Biology subjects

Fung, E.

Publications and source records attributed to Fung, E..

3 recordsLinked to original sources

bioRxiv2020

Spontaneous Axonal ER Ca2+ Waves Mediate A Shift From Action Potential-Dependent to Independent Glutamate Release in the YAC128 HD-Model

Action potential-independent (miniature) neurotransmission occurs at all chemical synapses, but remains poorly understood, particularly in pathological contexts. Spontaneous release of Ca2+ from the axonal endoplasmic reticulum (ER) is thought to facilitated miniature neurotransmission, and aberrant ER Ca2+ handling is notably implicated in the progression of Huntingtons disease (HD) and other neurodegenerative diseases. Here, we report elevated glutamate-mediated miniature synaptic event frequencies in YAC128 (HD-model) cortical neurons, which pharmacological experiments suggest is mediated by enhanced spontaneous ER Ca2+ release. Calcium imaging using an axon-localized sensor revealed slow action potential (AP)-independent axonal Ca2+ waves, which were more common in YAC128 cortical neurons. Conversely, spontaneous axonal ER Ca2+ release was associated with reduced AP-dependent axonal Ca2+ events and consequent glutamate release. Together, our results suggest spontaneous release of axonal ER Ca2+ stores oppositely regulates activity-dependent and -independent neurotransmitter release in HD, with potential implications for the fidelity and plasticity of cortical excitatory signaling.

neuroscience↗

bioRxiv2019

Development and clinical validation of a targeted RNAseq panel (Fusion-STAMP) for diagnostic and predictive gene fusion detection in solid tumors

RNA sequencing is emerging as a powerful technique to detect a diverse array of fusions in human neoplasia, but few clinically validated assays have been described to date. We designed and validated a hybrid-capture RNAseq assay for FFPE tissue (Fusion-STAMP). It fully targets the transcript isoforms of 43 genes selected for their known impact as actionable targets of existing and emerging anti-cancer therapies (especially in lung adenocarcinomas), prognostic features, and/or utility as diagnostic cancer biomarkers (especially in sarcomas). 57 fusion results across 34 samples were evaluated. Fusion-STAMP demonstrated high overall accuracy with 98% sensitivity and 94% specificity for fusion detection. There was high intra- and inter-run reproducibility. Detection was sensitive to approximately 10% tumor, though this is expected to be impacted by fusion transcript expression levels, hybrid capture efficiency, and RNA quality. Challenges of clinically validating RNA sequencing for fusion detection include a low average RNA quality in FFPE specimens, and variable RNA total content and expression profile per cell. These challenges contribute to highly variable on-target rates, total read pairs, and total mapped read pairs. False positive results may be caused by intergenic splicing, barcode hopping / index hopping, or misalignment. Despite this, Fusion-STAMP demonstrates high overall performance metrics for qualitative fusion detection and is expected to provide clinical utility in identifying actionable fusions.

genomics↗

bioRxiv2019

The SMYD3 methyltransferase promotes myogenesis by activating the myogenin regulatory network

The coordinated expression of myogenic regulatory factors, including MyoD and myogenin, orchestrates the steps of skeletal muscle development, from myoblast proliferation and cell-cycle exit, to myoblast fusion and myotubes maturation. Yet, it remains unclear how key transcription factors and epigenetic enzymes cooperate to guide myogenic differentiation. Proteins of the SMYD (SET and MYND domain-containing) methyltransferase family participate in cardiac and skeletal myogenesis during development in zebrafish, Drosophila and mice. Here, we show that the mammalian SMYD3 methyltransferase coordinates skeletal muscle differentiation in vitro. Overexpression of SMYD3 in myoblasts promoted muscle differentiation and myoblasts fusion. Conversely, silencing of endogenous SMYD3 or its pharmacological inhibition impaired muscle differentiation. Genome-wide transcriptomic analysis of murine myoblasts, with silenced or overexpressed SMYD3, revealed that SMYD3 impacts skeletal muscle differentiation by targeting the key muscle regulatory factor myogenin. The role of SMYD3 in the regulation of skeletal muscle differentiation and myotube formation, partially via the myogenin transcriptional network, highlights the importance of methyltransferases in mammalian myogenesis.

cell biology↗