify Pol II progression from the initiation, through the pause-region, into elongation and termination. Triggering transcriptional change by heat stress reveals instant reprogramming of genes via promoter-proximal pause-regulation and enhancers via initiation. Enhancers within a cluster mount a unified response. This study identifies functional genomic regions de novo, characterizes transcriptional architectures of genes, enhancers, and enhancer clusters, quantifies RNA synthesis and stability, and reveals mechanisms of transcription in Canis lupus familiaris.

genomics↗

Neuromodulatory effects on synchrony and network reorganization in networks of coupled Kuramoto oscillators.

Neuromodulatory processes in the brain can critically change signal processing on a cellular level leading to dramatic changes in network level reorganization. Here, we use coupled non-identical Kuramoto oscillators to investigate how changes in the shape of phase response curves from Type 1 to Type 2, mediated by varying ACh levels, coupled with activity dependent plasticity may alter network reorganization. We first show that when plasticity is absent, the Type 1 networks, as expected, exhibit asynchronous dynamics with oscillators of the highest natural frequency robustly evolving faster in terms of their phase dynamics. At the same time, the Type 2 networks synchronize, with oscillators locked so that the ones with higher natural frequency have a constant phase lead as compared to the ones with lower natural frequency. This relationship establishes a robust mapping between the frequency and oscillators phases in the network, leading to structure/frequency mapping when plasticity is present. Further we show that while connection plasticity can produce stable synchrony (so called splay states) in Type 1 networks, the structure/frequency reorganization observed in Type 2 networks is not present.

neuroscience↗