Lactylation Of Glucose-6-phosphate Dehydrogenase Promoting Tumor Cell Proliferation

Metabolic reprogramming is one of the important characteristics of tumor cells.It is the mechanism by which cells promote cell proliferation and growth by changing metabolic patterns in order to meet energy requirements.It can not only help cells resist external stress,but also give cells new functions.Post Translational Modifications(PTMs)are modifications to increase the functional diversity of the proteome by adjusting the structure and function of enzymes.Many metabolites in metabolic reprogramming can be used as substrates for PTMs,which in turn serve as feedback and feedforward regulatory mechanisms for metabolic processes.Glucose-6-phosphate Dehydrogenase(G6PD),the first rate-limiting enzyme of the pentose phosphate pathway,plays a critical role in maintaining intracellular redox homeostasis and biosynthesis.Abnormal activation of G6PD leads to increased cell proliferation and increased resistance to external stress in many types of cancer.Lactate accumulation due to increased glycolysis is a common feature of all types of cancer.Lactate is not only an important source of substances and energy,but also regulates cell signaling and gene expression.One of the important pathways is to influence post-translational modification of proteins.Lactate as a metabolite has been found to play an important role in PTMs.Lysine lactylation(Kla)is a recently discovered post-translational modification driven by intracellular lactate.However,the effect of lactylation on the biological processes of tumor cells remains largely unknown.The purpose of this study is to explore whether G6PD will undergo lactylation modification in tumor cells,what is the effect of lactylation modification on G6PD,and what effect the occurrence of Lysine lactylation has on the existence of G6PD.In order to explore the relationship between lactic acid and G6PD,tumor cells under different growth states were taken,that is,tumor cells were grouped according to cell density,and the influence of lactate content on the lysine lactylation of G6PD was detected according to different medium colors.The results showed that the lactylation level of G6PD increased with the increase of lactate content.The results showed that the lactylation level of G6PD increased with the increase of lactate content.In order to explore the regulatory mechanism and significance of the increase of lactylation level of G6PD in cells,In this study,G6PD enzyme activity was first measured using the kit and was found to increase with increasing levels of lactylation.Secondly,the results of G6PD truncation experiment revealed that the NAD-binding domain(45-197)was the functional region that affected the lactylation level of G6PD.Finally,by constructing different lysine mutants,I found the main lysine sites in the NAD-binding domain that affect G6PD lactylation,and performed cell proliferation assays to find that cell proliferation was inhibited after G6PD failed to be lactylated.These results suggest that tumor cells enhance enzyme activity and promote cell proliferation by increasing the lactylation level of G6PD.In conclusion,this study found that lactylation occurs at G6PD in tumor cells can up-regulate its enzyme activity,promote cell proliferation and accelerate tumor progression.The findings of this paper will help to further understand the role of G6PD lactylation in tumor progression,and provide theoretical basis for the use of G6PD lactylation as a target for clinical diagnosis and treatment.