In JoVE (1)
Articles by Nikolay Ninov in JoVE
Analysis of Beta-cell Function Using Single-cell Resolution Calcium Imaging in Zebrafish Islets Sharan Janjuha1,2, Sumeet Pal Singh1, Nikolay Ninov1,2 1Center for Molecular and Cellular Bioengineering, TU Dresden, 2Paul Langerhans Institute Dresden of the Helmholtz Center Munich at the University Hospital Carl Gustav Carus of TU Dresden Beta-cell functionality is important for blood-glucose homeostasis, which is evaluated at single-cell resolution using a genetically encoded reporter for calcium influx.
Other articles by Nikolay Ninov on PubMed
Distinct Levels of Reactive Oxygen Species Coordinate Metabolic Activity with Beta-cell Mass Plasticity Scientific Reports. Jun, 2017 | Pubmed ID: 28652605 The pancreatic beta-cells control glucose homeostasis by secreting insulin in response to nutrient intake. The number of beta-cells is under tight metabolic control, as this number increases with higher nutrient intake. However, the signaling pathways matching nutrition with beta-cell mass plasticity remain poorly defined. By applying pharmacological and genetic manipulations, we show that reactive oxygen species (ROS) regulate dose-dependently beta-cell proliferation in vivo and in vitro. In particular, reducing ROS levels in beta-cells blocks their proliferation in response to nutrients. Using a non-invasive genetic sensor of intracellular hydrogen peroxide (HO), we reveal that glucose can directly increase the levels of HO. Furthermore, a moderate increase in HO levels can stimulate beta-cell proliferation. Interestingly, while high HO levels are inhibitory to beta-cell proliferation, they expand beta-cell mass in vivo by inducing rapid beta-cell neogenesis. Our study thus reveals a ROS-level-dependent mechanism linking nutrients with beta-cell mass plasticity. Hence, given the requirement of ROS for beta-cell mass expansion, antioxidant therapies should be applied with caution in diabetes.
Catching New Targets in Metabolic Disease with a Zebrafish Current Opinion in Pharmacology. 12, 2017 | Pubmed ID: 28888214 Traditionally, the development of novel therapeutics for metabolic diseases has relied mainly on high-throughput screening using biochemical or cell-based assays. While this approach represents a driving force in drug discovery, there is also a need to perform large-scale screens without disrupting inter-organ communication and tissue architecture, essential components for understanding the complexity of metabolic regulation and the identification of small molecules with appropriate biological activities in vivo. Hence, the zebrafish Danio rerio is gaining popularity in metabolic research and drug discovery, as this animal model allows screening of small molecules in the context of the whole-organism. Moreover, the zebrafish exhibits conserved function of the pancreas, liver and adipose tissue, which can be leveraged to identify novel targets in metabolic regulation, as well as to study the role of conserved genes associated with the risk of metabolic diseases in humans. Here we highlight recent advances in the identification of targets in metabolic regulation using the zebrafish as a model.