The phytohormone auxin plays crucial roles in nearly every aspect of plant growth and development.Auxin signaling is activated through the phytohormone-induced proteasomal degradation of the Auxin/INDOLE-3-ACETIC ACID(Aux/IAA)family of transcriptional repressors.Notably,many auxin-modulated physiological processes are also regulated by nitric oxide(NO)that executes its biological effects predominantly through protein S-nitrosylation at specific cysteine residues.However,little is known about the molecular mechanisms in regulating the interactive NO and auxin networks.Here,we show that NO represses auxin signaling by inhibiting IAA17 protein degradation.NO induces the S-nitrosylation of Cys-70 located in the intrinsically disordered region of IAA17,which inhibits the TIR1-IAA17 interaction and consequently the proteasomal degradation of IAA17.The accumulation of a higher level of IAA17 attenuates auxin response.Moreover,an IAA17^(C70W)nitrosomimetic mutation renders the accumulation of a higher level of the mutated protein,thereby causing partial resistance to auxin and defective lateral root development.Taken together,these results suggest that S-nitrosylation of IAA17 at Cys-70 inhibits its interaction with TIR1,thereby negatively regulating auxin signaling.This study provides unique molecular insights into the redox-based auxin signaling in regulating plant growth and development.
Background:Keloids are aberrant dermal wound healing characterized by invasive growth,extracellular matrix deposition,cytokine overexpression and easy recurrence.Many factors have been implicated as pathological causes of keloids,particularly hyperactive inflammation,tension alignment and genetic predisposition.S-Nitrosylation(SNO),a unique form of protein modification,is associated with the local inflammatory response but its function in excessive fibrosis and keloid formation remains unknown.We aimed to discover the association between protein SNO and keloid formation.Methods:Normal and keloid fibroblasts were isolated from collected normal skin and keloid tissues.The obtained fibroblasts were cultured in DMEM supplemented with 10%fetal bovine serum and 1%penicillin/streptomycin.The effects of DJ-1 on cell proliferation,apoptosis,migration and invasion,and on the expression of proteins were assayed.TurboID-based proximity labelling and liquid chromatography-mass spectrometry were conducted to explore the potential targets of DJ-1.Biotin-switch assays and transnitrosylation reactions were used to detect protein SNO.Quantitative data were compared by two-tailed Student’s t test.Results:We found that DJ-1 served as an essential positive modulator to facilitate keloid cell proliferation,migration and invasion.A higher S-nitrosylated DJ-1(SNO-DJ-1)level was observed in keloids,and the effect of DJ-1 on keloids was dependent on SNO of the Cys106 residue of the DJ-1 protein.SNO-DJ-1 was found to increase the level of phosphatase and tensin homolog(PTEN)S-nitrosylated at its Cys136 residue via transnitrosylation in keloids,thus diminishing the phosphatase activity of PTEN and activating the PI3K/AKT/mTOR pathway.Furthermore,Cys106-mutant DJ-1 is refractory to SNO and abrogates DJ-1-PTEN coupling and the SNO of the PTEN protein,thus repressing the PI3K/AKT/mTOR pathway and alleviating keloid formation.Importantly,the biological effect of DJ-1 in keloids is dependent on the SNO-DJ-1/SNO-PTEN/PI3K/AKT/mTOR axis.Conclusi
This research aimed to investigate the regulation of energy metabolism by protein S-nitrosylation utilizing the in vitro muscle glycolysis model.Longissimus thoracis(LT)muscles homogenates were treated with nitric oxide donor NOR-3((±)-(E)-4-Ethyl-2-(E)-hydroxyimino-5-nitro-3-hexenamide)and control(0.1 M K_(2)HPO_(4))under different pH conditions(6.5,6.0 and 5.5)in vitro buffer system for 24 h,respectively.Results indicated that the NOR-3 treatment group had a significantly higher pH decline rate than the control group and resulted in a higher lactate accumulation and glycogen degradation at 24 h compared with the control group(p<0.05).Moreover,NOR-3 treatment significantly increased the activities along with S-nitrosylation levels of lactate dehydrogenase and glycogen phosphorylase at pH 6.5 in a concentration-dependent manner(p<0.05).In addition,low pH could weaken the NOR-3 treatment effect and inhibit glycolysis rate.Thus,protein S-nitrosylation could play a role in regulating postmortem glycolysis in vitro model even at low pH conditions.
