Possible therapeutics for Pseudomyxoma peritonei: a rare, lethal, and the least investigated disease

Pseudomyxoma peritonei (PMP) refers to a growth disorder characterized by glycoprotein neoplasm in the peritoneum, where mucin oversecretion occurs. The tumors of the appendix region are well associated with PMP; however, ovarian, colon, stomach, pancreas, and urachus tumors have also been linked to PMP. Other mucinous tumors in the pelvis, paracolic gutters, greater omentum, retrohepatic space, and Treitz ligament can be the reason for PMP. Despite being rare and having a slow growth rate, PMP can be lethal without treatment. It is treated with neoadjuvant chemotherapy with the option of cytoreductive surgery and intraperitoneal chemotherapy. In the current study, we hypothesize that there may be novel gentle ways to inhibit or eliminate the mucin. Dr. David Morris has used mucolytics - such as bromelain and N-acetyl cysteine to solubilize mucin. In the present review, we aimed to study the regulation of mucin expression by promoter methylation, and drugs that can inhibit mucin, such as boldine, amiloride, naltrexone, dexamethasone, and retinoid acid receptors antagonist. This review also explored some possible pathways, such as inhibition of Na + , Ca2+ channels and induction of DNA methyltransferase along with inhibition of ten-eleven translocation enzymes, which can be good targets to control mucin. Mucins are strong adhesive molecules that play great roles in clinging to cells or cell to cell. Besides, they have been greatly involved in metastasis and also act as disease markers for cancers. Diagnostic markers may have exclusive roles in disease initiation and progression. Therefore, the present review explores various drugs to control and target mucin in various diseases, specifically cancers. (AU)

Lack of methylation changes in GJB2 and RB1 non-coding regions of cochlear implant patients with sensorineural hearing loss

Objective@#Recent advances in epigenetic studies continue to reveal novel mechanisms of gene regulation and control, however little is known on the role of epigenetics in sensorineural hearing loss (SNHL) in humans. We aimed to investigate the methylation patterns of two regions, one in RB1 and another in GJB2 in Filipino patients with SNHL compared to hearing control individuals. @*Methods@#We investigated an RB1 promoter region that was previously identified as differentially methylated in children with SNHL and lead exposure. Additionally, we investigated a sequence in an enhancer-like region within GJB2 that contains four CpGs in close proximity. Bisulfite conversion was performed on salivary DNA samples from 15 children with SNHL and 45 unrelated ethnically-matched individuals. We then performed methylation-specific real-time PCR analysis (qMSP) using TaqMan® probes to determine percentage methylation of the two regions. @*Results@#Using qMSP, both our cases and controls had zero methylation at the targeted GJB2 and RB1 regions. @*Conclusion@#Our study showed no changes in methylation at the selected CpG regions in RB1 and GJB2 in the two comparison groups with or without SNHL. This may be due to a lack of environmental exposures to these target regions. Other epigenetic marks may be present around these regions as well as those of other HL-associated genes.

Effects of RNA M6A demethylase ALKBH5 gene deficiency on morphology and function of cerebellum in aged mice / 中华病理学杂志

Objective: To investigate the effects of RNA m6A demethylase ALKBH5 gene deficiency on cerebellar morphology and function in the aged mice, and to explore the role of ALKBH5 in cerebellar degeneration. Methods: Western blot was performed to detect the protein level of ALKBH5 in the cerebellum of wild-type mice of various ages. The expression of NeuN, Calbindin-D28K, MAP2, GFAP and other proteins in the cerebella of middle-aged (12-month-old) and aged (18-month-old) wild-type mice and ALKBH5-/- mice was examined using immunohistochemistry. The balance beam test and gait analysis were performed to test the balance ability and motor coordination of the mice. Results: With aging of the mice, the expression of ALKBH5 in the cerebellum increased gradually in an age-dependent manner. In the aged mice, but not middle-aged mice, the body weight, whole brain weight and cerebellum weight of ALKBH5-/- mice decreased by 15%, 10% and 21%, respectively (P<0.05). The expression of ALKBH5 in the Purkinje cells was much higher than that in other types of neural cells. Correspondingly, ALKBH5-deficiency caused 40% reduction in the number of Purkinje cells, as well as the length and density of neuronal dendrites in the aged mice (P<0.01). In addition, the time for the aged ALKBH5-/- mice to pass the balance beam was 70% longer than that of the wild type mice of the same age, with unstable gaits (P<0.01). Conclusions: Gene deficiency of RNA m6A demethylase ALKBH5 causes cerebellar atrophy, Purkinje neuron loss and damage in the aged mice. These changes eventually affect mice's motor coordination and balance ability. These results suggest that imbalanced RNA m6A methylation may lead to neurodegenerative lesions in the cerebellum of mice.

Association Analysis Between Methylation of SCARB1 Gene Promoter and Coronary Heart Disease / 中国医学科学院学报

Objective To explore the relationship between scavenger receptor class B member 1 (SCARB1) gene promoter methylation and the pathogenesis of coronary artery disease. Methods A total of 120 patients with coronary heart disease treated in Renji Hospital affiliated to Shanghai Jiao Tong University School of Medicine from December 2018 to May 2020 were selected as the case group,while 140 gender and age matched healthy participants were randomly selected as the control group for a case-control study.The methylation status was detected by high-throughput target sequencing after bisulfite converting,and the methylation of CpG sites in the promoter region of SCARB1 gene was compared between the two groups. Results The case group showed higher methylation level of SCARB1+67 and lower methylation level of SCARB1+134 than the control group (both P<0.001),and the differences remained statistically significant in men (both P<0.001) and women (both P<0.001).The overall methylation level in the case group was lower than that in the control group [(80.27±2.14)% vs.(81.11±1.27)%;P=0.006],while this trend was statistically significant only in men (P=0.002). Conclusion The methylation of SCARB1 gene promotor is associated with the pathogenesis and may participate in the occurrence and development of coronary heart disease.

The engagement of histone lysine methyltransferases with nucleosomes: structural basis, regulatory mechanisms, and therapeutic implications

Histone lysine methyltransferases (HKMTs) deposit methyl groups onto lysine residues on histones and play important roles in regulating chromatin structure and gene expression. The structures and functions of HKMTs have been extensively investigated in recent decades, significantly advancing our understanding of the dynamic regulation of histone methylation. Here, we review the recent progress in structural studies of representative HKMTs in complex with nucleosomes (H3K4, H3K27, H3K36, H3K79, and H4K20 methyltransferases), with emphasis on the molecular mechanisms of nucleosome recognition and trans-histone crosstalk by these HKMTs. These structural studies inform HKMTs' roles in tumorigenesis and provide the foundations for developing new therapeutic approaches targeting HKMTs in cancers.

Research Progress of m6A Demethylase FTO and Its Inhibitors in Acute Myeloid Leukemia --Review / 中国实验血液学杂志

Obesity-associated protein (FTO) is an important m6A demethylase that regulates RNA methylation modification and can promote the proliferation of acute myeloid leukemia(AML) cells. FTO regulates the methylation level of AML through multiple cellular signaling pathways such as FTO/RARA/ASB2, FTO/m6A/CEBPA, and PDGFRB/ERK, and participates in the occurrence, development, treatment and prognosis of AML. At present, studies have found that a variety of inhibitors targeting FTO have shown good anti-leukemia effects, and the study of FTO will provide new ideas for the treatment of AML. This review focus on the mechanism of action of FTO in AML and the research progress of FTO inhibitors in AML.

Research progress of m6A methylation in prostate cancer / 亚洲男科学杂志(英文版)

N6-methyladenosine (m6A) is a ubiquitous RNA modification in mammals. This modification is "written" by methyltransferases and then "read" by m6A-binding proteins, followed by a series of regulation, such as alternative splicing, translation, RNA stability, and RNA translocation. At last, the modification is "erased" by demethylases. m6A modification is essential for normal physiological processes in mammals and is also a very important epigenetic modification in the development of cancer. In recent years, cancer-related m6A regulation has been widely studied, and various mechanisms of m6A regulation in cancer have also been recognized. In this review, we summarize the changes of m6A modification in prostate cancer and discuss the effect of m6A regulation on prostate cancer progression, aiming to profile the potential relevance between m6A regulation and prostate cancer development. Intensive studies on m6A regulation in prostate cancer may uncover the potential role of m6A methylation in the cancer diagnosis and cancer therapy.

Role of N6-methyladenosine RNA methylation in central nervous system: a review / 生物工程学报

There are a variety of post-transcriptional modifications in mRNA, which regulate the stability, splicing, translation, transport and other processes of mRNA, followed by affecting cell development, body immunity, learning and cognition and other important physiological functions. m6A modification is one of the most abundant post-transcriptional modifications widely existing in mRNA, regulating the metabolic activities of RNA and affecting gene expression. m6A modified homeostasis is critical for the development and maintenance of the nervous system. In recent years, m6A modification has been found in neurodegenerative diseases, mental diseases and brain tumors. This review summarizes the role of m6A methylation modification in the development, function and related diseases of the central nervous system in recent years, providing potential clinical therapeutic targets for neurological diseases.

The role of methylation of placental glucocorticoid response gene in the association between pregnancy-related anxiety in the third trimester and birth outcomes / 中华预防医学杂志

Objective: To investigate the role of methylation of placental glucocorticoid response gene in the association between pregnancy-related anxiety in the third trimester and birth outcomes. Methods: Based on a prospective cohort study, singleton live births and their mothers from the Ma'anshan Birth Cohort Study (MABC) were included as participants in this study. The maternal pregnancy-related anxiety symptoms in the third trimester of pregnancy were evaluated by using the Pregnancy-related Anxiety Questionnaire. The neonatal birth outcomes were collected from medical records. The placental tissues from 300 pregnant women with pregnancy-related anxiety and 300 without pregnancy-related anxiety were collected to detect the methylation of FKBP5, NR3C1 and HSD11B2 genes using the Methyl Target approach. The methylation factors were extracted by exploratory factor analysis. Linear regression or logistic regression models were used to analyze the association between pregnancy-related anxiety in the third trimester, methylation factor scores, and birth outcomes. The mediating role of methylation factors in the association between pregnancy-related anxiety in the third trimester and birth outcomes was analyzed by using the Process procedure. Results: The mean age of 2 833 pregnant women was (26.60±3.60) years old. After adjusting for confounding factors, pregnancy-related anxiety in the third trimester increased the risk of small-for-gestational-age (OR=1.32, 95%CI:1.00-1.74). A total of 5 methylation factors were extracted, and the factor 5 was loaded with FKBP5 CpGs 18-21. Pregnancy-related anxiety in the third trimester was negatively correlated with the factor 5 (β=-0.24,95%CI:-0.44--0.05). The factor 5 was positively correlated with the gestational age (β=0.17, 95%CI:0.06-0.27). In addition, the factor 2 (β=0.02,95%CI:0.00-0.04) and factor 3 (β=0.03,95%CI:0.01-0.05) were positively correlated with 5-min Apgar score after delivery. However, this study did not found the mediating role of the scores of the factor characterized by FKBP5 in the relationship between pregnancy-related anxiety and birth outcomes. Conclusion: Pregnancy-related anxiety in the third trimester may reduce the methylation level of FKBP5 CpGs 18-21 in placental tissues and is associated with the risk of small-for-gestational-age.

Mannich bases derivatives of 2-Phenyl-5-Benzimidazole sulfonic acid; Synthesis, Characterization, Computational studies and Biological evaluation

Abstract A new series of N-Mannich bases of 2-Phenyl-5-benzimidazole sulfonic acid have been synthesized through amino methylation reaction with secondary amines. The two moieties were held together through a methylene bridge, which comes from formaldehyde (Formalin Solution 37%) used in the reaction. Chemical structures of the newly synthesized compounds have been confirmed using FT-IR, 1HNMR and 13CNMR. Different in vitro assays including Anti-oxidant, Enzyme inhibition, Anti-microbial and Cytotoxicity assay were performed to evaluate the biological potential with reference to the standard drug. Among the synthesized library, compound 3a shows maximum alpha-glucosidase inhibition with an IC50 value of 66.66 µg/ml, compound 3d was found most toxic with LC50 value of 10.17 µg/ml. ADME evaluation studies were performed with the help of Molinspiration online software. Docking calculations were also performed. Given the importance of the nucleus involved, the synthesized compound might find extensive medicinal applications as reported in the literature.

Research progress on regulation of N6-adenylate methylation modification in lipid metabolism disorders / 生理学报

Lipid metabolism is a complex physiological process, which is closely related to nutrient regulation, hormone balance and endocrine function. It involves the interactions of multiple factors and signal transduction pathways. Lipid metabolism disorder is one of the main mechanisms to induce a variety of diseases, such as obesity, diabetes, non-alcoholic fatty liver disease, hepatitis, hepatocellular carcinoma and their complications. At present, more and more studies have found that the "dynamic modification" of N6-adenylate methylation (m6A) on RNA represents a new "post-transcriptional" regulation mode. m6A methylation modification can occur in mRNA, tRNA, ncRNA, etc. Its abnormal modification can regulate gene expression changes and alternative splicing events. Many latest references have reported that m6A RNA modification is involved in the epigenetic regulation of lipid metabolism disorder. Based on the major diseases induced by lipid metabolism disorders, we reviewed the regulatory roles of m6A modification in the occurrence and development of those diseases. These overall findings inform further in-depth investigations of the underlying molecular mechanisms regarding the pathogenesis of lipid metabolism disorders from the perspective of epigenetics, and provide reference for health prevention, molecular diagnosis and treatment of related diseases.

VIPR1 promoter methylation promotes transcription factor AP-2α binding to inhibit VIPR1 expression and promote hepatocellular carcinoma cell growth in vitro / 南方医科大学学报

OBJECTIVE@#To explore the transcriptional regulation mechanism and biological function of low expression of vasoactive intestinal peptide receptor 1 (VIPR1) in hepatocellular carcinoma (HCC).@*METHODS@#We constructed plasmids carrying wild-type VIPR1 promoter or two mutant VIPR1 promoter sequences for transfection of the HCC cell lines Hep3B and Huh7, and examined the effect of AP-2α expression on VIPR1 promoter activity using dual-luciferase reporter assay. Pyrosequencing was performed to detect the changes in VIPR1 promoter methylation level in HCC cells treated with a DNA methyltransferase inhibitor (DAC). Chromatin immunoprecipitation was used to evaluate the binding ability of AP-2α to VIPR1 promoter. Western blotting was used to assess the effect of AP-2α knockdown on VIPR1 expression and examine the differential expression of VIPR1 in the two cell lines. The effects of VIPR1 overexpression and knockdown on the proliferation, cell cycle and apoptosis of HCC cells were analyzed using CCK8 assay and flow cytometry. We also observed the growth of HCC xenograft with lentivirus-mediated over-expression of VIPR1 in nude mice.@*RESULTS@#Compared with the wild-type VIPR1 promoter group, co-transfection with the vector carrying two promoter mutations and the AP-2α-over-expressing plasmid obviously restored the luciferase activity in HCC cells (P < 0.05). DAC treatment of the cells significantly decreased the methylation level of VIPR1 promoter and inhibited the binding of AP-2α to VIPR1 promoter (P < 0.01). The HCC cells with AP-2α knockdown showed increased VIPR1 expression, which was lower in Huh7 cells than in Hep3B cells. VIPR1 overexpression in HCC cells caused significant cell cycle arrest in G2/M phase (P < 0.01), promoted cell apoptosis (P < 0.001), and inhibited cell proliferation (P < 0.001), while VIPR1 knockdown produced the opposite effects. In the tumor-bearing nude mice, VIPR1 overexpression in the HCC cells significantly suppressed the increase of tumor volume (P < 0.001) and weight (P < 0.05).@*CONCLUSION@#VIPR1 promoter methylation in HCC promotes the binding of AP-2α and inhibits VIPR1 expression, while VIPR1 overexpression causes cell cycle arrest, promotes cell apoptosis, and inhibits cell proliferation and tumor growth.

Histone methylation and diabetic cardiomyopathy / 生理学报

Histone methylation is one of the key post-translational modifications that plays a critical role in various heart diseases, including diabetic cardiomyopathy. A great deal of evidence has shown that histone methylation is closely related to hyperglycemia, insulin resistance, lipid and advanced glycation end products deposition, inflammatory and oxidative stress, endoplasmic reticulum stress and cell apoptosis, and these pathological factors play an important role in the pathogenesis of diabetic cardiomyopathy. In order to provide a novel theoretical basis and potential targets for the treatment of diabetic cardiomyopathy from the perspective of epigenetics, this review discussed and elucidated the association between histone methylation and the pathogenesis of diabetic cardiomyopathy in details.

Roles of m6A modification in neurological diseases / 中南大学学报(医学版)

N6-methyladenosine (m6A) methylation modification is one of the most common epigenetic modifications for eukaryotic mRNA. Under the catalytic regulation of relevant enzymes, m6A participates in the body's pathophysiological processes via mediating RNA transcription, splicing, translation, and decay. In the past, we mainly focused on the regulation of m6A in tumors such as hematological tumors, cervical cancer, breast cancer. In recent years, it has been found that m6A is enriched in mRNAs of neurogenesis, cell cycle, and neuron differentiation. Its regulation in the nervous system is gradually being recognized. When the level of m6A modification and the expression levels of relevant enzyme proteins are changed, it will cause neurological dysfunction and participate in the occurrence and conversion of neurological diseases. Recent studies have found that the m6A modification and its associated enzymes were involved in major depressive disorder, Parkinson's disease, Alzheimer's disease, Fragile X syndrome, amyotrophic lateral sclerosis, and traumatic brain injury, and they also play a key role in the development of neurological diseases and many other neurological diseases. This paper mainly reviewed the recent progress of m6A modification-related enzymes, focusing on the impact of m6A modification and related enzyme-mediated regulation of gene expression on the central nervous system diseases, so as to provide potential targets for the prevention of neurological diseases.

Comprehensive Analysis of the Relationship between m6A Methylation Patterns and Immune Microenvironment in Lung Adenocarcinoma / 中国肺癌杂志

BACKGROUND@#m6A RNA methylation modification plays an important role in the occurrence and progression of lung cancer and regulates tumor immunity. Current studies mostly focus on the differential expression of some specific m6A effectors and infiltrating immune cell. m6A methylation modification is the result of mutual adjustment and balance between effectors, and changes in the expression of one or two effectors are far from enough to reflect the panorama of m6A methylation. The role of m6A in the immune microenvironment of lung adenocarcinoma (LUAD) is still poorly understood. The aim of this study is to investigate the effect of different m6A modification patterns in immune microenvironment of LUAD.@*METHODS@#LUAD data was obtained from The Cancer Genome Atlas (TCGA), University of California Santa Cruz Xena (UCSC Xena) and Gene Expression Omnibus (GEO) databases. Gene mutation, differential expression and survival analysis were performed for 24 m6A effectors. The m6A modification pattern was constructed by unsupervised clustering method, and the m6A clusters survival analysis, gene set variation analysis, immune score and immune cell infiltration analysis were performed. The association between LRPPRC protein expression levels and infiltration of CD8+ cytotoxic T lymphocytes and CD68+ macrophages in the tumor microenvironment was validated by immunohistochemistry in LUAD tissue microarray with 68 cases.@*RESULTS@#The mutations of m6A effector were found in 150 of 567 LUAD cases with a frequency of 26.46%. 6 readers and 3 writers were significantly up regulated in LUAD tissues compared with normal tissues. IGF2BP1 and HNRNPC are the independent risk factors for prognosis of LUAD. Abundant cross-talks among writers, erasers and readers were demonstrated. Three m6A modification patterns with different immune cell infiltration characteristics and clinical prognosis were established. Among m6A effectors, LRPPRC was found to be inversely associated with the infiltration of CD8+ cytotoxic T lymphocytes and CD68+ macrophages, and was validated in 68 LUAD tissues.@*CONCLUSIONS@#m6A modification patterns play non-negligible roles in regulating the immune microenvironment. LRPPRC has potential to be a new biomarker for checkpoint inhibitor immunotherapy.

Crosstalk between CpG Methylation and Polymorphisms (CpG-SNPs) in the Promotor Region of DIO2 in Kashin-Beck Disease / 中国医学科学杂志(英文版)

Objective This study was designed to determine the methylation profile of four CpGs and the genotypes of two CpG-SNPs located in promoter region of DIO2 in patients with Kashin-Beck disease (KBD). We also analyzed the interaction between the CpGs methylations and CpG-SNPs. Methods Whole blood specimens were collected from 16 KBD patients and 16 healthy subjects. Four CpGs and two CpG-SNPs in the promoter regions of DIO2 were detected using matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS). The CpGs methylation levels were compared between samples from KBD patients and healthy subjects. The methylation levels were also analyzed in KBD patients with different CpG-SNP genotypes. Results The mRNA expression of DIO2 in whole blood of KBD patients was significnatly lower than in healthy controls (P <0.05). The methylation levels of DIO2-1_CpG_3 in KBD patients were significantly higher than those in healthy controls (P <0.05). The methylation levels of four CpGs were not significantly different between KBD patients and healthy controls. The methylation level of DIO2-1_CpG_3 in the promoter region of DIO2 in KBD patients with GA/AA genotype was significantly higher than that of KBD patients with GG genotype (P <0.05). Conclusion The methylation level of DIO2 increases in KBD patients. Similar trends exist in KBD carriers of variant genotypes of CpG-SNPs DIO2 rs955849187.

Accurate quantification of 3'-terminal 2'-O-methylated small RNAs by utilizing oxidative deep sequencing and stem-loop RT-qPCR / 医学前沿

The continuing discoveries of novel classes of RNA modifications in various organisms have raised the need for improving sensitive, convenient, and reliable methods for quantifying RNA modifications. In particular, a subset of small RNAs, including microRNAs (miRNAs) and Piwi-interacting RNAs (piRNAs), are modified at their 3'-terminal nucleotides via 2'-O-methylation. However, quantifying the levels of these small RNAs is difficult because 2'-O-methylation at the RNA 3'-terminus inhibits the activity of polyadenylate polymerase and T4 RNA ligase. These two enzymes are indispensable for RNA labeling or ligation in conventional miRNA quantification assays. In this study, we profiled 3'-terminal 2'-O-methyl plant miRNAs in the livers of rice-fed mice by oxidative deep sequencing and detected increasing amounts of plant miRNAs with prolonged oxidation treatment. We further compared the efficiency of stem-loop and poly(A)-tailed RT-qPCR in quantifying plant miRNAs in animal tissues and identified stem-loop RT-qPCR as the only suitable approach. Likewise, stem-loop RT-qPCR was superior to poly(A)-tailed RT-qPCR in quantifying 3'-terminal 2'-O-methyl piRNAs in human seminal plasma. In summary, this study established a standard procedure for quantifying the levels of 3'-terminal 2'-O-methyl miRNAs in plants and piRNAs. Accurate measurement of the 3'-terminal 2'-O-methylation of small RNAs has profound implications for understanding their pathophysiologic roles in biological systems.

METTL3-mediated m6A RNA methylation regulates dorsal lingual epithelium homeostasis / 国际口腔科学杂志·英文版

The dorsal lingual epithelium, which is composed of taste buds and keratinocytes differentiated from K14+ basal cells, discriminates taste compounds and maintains the epithelial barrier. N6-methyladenosine (m6A) is the most abundant mRNA modification in eukaryotic cells. How METTL3-mediated m6A modification regulates K14+ basal cell fate during dorsal lingual epithelium formation and regeneration remains unclear. Here we show knockout of Mettl3 in K14+ cells reduced the taste buds and enhanced keratinocytes. Deletion of Mettl3 led to increased basal cell proliferation and decreased cell division in taste buds. Conditional Mettl3 knock-in mice showed little impact on taste buds or keratinization, but displayed increased proliferation of cells around taste buds in a protective manner during post-irradiation recovery. Mechanically, we revealed that the most frequent m6A modifications were enriched in Hippo and Wnt signaling, and specific peaks were observed near the stop codons of Lats1 and FZD7. Our study elucidates that METTL3 is essential for taste bud formation and could promote the quantity recovery of taste bud after radiation.

DNMT1-mediated PPARα methylation aggravates damage of retinal tissues in diabetic retinopathy mice

BACKGROUND: Peroxisome proliferator-activated receptor alpha (PPARα) is associated with diabetic retinopathy (DR), and the underlying mechanism is still unclear. Aim of this work was to investigate the mechanism of PPARα in DR. METHODS: Human retinal capillary pericytes (HRCPs) were treated with high glucose (HG) to induce DR cell model. DR mouse model was established by streptozotocin injection, and then received 5-Aza-2-deoxycytidine (DAC; DNA methyltransferase inhibitor) treatment. Hematoxylin-eosin staining was performed to assess retinal tissue damage. PPARα methylation was examined by Methylation-Specific PCR. Flow cytometry and DCFH-DA fluorescent probe was used to estimate apoptosis and reactive oxygen species (ROS). The interaction between DNA methyltransferase-1 (DNMT1) and PPARα promoter was examined by Chromatin Immunoprecipitation. Quantitative real-time PCR and western blot were performed to assess gene and protein expression. RESULTS: HG treatment enhanced the methylation levels of PPARα, and repressed PPARα expression in HRCPs. The levels of apoptotic cells and ROS were significantly increased in HRCPs in the presence of HG. Moreover, DNMT1 was highly expressed in HG-treated HRCPs, and DNMT1 interacted with PPARα promoter. PPARα overexpression suppressed apoptosis and ROS levels of HRCPs, which was rescued by DNMT1 up-regulation. In DR mice, DAC treatment inhibited PPARα methylation and reduced damage of retinal tissues. CONCLUSION: DNMT1-mediated PPARα methylation promotes apoptosis and ROS levels of HRCPs and aggravates damage of retinal tissues in DR mice. Thus, this study may highlight novel insights into DR pathogenesis.

Application of methyltransferases in microbial synthesis of natural products / 生物工程学报

Methyltransferases (MTs) constitute a large group of enzymes that catalyze the transfer of a methyl moiety, most frequently from S-adenosyl-L-methionine, to their substrates. It plays an essential role in regulation of gene expression and synthesis of many natural compounds. Owing to its broad substrate spectrum, MTs make important contributions to diversify the spectrum of products through methylation modifications. Recently, great progress has been made in application of MTs for the biosynthesis of various natural products including phenylpropane compounds, fragrances, hormones and antibiotics, which is summarized in this review. Moreover, we highlighted the strategies of using MTs for efficient production and for expanding the diversity of these methylated natural products, and discussed the current challenges and future prospects in this area.