Biology subjects

Formosa, B.

Publications and source records attributed to Formosa, B..

3 recordsLinked to original sources

bioRxiv2022

Possible Mechanism of Porosome-Mediated Exosome Release

Supramolecular cup-shaped lipoprotein structures called porosomes embedded in the cell plasma membrane mediate fractional release of intra-vesicular contents from cells during secretion. The presence of porosomes, have been documented in many cell types including neurons, acinar cells of the exocrine pancreas, growth hormone secreting cells of the pituitary, and mouse insulin-secreting beta cell insulinomas called Min6. Electron micrographs of the nerve terminal in rat brain and of Min6 cells, suggest that besides the docking, fusion and content release of neurotransmitter containing synaptic vesicles and insulin containing granules, multi-vesicular bodies and exosome-like vesicles are released at the porosome complex. To test this hypothesis, the porosome-associated calcium transporting ATPase 1 [SPCA1] encoded by the ATP2C1 gene, was knocked-out in Min6 cells using CRISPR, to study glucose-stimulated insulin and exosome release. In agreement with electron micrographs, results from the study demonstrate a loss of both glucose-stimulated insulin and exosome release in the ATP2C1 knockout Min6 cells. These results further confirm the role of the porosome complex in insulin secretion and establishes a new paradigm in porosome-mediated exosome release in beta cells of the endocrine pancreas.

cell biology↗

bioRxiv2020

Skeletal Muscle Remodeling in Immobilized Patients: Determined Using a Parameter Estimation Histomorphometric Approach

Skeletal muscle biopsy commonly used for light microscopic, electron microscopic and biochemical and transcriptional evaluation remains the gold standard for establishing the etiology of a myopathy. While most myopathies exhibit one or more phenotypes, early stages or several metabolic myopathies often exhibit normal muscle morphology, making diagnosis difficult. In such cases where standard staining techniques fail to offer definitive diagnostic information, a combination of expensive and time-consuming electron microscopy and biochemical testing is required to provide definitive diagnosis. As a step toward overcoming these limitations in diagnostic pathology of skeletal muscle tissue, here we report the application of parameter estimation machine learning approaches on immunofluorescent images of human skeletal muscle tissue acquired using fluorescent microscopy. The machine learning morphometric approach enables the recognition of fine cellular changes in skeletal muscle tissue, allowing determination of skeletal muscle remodeling as a consequence of immobilization.

cell biology↗

bioRxiv2019

Differential expansion microscopy

Expansion microscopy (ExM) involves the use of hydration-competent polymers to physically expand biological specimens approximately 4-fold linear increase to achieve 70 nanometer resolution using an ordinary diffraction limited optical microscope. Optimal conditions however for antigen retention during the expansion process and the relative expansion between organelles within cells has remained unclear. It is reported that different tissues expand to different extents, suggesting that although isotropic expansion is believed to occur, different subcellular compartments with different composition would undergo anisotropic or differential expansion (DiEx). Consequently, there would be distortion of the native shape and size of subcellular compartments upon expansion, parameters which are critical in assessing cellular states in health and disease. Here we report optimal fixation and expansion conditions that retain structural integrity of cells while exhibiting up to 8-fold linear and therefore 512-fold volumetric expansion. Anisotropic expansion is observed not just between tissues, but between different subcellular compartments and even within subcellular compartments. Combining image analysis and machine learning, we provide an approach for the rapid and precise measurement of cellular and subcellular structures in expanded tissue. Using both manual and computation assessment of morphometric parameters, we demonstrate expansion to be anisotropic and name this method differential expansion microscopy (DiExM).

cell biology↗