The Role of lipid peroxidation end product, 4-Hydroxy-2-Nonenal in cell signalling

Official URL: http://risc01.sabanciuniv.edu/record=b1064212 (Table of Contents)

Lipid peroxidation end products gained special interest and attention in recentyearsas mediators and inducers of signal transduction. In the present study, theoxidative and cytotoxic effects of a lipid peroxidation end product,4-hydoxy nonenal (4-HNE) has been studied and compared with that of a well known oxidant hydrogenperoxide (H2O2) in 3T3 fibroblast cell line. Cell morphology and viability studiesshowed that both H2O2 and 4-HNE could cause significant cellular deformations andloss of viability. Light microscopy results revealed that incubation of cells with 500 M H2O2 for 24 hr or longer periods resulted in the formation of apoptotic bodies.Similar results have been observed when cells were incubated with 4-HNE atconcentrations as low as 5, 15, 25, and 35 M. In a concentration dependent manner, cells became thicker and when 35 M 4-HNE was used detachment and membraneblebbings that are indicating apoptosis have been clearly observed. Treatment of cellsfor 24 hr with 25 and 50 M 4-HNE caused 25 % and 93 % loss in cell viabilityrespectively. Intracellular ROS production has been monitored by a florescent probe, DCFH-DA.When cells were treated with 5 M 4-HNE, a significant increase in florescenceintensity has been observed when compared to the control cells. Two structurally ifferent antioxidants; á-tocopherol and resveratrol prevented 4-HNE-induced ROSproduction to a significant extent when they were used at 50 M concentration. Thisfinding provided further evidence for the production of ROS. Differential staining byusing fluorescent probes and DNA fragmentation analysis results indicated that 10 M4-HNE induced apoptosis and the effect was again overcome by the antioxidants;vitamin E and resveratrol. Furthermore, a combination of acridine orange (AO),Hoechst (HO), and propidium iodide (PI) florescent dyes have been used todifferentiate viable, apoptotic and late apoptotic/necrotic cells respectively. Differentialstaining results indicated that when cells were incubated with 25 M4-HNE for 24 hr. apoptotic cells have been observed with condensed orange nucleus whereas viable cellswere seen with green nucleus. The results are discussed in the light of cellular signalling mechanisms induced by 4-HNE leading to apoptosis via effecting the overall redox status of the cell.