Effect of Overproduction of Mitochondrial Uncoupling Protein 2 on Cos7 Cells: Induction of Senescent-like Morphology and Oncotic Cell Death

Title:Effect of Overproduction of Mitochondrial Uncoupling Protein 2 on Cos7 Cells: Induction of Senescent-like Morphology and Oncotic Cell Death

Volume: 9 Issue: 3

Author(s): Koji Nishio and Qian Ma

Affiliation:

Keywords: Cellular senescence, Cos7 cells and oncotic cell death, mitochondrial carrier family, mitochondrial membrane potential, senescent morphology, UCP2.

Abstract: Background: The maintenance of mitochondrial membrane potential is essential for cell growth and survival. Mitochondrial uncoupling protein 2 plays the most important roles in uncoupling oxidative phosphorylation and decreasing mitochondrial O2- production by regulating the mitochondrial membrane potential. We propose that mouse UCP2 has two glycine-rich motifs, motif 1: EGIRGLWKG (170-178) and a known Walker A-like motif 2: EGPRAFYKG (264-272). These motifs seem to be important for the function of UCP2.

Objective: We investigated the biological effects of overproduced-UCP2 and its physiological consequence in Cos7 cells.

Method: We introduced several amino acid changes in the motif 1. The expression vectors of the green fluorescent protein (GFP)-fused UCP2 and mutant UCP2 were constructed and expressed in Cos7 cells.

Result: The UCP2-GFP-expressed cells significantly down-regulated the mitochondrial membrane potentials and induced the enlarged cell shapes. Next we generated the stably UCP2-GFP-expressed Cos7 cells by selection with the antibiotic Genecitin (G418). Within the first few weeks following G418-selection, the stably UCP2-GFP-expressed cells could not divide well and gradually manifested the irregular and enlarged senescent-like cell morphology. The UCP2/K177E- or UCP2/G174L-expressed cells did not induce the enlarged cell shapes. Hence, UCP2/K177E and UCP2/G174L produced the functional incompetence of the glycine-rich motif 1. The senescent-like cells significantly decreased the mitochondrial membrane potentials and finally died nearly one month.

Conclusion: Overproduction of UCP2 irreversibly reduces the mitochondrial membrane potentials and induces the senescent-like morphology and finally oncotic cell death in Cos7 cells. These changes seem to occur from the irreversible metabolic changes following total loss of cellular ATP.

Cite this article as:

Nishio Koji and Ma Qian, Effect of Overproduction of Mitochondrial Uncoupling Protein 2 on Cos7 Cells: Induction of Senescent-like Morphology and Oncotic Cell Death, Current Aging Science 2016; 9 (3) . https://dx.doi.org/10.2174/1874609809666160211125332