Objective·To establish a research framework for serotonylation of proteins and to provide a methodological basis for the identification of serotonylated proteins.Methods·The Cancer Genome Atlas(TCGA)and Genotype-Tissue Expression(GTEx)databases were used to analyze the expression of the transglutaminase 2(TGM2)gene,which encodes the key enzyme for serotonylation,and the solute carrier family 6(SLC6A4)gene,which encodes the serotonin transporter(SERT),in normal and pan-cancer tissues.5-Propargyltryptamide(5-PT),a serotonin derivative,was synthesized stepwise from serotonin hydrochloride,and its structure was characterized by the Fourier transform infrared spectroscopy(FT-IR),proton nuclear magnetic resonance(1H-NMR),carbon nuclear magnetic resonance(13C-NMR),and time-of-flight mass spectrometry(TOF-MS).The intracellular uptake of 5-PT in the human pancreatic cancer cell line AsPC-1 and mouse immune cells,including CD4+T cells,CD8+T cells,and bone marrow-derived macrophages(BMDMs),was detected by using flow cytometry.Click chemistry,co-immunoprecipitation,and mass spectrometry analysis techniques were employed to identify serotonylated proteins,and Kyoto Encyclopedia of Genes and Genomes(KEGG)enrichment analysis was performed.Results·Bioinformatics analysis indicated that TGM2 and SLC6A4 were widely expressed in various normal tissues and across pan-cancer tissues.The flow cytometry results showed that the synthesized 5-PT can be taken up into the human pancreatic cancer cell line AsPC-1 and mouse immune cells,including CD4+T cells,CD8+T cells,and BMDMs,via the SERT.Mass spectrometry analysis data showed that a significant amount of serotonylated proteins were enriched in various cells treated with 5-PT.KEGG enrichment analysis revealed that these proteins were involved in important pathways related to glycolysis and amino acid synthesis.Conclusion·By using the synthesized 5-PT,multiple serotonylated proteins are enriched in various cell types.A research system for identifying serotonylated proteins has been successfully established,providing a relatively simple and efficient method for studying protein serotonylation.

Objective·To establish a research framework for serotonylation of proteins and to provide a methodological basis for the identification of serotonylated proteins.Methods·The Cancer Genome Atlas(TCGA)and Genotype-Tissue Expression(GTEx)databases were used to analyze the expression of the transglutaminase 2(TGM2)gene,which encodes the key enzyme for serotonylation,and the solute carrier family 6(SLC6A4)gene,which encodes the serotonin transporter(SERT),in normal and pan-cancer tissues.5-Propargyltryptamide(5-PT),a serotonin derivative,was synthesized stepwise from serotonin hydrochloride,and its structure was characterized by the Fourier transform infrared spectroscopy(FT-IR),proton nuclear magnetic resonance(1H-NMR),carbon nuclear magnetic resonance(13C-NMR),and time-of-flight mass spectrometry(TOF-MS).The intracellular uptake of 5-PT in the human pancreatic cancer cell line AsPC-1 and mouse immune cells,including CD4+T cells,CD8+T cells,and bone marrow-derived macrophages(BMDMs),was detected by using flow cytometry.Click chemistry,co-immunoprecipitation,and mass spectrometry analysis techniques were employed to identify serotonylated proteins,and Kyoto Encyclopedia of Genes and Genomes(KEGG)enrichment analysis was performed.Results·Bioinformatics analysis indicated that TGM2 and SLC6A4 were widely expressed in various normal tissues and across pan-cancer tissues.The flow cytometry results showed that the synthesized 5-PT can be taken up into the human pancreatic cancer cell line AsPC-1 and mouse immune cells,including CD4+T cells,CD8+T cells,and BMDMs,via the SERT.Mass spectrometry analysis data showed that a significant amount of serotonylated proteins were enriched in various cells treated with 5-PT.KEGG enrichment analysis revealed that these proteins were involved in important pathways related to glycolysis and amino acid synthesis.Conclusion·By using the synthesized 5-PT,multiple serotonylated proteins are enriched in various cell types.A research system for identifying serotonylated proteins has been successfully established,providing a relatively simple and efficient method for studying protein serotonylation.