The circadian clock plays a critical role in regulating various physiological processes, including gene expression, metabolic regulation, immune response, and the sleep-wake cycle in living organisms. Post-translational modifications (PTMs) are crucial regulatory mechanisms to maintain the precise oscillation of the circadian clock. By modulating the stability, activity, cell localization and protein-protein interactions of core clock proteins, PTMs enable these proteins to respond dynamically to environmental and intracellular changes, thereby sustaining the periodic oscillations of the circadian clock. Different types of PTMs exert their effects through distincting molecular mechanisms, collectively ensuring the proper function of the circadian system. This review systematically summarized several major types of PTMs, including phosphorylation, acetylation, ubiquitination, SUMOylation and oxidative modification, and overviewed their roles in regulating the core clock proteins and the associated pathways, with the goals of providing a theoretical foundation for the deeper understanding of clock mechanisms and the treatment of diseases associated with circadian disruption.
Protein Processing, Post-Translational/physiology* ; Circadian Rhythm/physiology* ; Humans ; Animals ; CLOCK Proteins/physiology* ; Circadian Clocks/physiology* ; Phosphorylation ; Acetylation ; Ubiquitination ; Sumoylation

BACKGROUND: Dysfunction of the gap junction channel protein connexin 43 (Cx43) contributes to myocardial ischemia/reperfusion (I/R)-induced ventricular arrhythmias. Cx43 can be regulated by small ubiquitin-like modifier (SUMO) modification. Protein inhibitor of activated STAT Y (PIASy) is an E3 SUMO ligase for its target proteins. However, whether Cx43 is a target protein of PIASy and whether Cx43 SUMOylation plays a role in I/R-induced arrhythmias are largely unknown. METHODS: Male Sprague-Dawley rats were infected with PIASy short hairpin ribonucleic acid (shRNA) using recombinant adeno-associated virus subtype 9 (rAAV9). Two weeks later, the rats were subjected to 45 min of left coronary artery occlusion followed by 2 h reperfusion. Electrocardiogram was recorded to assess arrhythmias. Rat ventricular tissues were collected for molecular biological measurements. RESULTS: Following 45 min of ischemia, QRS duration and QTc intervals statistically significantly increased, but these values decreased after transfecting PIASy shRNA. PIASy downregulation ameliorated ventricular arrhythmias induced by myocardial I/R, as evidenced by the decreased incidence of ventricular tachycardia and ventricular fibrillation, and reduced arrythmia score. In addition, myocardial I/R statistically significantly induced PIASy expression and Cx43 SUMOylation, accompanied by reduced Cx43 phosphorylation and plakophilin 2 (PKP2) expression. Moreover, PIASy downregulation remarkably reduced Cx43 SUMOylation, accompanied by increased Cx43 phosphorylation and PKP2 expression after I/R. CONCLUSION PIASy downregulation inhibited Cx43 SUMOylation and increased PKP2 expression, thereby improving ventricular arrhythmias in ischemic/reperfused rats heart.
Rats ; Male ; Animals ; Myocardial Reperfusion Injury/metabolism* ; Connexin 43/genetics* ; Sumoylation ; Down-Regulation ; Rats, Sprague-Dawley ; Arrhythmias, Cardiac/drug therapy* ; Myocardial Ischemia/metabolism* ; RNA, Small Interfering/metabolism*

This study aims to investigate the impact of hepatocyte nuclear factor 1β (HNF1b) on macrophage sortilin-mediated lipid metabolism and aortic atherosclerosis and explore the role of the flavone of Polygonatum odoratum (PAOA-flavone)-promoted small ubiquitin-related modifier (SUMO) modification in the atheroprotective efficacy of HNF1b. HNF1b was predicted to be a transcriptional regulator of sortilin expression via bioinformatics, dual-luciferase reporter gene assay, and chromatin immunoprecipitation. HNF1b overexpression decreased sortilin expression and cellular lipid contents in THP-1 macrophages, leading to a depression in atherosclerotic plaque formation in low-density lipoprotein (LDL) receptor-deficient (LDLR^-/-) mice. Multiple SUMO1-modified sites were identified on the HNF1b protein and co-immunoprecipitation confirmed its SUMO1 modification. The SUMOylation of HNF1b protein enhanced the HNF1b-inhibited effect on sortilin expression and reduced lipid contents in macrophages. PAOA-flavone treatment promoted SUMO-activating enzyme subunit 1 (SAE1) expression and SAE1-catalyzed SUMOylation of the HNF1b protein, which prevented sortilin-mediated lipid accumulation in macrophages and the formation of atherosclerotic plaques in apolipoprotein E-deficient (ApoE^-/-) mice. Interference with SAE1 abrogated the improvement in lipid metabolism in macrophage cells and atheroprotective efficacy in vivo upon PAOA-flavone administration. In summary, HNF1b transcriptionally suppressed sortilin expression and macrophage lipid accumulation to inhibit aortic lipid deposition and the development of atherosclerosis. This anti-atherosclerotic effect was enhanced by PAOA-flavone-facilitated, SAE1-catalyzed SUMOylation of the HNF1b protein.
Mice ; Animals ; Polygonatum/metabolism* ; Sumoylation ; Hepatocyte Nuclear Factor 1-beta/metabolism* ; Atherosclerosis/metabolism* ; Flavones ; Lipids

Objective: To inhibit the stemness maintenance potential of endometrial cancer and increase the sensitivity of endometrial cancer side population cells to chemotherapy drugs by inducing extensive deSUMOylation modification of proteins. Methods: Flow cytometry was used to sort and culture CD133(+) CD44(+) KLE endometrial cancer cell clone spheres. Protein expression level of small ubiquitin-related modifier 1 (SUMO1) and two stemness maintenance genes of tumor side population cells, octamer binding transcription factor-4 (Oct4) and sex determining region Y-box2 (Sox2), were detected by western blotting method. Lentivirus-mediated Sentrin/SUMO-specific proteases 1 (SENP1) gene was stably transfected into KLE side population cells. Western blotting was used to detect the protein expressions of SENP1, SUMO1, Oct4 and Sox2. The clone formation rate was compared between KLE side population cells with or without SENP1 overexpression. Flow cytometry was applied to detect cell cycle changes. 3-(4, 5-Dimethylthiazole-2)-2, 5-diphenyl-tetrazolium bromide (MTT) experiment and flow cytometry apoptosis method were used to detect the chemosensitivity of the side population of endometrial cancer cells to cisplatin. Tumor-bearing mouse models of endometrial cancer were established to detect the effect of SENP1 overexpression on the chemotherapy sensitivity of cisplatin. Results: Compared with CD133(-)CD44(-) KLE cells, CD133(+) CD44(+) KLE side population cells could form clonal spheres and express higher levels of SUMO1, Oct4 and Sox2 proteins (P<0.05). Compared with KLE side population cells that were not transfected with SENP1 gene, the expression level of SENP1 protein in KLE side population cells overexpressing SUMO1、Oct4 and Sox2 were lower. The clonal sphere formation rate was reduced from (25.67±5.44)% to (7.46±1.42)%, and cell cycle shifted from G(0)/G(1) phase to G(2) phase. IC(50) of cisplatin decreased from (55.46±6.14) μg/ml to (11.55±3.12) μg/ml, and cell apoptosis rate increased from (9.76±2.09)% to (16.79±3.44)%. Overexpression of SENP1 could reduce the tumorigenesis rate of KLE side population cells in vivo and increase their chemotherapy sensitivity to cisplatin (P<0.05). Conclusion: Overexpression of SENP1 can induce protein deSUMOylation modification, inhibit the stemness maintenance potential of endometrial cancer side population cells, and enhance their chemotherapy sensitivity, which provides a new reference for gene therapy of endometrial cancer.
Animals ; Female ; Humans ; Mice ; Apoptosis ; Cell Line, Tumor ; Cisplatin/pharmacology* ; Cysteine Endopeptidases/metabolism* ; Endometrial Neoplasms/genetics* ; Side-Population Cells/pathology* ; Sumoylation

OBJECTIVE: Small ubiquitin-related modifiers (SUMOs) are a group of post-translational modification proteins extensively expressed in eukaryotes. Abnormal SUMOylation can lead to the development of various diseases. This article summarizes the progress on research of the role of SUMOs in various types of kidney diseases to further increase the understanding of the regulatory functions of SUMOylation in the pathogenesis of kidney diseases. DATA SOURCES: This review was based on articles published in the PubMed databases up to January 2018, using the keywords including "SUMOs," "SUMOylation," and "kidney diseases." STUDY SELECTION: Original articles and critical reviews about SUMOs and kidney disease were selected for this review. A total of 50 studies were in English. RESULTS: SUMO participates in the activation of NF-κB inflammatory signaling pathway, playing a central regulatory role in the inflammation and progression of DN, and the secretion of various chemokines in AKI. SUMO involves in the regulation of TG2 and Nrf2 antioxidant stress, affecting renal tubular injury in AKI. SUMO affects the MAPK/ERK pathway, regulating intracellular signal transduction, modulating the transcription and expression of effector molecules in DN. SUMO contributes to the TGF-β/Smad pathway, leading to fibrosis of the kidney. The conjugate combination of SUMO and p53 regulates cell proliferation and apoptosis, and participates in the regulation of tumorigenesis. In addition, SUMOylation of MITF modulates renal tumors secondary to melanoma, Similarly, SUMOylation of tumor suppressor gene VHL regulates the occurrence of renal cell carcinoma in VHL syndrome. CONCLUSIONS Tissue injury, inflammatory responses, fibrosis, apoptosis, and tumor proliferation in kidney diseases all involve SUMOs. Further research of the substrate SUMOylation and regulatory mechanisms of SUMO in kidney diseases will improve and develop new treatment measures and strategies targeting kidney diseases.
Acute Kidney Injury ; etiology ; Carcinoma, Renal Cell ; etiology ; Diabetic Nephropathies ; etiology ; Fibrosis ; Humans ; Kidney ; pathology ; Kidney Diseases ; etiology ; metabolism ; Kidney Neoplasms ; etiology ; SUMO-1 Protein ; physiology ; Sumoylation

The chromosomal aneuploidy in oocytes is one of main causes of abortion and neonatal birth defects.It is mainly due to the premature separation of sister chromatid caused by the loss of Cohesin protein complex and the non-disjunction sister chromatids caused by abnormal microtubule dynamics aneuploidy.As a pathway of protein post-translational modification,SUMO modification(or SUMOylation)involves many physiological regulation processes including cell proliferation,differentiation,apoptosis,and cycle regulation.In the oocytes,SUMOylation can regulate the localization of Cohesin protein complex on the chromosome to affect the chromosomal aneuploidy in oocytes caused by premature separation of sister chromatid.On the other hand,SUMOylation can regulate the microtubule dynamics to affect the chromosomal aneuploidy in oocytes caused by non-disjunction sister chromatids.Therefore,SUMOylation plays an important role in regulating the chromosomal aneuploidy of oocytes;the exact mechanisms via which the SUMOylated substrates affect aneuploidy in oocytes remain unclear.This articles reviews the roles of SUMOylation in premature separation and non-isolated chromatid aneuploidy in oocyte from the effects of SUMOylationon Cohesin protein complex and microtubule dynamics.
Aneuploidy ; Cell Cycle Proteins ; Chromatids ; Chromosomal Proteins, Non-Histone ; Chromosome Segregation ; Humans ; Microtubules ; Oocytes ; cytology ; Sumoylation

OBJECTIVETo study the expression of SUMO-modified CCAAT enhancer binding protein α (C/EBPα) in preterm rat model of bronchopulmonary dysplasisa (BPD) induced by hyperoxia exposure and its role.

METHODSEighteen preterm rats were randomly divided into an air group and a hyperoxia group (n=9 each). The model of BPD was prepared in preterm rats exposed to hyperoxia. The rats from the two groups were sacrificed on postnatal days 4, 7 and 14 respectively (3 rats at each time) and lung tissues were harvested. Periodic acid-Schiff (PAS) staining was used to observe the differentiation of rat lung tissues. Ki67 expression was detected by immunohistochemistry. Western blot was used to measure the protein expression of small ubiquitin-related modifier-1(SUMO1) and C/EBPα. A co-immunoprecipitation assay was performed to measure the protein expression of SUMO-modified C/EBPα.

RESULTSCompared with the air group, the hyperoxia group showed a decreased glycogen content in the lung tissue on postnatal day 4, and an increased content on postnatal days 7 and 14. Over the time of hyperoxia exposure, the hyperoxia group showed an increased expression of Ki67 in the lung tissue compared with the air group at all time points. Compared with the air group, the protein expression of C/EBPα increased on postnatal day 4 and decreased on postnatal days 7 and 14 in the hyperoxia group (P<0.05). The hyperoxia group had significantly upregulated expression of SUMO1 and SUMO-modified C/EBPα compared with the air group at all time points (P<0.05). In the hyperoxia group, the protein expression of SUMO-modified C/EBPα was positively correlated with the glycogen content (r=0.529, P<0.05) and the expression of Ki67 (r=0.671, P<0.05).

CONCLUSIONSHyperoxia may induce over-proliferation and differentiation disorders of alveolar epithelial cells in preterm rat model of BPD, possibly through an increased expression of SUMO-modified C/EBP&alpha.

Animals ; Animals, Newborn ; Bronchopulmonary Dysplasia ; etiology ; metabolism ; pathology ; CCAAT-Enhancer-Binding Protein-alpha ; metabolism ; Cell Proliferation ; Disease Models, Animal ; Hyperoxia ; complications ; pathology ; Ki-67 Antigen ; analysis ; Pulmonary Alveoli ; pathology ; Rats ; Rats, Sprague-Dawley ; Sumoylation

Sumoylation, the conjugation of a small ubiquitin-like modifier (SUMO) protein to a target, has diverse cellular effects. However, the functional roles of the SUMO modification during myogenesis have not been fully elucidated. Here, we report that basal sumoylation of histone deacetylase 1 (HDAC1) enhances the deacetylation of MyoD in undifferentiated myoblasts, whereas further sumoylation of HDAC1 contributes to switching its binding partners from MyoD to Rb to induce myocyte differentiation. Differentiation in C2C12 skeletal myoblasts induced new immunoblot bands above HDAC1 that were gradually enhanced during differentiation. Using SUMO inhibitors and sumoylation assays, we showed that the upper band was caused by sumoylation of HDAC1 during differentiation. Basal deacetylase activity was not altered in the SUMO modification-resistant mutant HDAC1 K444/476R (HDAC1 2R). Either differentiation or transfection of SUMO1 increased HDAC1 activity that was attenuated in HDAC1 2R. Furthermore, HDAC1 2R failed to deacetylate MyoD. Binding of HDAC1 to MyoD was attenuated by K444/476R. Binding of HDAC1 to MyoD was gradually reduced after 2 days of differentiation. Transfection of SUMO1 induced dissociation of HDAC1 from MyoD but potentiated its binding to Rb. SUMO1 transfection further attenuated HDAC1-induced inhibition of muscle creatine kinase luciferase activity that was reversed in HDAC1 2R. HDAC1 2R failed to inhibit myogenesis and muscle gene expression. In conclusion, HDAC1 sumoylation plays a dual role in MyoD signaling: enhancement of HDAC1 deacetylation of MyoD in the basally sumoylated state of undifferentiated myoblasts and dissociation of HDAC1 from MyoD during myogenesis.
Creatine Kinase, MM Form ; Gene Expression ; Histone Deacetylase 1 ; Histone Deacetylases ; Histones ; Luciferases ; Muscle Cells ; Muscle Development ; Myoblasts ; Myoblasts, Skeletal ; Sumoylation ; Transfection

Animals ; Fragile X Mental Retardation Protein ; metabolism ; Fragile X Syndrome ; metabolism ; Humans ; Neurons ; metabolism ; RNA-Binding Proteins ; metabolism ; Receptor, Metabotropic Glutamate 5 ; metabolism ; Sumoylation ; physiology

Estrogen receptor (ER) and progesterone receptor (PR) are two important members of steroid receptors family, an evolutionarily conserved family of transcription factors. Upon binding to their ligands, ER and PR enter cell nucleus to interact with specific DNA element in the context of chromatin to initiate the transcription of diverse target genes, which largely depends on the timely recruitment of a wide range of cofactors. Moreover, the interactions between steroid hormones and their respective receptors also trigger post-translational modifications on these receptors to fine-tune their transcriptional activities. Besides the well-known phosphorylation modifications on tyrosine and serine/threonine residues, recent studies have identified several other covalent modifications, such as ubiquitylation and sumoylation. These post-translational modifications of steroid receptors affect its stability, subcellular localization, and/or cofactor recruitment; eventually influence the duration and extent of transcriptional activation. This review is to focus on the recent research progress on the transcriptional activation of nuclear ER and PR as well as their physiological functions in early pregnancy, which may help us to better understand related female reproductive diseases.
Ligands ; Phosphorylation ; Receptors, Estrogen ; Receptors, Progesterone ; Sumoylation ; Transcriptional Activation