Biology subjects

Tarasov, A.

Publications and source records attributed to Tarasov, A..

3 recordsLinked to original sources

bioRxiv2020

Release of insulin granules by simultaneous, high-speed correlative SICM-FCM

Exocytosis of peptides and steroids stored in a dense core vesicular (DCV) form is the final step of every secretory pathway, indispensable for the function of nervous, endocrine and immune systems. The lack of live imaging techniques capable of direct, label-free visualisation of DCV release makes many aspects of the exocytotic process inaccessible to investigation. We describe the application of correlative scanning ion conductance and fluorescence confocal microscopy (SICM-FCM) to study the exocytosis of individual granules of insulin from the top, non-adherent, surface of pancreatic {beta}-cells. Using SICM-FCM, we were first to directly follow the topographical changes associated with physiologically-induced release of insulin DCVs. This allowed us to report the kinetics of the full fusion of the insulin vesicle as well as the subsequent solubilisation of the released insulin crystal.

cell biology↗

bioRxiv2019

METASPACE: A community-populated knowledge base of spatial metabolomes in health and disease

Metabolites, lipids, and other small molecules are key constituents of tissues supporting cellular programs in health and disease. Here, we present METASPACE, a community-populated knowledge base of spatial metabolomes from imaging mass spectrometry data. METASPACE is enabled by a high-performance engine for metabolite annotation in a confidence-controlled way that makes results comparable between experiments and laboratories. By sharing their results publicly, engine users continuously populate a knowledge base of annotated spatial metabolomes in tissues currently including over 3000 datasets from human cancer cohorts, whole-body sections of animal models, and various organs. The spatial metabolomes can be visualized, explored and shared using a web app as well as accessed programmatically for large-scale analysis. By using novel computational methods inspired by natural language processing, we illustrate that METASPACE provides molecular coverage beyond the capacity of any individual laboratory and opens avenues towards comprehensive metabolite atlases on the levels of tissues and organs.

systems biology↗

bioRxiv2017

Electrophysiological properties of human β-cell lines EndoC-βH1 and -βH2 conform with human β-cells

The electrophysiological and secretory properties of the human {beta}-cell lines EndoC-{beta}H1 and EndoC-{beta}H2 were investigated. Both cell lines respond to glucose (6-20mM) with 2-to 3-fold stimulation of insulin secretion, an effect that was mimicked by tolbutamide (0.2mM) and reversed by diazoxide (0.5mM). Glucose-induced insulin release correlated with an elevation of [Ca2+]i, membrane depolarization and increased action potential firing. KATP channel activity at 1mM glucose is low and increasing glucose to 6 or 20mM reduced KATP channel activity to the same extent as application of the KATP channel blocker tolbutamide (0.2mM). The upstroke of the action potentials in EndoC-{beta}H1 and -{beta}H2 cells observed at high glucose principally reflects activation of L- and P/Q-type Ca2+ channels with some small contribution of TTX-sensitive Na+ channels. Action potential repolarization involves activation of voltage-gated Kv2.2 channels and large-conductance Ca2+-activated K+ channels. Exocytosis (measured by measurements of membrane capacitance) was triggered by membrane depolarizations >10ms to membrane potentials above -30mV. Both cell lines were well-granulated (6,000-15,000 granules/cell) and granules consisted of a central insulin core surrounded by a clear halo. We conclude that the EndoC-{beta}H1 and -{beta}H2 cells share many features of primary human {beta}-cells and that they represent a useful experimental model.

cell biology↗