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Biology subjects

Ozkan, S.

Publications and source records attributed to Ozkan, S..

2 recordsLinked to original sources

Evaluation of enzyme activity predictions for variants of unknown significance in Arylsulfatase A

Continued advances in variant effect prediction are necessary to demonstrate the ability of machine learning methods to accurately determine the clinical impact of variants of unknown significance (VUS). Towards this goal, the ARSA Critical Assessment of Genome Interpretation (CAGI) challenge was designed to characterize progress by utilizing 219 experimentally assayed missense VUS in the Arylsulfa-tase A (ARSA) gene to assess the performance of community-submitted predictions of variant functional effects. The challenge involved 15 teams, and evaluated additional predictions from established and recently released models. Notably, a model developed by participants of a genetics and coding bootcamp, trained with standard machine-learning tools in Python, demonstrated superior performance among sub-missions. Furthermore, the study observed that state-of-the-art deep learning methods provided small but statistically significant improvement in predictive performance compared to less elaborate techniques. These findings underscore the utility of variant effect prediction, and the potential for models trained with modest resources to accurately classify VUS in genetic and clinical research.

genetics↗

Phospholipid Scramblase-1 is required for efficient neurotransmission and synaptic vesicle retrieval at cerebellar synapses

Structural phospholipids are asymmetrically distributed at the plasma membrane, with phosphatidylethanolamine and phosphatidylserine (PS) virtually absent from the outer leaflet. This asymmetric lipid distribution is transiently altered during specific biological processes including calcium-regulated exocytosis. However, the impact of this transient remodeling of membrane asymmetry on presynaptic function remains unknown. PhosphoLipid SCRamblase 1 (PLSCR1), a protein that randomizes phospholipid distribution between the two leaflets of the plasma membrane in response to calcium activation is an ideal candidate to alter this asymmetry. We therefore set out to determine the role of PLSCR1 in both neurotransmitter release and synaptic vesicle recycling by combining electron microscopy, optical live cell imaging of pHluorin probes and electrophysiology in cerebellar granule cells (GrC) from Plscr1 knock-out mice (Plscr1-/-). We report that PLSCR1 is expressed in GrCs and that PLSCR1-dependent PS egress occurred at synapses in response to neuron stimulation. Furthermore, synaptic transmission is impaired at GrC Plscr1-/- synapses and both PS egress and synaptic vesicle endocytosis are inhibited in Plscr1-/- cultured neurons, demonstrating that PLSCR1 controls phospholipid asymmetry remodeling and synaptic vesicle retrieval following neurotransmitter release. Altogether, our data reveal a key role for PLSCR1 in synaptic vesicle recycling and provide the first evidence that phospholipid scrambling at the plasma membrane is a prerequisite for optimal presynaptic performance.

cell biology↗