Insulin induces an increase in cytosolic glucose levels in 3T3-L1 cells with inhibited glycogen synthase activation

Haque Chowdhury, Helena (author), Kreft, Marko (author), Jensen, Jørgen (author), Zorec, Robert (author)

Glucose is an important source of energy for mammalian cells and enters the cytosol via glucose transporters. It has been thought for a long time that glucose entering the cytosol is swiftly phosphorylated in most cell types; hence the levels of free glucose are very low, beyond the detection level. However, the introduction of new fluorescence resonance energy transfer-based glucose nanosensors has made it possible to measure intracellular glucose more accurately. Here, we used the fluorescent indicator protein (FLIPglu-600µ) to monitor cytosolic glucose dynamics in mouse 3T3-L1 cells in which glucose utilization for glycogen synthesis was inhibited. The results show that cells exhibit a low resting cytosolic glucose concentration. However, in cells with inhibited glycogen synthase activation, insulin induced a robust increase in cytosolic free glucose. The insulin-induced increase in cytosolic glucose in these cells is due to an imbalance between the glucose transported into the cytosol and the use of glucose in the cytosol. In untreated cells with sensitive glycogen synthase activation, insulin stimulation did not result in a change in the cytosolic glucose level. This is the first report of dynamic measurements of cytosolic glucose levels in cells devoid of the glycogen synthesis pathway.

• Language: English
• Keywords: glucose, nanosensor, insulin, FRET, 3T3-L1 fibroblast, glycogen
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: MF - Faculty of Medicine; BF - Biotechnical Faculty
• Publication status: Published
• Publication version: Version of Record
• Year: 2014
• Number of pages: Str. 17827-17837
• Numbering: Vol. 15, iss. 10
• PID: 20.500.12556/RUL-130625
• UDC: 616-092
• ISSN on article: 1422-0067
• DOI: 10.3390/ijms151017827
• COBISS.SI-ID: 33641177
• Publication date in RUL: 16.09.2021

Record is a part of a journal

• Title: International journal of molecular sciences
• Shortened title: Int. j. mol. sci.
• Publisher: MDPI
• ISSN: 1422-0067
• COBISS.SI-ID: 2779162

Licences

• License: CC BY 3.0, Creative Commons Attribution 3.0 Unported
• Link: https://creativecommons.org/licenses/by/3.0/deed.en
• Description: You are free to reproduce and redistribute the material in any medium or format. You are free to remix, transform, and build upon the material for any purpose, even commercially. You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use. You may not apply legal terms or technological measures that legally restrict others from doing anything the license permits.
• Licensing start date: 02.10.2014

Secondary language

• Language: Slovenian
• Keywords: glukoza, nanosenzor, inzulin

Projects

• Funder: ARRS - Slovenian Research Agency
• Project number: P3-0310
• Name: Celična fiziologija1 10-7