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Krako Jakovljevic 2019 MiP2019

From Bioblast
Nina Krako Jakovljevic
Lower insulin sensitivity differently affects mitochondrial coupling in liver and muscle cells.

Link: MiP2019

Krako Jakovljevic N, Pavlovic K, Zujovic T1, Isakovic AM, Jovanovic M, Markovic I, Martinovic T, Ciric D, Kravic-Stevovic T, Bumbaširevic V, Lalic NM (2019)

Event: MiP2019


Condition in which cell, tissue, organ or an organism require higher insulin concentration to obtain a quantitatively normal biological response is called insulin resistance (IR). This state of lowered insulin sensitivity leads to an inadequate response of peripheral tissues (skeletal muscle, adipose tissue and liver) to insulin and consequently to type 2 diabetes pathology. Cell viability, mitochondrial respiration, reactive oxygen species (ROS) production and mitochondrial morphology were assessed in C2C12 mouse myoblasts and Huh7 human hepatocellular carcinoma cells in order to find if there is any cell type specific difference that could potentially be ascribed to tissue specific mechanisms of IR.

Cells were treated with chronic (24h) insulin or palmitate to induce IR. Insulin sensitivity was assayed by immunoblot, measuring the level of phosphorylation of Akt (Ser473). Cell viability was assessed by acid phosphatase assay. Mitochondrial respiration was measured by high resolution respirometry, ROS production by flow cytometry and mitochondrial morphology was examined by electron microscopy.

Chronic insulin treatment in both cell lines (C2C12 and Huh7) causes a decrease in phosphorylation of Akt, which is a hallmark of insulin resistance at the cellular level. The same effect was observed in both cell lines after chronic palmitate treatment. Chronic insulin treatment does not affect viability of (C2C12 and Huh7), while palmitate treatment decreases cell viability in both cell types. Chronic insulin treatment does not affect mitochondrial respiration, at variance with chronic palmitate treatment, which decreases respiration in C2C12 and Huh7 cells. However, chronic insulin treatment causes a decrease in respiratory acceptor control ratio (RCR) in C2C12, as observed with palmitate treatment. This is not the case for Huh7 cells, where RCR is unchanged after insulin treatment, while lowered only after palmitate treatment. Total ROS production does not change significantly in either cell line. Both C2C12 and Huh7 cells showed preserved mitochondrial morphology after chronic insulin treatment, while chronic palmitate treatment causes alterations of mitochondrial morphology in both cell lines.

To conclude, while chronic palmitate treatment showed to be cytotoxic in both C2C12 and Huh7 cells, chronic insulin treatment did not affect cell viability nor mitochondrial respiration. The difference found in RCR between insulin treated C2C12 and Huh7 cells is due to their OXPHOS coupling efficiency, which is an innate property of cells, it reflects differences between the metabolism of myocytes and hepatocytes and could indicate potential specificities in regulation of insulin sensitivity at the tissue level.

Bioblast editor: Plangger M, Tindle-Solomon L O2k-Network Lab: RS Belgrade Lalic NM

Labels: MiParea: Respiration, Comparative MiP;environmental MiP  Pathology: Diabetes 

Organism: Human, Mouse  Tissue;cell: Skeletal muscle, Liver 

HRR: Oxygraph-2k 


Krako Jakovljević N(1), Pavlović K(1), Žujović T(1), Isaković AM(2), Jovanović M(2), Marković I(2), Martinović T(3), Ćirić D(3), Kravić-Stevović T(3), Bumbaširević V(3), Lalić NM(1)
  1. Clinic Endocrinology, Diabetes Metabolic Diseases, CCS
  2. Inst Medical Clinical Biochemistry
  3. Inst Histology Embriology; Fac Medicine; Univ Belgrade, Serbia. - [email protected]