TY - JOUR
T1 - Nicotinamide, a glucose-6-phosphate dehydrogenase non-competitive mixed inhibitor, modifies redox balance and lipid accumulation in 3T3-L1 cells
AU - Torres-Ramírez, Nayeli
AU - Baiza-Gutman, Luis Arturo
AU - García-Macedo, Rebeca
AU - Ortega-Camarillo, Clara
AU - Contreras-Ramos, Alejandra
AU - Medina-Navarro, Rafael
AU - Cruz, Miguel
AU - Ibáñez-Hernández, Miguel Ángel
AU - Díaz-Flores, Margarita
PY - 2013/12/18
Y1 - 2013/12/18
N2 - Aims: Excessive energy uptake of dietary carbohydrates results in their storage as fat and requires glucose-6-phosphate dehydrogenase (G6PD)-mediated NADPH production. We sought to assess whether the nicotinamide-induced reduction of G6PD activity might modulate redox balance and lipid accumulation in 3T3-L1 cells. Main methods: 3T3-L1 preadipocytes (days 4 and 6 of differentiation) and adipocytes were cultured in the presence of 5 or 25 mM glucose. The cells cultured in 25 mM glucose were supplemented with nicotinamide (5-15 mM). Next, we evaluated the following parameters: cell viability, apoptosis, lipid accumulation, lipolysis, reducing power, reactive oxygen species (ROS), NAD(P)H and NAD(P)+, isocitrate dehydrogenase (IDP), malic enzyme and G6PD, as well as the protein and mRNA levels of G6PD. We also analysed the kinetics of the nicotinamide-induced inhibition of G6PD. Key findings: G6PD mRNA levels increased at day 4 of adipocyte differentiation, whereas G6PD activity progressively increased at days 4 and 6 of differentiation and was reduced in adipocytes. Concomitantly, ROS, reducing power and lipid accumulation increased gradually as the preadipocytes matured into adipocytes. High glucose increased the activity of G6PD, which coincided with an increase in ROS, reducing power and lipid accumulation. All of these changes are prevented by nicotinamide, with the exception of lipid accumulation in adipocytes. Nicotinamide increased IDP activity without affecting NADPH levels. Lastly, nicotinamide inhibited G6PD in a non-competitive mixed way. Significance: Nicotinamide modulates G6PD via a non-competitive mixed inhibition and decreases high glucose-dependent oxidative stress and lipid accumulation. Nicotinamide maintains NADPH levels by increasing the activity of IDP.
AB - Aims: Excessive energy uptake of dietary carbohydrates results in their storage as fat and requires glucose-6-phosphate dehydrogenase (G6PD)-mediated NADPH production. We sought to assess whether the nicotinamide-induced reduction of G6PD activity might modulate redox balance and lipid accumulation in 3T3-L1 cells. Main methods: 3T3-L1 preadipocytes (days 4 and 6 of differentiation) and adipocytes were cultured in the presence of 5 or 25 mM glucose. The cells cultured in 25 mM glucose were supplemented with nicotinamide (5-15 mM). Next, we evaluated the following parameters: cell viability, apoptosis, lipid accumulation, lipolysis, reducing power, reactive oxygen species (ROS), NAD(P)H and NAD(P)+, isocitrate dehydrogenase (IDP), malic enzyme and G6PD, as well as the protein and mRNA levels of G6PD. We also analysed the kinetics of the nicotinamide-induced inhibition of G6PD. Key findings: G6PD mRNA levels increased at day 4 of adipocyte differentiation, whereas G6PD activity progressively increased at days 4 and 6 of differentiation and was reduced in adipocytes. Concomitantly, ROS, reducing power and lipid accumulation increased gradually as the preadipocytes matured into adipocytes. High glucose increased the activity of G6PD, which coincided with an increase in ROS, reducing power and lipid accumulation. All of these changes are prevented by nicotinamide, with the exception of lipid accumulation in adipocytes. Nicotinamide increased IDP activity without affecting NADPH levels. Lastly, nicotinamide inhibited G6PD in a non-competitive mixed way. Significance: Nicotinamide modulates G6PD via a non-competitive mixed inhibition and decreases high glucose-dependent oxidative stress and lipid accumulation. Nicotinamide maintains NADPH levels by increasing the activity of IDP.
KW - Adipocyte
KW - Adipogenesis
KW - Glucose-6-phosphate dehydrogenase
KW - Lipids
KW - NAD(P)
KW - NAD(P)H
KW - Nicotinamide
KW - Oxidative stress
KW - Reductive power
UR - http://www.scopus.com/inward/record.url?scp=84889097679&partnerID=8YFLogxK
U2 - 10.1016/j.lfs.2013.10.023
DO - 10.1016/j.lfs.2013.10.023
M3 - Artículo
SN - 0024-3205
VL - 93
SP - 975
EP - 985
JO - Life Sciences
JF - Life Sciences
IS - 25-26
ER -