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Creamer, T.

Publications and source records attributed to Creamer, T..

2 recordsLinked to original sources

Comparative analysis of single-cell and single-nucleus RNA-sequencing in a rabbit model of retinal detachment-related proliferative vitreoretinopathy.

Structured AbstractO_ST_ABSPurposeC_ST_ABSProliferative vitreoretinopathy (PVR) is the most common cause of failure of retinal reattachment surgery and the molecular changes leading to this aberrant wound healing process is currently unknown. We aimed to study PVR pathogenesis using single-cell transcriptomics to dissect cellular heterogeneity in a rabbit PVR model. MethodsPVR was induced unilaterally in Dutch Belted rabbits. At different timepoints following PVR induction, retinas were dissociated into either cells or nuclei suspension and processed for single-cell or single-nucleus RNA sequencing (scRNA-seq or snRNA-seq). ResultsscRNA-Seq and snRNA-Seq were conducted on retinas at 4 hours and 14 days after disease induction. While the capture rate of unique molecular identifiers (UMI) and genes were greater in scRNA-seq samples, overall gene expression profiles of individual cell types were highly correlated between scRNA-seq and snRNA-seq. A major disparity between the two sequencing modalities is the cell type capture rate, however, with glial cell types over-represented in scRNA-seq, and inner retinal neurons were enriched by snRNA-seq. Furthermore, fibrotic Muller glia were over-represented in snRNA-seq samples, while reactive Muller glia were in scRNA-seq samples. Trajectory analyses were similar between the two methods, allowing for the combined analysis of the scRNA-seq and snRNA-seq datasets. ConclusionsThese findings highlight limitations of both scRNA-seq and snRNA-seq analysis and imply that use of both techniques can more accurately identify transcriptional networks critical for aberrant fibrogenesis in PVR.

neuroscience↗

Molecular basis of calmodulin-dependent calcineurin activation

Calcineurin (CaN) is a calcium-dependent phosphatase involved in numerous signaling pathways. Its activation by Ca2+ is in part driven by binding of calmodulin (CaM) to a Calmodulin (CaM)-recognition motif within the phosphatases regulatory domain (RD); how-ever, secondary interactions between CaM and the Calcineurin (CaN) regulatory domain may be necessary to fully activate CaN [1]. Specifically, it has been shown that the CaN regulatory domain folds upon CaM binding and that there is a region C-terminal to the canonical CaM-binding region, the distal helix, that assumes an helix fold and contributes to activation [1]. We hypothesized in Dunlap et al [1] that this putative helical distal helix is capable of binding CaM in a region distinct from the canonical CaM binding region (CaMBR) site, whereby CaN is activated. To test this hypothesis, we utilized molecular simulations including replica-exchange molecular dynamics, protein-protein docking and computational mutagene-sis to model distal helix conformations. From these simulations we have isolated a potential binding site on CaM (site D) that facilitates moderate affinity inter-protein interactions that may attenuate CaN auto-inhibition. Further, molecular simulations of the distal helix A454E mutation demonstrated weakened distal helix/CaM interactions that were previously shown to impair CaN activity. K30E and G40D mutations of CaM at site D presented similar de-creases in binding affinity predicted by simulations. The prediction was correlated with a phosphatase assay in which these two mutants show reduced CaN activity. This study there-fore provides a potential structural basis for the role of secondary CaM/CaN interactions in mediating CaN activation.

molecular biology↗