Salsolinol(1-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline,Sal)is a catechol isoquinoline that causes neurotoxicity and shares structural similarity with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine,an environme...Salsolinol(1-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline,Sal)is a catechol isoquinoline that causes neurotoxicity and shares structural similarity with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine,an environmental toxin that causes Parkinson's disease.However,the mechanism by which Sal mediates dopaminergic neuronal death remains unclear.In this study,we found that Sal significantly enhanced the global level of N~6-methyladenosine(m~6A)RNA methylation in PC12 cells,mainly by inducing the downregulation of the expression of m~6A demethylases fat mass and obesity-associated protein(FTO)and alk B homolog 5(ALKBH5).RNA sequencing analysis showed that Sal downregulated the Hippo signaling pathway.The m~6A reader YTH domain-containing family protein 2(YTHDF2)promoted the degradation of m~6A-containing Yes-associated protein 1(YAP1)mRNA,which is a downstream key effector in the Hippo signaling pathway.Additionally,downregulation of YAP1 promoted autophagy,indicating that the mutual regulation between YAP1 and autophagy can lead to neurotoxicity.These findings reveal the role of Sal on m~6A RNA methylation and suggest that Sal may act as an RNA methylation inducer mediating dopaminergic neuronal death through YAP1 and autophagy.Our results provide greater insights into the neurotoxic effects of catechol isoquinolines compared with other studies and may be a reference for assessing the involvement of RNA methylation in the pathogenesis of Parkinson's disease.展开更多
Choline is a crucial factor in the regulation of sperm membrane structure and fluidity, and this nutrient plays an important role in the maturation and fertilizing capacity of spermatozoa. Transcripts of phosphatidyle...Choline is a crucial factor in the regulation of sperm membrane structure and fluidity, and this nutrient plays an important role in the maturation and fertilizing capacity of spermatozoa. Transcripts of phosphatidylethanolamine N-methyltransferase （PEMT） and choline dehydrogenase （CHDH）, two basic enzymes of choline metabolism, have been observed in the human testis, demonstrating their gene expression in this tissue. In the present study, we explored the contribution of the PEMTand CHDHgene variants to sperm parameters. Two hundred oligospermic and 250 normozoospermic men were recruited. DNA was extracted from the spermatozoa, and the PEMT -774G〉C and CHDH ＋432G〉T polymorphisms were genotyped. The genotype distribution of the PEMT-774G〉C polymorphism did not differ between oligospermic and normozoospermic men. In contrast, in the case of the CHDH ＋432G〉T polymorphism, oligospermic men presented the CHDH432GIG genotype more frequently than normozoospermic men （62% vs. 42%, P〈0.001）. The PEMT774GIG genotype was associated with a higher sperm concentration compared to the PEMT774GIC and 774C/C genotypes in oligospermic men （12.5±5.6× 10^6 spermatozoa m1-1 vs. 8.3±5.2×10^6 spermatozoa m1-1, P〈0.002） and normozoospermic men （81.5±55.6×10^6 vs. 68.1±44.5×10^6 spermatozoa m1-1, P〈0.006）. In addition, the CHDH432G/G genotype was associated with higher sperm concentration compared to CHDH432G.T and 432T/T genotypes in oligospermic （11.8±5.1×10^6 vs. 7.8±5.3×10^6 spermatozoa m1-1, P〈0.003） and normozoospermic men （98.6±62.2×10^6 vs. 58.8±＋33.6×10^6 spermatozoa m1-1, P〉0.001）. In our series, the PEMT-774G〈C and CHDH ＋432G〈T polymorphisms were associated with sperm concentration. This finding suggests a possible influence of these genes on sperm quality.展开更多
AIM： To analyse the role of two common polymorphisms in genes coding for histamine metabolising enzymes as it relates to the risk to develop ulcerative colitis （UC） and the clinical course of these patients. METHOD...AIM： To analyse the role of two common polymorphisms in genes coding for histamine metabolising enzymes as it relates to the risk to develop ulcerative colitis （UC） and the clinical course of these patients. METHODS： A cohort of 229 unrelated patients with UC recruited from a single centre and 261 healthy volunteers were analysed for the presence of Thr105Ile and His645Asp amino acid substitutions at histamine N-methyltransferase （HNMT） and diamine oxidase （ABP1） enzymes, respectively, by amplification-restriction procedures. All patients were phenotyped and followed up for at least 2 years （mean time 11 years）. RESULTS： There were no significant differences in the distribution of ABP1 alleles between ulcerative colitis patients and healthy individuals [OR （95% CI） for variant alleles = 1.22 （0.91-1.61）]. However, mutated ABP1 alleles were present with higher frequency among the 58 patients that required immunosuppresive drugs [OR （95 % CI） for carriers of mutated alleles 2.41 （1.21-4.83; P=0.006）], with a significant gene-dose effect （P= 0.0038）. In agreement with the predominant role of ABP1 versus HNMT on local histamine metabolism in human bowel, the frequencies for carriers of HNMT genotypes or mutated alleles were similar among patients,regardless clinical evolution, and control individuals. CONCLUSION： The His645Asp polymorphism of the histamine metabolising enzyme ABP1 is related to severity of ulcerative colitis.展开更多
Parkinson’s disease is a common chronic neurodegenerative disease.N-methylation can enhance the neurotoxiicity to dopaminergic neuron in the metabolic process of catechol isoquinolines and Salsolinol N-methyltransfer...Parkinson’s disease is a common chronic neurodegenerative disease.N-methylation can enhance the neurotoxiicity to dopaminergic neuron in the metabolic process of catechol isoquinolines and Salsolinol N-methyltransferases (SNMT) may play an important role in the pathogenesis of PD.A new method including SNMT purification and detecting SNMT activity was developed and displays an excellent sensitivity and stability.In addition,the SNMT activity in Wistar rats substantia nigra,striatum and cerebellum.展开更多
Objective The selective loss of dopaminergic neurons in Parkinson＇s disease is suspected to correlate with the increase of cellular iron, which may be involved in the pathogenesis of PD by promotion of oxidative stre...Objective The selective loss of dopaminergic neurons in Parkinson＇s disease is suspected to correlate with the increase of cellular iron, which may be involved in the pathogenesis of PD by promotion of oxidative stress. This research investigated dopamine-induced oxidative stress toxicity contributed by iron and the production of dopamine-derived neurotoxins in dopaminergic SH-SYSY cells. Methods After the SH-SYSY cells were pre-incubated with dopamine and Fe^2＋ for 24 h, the cell viability, hydroxyl radical, melondialdehyde, cell apoptosis, and catechol isoquinolines were measured by lactate dehydrogenase assay, salicylic acid trapping method, thiobarbuteric acid assay, Hoechst 33258 staining and HPLC-electrochemical detection （HPLC-ECD）, respectively. Results （1） Optimal dopamine （150 μmol/L） and Fe^2＋ （40 or 80 μmol/L） significantly increased the concentrations of hydroxy radicals and melondialdehyde in SH-SYSY cells. （2） Induction with dopamine alone or dopamine and Fe^2＋ （dopamine/Fe^2＋） caused cell apoptosis. （3） Compared with untreated cells, the catechol isoquinolines, salsolinol and N-methyl-salsolinol in dopamine/Fe^2＋-induced cells were detected in increasing amounts. Conclusion Due to dopamine/Fe^2＋-induced oxidative stress similar to the state in the parkinsonian substantia nigra neurons, dopamine and Fe^2＋ impaired SH-SYSY cells could be used as the cell oxidative stress model of Parkinson＇s disease. The catechol isoquinolines detected in cells may be involved in the pathogenesis of Parkinson＇s disease as potential neurotoxins.展开更多
Objective: To understand the function of nicotinamide N-methyltransferase (NNMT) protein as tumor biomarker in renal carcinoma. Methods: Recombinant NNMT protein was used to prepare monoclonal antibodies by hybridoma ...Objective: To understand the function of nicotinamide N-methyltransferase (NNMT) protein as tumor biomarker in renal carcinoma. Methods: Recombinant NNMT protein was used to prepare monoclonal antibodies by hybridoma technique. The diagnostic and prognostic function of NNMT protein in renal carcinoma was evaluated by analyzing 74 renal cancer tissues through immunohistochemical staining for NNMT by using the prepared antibodies. Results: Two hybridomas named 2F8 and 1E7 stably secreting the monoclonal antibodies were isolated successfully, and characters such as isotypes and specificity were determined. NNMT protein was significantly up-regulated in renal cancer and significantly associated with tumor histology and ages. The univariate survival analysis demonstrated that the pT-status, high levels of NNMT, and distant metastasis were significant prognosticators. Conclusion: NNMT is over-expressed in a large proportion in renal cell cancers. High NNMT expression is significantly associated with unfavorable prognosis. However, the prognostic value of NNMT needs further verification in larger sample sizes.展开更多
Cellular metabolism-induced epigenetic regulation is essential for the maintenance of cellular homeostasis.Nicotinamide N-methyltransferase(NNMT)is emerging as a key point of intersection between cellular metabolism a...Cellular metabolism-induced epigenetic regulation is essential for the maintenance of cellular homeostasis.Nicotinamide N-methyltransferase(NNMT)is emerging as a key point of intersection between cellular metabolism and epigenetic regulation and has a central role in various physiological and pathological processes.NNMT catalyzes the methylation of nicotinamide(NAM)using the universal methyl donor S-adenosyl methionine(SAM)to yield S-adeno-syl-L-homocysteine(SAH)and N1-methylnicotinamide(MNAM),directly linking methylation balance with nicotinamide adenosine dinucleotide(NAD+)contents.NNMT acts on either the SAM-methylation balance or both NAD+metabolism,depending on the tissue involved or pathological settings where metabolic demand is increased.Under physiological conditions,the liver act as an essential metabolic organ with abundant NNMT expression,while NNMT hepatic function is not mediated by its methyltransferase activity due to other major methyltransferases such as glycine N-methyltransferase(GNMT)in the liver.However,hepatic NNMT,as well as its metabolite is improperly regulated and linked to the worse pathological states in liver diseases,including alcoholic liver disease,non-alcoholic fatty liver disease(NAFLD),liver cirrhosis,and hepatocellular carcinoma(HCC),suggesting a potential role in the process of liver diseases.In this review,we summarize how NNMT regulates cell methylation balance and NAD metabolism,and extensively outline the current knowledge concerning the functions of NNMT in hepatic metabolism including glucose,lipid and energy,with a specific focus on the contribution of NNMT to the pathophysiology of liver-related diseases.NNMT is involved in the development and progression of liver diseases.Understanding the complex NNMT regulatory network and its effects on pathogenesis could provide new therapeutic strategies in the context of liver diseases.展开更多
A new method for the quantitative determination of the enantiomers of salsolinol, an endogenous neurotoxin, was reported. Enantiomeric separation of salsolinol was obtained by capillary zone electrophoresis using hydr...A new method for the quantitative determination of the enantiomers of salsolinol, an endogenous neurotoxin, was reported. Enantiomeric separation of salsolinol was obtained by capillary zone electrophoresis using hydroxypropyl-β-cyclodextrin （HP-β-CD） as chiral selector. Coupled with UV detection, this separation was applied to the determination of R,S-salsolinol in dried banana chips, and both R- and S-salsolinol were found at 40 ktg/g level.展开更多
Creatine is a naturally occurring derivative of an amino acid commonly utilized in functional foods and pharmaceuticals.Nevertheless,the current industrial synthesis of creatine relies on chemical processes,which may ...Creatine is a naturally occurring derivative of an amino acid commonly utilized in functional foods and pharmaceuticals.Nevertheless,the current industrial synthesis of creatine relies on chemical processes,which may hinder its utilization in certain applications.Therefore,a biological approach was devised that employs whole-cell biocatalysis in the bacterium Corynebacterium glutamicum,which is considered safe for use in food production,to produce safe-for-consumption creatine.The objective of this study was to identify a guanidinoacetate N-methyltransferase(GAMT)with superior catalytic activity for creatine production.Through employing whole-cell biocatalysis,a gamt gene from Mus caroli(Mcgamt)was cloned and expressed in C.glutamicum ATCC 13032,resulting in a creatine titer of 3.37 g/L.Additionally,the study employed a promoter screening strategy that utilized nine native strong promoters in C.glutamicum to enhance the expression level of GAMT.The highest titer was achieved using the P1676 promoter,reaching 4.14 g/L.The conditions of whole-cell biocatalysis were further optimized,resulting in a creatine titer of 5.42 g/L.This is the first report of successful secretory creatine expression in C.glutamicum,which provides a safer and eco-friendly approach for the industrial production of creatine.展开更多
基金supported by the National Natural Science Foundation of China,Nos.82271283(to XC),91854115(to JW),31970044(to JW)the Natural Science Foundation of Beijing,No.7202001(to XC)the Scientific Research Project of Beijing Educational Committee,No.KM202010005022(to XC)。
文摘Salsolinol(1-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline,Sal)is a catechol isoquinoline that causes neurotoxicity and shares structural similarity with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine,an environmental toxin that causes Parkinson's disease.However,the mechanism by which Sal mediates dopaminergic neuronal death remains unclear.In this study,we found that Sal significantly enhanced the global level of N~6-methyladenosine(m~6A)RNA methylation in PC12 cells,mainly by inducing the downregulation of the expression of m~6A demethylases fat mass and obesity-associated protein(FTO)and alk B homolog 5(ALKBH5).RNA sequencing analysis showed that Sal downregulated the Hippo signaling pathway.The m~6A reader YTH domain-containing family protein 2(YTHDF2)promoted the degradation of m~6A-containing Yes-associated protein 1(YAP1)mRNA,which is a downstream key effector in the Hippo signaling pathway.Additionally,downregulation of YAP1 promoted autophagy,indicating that the mutual regulation between YAP1 and autophagy can lead to neurotoxicity.These findings reveal the role of Sal on m~6A RNA methylation and suggest that Sal may act as an RNA methylation inducer mediating dopaminergic neuronal death through YAP1 and autophagy.Our results provide greater insights into the neurotoxic effects of catechol isoquinolines compared with other studies and may be a reference for assessing the involvement of RNA methylation in the pathogenesis of Parkinson's disease.
文摘Choline is a crucial factor in the regulation of sperm membrane structure and fluidity, and this nutrient plays an important role in the maturation and fertilizing capacity of spermatozoa. Transcripts of phosphatidylethanolamine N-methyltransferase （PEMT） and choline dehydrogenase （CHDH）, two basic enzymes of choline metabolism, have been observed in the human testis, demonstrating their gene expression in this tissue. In the present study, we explored the contribution of the PEMTand CHDHgene variants to sperm parameters. Two hundred oligospermic and 250 normozoospermic men were recruited. DNA was extracted from the spermatozoa, and the PEMT -774G〉C and CHDH ＋432G〉T polymorphisms were genotyped. The genotype distribution of the PEMT-774G〉C polymorphism did not differ between oligospermic and normozoospermic men. In contrast, in the case of the CHDH ＋432G〉T polymorphism, oligospermic men presented the CHDH432GIG genotype more frequently than normozoospermic men （62% vs. 42%, P〈0.001）. The PEMT774GIG genotype was associated with a higher sperm concentration compared to the PEMT774GIC and 774C/C genotypes in oligospermic men （12.5±5.6× 10^6 spermatozoa m1-1 vs. 8.3±5.2×10^6 spermatozoa m1-1, P〈0.002） and normozoospermic men （81.5±55.6×10^6 vs. 68.1±44.5×10^6 spermatozoa m1-1, P〈0.006）. In addition, the CHDH432G/G genotype was associated with higher sperm concentration compared to CHDH432G.T and 432T/T genotypes in oligospermic （11.8±5.1×10^6 vs. 7.8±5.3×10^6 spermatozoa m1-1, P〈0.003） and normozoospermic men （98.6±62.2×10^6 vs. 58.8±＋33.6×10^6 spermatozoa m1-1, P〉0.001）. In our series, the PEMT-774G〈C and CHDH ＋432G〈T polymorphisms were associated with sperm concentration. This finding suggests a possible influence of these genes on sperm quality.
基金Supported by Grants SAF 2003-00967 from Ministerio de Ciencia y Tecnología and FIS 02/0255 from Fondo de Investigación Sanitaria,Instituto de Salud Carlos Ⅲ,Madrid,Spain
文摘AIM： To analyse the role of two common polymorphisms in genes coding for histamine metabolising enzymes as it relates to the risk to develop ulcerative colitis （UC） and the clinical course of these patients. METHODS： A cohort of 229 unrelated patients with UC recruited from a single centre and 261 healthy volunteers were analysed for the presence of Thr105Ile and His645Asp amino acid substitutions at histamine N-methyltransferase （HNMT） and diamine oxidase （ABP1） enzymes, respectively, by amplification-restriction procedures. All patients were phenotyped and followed up for at least 2 years （mean time 11 years）. RESULTS： There were no significant differences in the distribution of ABP1 alleles between ulcerative colitis patients and healthy individuals [OR （95% CI） for variant alleles = 1.22 （0.91-1.61）]. However, mutated ABP1 alleles were present with higher frequency among the 58 patients that required immunosuppresive drugs [OR （95 % CI） for carriers of mutated alleles 2.41 （1.21-4.83; P=0.006）], with a significant gene-dose effect （P= 0.0038）. In agreement with the predominant role of ABP1 versus HNMT on local histamine metabolism in human bowel, the frequencies for carriers of HNMT genotypes or mutated alleles were similar among patients,regardless clinical evolution, and control individuals. CONCLUSION： The His645Asp polymorphism of the histamine metabolising enzyme ABP1 is related to severity of ulcerative colitis.
文摘Parkinson’s disease is a common chronic neurodegenerative disease.N-methylation can enhance the neurotoxiicity to dopaminergic neuron in the metabolic process of catechol isoquinolines and Salsolinol N-methyltransferases (SNMT) may play an important role in the pathogenesis of PD.A new method including SNMT purification and detecting SNMT activity was developed and displays an excellent sensitivity and stability.In addition,the SNMT activity in Wistar rats substantia nigra,striatum and cerebellum.
基金This work was supported by the National Natural Science Foundation of China （No. 20435020, No. 20275005, and No. 30670645）.
文摘Objective The selective loss of dopaminergic neurons in Parkinson＇s disease is suspected to correlate with the increase of cellular iron, which may be involved in the pathogenesis of PD by promotion of oxidative stress. This research investigated dopamine-induced oxidative stress toxicity contributed by iron and the production of dopamine-derived neurotoxins in dopaminergic SH-SYSY cells. Methods After the SH-SYSY cells were pre-incubated with dopamine and Fe^2＋ for 24 h, the cell viability, hydroxyl radical, melondialdehyde, cell apoptosis, and catechol isoquinolines were measured by lactate dehydrogenase assay, salicylic acid trapping method, thiobarbuteric acid assay, Hoechst 33258 staining and HPLC-electrochemical detection （HPLC-ECD）, respectively. Results （1） Optimal dopamine （150 μmol/L） and Fe^2＋ （40 or 80 μmol/L） significantly increased the concentrations of hydroxy radicals and melondialdehyde in SH-SYSY cells. （2） Induction with dopamine alone or dopamine and Fe^2＋ （dopamine/Fe^2＋） caused cell apoptosis. （3） Compared with untreated cells, the catechol isoquinolines, salsolinol and N-methyl-salsolinol in dopamine/Fe^2＋-induced cells were detected in increasing amounts. Conclusion Due to dopamine/Fe^2＋-induced oxidative stress similar to the state in the parkinsonian substantia nigra neurons, dopamine and Fe^2＋ impaired SH-SYSY cells could be used as the cell oxidative stress model of Parkinson＇s disease. The catechol isoquinolines detected in cells may be involved in the pathogenesis of Parkinson＇s disease as potential neurotoxins.
基金Project supported by the Science Foundation of Health Bureau of Zhejiang Province (Nos. 2005A055 and 2008B114)the Science Foundation of Education Bureau of Zhejiang Province (No. 20061271), China
文摘Objective: To understand the function of nicotinamide N-methyltransferase (NNMT) protein as tumor biomarker in renal carcinoma. Methods: Recombinant NNMT protein was used to prepare monoclonal antibodies by hybridoma technique. The diagnostic and prognostic function of NNMT protein in renal carcinoma was evaluated by analyzing 74 renal cancer tissues through immunohistochemical staining for NNMT by using the prepared antibodies. Results: Two hybridomas named 2F8 and 1E7 stably secreting the monoclonal antibodies were isolated successfully, and characters such as isotypes and specificity were determined. NNMT protein was significantly up-regulated in renal cancer and significantly associated with tumor histology and ages. The univariate survival analysis demonstrated that the pT-status, high levels of NNMT, and distant metastasis were significant prognosticators. Conclusion: NNMT is over-expressed in a large proportion in renal cell cancers. High NNMT expression is significantly associated with unfavorable prognosis. However, the prognostic value of NNMT needs further verification in larger sample sizes.
基金supported by grants from the National Natural Science Fund of China(NSFC)(No.82071590).
文摘Cellular metabolism-induced epigenetic regulation is essential for the maintenance of cellular homeostasis.Nicotinamide N-methyltransferase(NNMT)is emerging as a key point of intersection between cellular metabolism and epigenetic regulation and has a central role in various physiological and pathological processes.NNMT catalyzes the methylation of nicotinamide(NAM)using the universal methyl donor S-adenosyl methionine(SAM)to yield S-adeno-syl-L-homocysteine(SAH)and N1-methylnicotinamide(MNAM),directly linking methylation balance with nicotinamide adenosine dinucleotide(NAD+)contents.NNMT acts on either the SAM-methylation balance or both NAD+metabolism,depending on the tissue involved or pathological settings where metabolic demand is increased.Under physiological conditions,the liver act as an essential metabolic organ with abundant NNMT expression,while NNMT hepatic function is not mediated by its methyltransferase activity due to other major methyltransferases such as glycine N-methyltransferase(GNMT)in the liver.However,hepatic NNMT,as well as its metabolite is improperly regulated and linked to the worse pathological states in liver diseases,including alcoholic liver disease,non-alcoholic fatty liver disease(NAFLD),liver cirrhosis,and hepatocellular carcinoma(HCC),suggesting a potential role in the process of liver diseases.In this review,we summarize how NNMT regulates cell methylation balance and NAD metabolism,and extensively outline the current knowledge concerning the functions of NNMT in hepatic metabolism including glucose,lipid and energy,with a specific focus on the contribution of NNMT to the pathophysiology of liver-related diseases.NNMT is involved in the development and progression of liver diseases.Understanding the complex NNMT regulatory network and its effects on pathogenesis could provide new therapeutic strategies in the context of liver diseases.
基金accepted November 6, 2005. Project supported by the National Natural Science Foundation of China （No. 20265001）.
文摘A new method for the quantitative determination of the enantiomers of salsolinol, an endogenous neurotoxin, was reported. Enantiomeric separation of salsolinol was obtained by capillary zone electrophoresis using hydroxypropyl-β-cyclodextrin （HP-β-CD） as chiral selector. Coupled with UV detection, this separation was applied to the determination of R,S-salsolinol in dried banana chips, and both R- and S-salsolinol were found at 40 ktg/g level.
基金funded by National Natural Science Foundation of China(no.32272279)the Key R&D project of Qingdao Science and Technology Plan(22-3-3-hygg-29-hy).
文摘Creatine is a naturally occurring derivative of an amino acid commonly utilized in functional foods and pharmaceuticals.Nevertheless,the current industrial synthesis of creatine relies on chemical processes,which may hinder its utilization in certain applications.Therefore,a biological approach was devised that employs whole-cell biocatalysis in the bacterium Corynebacterium glutamicum,which is considered safe for use in food production,to produce safe-for-consumption creatine.The objective of this study was to identify a guanidinoacetate N-methyltransferase(GAMT)with superior catalytic activity for creatine production.Through employing whole-cell biocatalysis,a gamt gene from Mus caroli(Mcgamt)was cloned and expressed in C.glutamicum ATCC 13032,resulting in a creatine titer of 3.37 g/L.Additionally,the study employed a promoter screening strategy that utilized nine native strong promoters in C.glutamicum to enhance the expression level of GAMT.The highest titer was achieved using the P1676 promoter,reaching 4.14 g/L.The conditions of whole-cell biocatalysis were further optimized,resulting in a creatine titer of 5.42 g/L.This is the first report of successful secretory creatine expression in C.glutamicum,which provides a safer and eco-friendly approach for the industrial production of creatine.
