Involvement of intracellular organelle stress,autophagy and ferropto-sis in cobalt chloride-induced vascular smooth muscle cell injury
AIM:To investigate the relationship be-tween vascular smooth muscle cell(VSMC)injury,or-ganelle stress response and autophagic cell death(autophagy)and ferroptosis induced by the chemi-cal hypoxia inducer cobalt chloride(CoCl2)through the bioinformatics analysis and in vitro cell experi-mentation.METHODS:The dataset GSE119226 of VSMC treated with cobalt chloride was acquired from the gene expression database(GEO).The R lan-guage was used to investigate the relationship be-tween CoCl2 treatment and organelle stress re-sponse(Golgi stress,endoplasmic reticulum stress)and two forms of cell death(ferroptosis and autoph-agic cell death).With primary cultured rat VSMC(rVSMC)and CoCl2-induced anoxia model,the chang-es in cell viability were detected by CCK-8 method,and reactive oxygen species(ROS)levels were mea-sured using DCFH-DA method.The expression levels of HIF-1α(a key molecule in hypoxia),Golgi stress markers GM130 and p115,endoplasmic reticulum stress markers GRP78 and CHOP,autophagy markers LC3-Ⅱ/LC3-Ⅰ and Beclin1,and ferroptosis markers GPx4 and xCT were detected by Western blot.The ef-fect of inducing or inhibiting organelle stress and cell death on the CoCl2-induced cell damage was also ob-served.RESULTS:Differentially expressed genes analysis of GSE119226 dataset showed that CoCl2 treatment of VSMCs had significant effects on organ-elle function and stress response,autophagy and fer-roptosis-related genes,in which endoplasmic reticu-lum stress,protein processing in endoplasmic reticu-lum,regulation of Golgi to plasma membrane pro-tein transport,autophagy/autophagic cell death,and ferroptosis pathways were remarkably en-riched.The results of in vitro experiment showed that compared with normal rVSMC,cell viability was significantly decreased after CoCl2 treatment,as well as HIF-1α protein expression and ROS levels in rVSMCs were increased.In rVSMC treated with Co-Cl2,the expression levels of Golgi structural proteins GM130 and p115(reflecting the occurrence of Golgi stress)were decreased,while the markers GRP78 and CHOP(reflecting the occurrence of endoplasmic reticulum stress)were increased.At the same time,CoCl2 treatment also reduced the expression of au-tophagy markers LC3-Ⅱ/LC3-Ⅰ and Beclin1(indicating the decrease levels of autophagy),while the expres-sion of ferroptosis markers GPx4 and xCT were de-creased(indicating the occurrence of ferroptosis).Compared with CoCl2 treatment group,induced Gol-gi stress,endoplasmic reticulum stress,or ferropto-sis could further reduce cell viability,while inhibition of these processes could improve cell viability.On the other hand,increasing the level of autophagy can improve the cell viability.CONCLUSION:Hypoxia induced by cobalt chloride can lead to VSMC injury.Golgi stress,endoplasmic reticulum stress,ferropto-sis,and the reduction of autophagy level play an im-portant role in it.Inhibition of organelle stress re-sponse and ferroptosis,or increase of autophagy lev-el can improve VSMC injury caused by cobalt chlo-ride.