Mitochondrial dysfunction is induced by high levels of glucose and free fatty acids in 3T3-L1 adipocytes.
Hyperglycemia and high free fatty acids (FFAs) are two well-known characteristics of type 2 diabetes, and are also implicated in the etiology of insulin resistance. However, their roles in mitochondrial dysfunction of white adipocytes are not well-studied. In this study, we investigated the effects of high glucose (25 mM), high free fatty acids (FFAs, 1mM), or a combination of both high glucose+high FFAs on mitochondrial function in differentiated 3T3-L1 adipocytes after 48 h of treatment. We found that high glucose, high FFAs, or high glucose+high FFAs reduced insulin-stimulated glucose uptake in differentiated 3T3-L1 adipocytes. In addition, the mitochondria became smaller and more compact. Levels of the mitofusion protein mfn1 decreased and levels of the mitofission protein Drp1 increased as compared to controls. NRF1 was downregulated, and PGC-1 beta levels were diminished in the high glucose and high glucose+high FFAs conditions. Levels of PGC-1 alpha and mtTFA mRNA were greatly downregulated. No difference was found in the mitochondrial DNA (mtDNA) and intracellular ATP levels of treated cells compared to control cells. Cells treated with high glucose or high FFAs accumulated significant amounts of reactive oxygen species (ROS) and displayed a loss of the mitochondrial membrane potential. High glucose and high glucose+high FFAs led to similar decreases in intramitochondrial calcium concentration, although high FFAs had no effect. Therefore, high glucose and high FFAs can regulate insulin sensitivity, and mitochondrial dysfunction may occur in this process.
Gao
Chun-Lin
CL
Department of Pediatrics, Nanjing Maternal and Child Health Hospital of Nanjing Medical University, Nanjing 210004, China.
Zhu
Chun
C
Zhao
Ya-Ping
YP
Chen
Xiao-Hui
XH
Ji
Chen-Bo
CB
Zhang
Chun-Mei
CM
Zhu
Jin-Gai
JG
Xia
Zheng-Kun
ZK
Tong
Mei-Ling
ML
Guo
Xi-Rong
XR
D041721:3T3-L1 Cells; D000255:Adenosine Triphosphate / Q000378:metabolism; D017667:Adipocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism* / Q000648:ultrastructure; D000818:Animals; D002118:Calcium / Q000378:metabolism; D004272:DNA, Mitochondrial / Q000378:metabolism; D005230:Fatty Acids, Nonesterified / Q000494:pharmacology*; D005947:Glucose / Q000494:pharmacology*; D007328:Insulin / Q000494:pharmacology; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D051379:Mice; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism* / Q000648:ultrastructure; D017382:Reactive Oxygen Species / Q000378:metabolism
D004272:DNA, Mitochondrial; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D017382:Reactive Oxygen Species; D000255:Adenosine Triphosphate; D005947:Glucose; D002118:Calcium