RSUME, a small RWD-containing protein, enhances SUMO conjugation and stabilizes HIF-1alpha during hypoxia

MYLIP attenuates hypoxia tolerance by inducing K27-linked polyubiquitination and subsequent proteasomal degradation of HIF-α

Hypoxia tolerance is mainly controlled by the hypoxia signaling pathway and HIF-1α/2α serve as master regulators in this pathway. Here we identify MYLIP, an E3 ubiquitin ligase thought to specifically target lipoprotein receptors, as a downstream target of HIF-2α and a negative regulator of both HIF-1α and HIF-2α. MYLIP interacts with HIF-1α/2α and catalyzes K27-linked polyubiquitination at lysine 118/442 (HIF-1α) or lysine 117 (HIF-2α). This modification induces proteasomal degradation of HIF-1α, resulting in inhibition of hypoxia signaling. Furthermore, Mylip-deficient bluntsnout bream, zebrafish and mice are more tolerant to hypoxia. These findings reveal a role for MYLIP in regulating hypoxia signaling and identify a target for the development of fish strains with high hypoxia tolerance for the benefit of the aquaculture industry.

Increased SUMO-activating enzyme subunit 1 promotes glycolysis and fibrotic phenotype of diabetic nephropathy

Renal fibrosis is a prominent feature of diabetic nephropathy (DN), and the connection between renal fibrosis and abnormal glycolysis is not fully understood. SUMO-activating enzyme subunit 1 (SAE1) plays a crucial role in the SUMO modification process and is related to abnormal glycolysis. Despite this, the specific role of SAE1 in DN and its mechanism are not well defined. To investigate this, a streptozotocin-induced diabetic CD1 mice model was used, with SAE1 suppression achieved through systemic administration of SAE1 siRNA. In parallel, human renal proximal tubular tubule HK2 cells transfected with siSAE1 were exposed to high glucose for in vitro studies. The study revealed that SAE1 levels were elevated in diabetic kidney, and the deletion of SAE1 mitigated renal fibrosis in DN mice. Such suppression in SAE1 was associated with the lower expression of hypoxia inducible factor-1α (HIF-1α) and 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3), these alterations subsequently improved abnormal glycolysis and mesenchymal transformations in vivo and in vitro. Further experiments discovered that SAE1 stabilized transcription factor HIF-1α expression through SUMOylation, promoting PFKFB3 transcription, which enhanced glycolysis characterized by increased PFK1 activity and lactate production. Additionally, pharmacological inhibition of PFKFB3 reduced renal fibrosis in DN mice, while overexpression of PFKFB3 partly restored the glycolysis and mesenchymal transformations inhibited by SAE1 knockdown in vitro. These data demonstrate that SAE1 promotes abnormal glycolysis by HIF-1α/PFKFB3 which is responsible for the fibrotic phenotype of diabetic kidney. Inhibition of SAE1 could be an alternative strategy in combating diabetes associated-kidney fibrosis via improving aberrant glycolysis.

Spring viremia of carp virus infection induces hypoxia response in zebrafish by stabilizing hif1α

The hypoxia signaling pathway controls hypoxia adaptation and tolerance of organisms, which is regulated by multiple mechanisms. Viral infection elicits various pathophysiological responses in the host. However, whether viral infection can affect the hypoxia response is not yet fully understood. In this study, we found that Spring viremia of carp virus (SVCV) infection in zebrafish caused symptoms similar to those in zebrafish under hypoxic conditions. Further assays indicated that SVCV infection activated the hypoxia signaling pathway in zebrafish. In addition, SVCV infection caused increased glycolysis and reactive oxygen species (ROS) levels in cells. Mechanistically, SVCV-G protein interacted with hif1α-a/b and attenuated their K48-linked polyubiquitination, leading to their stabilization and subsequent enhancement of target gene expression. Moreover, treatment with the HIF1α-specific inhibitor PX478 enhanced the antiviral ability against SVCV infection in zebrafish and zebrafish cells. This study reveals a relationship between SVCV infection and the hypoxia signaling pathway in fish and provides a strategy for reducing the damage of viral disease in the aquaculture industry.

IMPORTANCE

Viral infection triggers various pathophysiological responses in the host. The hypoxia signaling pathway controls hypoxia adaptation and tolerance of organisms. However, whether viral infection can affect the hypoxia response is not yet fully understood. This study showed that Spring viremia of carp virus (SVCV) infection activated the hypoxia signaling pathway and induced a hypoxia response. The SVCV-G protein interacted with hif1α-a/b and reduced their K48-linked polyubiquitination, leading to their stabilization and subsequent enhancement of target gene expression. Additionally, treatment with the HIF1α-specific inhibitor PX478 enhanced the antiviral ability against SVCV infection in zebrafish and zebrafish cells. Our findings not only reveal a relationship between SVCV infection and the hypoxia signaling pathway in fish but also provide a strategy for reducing the damage of viral disease in the aquaculture industry.

SENP1 reduces oxidative stress and apoptosis in renal ischaemia-reperfusion injury by deSUMOylation of HIF-1α

Renal ischaemia-reperfusion injury (RIRI) is a primary cause of acute kidney damage, occurring frequently in situations like renal transplantation, yet the underlying mechanisms were not fully understood. Sentrin-specific protease 1 (SENP1) is an important member of the SENP family, which is widely involved in various diseases. However, the role of SENP1 in RIRI has been unclear. In our study, we discovered that SENP1 was involved in RIRI and reduced renal cell apoptosis and oxidative stress at elevated levels. Further mechanistic studies showed that hypoxia-inducible factor-1α (HIF-1α) was identified as a substrate of SENP1. Furthermore, SENP1 deSUMOylated HIF-1α, which reduced the degradation of HIF-1α, and exerted a renoprotective function. In addition, the protective function was lost after application of the HIF-1α specific inhibitor KC7F2. Briefly, our results fully demonstrated that SENP1 reduced the degradation of HIF-1α and attenuated oxidative stress and apoptosis in RIRI by regulating the deSUMOylation of HIF-1α, suggesting that SENP1 may serve as a potential therapeutic target for the treatment of RIRI.

Unravelling the molecular interplay: SUMOylation, PML nuclear bodies and vascular cell activity in health and disease

In the seemingly well-researched field of vascular research, there are still many underestimated factors and molecular mechanisms. In recent years, SUMOylation has become increasingly important. SUMOylation is a post-translational modification in which small ubiquitin-related modifiers (SUMO) are covalently attached to target proteins. Sites where these SUMO modification processes take place in the cell nucleus are PML nuclear bodies (PML-NBs) - multiprotein complexes with their essential main component and organizer, the PML protein. PML and SUMO, either alone or as partners, influence a variety of cellular processes, including regulation of transcription, senescence, DNA damage response and defence against microorganisms, and are involved in innate immunity and inflammatory responses. They also play an important role in maintaining homeostasis in the vascular system and in pathological processes leading to the development and progression of cardiovascular diseases. This review summarizes information about the function of SUMO(ylation) and PML(-NBs) in the human vasculature from angiogenesis to disease and highlights their clinical potential as drug targets.

SUMOylation regulation of ribosome biogenesis: Emerging roles for USP36

Ribosome biogenesis is essential for cell growth, proliferation, and animal development. Its deregulation leads to various human disorders such as ribosomopathies and cancer. Thus, tight regulation of ribosome biogenesis is crucial for normal cell homeostasis. Emerging evidence suggests that posttranslational modifications such as ubiquitination and SUMOylation play a crucial role in regulating ribosome biogenesis. Our recent studies reveal that USP36, a nucleolar deubiquitinating enzyme (DUB), acts also as a SUMO ligase to regulate nucleolar protein group SUMOylation, thereby being essential for ribosome biogenesis. Here, we provide an overview of the current understanding of the SUMOylation regulation of ribosome biogenesis and discuss the role of USP36 in nucleolar SUMOylation.

Emerging Role of GCN1 in Disease and Homeostasis

GCN1 is recognized as a factor that is essential for the activation of GCN2, which is a sensor of amino acid starvation. This function is evolutionarily conserved from yeast to higher eukaryotes. However, recent studies have revealed non-canonical functions of GCN1 that are independent of GCN2, such as its participation in cell proliferation, apoptosis, and the immune response, beyond the borders of species. Although it is known that GCN1 and GCN2 interact with ribosomes to accomplish amino acid starvation sensing, recent studies have reported that GCN1 binds to disomes (i.e., ribosomes that collide each other), thereby regulating both the co-translational quality control and stress response. We propose that GCN1 regulates ribosome-mediated signaling by dynamically changing its partners among RWD domain-possessing proteins via unknown mechanisms. We recently demonstrated that GCN1 is essential for cell proliferation and whole-body energy regulation in mice. However, the manner in which ribosome-initiated signaling via GCN1 is related to various physiological functions warrants clarification. GCN1-mediated mechanisms and its interaction with other quality control and stress response signals should be important for proteostasis during aging and neurodegenerative diseases, and may be targeted for drug development.

Thymoquinone regulates microglial M1/M2 polarization after cerebral ischemia-reperfusion injury via the TLR4 signaling pathway

Acute ischemic stroke followed by microglia activation, and the regulation of neuroinflammatory responses after ischemic injury involves microglia polarization. microglia polarization is involved in the regulation of neuroinflammatory responses and ischemic stroke-related brain damage. Thymoquinone (TQ) is an anti-inflammatory agent following ischemic stroke onset. However, the significance of TQ in microglia polarization following acute ischemic stroke is still unclear. We predicted that TQ might have neuroprotective properties by modulating microglia polarization. In this work, we mimicked the clinical signs of acute ischemic stroke using a mouse middle cerebral artery ischemia-reperfusion (I/R) model. It was discovered that TQ treatment decreased I/R-induced infarct volume, cerebral oedema, and promoted neuronal survival, as well as improved the histopathological changes of brain tissue. The sensorimotor function was assessed by the Garica score, foot fault test, and corner test, and it was found that TQ could improve the motor deficits caused by I/R. Secondly, real-time fluorescence quantitative PCR, immuno-fluorescence, ELISA, and western blot were used to detect the expression of M1/M2-specific markers in microglia to explore the role of TQ in the modulation of microglial cell polarization after cerebral ischemia-reperfusion. We found that TQ was able to promote the polarization of microglia with extremely secreted inflammatory factors from M1 type to M2 type. Furthermore, TQ could block the TLR4/NF-κB signaling pathway via Hif-1α activation which subsequently may attenuate microglia differentiation following the cerebral ischemia, establishing a mechanism for the TQ's beneficial effects in the cerebral ischemia-reperfusion model.

USP38 promotes deubiquitination of K11-linked polyubiquitination of HIF1α at Lys769 to enhance hypoxia signaling

HIF1α is one of the master regulators of the hypoxia signaling pathway and its activation is regulated by multiple post-translational modifications (PTMs). Deubiquitination mediated by deubiquitylating enzymes (DUBs) is an essential PTM that mainly modulates the stability of target proteins. USP38 belongs to the ubiquitin-specific proteases (USPs). However, whether USP38 can affect hypoxia signaling is still unknown. In this study, we used quantitative real-time PCR assays to identify USPs that can influence hypoxia-responsive gene expression. We found that overexpression of USP38 increased hypoxia-responsive gene expression, but knockout of USP38 suppressed hypoxia-responsive gene expression under hypoxia. Mechanistically, USP38 interacts with HIF1α to deubiquitinate K11-linked polyubiquitination of HIF1α at Lys769, resulting in stabilization and subsequent activation of HIF1α. In addition, we show that USP38 attenuates cellular ROS and suppresses cell apoptosis under hypoxia. Thus, we reveal a novel role for USP38 in the regulation of hypoxia signaling.

HIF-1α and periodontitis: Novel insights linking host-environment interplay to periodontal phenotypes

Periodontitis, the sixth most prevalent epidemic disease globally, profoundly impacts oral aesthetics and masticatory functionality. Hypoxia-inducible factor-1α (HIF-1α), an oxygen-dependent transcriptional activator, has emerged as a pivotal regulator in periodontal tissue and alveolar bone metabolism, exerts critical functions in angiogenesis, erythropoiesis, energy metabolism, and cell fate determination. Numerous essential phenotypes regulated by HIF are intricately associated with bone metabolism in periodontal tissues. Extensive investigations have highlighted the central role of HIF and its downstream target genes and pathways in the coupling of angiogenesis and osteogenesis. Within this concise perspective, we comprehensively review the cellular phenotypic alterations and microenvironmental dynamics linking HIF to periodontitis. We analyze current research on the HIF pathway, elucidating its impact on bone repair and regeneration, while unraveling the involved cellular and molecular mechanisms. Furthermore, we briefly discuss the potential application of targeted interventions aimed at HIF in the field of bone tissue regeneration engineering. This review expands our biological understanding of the intricate relationship between the HIF gene and bone angiogenesis in periodontitis and offers valuable insights for the development of innovative therapies to expedite bone repair and regeneration.

The emerging roles of SUMOylation in pulmonary diseases

Small ubiquitin-like modifier mediated modification (SUMOylation) is a critical post-translational modification that has a broad spectrum of biological functions, including genome replication and repair, transcriptional regulation, protein stability, and cell cycle progression. Perturbation or deregulation of a SUMOylation and deSUMOylation status has emerged as a new pathophysiological feature of lung diseases. In this review, we highlighted the link between SUMO pathway and lung diseases, especially the sumoylated substrate such as C/EBPα in bronchopulmonary dysplasia (BDP), PPARγ in pneumonia, TFII-I in asthma, HDAC2 in chronic obstructive pulmonary disease (COPD), KLF15 in hypoxic pulmonary hypertension (HPH), SMAD3 in idiopathic pulmonary fibrosis (IPF), and YTHDF2 in cancer. By exploring the impact of SUMOylation in pulmonary diseases, we intend to shed light on its potential to inspire the development of innovative diagnostic and therapeutic strategies, holding promise for improving patient outcomes and overall respiratory health.

The emerging roles of SUMOylation in the tumor microenvironment and therapeutic implications

Tumor initiation, progression, and response to therapies depend to a great extent on interactions between malignant cells and the tumor microenvironment (TME), which denotes the cancerous/non-cancerous cells, cytokines, chemokines, and various other factors around tumors. Cancer cells as well as stroma cells can not only obtain adaption to the TME but also sculpt their microenvironment through a series of signaling pathways. The post-translational modification (PTM) of eukaryotic cells by small ubiquitin-related modifier (SUMO) proteins is now recognized as a key flexible pathway. Proteins involved in tumorigenesis guiding several biological processes including chromatin organization, DNA repair, transcription, protein trafficking, and signal conduction rely on SUMOylation. The purpose of this review is to explore the role that SUMOylation plays in the TME formation and reprogramming, emphasize the importance of targeting SUMOylation to intervene in the TME and discuss the potential of SUMOylation inhibitors (SUMOi) in ameliorating tumor prognosis.

Construction and verification of atopic dermatitis diagnostic model based on pyroptosis related biological markers using machine learning methods

OBJECTIVE

The aim of this study was to construct a model used for the accurate diagnosis of Atopic dermatitis (AD) using pyroptosis related biological markers (PRBMs) through the methods of machine learning.

METHOD

The pyroptosis related genes (PRGs) were acquired from molecular signatures database (MSigDB). The chip data of GSE120721, GSE6012, GSE32924, and GSE153007 were downloaded from gene expression omnibus (GEO) database. The data of GSE120721 and GSE6012 were combined as the training group, while the others were served as the testing groups. Subsequently, the expression of PRGs was extracted from the training group and differentially expressed analysis was conducted. CIBERSORT algorithm calculated the immune cells infiltration and differentially expressed analysis was conducted. Consistent cluster analysis divided AD patients into different modules according to the expression levels of PRGs. Then, weighted correlation network analysis (WGCNA) screened the key module. For the key module, we used Random forest (RF), support vector machines (SVM), Extreme Gradient Boosting (XGB), and generalized linear model (GLM) to construct diagnostic models. For the five PRBMs with the highest model importance, we built a nomogram. Finally, the results of the model were validated using GSE32924, and GSE153007 datasets.

RESULTS

Nine PRGs were significant differences in normal humans and AD patients. Immune cells infiltration showed that the activated CD4+ memory T cells and Dendritic cells (DCs) were significantly higher in AD patients than normal humans, while the activated natural killer (NK) cells and the resting mast cells were significantly lower in AD patients than normal humans. Consistent cluster analysis divided the expressing matrix into 2 modules. Subsequently, WGCNA analysis showed that the turquoise module had a significant difference and high correlation coefficient. Then, the machine model was constructed and the results showed that the XGB model was the optimal model. The nomogram was constructed by using HDAC1, GPALPP1, LGALS3, SLC29A1, and RWDD3 five PRBMs. Finally, the datasets GSE32924 and GSE153007 verified the reliability of this result.

CONCLUSIONS

The XGB model based on five PRBMs can be used for the accurate diagnosis of AD patients.

SUMOylation and the oncogenic E17K mutation affect AKT1 subcellular distribution and impact on Nanog-binding dynamics to chromatin in embryonic stem cells

AKT/PKB is a kinase involved in the regulation of a plethora of cell processes. Particularly, in embryonic stem cells (ESCs), AKT is crucial for the maintenance of pluripotency. Although the activation of this kinase relies on its recruitment to the cellular membrane and subsequent phosphorylation, multiple other post-translational modifications (PTMs), including SUMOylation, fine-tune its activity and target specificity. Since this PTM can also modify the localization and availability of different proteins, in this work we explored if SUMOylation impacts on the subcellular compartmentalization and distribution of AKT1 in ESCs. We found that this PTM does not affect AKT1 membrane recruitment, but it modifies the AKT1 nucleus/cytoplasm distribution, increasing its nuclear presence. Additionally, within this compartment, we found that AKT1 SUMOylation also impacts on the chromatin-binding dynamics of NANOG, a central pluripotency transcription factor. Remarkably, the oncogenic E17K AKT1 mutant produces major changes in all these parameters increasing the binding of NANOG to its targets, also in a SUMOylation dependent manner. These findings demonstrate that SUMOylation modulates AKT1 subcellular distribution, thus adding an extra layer of regulation of its function, possibly by affecting the specificity and interaction with its downstream targets.

RNA-binding proteins in degenerative joint diseases: A systematic review

RNA-binding proteins (RBPs), which are conserved proteins comprising multiple intermediate sequences, can interact with proteins, messenger RNA (mRNA) of coding genes, and non-coding RNAs to perform different biological functions, such as the regulation of mRNA stability, selective polyadenylation, and the management of non-coding microRNA (miRNA) synthesis to affect downstream targets. This article will highlight the functions of RBPs, in degenerative joint diseases (intervertebral disc degeneration [IVDD] and osteoarthritis [OA]). It will reviews the latest advancements on the regulatory mechanism of RBPs in degenerative joint diseases, in order to understand the pathophysiology, early diagnosis and treatment of OA and IVDD from a new perspective.

SUMOylation mediates the disassembly of the Smad4 nuclear export complex via RanGAP1 in KELOIDS

Sentrin/small ubiquitin-like modifier (SUMO) has emerged as a powerful mediator regulating biological processes and participating in pathophysiological processes that cause human diseases, such as cancer, myocardial fibrosis and neurological disorders. Sumoylation has been shown to play a positive regulatory role in keloids. However, the sumoylation mechanism in keloids remains understudied. We proposed that sumoylation regulates keloids via a complex. RanGAP1 acted as a synergistic, functional partner of SUMOs in keloids. Nuclear accumulation of Smad4, a TGF-β/Smad pathway member, was associated with RanGAP1 after SUMO1 inhibition. RanGAP1*SUMO1 mediated the nuclear accumulation of Smad4 due to its impact on nuclear export and reduction in the dissociation of Smad4 and CRM1. We clarified a novel mechanism of positive regulation of sumoylation in keloids and demonstrated the function of sumoylation in Smad4 nuclear export. The NPC-associated RanGAP1*SUMO1 complex functions as a disassembly machine for the export receptor CRM1 and Smad4. Our research provides new perspectives for the mechanisms of keloids and nucleocytoplasmic transport.

Expression of RSUME is associated with poor prognosis in clear cell Renal Carcinoma: involvement of ROS related metabolism

INTRODUCTION

RSUME (RWD domain-containing protein SUMO Enhancer), RWD domain containing 3 (RWDD3) gene product, is upregulated by hypoxia and expressed in organs prone to develop von Hippel-Lindau (VHL) syndrome tumors.

MATERIALS AND METHODS

We evaluated RSUME prognostic value in clear cell renal cell carcinoma (ccRCC) based mainly on the dataset (KIRC) from patients in The Cancer Genome Atlas (TCGA). Wilcoxon signed-rank test and one-way analysis of variance (ANOVA) followed by Tukey's test were used to evaluate relationships between clinicopathological features and RSUME expression and univariate and multivariate Cox regression analysis methods were used to evaluate prognostic factors. The biological function of RSUME was assessed by gene set enrichment analysis (GSEA). For validation, total amount of ROS was detected in ccRCC cell lines using dichlorofluorescin diacetate.

RESULTS

RSUME is highly expressed in tumor tissues compared with normal tissues (P = .006, P = .039, P = .002, P = .036, P < .001) and associates with tumor T (P = .018) and tumor M (P = .036) advanced stages and higher extent cysts (P = .005). RSUME expression appears to be an independent risk factor for overall survival (OS) (P = .002) and disease-specific survival (DSS) (P = .026) in ccRCC patients. GSEA showed enrichment of relevant glycerophospholipid- and ROS-related pathways in RSUME high-expression phenotype. ROS diminished levels in RSUME-silenced ccRCC cell lines validated RSUME relevance in ROS-related pathways.

CONCLUSION

RSUME high expression may predict poor prognosis in ccRCC and impact through its action on metabolism and ROS related pathways.

Intermittent hypoxia treatments cause cellular priming in human microglia

Obstructive sleep apnoea syndrome (OSAS) is a sleep-disordered breathing characterized by nocturnal collapses of the upper airway resulting in cycles of blood oxygen partial pressure oscillations, which lead to tissue and cell damage due to intermittent hypoxia (IH) episodes. Since OSAS-derived IH may lead to cognitive impairment through not fully cleared mechanisms, herein we developed a new in vitro model mimicking IH conditions to shed light on its molecular effects on microglial cells, with particular attention to the inflammatory response. The in vitro model was set-up and validated by measuring the hypoxic state, HIF-1α levels, oxidative stress by ROS production and mitochondrial activity by MTS assay. Then, the mRNA and protein levels of certain inflammatory markers (NF-κB and interleukin 6 (IL-6)) after different IH treatment protocols were investigated. The IH treatments followed by a normoxic period were not able to produce a high inflammatory state in human microglial cells. Nevertheless, microglia appeared to be in a state characterized by increased expression of NF-κB and markers related to a primed phenotype. The microglia exposed to IH cycles and stimulated with exogenous IL-1β resulted in an exaggerated inflammatory response with increased NF-κB and IL-6 expression, suggesting a role for primed microglia in OSAS-driven neuroinflammation.

A prognosis marker MUC1 correlates with metabolism and drug resistance in bladder cancer: a bioinformatics research

Background

MUC1 is a type I transmembrane protein that plays an important role in tumor cell signal transduction. Although current studies have shown that MUC1 is upregulated in bladder cancer (BC), the specific mechanism is still unclear.

Methods

We performed expression analysis, gene set enrichment analysis, survival analysis, immune infiltration analysis, drug sensitivity analysis, and metabolism-related gene expression analysis on TCGA-BLCA, GES31684 and GSE13507.

Results

The expression of MUC1 in the tumor and lymphatic metastasis positive samples was significantly increased. Genes related to MUC1 expression were significantly enriched in immune response, ribosomes, exosomes, and energy metabolism. The results of the immune infiltration analysis showed that M1 macrophages in BC with high MUC1 expression were significantly decreased. Expression of MUC1 increases drug resistance in BC patients. In addition, MUC1 increases glycolysis, glucose uptake, and lactate production by inducing metabolic reprogramming.

Conclusion

MUC1 has a significant effect on the metabolism and immune cell infiltration of BC, which may be the cause of increased drug resistance, and can be used as a molecular target for the diagnosis and treatment of BC.

Hallmarks of Cancer Expression in Oral Lichen Planus: A Scoping Review of Systematic Reviews and Meta-Analyses

Oral lichen planus (OLP) is a common chronic inflammatory disease of unknown etiology and likely autoimmune nature that is currently considered an oral potentially malignant disorder, implying that patients suffering from this process are at risk of developing oral cancer in their lifetime. The molecular alterations that develop in OLP and that make the affected oral epithelium predisposed to malignancy are unknown, although, as in other autoimmune diseases (ulcerative colitis, primary biliary cirrhosis, etc.), they may be linked to oncogenesis-promoting effects mediated by the inflammatory infiltrate. So far there is no in-depth knowledge on how these hallmarks of cancer are established in the cells of the oral epithelium affected by OLP. In this scoping review of systematic reviews and meta-analyses the state of evidence based knowledge in this field is presented, to point out gaps of evidence and to indicate future lines of research. MEDLINE, Embase, Cochrane Library and Dare were searched for secondary-level studies published before October 2022. The results identified 20 systematic reviews and meta-analyses critically appraising the hallmarks tumor-promoting inflammation (n = 17, 85%), sustaining proliferative signaling (n = 2, 10%), and evading growth suppressors (n = 1, 5%). No evidence was found for the other hallmarks of cancer in OLP. In conclusion, OLP malignization hypothetically derives from the aggressions of the inflammatory infiltrate and a particular type of epithelial response based on increased epithelial proliferation, evasion of growth-suppressive signals and lack of apoptosis. Future evidence-based research is required to support this hypothesis.

Role of SUMOylation in Neurodegenerative Diseases

Neurodegenerative diseases (NDDs) are irreversible, progressive diseases with no effective treatment. The hallmark of NDDs is the aggregation of misfolded, modified proteins, which impair neuronal vulnerability and cause brain damage. The loss of synaptic connection and the progressive loss of neurons result in cognitive defects. Several dysregulated proteins and overlapping molecular mechanisms contribute to the pathophysiology of NDDs. Post-translational modifications (PTMs) are essential regulators of protein function, trafficking, and maintaining neuronal hemostasis. The conjugation of a small ubiquitin-like modifier (SUMO) is a reversible, dynamic PTM required for synaptic and cognitive function. The onset and progression of neurodegenerative diseases are associated with aberrant SUMOylation. In this review, we have summarized the role of SUMOylation in regulating critical proteins involved in the onset and progression of several NDDs.

Methyltransferase SMYD3 impairs hypoxia tolerance by augmenting hypoxia signaling independent of its enzymatic activity

Hypoxia-inducible factor (HIF)1α, a main transcriptional regulator of the cellular response to hypoxia, also plays important roles in oxygen homeostasis of aerobic organisms, which is regulated by multiple mechanisms. However, the full cellular response to hypoxia has not been elucidated. In this study, we found that expression of SMYD3, a methyltransferase, augments hypoxia signaling independent of its enzymatic activity. We demonstrated SMYD3 binds to and stabilizes HIF1α via co-immunoprecipitation and Western blot assays, leading to the enhancement of HIF1α transcriptional activity under hypoxia conditions. In addition, the stabilization of HIF1α by SMYD3 is independent of HIF1α hydroxylation by prolyl hydroxylases and the intactness of the von Hippel-Lindau ubiquitin ligase complex. Furthermore, we showed SMYD3 induces reactive oxygen species accumulation and promotes hypoxia-induced cell apoptosis. Consistent with these results, we found smyd3-null zebrafish exhibit higher hypoxia tolerance compared to their wildtype siblings. Together, these findings define a novel role of SMYD3 in affecting hypoxia signaling and demonstrate that SMYD3-mediated HIF1α stabilization augments hypoxia signaling, leading to the impairment of hypoxia tolerance.

OTUB1 augments hypoxia signaling via its non-canonical ubiquitination inhibition of HIF-1α during hypoxia adaptation

As a main regulator of cellular responses to hypoxia, the protein stability of hypoxia-inducible factor (HIF)-1α is strictly controlled by oxygen tension dependent of PHDs-catalyzed protein hydroxylation and pVHL complex-mediated proteasomal degradation. Whether HIF-1α protein stability as well as its activity can be further regulated under hypoxia is not well understood. In this study, we found that OTUB1 augments hypoxia signaling independent of PHDs/VHL and FIH. OTUB1 binds to HIF-1α and depletion of OTUB1 reduces endogenous HIF-1α protein under hypoxia. In addition, OTUB1 inhibits K48-linked polyubiquitination of HIF-1α via its non-canonical inhibition of ubiquitination activity. Furthermore, OTUB1 promotes hypoxia-induced glycolytic reprogramming for cellular metabolic adaptation. These findings define a novel regulation of HIF-1α under hypoxia and demonstrate that OTUB1-mediated HIF-1α stabilization positively regulates HIF-1α transcriptional activity and benefits cellular hypoxia adaptation.

The effect of HIF on metabolism and immunity

Cellular hypoxia occurs when the demand for sufficient molecular oxygen needed to produce the levels of ATP required to perform physiological functions exceeds the vascular supply, thereby leading to a state of oxygen depletion with the associated risk of bioenergetic crisis. To protect against the threat of hypoxia, eukaryotic cells have evolved the capacity to elicit oxygen-sensitive adaptive transcriptional responses driven primarily (although not exclusively) by the hypoxia-inducible factor (HIF) pathway. In addition to the canonical regulation of HIF by oxygen-dependent hydroxylases, multiple other input signals, including gasotransmitters, non-coding RNAs, histone modifiers and post-translational modifications, modulate the nature of the HIF response in discreet cell types and contexts. Activation of HIF induces various effector pathways that mitigate the effects of hypoxia, including metabolic reprogramming and the production of erythropoietin. Drugs that target the HIF pathway to induce erythropoietin production are now approved for the treatment of chronic kidney disease-related anaemia. However, HIF-dependent changes in cell metabolism also have profound implications for functional responses in innate and adaptive immune cells, and thereby heavily influence immunity and the inflammatory response. Preclinical studies indicate a potential use of HIF therapeutics to treat inflammatory diseases, such as inflammatory bowel disease. Understanding the links between HIF, cellular metabolism and immunity is key to unlocking the full therapeutic potential of drugs that target the HIF pathway.

Hypoxia-dependent changes in cellular metabolism have important implications for the effective functioning of multiple immune cell subtypes. This Review describes the inputs that shape the hypoxic response in individual cell types and contexts, and the implications of this response for cellular metabolism and associated alterations in immune cell function.

Hypoxia is a common feature of particular microenvironments and at sites of immunity and inflammation, resulting in increased activity of the hypoxia-inducible factor (HIF).

In addition to hypoxia, multiple inputs modulate the activity of the HIF pathway, allowing nuanced downstream responses in discreet cell types and contexts.

HIF-dependent changes in cellular metabolism mitigate the effects of hypoxia and ensure that energy needs are met under conditions in which oxidative phosphorylation is reduced.

HIF-dependent changes in metabolism also profoundly affect the phenotype and function of immune cells.

The immunometabolic effects of HIF have important implications for targeting the HIF pathway in inflammatory disease.

SUMOylation in peripheral tissues under low perfusion-related pathological states

SUMOylation is described as a posttranslational protein modification (PTM) that is involved in the pathophysiological processes underlying several conditions related to ischemia- and reperfusion-induced damage. Increasing evidence suggests that, under low oxygen levels, SUMOylation might be part of an endogenous mechanism, which is triggered by injury to protect cells within the central nervous system. However, the role of ischemia-induced SUMOylation in the periphery is still unclear. This article summarizes the results of recent studies regarding SUMOylation profiles in several diseases characterized by impaired blood flow to the cardiorenal, gastrointestinal, and respiratory systems. Our review shows that although ischemic injury per se does not always increase SUMOylation levels, as seen in strokes, it seems that in most cases the positive modulation of protein SUMOylation after peripheral ischemia might be a protective mechanism. This complex relationship warrants further investigation, as the role of SUMOylation during hypoxic conditions differs from organ to organ and is still not fully elucidated.

The JMJD Family Histone Demethylases in Crosstalk Between Inflammation and Cancer

Inflammation has emerged as a key player in regulating cancer initiation, progression, and therapeutics, acting as a double edged sword either facilitating cancer progression and therapeutic resistance or inducing anti-tumor immune responses. Accumulating evidence has linked the epigenetic modifications of histones to inflammation and cancer, and histone modifications-based strategies have shown promising therapeutic potentials against cancer. The jumonji C domain-containing (JMJD) family histone demethylases have exhibited multiple regulator functions in inflammatory processes and cancer development, and a number of therapeutic strategies targeting JMJD histone demethylases to modulate inflammatory cells and their products have been successfully evaluated in clinical or preclinical tumor models. This review summarizes current understanding of the functional roles and mechanisms of JMJD histone demethylases in crosstalk between inflammation and cancer, and highlights recent clinical and preclinical progress on harnessing the JMJD histone demethylases to regulate cancer-related inflammation for future cancer therapeutics.

Impact of RSUME Actions on Biomolecular Modifications in Physio-Pathological Processes

The small RWD domain-containing protein called RSUME or RWDD3 was cloned from pituitary tumor cells with increasing tumorigenic and angiogenic proficiency. RSUME expression is induced under hypoxia or heat shock and is upregulated, at several pathophysiological stages, in tissues like pituitary, kidney, heart, pancreas, or adrenal gland. To date, several factors with essential roles in endocrine-related cancer appear to be modulated by RWDD3. RSUME regulates, through its post-translational (PTM) modification, pituitary tumor transforming gene (PTTG) protein stability in pituitary tumors. Interestingly, in these tumors, another PTM, the regulation of EGFR levels by USP8, plays a pathogenic role. Furthermore, RSUME suppresses ubiquitin conjugation to hypoxia-inducible factor (HIF) by blocking VHL E3-ubiquitin ligase activity, contributing to the development of von Hippel-Lindau disease. RSUME enhances protein SUMOylation of specific targets involved in inflammation such as IkB and the glucocorticoid receptor. For many of its actions, RSUME associates with regulatory proteins of ubiquitin and SUMO cascades, such as the E2-SUMO conjugase Ubc9 or the E3 ubiquitin ligase VHL. New evidence about RSUME involvement in inflammatory and hypoxic conditions, such as cardiac tissue response to ischemia and neuropathic pain, and its role in several developmental processes, is discussed as well. Given the modulation of PTMs by RSUME in neuroendocrine tumors, we focus on its interactors and its mode of action. Insights into functional implications and molecular mechanisms of RSUME action on biomolecular modifications of key factors of pituitary adenomas and renal cell carcinoma provide renewed information about new targets to treat these pathologies.

Natural Products Against Renal Fibrosis via Modulation of SUMOylation

Renal fibrosis is the common and final pathological process of kidney diseases. As a dynamic and reversible post-translational modification, SUMOylation and deSUMOylation of transcriptional factors and key mediators significantly affect the development of renal fibrosis. Recent advances suggest that SUMOylation functions as the promising intervening target against renal fibrosis, and natural products prevent renal fibrosis via modulating SUMOylation. Here, we introduce the mechanism of SUMOylation in renal fibrosis and therapeutic effects of natural products. This process starts by summarizing the key mediators and enzymes during SUMOylation and deSUMOylation and its regulation role in transcriptional factors and key mediators in renal fibrosis, then linking the mechanism findings of SUMOylation and natural products to develop novel therapeutic candidates for treating renal fibrosis, and concludes by commenting on promising therapeutic targets and candidate natural products in renal fibrosis via modulating SUMOylation, which highlights modulating SUMOylation as a promising strategy for natural products against renal fibrosis.

Hypoxia Stimulates SUMOylation-Dependent Stabilization of KDM5B

Hypoxia is an important characteristic of the tumor microenvironment. Tumor cells can survive and propagate under the hypoxia stress by activating a series of adaption response. Herein, we found that lysine-specific demethylase 5B (KDM5B) was upregulated in gastric cancer (GC) under hypoxia conditions. The genetic knockdown or chemical inhibition of KDM5B impaired the growth of GC cell adapted to hypoxia. Interestingly, the upregulation of KDM5B in hypoxia response was associated with the SUMOylation of KDM5B. SUMOylation stabilized KDM5B protein by reducing the competitive modification of ubiquitination. Furthermore, the protein inhibitor of activated STAT 4 (PIAS4) was determined as the SUMO E3 ligase, showing increased interaction with KDM5B under hypoxia conditions. The inhibition of KDM5B caused significant downregulation of hypoxia-inducible factor-1α (HIF-1α) protein and target genes under hypoxia. As a result, co-targeting KDM5B significantly improved the antitumor efficacy of antiangiogenic therapy in vivo. Taken together, PIAS4-mediated SUMOylation stabilized KDM5B protein by disturbing ubiquitination-dependent proteasomal degradation to overcome hypoxia stress. Targeting SUMOylation-dependent KDM5B upregulation might be considered when the antiangiogenic therapy was applied in cancer treatment.

14-weeks combined exercise epigenetically modulated 118 genes of menopausal women with prediabetes

BACKGROUND

Pre-diabetes precedes Diabetes Mellitus (DM) disease and is a critical period for hyperglycemia treatment, especially for menopausal women, considering all metabolic alterations due to hormonal changes. Recently, the literature has demonstrated the role of physical exercise in epigenetic reprogramming to modulate the gene expression patterns of metabolic conditions, such as hyperglycemia, and prevent DM development. In the present study, we hypothesized that physical exercise training could modify the epigenetic patterns of women with poor glycemic control.

METHODS

48 post-menopause women aged 60.3 ± 4.5 years were divided according to their fasting blood glucose levels into two groups: Prediabetes Group, PG (n=24), and Normal Glucose Group, NGG (n=24). All participants performed 14 weeks of physical exercise three times a week. The Infinium Methylation EPIC BeadChip measured the participants' Different Methylated Regions (DMRs).

RESULTS

Before the intervention, the PG group had 12 DMRs compared to NGG. After the intervention, five DMRs remained different. Interestingly, when comparing the PG group before and after training, 118 DMRs were found. The enrichment analysis revealed that the genes were related to different biological functions such as energy metabolism, cell differentiation, and tumor suppression.

CONCLUSION

Physical exercise is a relevant alternative in treating hyperglycemia and preventing DM in post-menopause women with poor glycemic control.

Hsp70 Promotes SUMO of HIF-1α and Promotes Lung Cancer Invasion and Metastasis

Objective

This study aims to investigate the effect of heat shock protein-70 (Hsp70) on epithelial-mesenchymal transition (EMT) of lung cancer cells under heat stimulation and to explore its possible molecular mechanism.

Methods

qRT-PCR and immunohistochemistry assay were used to detect the expression of Hsp70 in lung cancer tissues and adjacent tissues. EdU assay was used to detect the cell activity. The effect of Hsp70 on the migration and invasion of A549 and NCI-H446 cells was detected by the wound-healing assay and Transwell assay. A tumor transplantation animal model was established to detect the effect of overexpression of Hsp70 on proliferation and metastasis of lung cancer cells. Western blot assay was used to detect the effect of thermal stimulation and overexpression of Hsp70 on SUMO modification of HIF-1α.

Results

The wound-healing rate of A549 and NCI-H446 cells under Hsp70 stimulation was significantly higher than blank control group. At the same time, the number of cells passing through the membrane increased significantly. Hypodermic tumor transplantation in nude mice proved that knockout Hsp70 can inhibit proliferation and metastasis of lung cancer cells. Thermal stimulation upregulated the expression of Hsp70 and promoted SUMO modification of HIF-1α, ultimately promoting the proliferation and metastasis of lung cancer. Inhibition of Hsp70 reverses the effect of thermal stimulation on lung cancer by reducing the SUMO modification of HIF-1α.

Conclusion

Thermal stimulation can promote EMT in A549 and NCI-H446 cells and promote cell migration and invasion in vitro and in vivo by upregulation of Hsp70. This process is associated with the promotion of SUMO modification of HIF-1α.

Oxygen-sensing mechanisms in development and tissue repair

Under normoxia, hypoxia inducible factor (HIF) α subunits are hydroxylated by PHDs (prolyl hydroxylase domain proteins) and subsequently undergo polyubiquitylation and degradation. Normal embryogenesis occurs under hypoxia, which suppresses PHD activities and allows HIFα to stabilize and regulate development. In this Primer, we explain molecular mechanisms of the oxygen-sensing pathway, summarize HIF-regulated downstream events, discuss loss-of-function phenotypes primarily in mouse development, and highlight clinical relevance to angiogenesis and tissue repair.

Therapeutic Potential of Targeting the SUMO Pathway in Cancer

SUMOylation is a dynamic and reversible post-translational modification, characterized more than 20 years ago, that regulates protein function at multiple levels. Key oncoproteins and tumor suppressors are SUMO substrates. In addition to alterations in SUMO pathway activity due to conditions typically present in cancer, such as hypoxia, the SUMO machinery components are deregulated at the genomic level in cancer. The delicate balance between SUMOylation and deSUMOylation is regulated by SENP enzymes possessing SUMO-deconjugation activity. Dysregulation of SUMO machinery components can disrupt the balance of SUMOylation, contributing to the tumorigenesis and drug resistance of various cancers in a context-dependent manner. Many molecular mechanisms relevant to the pathogenesis of specific cancers involve SUMO, highlighting the potential relevance of SUMO machinery components as therapeutic targets. Recent advances in the development of inhibitors targeting SUMOylation and deSUMOylation permit evaluation of the therapeutic potential of targeting the SUMO pathway in cancer. Finally, the first drug inhibiting SUMO pathway, TAK-981, is currently also being evaluated in clinical trials in cancer patients. Intriguingly, the inhibition of SUMOylation may also have the potential to activate the anti-tumor immune response. Here, we comprehensively and systematically review the recent developments in understanding the role of SUMOylation in cancer and specifically focus on elaborating the scientific rationale of targeting the SUMO pathway in different cancers.

Dissecting multiple roles of SUMOylation in prostate cancer

Protein modification with small ubiquitin-like modifiers (SUMOs) plays dual roles in prostate cancer (PCa) tumorigenesis and development. Any intermediary of the SUMO conjugation cycle going awry may forfeit the balance between tumorigenic potential and anticancer effects. Deregulated SUMOylation on the androgen receptor and oncoproteins also takes part in this pathological process, as exemplified by STAT3/NF-κB and tumor suppressors such as PTEN and p53. Here, we outline recent developments and discoveries of SUMOylation in PCa and present an overview of its multiple roles in PCa tumorigenesis/promotion and suppression, while elucidating its potential as a therapeutic target for PCa.

The SUMOylation of TAB2 mediated by TRIM60 inhibits MAPK/NF-κB activation and the innate immune response

Activation of the TAK1 signalosome is crucial for mediating the innate immune response to pathogen invasion and is regulated by multiple layers of posttranslational modifications, including ubiquitination, SUMOylation, and phosphorylation; however, the underlying molecular mechanism is not fully understood. In this study, TRIM60 negatively regulated the formation and activation of the TAK1 signalosome. Deficiency of TRIM60 in macrophages led to enhanced MAPK and NF-κB activation, accompanied by elevated levels of proinflammatory cytokines but not IFN-I. Immunoprecipitation-mass spectrometry assays identified TAB2 as the target of TRIM60 for SUMOylation rather than ubiquitination, resulting in impaired formation of the TRAF6/TAB2/TAK1 complex and downstream MAPK and NF-κB pathways. The SUMOylation sites of TAB2 mediated by TRIM60 were identified as K329 and K562; substitution of these lysines with arginines abolished the SUMOylation of TAB2. In vivo experiments showed that TRIM60-deficient mice showed an elevated immune response to LPS-induced septic shock and L. monocytogenes infection. Our data reveal that SUMOylation of TAB2 mediated by TRIM60 is a novel mechanism for regulating the innate immune response, potentially paving the way for a new strategy to control antibacterial immune responses.

SUMOylation as a Therapeutic Target for Myocardial Infarction

Myocardial infarction is a prevalent and life-threatening cardiovascular disease. The main goal of existing interventional therapies is to restore coronary reperfusion while few are designed to ameliorate the pathology of heart diseases via targeting the post-translational modifications of those critical proteins. Small ubiquitin-like modifier (SUMO) proteins are recently discovered to form a new type of protein post-translational modifications (PTM), known as SUMOylation. SUMOylation and deSUMOylation are dynamically balanced in the maintenance of various biological processes including cell division, DNA repair, epigenetic transcriptional regulation, and cellular metabolism. Importantly, SUMOylation plays a critical role in the regulation of cardiac functions and the pathology of cardiovascular diseases, especially in heart failure and myocardial infarction. This review summarizes the current understanding on the effects of SUMOylation and SUMOylated proteins in the pathophysiology of myocardial infarction and identifies the potential treatments against myocardial injury via targeting SUMO. Ultimately, this review recommends SUMOylation as a key therapeutic target for treating cardiovascular diseases.

Inflammation and tumor progression: signaling pathways and targeted intervention

Cancer development and its response to therapy are regulated by inflammation, which either promotes or suppresses tumor progression, potentially displaying opposing effects on therapeutic outcomes. Chronic inflammation facilitates tumor progression and treatment resistance, whereas induction of acute inflammatory reactions often stimulates the maturation of dendritic cells (DCs) and antigen presentation, leading to anti-tumor immune responses. In addition, multiple signaling pathways, such as nuclear factor kappa B (NF-kB), Janus kinase/signal transducers and activators of transcription (JAK-STAT), toll-like receptor (TLR) pathways, cGAS/STING, and mitogen-activated protein kinase (MAPK); inflammatory factors, including cytokines (e.g., interleukin (IL), interferon (IFN), and tumor necrosis factor (TNF)-α), chemokines (e.g., C-C motif chemokine ligands (CCLs) and C-X-C motif chemokine ligands (CXCLs)), growth factors (e.g., vascular endothelial growth factor (VEGF), transforming growth factor (TGF)-β), and inflammasome; as well as inflammatory metabolites including prostaglandins, leukotrienes, thromboxane, and specialized proresolving mediators (SPM), have been identified as pivotal regulators of the initiation and resolution of inflammation. Nowadays, local irradiation, recombinant cytokines, neutralizing antibodies, small-molecule inhibitors, DC vaccines, oncolytic viruses, TLR agonists, and SPM have been developed to specifically modulate inflammation in cancer therapy, with some of these factors already undergoing clinical trials. Herein, we discuss the initiation and resolution of inflammation, the crosstalk between tumor development and inflammatory processes. We also highlight potential targets for harnessing inflammation in the treatment of cancer.

SUMO conjugation susceptibility of Akt/protein kinase B affects the expression of the pluripotency transcription factor Nanog in embryonic stem cells

Akt/PKB is a kinase involved in the regulation of a wide variety of cell processes. Its activity is modulated by diverse post-translational modifications (PTMs). Particularly, conjugation of the small ubiquitin-related modifier (SUMO) to this kinase impacts on multiple cellular functions, such as proliferation and splicing. In embryonic stem (ES) cells, this kinase is key for pluripotency maintenance. Among other functions, Akt is known to promote the expression of Nanog, a central pluripotency transcription factor (TF). However, the relevance of this specific PTM of Akt has not been previously analyzed in this context. In this work, we study the effect of Akt1 variants with differential SUMOylation susceptibility on the expression of Nanog. Our results demonstrate that both, the Akt1 capability of being modified by SUMO conjugation and a functional SUMO conjugase activity are required to induce Nanog gene expression. Likewise, we found that the common oncogenic E17K Akt1 mutant affected Nanog expression in ES cells also in a SUMOylatability dependent manner. Interestingly, this outcome takes places in ES cells but not in a non-pluripotent heterologous system, suggesting the presence of a crucial factor for this induction in ES cells. Remarkably, the two major candidate factors to mediate this induction, GSK3-β and Tbx3, are non-essential players of this effect, suggesting a complex mechanism probably involving non-canonical pathways. Furthermore, we found that Akt1 subcellular distribution does not depend on its SUMOylatability, indicating that Akt localization has no influence on the effect on Nanog, and that besides the membrane localization of E17K Akt mutant, SUMOylation is also required for its hyperactivity. Our results highlight the impact of SUMO conjugation in the function of a kinase relevant for a plethora of cellular processes, including the control of a key pluripotency TF.

Lessons from Comparison of Hypoxia Signaling in Plants and Mammals

Hypoxia is an important stress for organisms, including plants and mammals. In plants, hypoxia can be the consequence of flooding and causes important crop losses worldwide. In mammals, hypoxia stress may be the result of pathological conditions. Understanding the regulation of responses to hypoxia offers insights into novel approaches for crop improvement, particularly for the development of flooding-tolerant crops and for producing better therapeutics for hypoxia-related diseases such as inflammation and cancer. Despite their evolutionary distance, plants and mammals deploy strikingly similar mechanisms to sense and respond to the different aspects of hypoxia-related stress, including low oxygen levels and the resulting energy crisis, nutrient depletion, and oxidative stress. Over the last two decades, the ubiquitin/proteasome system and the ubiquitin-like protein SUMO have been identified as key regulators that act in concert to regulate core aspects of responses to hypoxia in plants and mammals. Here, we review ubiquitin and SUMO-dependent mechanisms underlying the regulation of hypoxia response in plants and mammals. By comparing and contrasting these mechanisms in plants and mammals, this review seeks to pinpoint conceptually similar mechanisms but also highlight future avenues of research at the junction between different fields of research.

Regulation of the SIAH2-HIF-1 Axis by Protein Kinases and Its Implication in Cancer Therapy

The cellular response to hypoxia is a key biological process that facilitates adaptation of cells to oxygen deprivation (hypoxia). This process is critical for cancer cells to adapt to the hypoxic tumor microenvironment resulting from rapid tumor growth. Hypoxia-inducible factor 1 (HIF-1) is a transcription factor and a master regulator of the cellular response to hypoxia. The activity of HIF-1 is dictated primarily by its alpha subunit (HIF-1α), whose level and/or activity are largely regulated by an oxygen-dependent and ubiquitin/proteasome-mediated process. Prolyl hydroxylases (PHDs) and the E3 ubiquitin ligase Von Hippel-Lindau factor (VHL) catalyze hydroxylation and subsequent ubiquitin-dependent degradation of HIF-1α by the proteasome. Seven in Absentia Homolog 2 (SIAH2), a RING finger-containing E3 ubiquitin ligase, stabilizes HIF-1α by targeting PHDs for ubiquitin-mediated degradation by the proteasome. This SIAH2-HIF-1 signaling axis is important for maintaining the level of HIF-1α under both normoxic and hypoxic conditions. A number of protein kinases have been shown to phosphorylate SIAH2, thereby regulating its stability, activity, or substrate binding. In this review, we will discuss the regulation of the SIAH2-HIF-1 axis via phosphorylation of SIAH2 by these kinases and the potential implication of this regulation in cancer biology and cancer therapy.

Sumoylation as an Emerging Target in Therapeutics against Cancer

Sumoylation is the Post-translational modification gaining most of the research interest recently. Sumoylation is involved in various crucial functions of the cell such as regulation of cell cycle, DNA damage repair, apoptosis, etc. Oncology is advancing in radiotherapy, targeted chemotherapy, various forms of immunotherapy and targeted gene therapy. Researches are being conducted to prove its connotation with a variety of cancers and inhibitors are being developed to obstruct the fatal effect caused by misbalance of the SUMO-catalytic cycle. It has been shown that up-regulation of certain enzymes of Sumoylation correlates with cancer incidence in most of the cases. However, in some cases, down-regulation also associates with cancer invasion such as underexpression of UBC9 in initial stage breast cancer. This can aid in future study, treatment, and diagnosis of a variety of cancers including breast cancer, prostate cancer, lung adenocarcinoma, melanoma, multiple myeloma, etc. Various mechanistic assays are being developed and used to identify potential inhibitors against the dysregulated proteins of Sumoylation. This review summarizes the normal roles of the enzymes involved in the SUMOcatalytic cycle, their misbalanced regulation leading to tumorigenesis and nearly all the potent inhibitors identified to date, while after detailed studied it was observed that ML-792 could be a promising inhibitor in treating cancers by inhibiting Sumoylation enzymes.

Activation of TGR5 restores AQP2 expression via the HIF pathway in renal ischemia-reperfusion injury

Renal ischemia-reperfusion (I/R) injury is associated with markedly reduced protein expression of aquaporins (AQPs). Membrane G protein-coupled bile acid receptor-1 (TGR5) has shown protective roles in some kidney diseases. The purpose of the current study was to investigate whether activation of TGR5 prevented the decreased protein expression of AQPs in rodents with renal I/R injury and potential mechanisms. TGR5 agonist lithocholic acid (LCA) treatment reduced polyuria after renal I/R injury in rats. LCA prevented the decreased abundance of AQP2 protein and upregulated hypoxia-inducible factor (HIF)-1α protein expression, which were associated with decreased protein abundance of NF-κB p65 and IL-1β. After renal I/R, mice with tgr5 gene deficiency exhibited further decreases in AQP2 and HIF-1α protein abundance and increases of IL-1β and NF-κB p65 protein expression compared with wild-type mice. In primary cultured inner medullary collecting duct cells with hypoxia/reoxygenation, LCA induced markedly increased protein expression of AQP2 and HIF-1α, which were partially prevented by the PKA inhibitor H89. FG4592, a prolyl-4-hydroxylase domain-containing protein inhibitor, increased HIF-1α and AQP2 protein abundance in association with decreased NF-κB p65 protein expression in inner medullary collecting duct cells with hypoxia/reoxygenation. In conclusion, TGR5 stimulation by LCA prevented downregulation of renal AQPs in kidney with I/R injury, likely through activating HIF-1α signaling and suppressing inflammatory responses.NEW & NOTEWORTHY Stimulation of the membrane G protein-coupled bile acid receptor TGR5 by lithocholic acid (LCA) reduced polyuria in rats with renal ischemia-reperfusion (I/R) injury. LCA increased abundance of aquaporin-2 (AQP2) protein and upregulated hypoxia-inducible factor (HIF)-1α protein expression in association with decreased NF-κB p65 and IL-1β. After I/R, mice with tgr5 gene deficiency exhibited more severe decreases in AQP2 and HIF-1α protein abundance and inflammatory responses. TGR5 activation exhibits a protective role in acute renal injury induced by I/R.

Inhibition of SUMO2/3 antagonizes isoflurane-induced cancer-promoting effect in hepatocellular carcinoma Hep3B cells

Surgery for patients with complicated liver cancer often results in a long exposure to anesthesia with an increase in side effects. Continued long-term exposure to isoflurane may promote liver cancer progression. Small ubiquitin-like modifier (SUMO) 2 and 3, also known as SUMO2/3, conjugates to substrate proteins when cells undergo acute stress. However, whether or not SUMO2/3 is involved in isoflurane-mediated liver cancer progression is unknown. In the present study, hepatocellular carcinoma (HCC) cells were exposed to 2% isoflurane for 12 h, followed by 36 h of drug withdrawal, and the formation of SUMO2/3 conjugates and cancer behavioral characteristics were studied. The results demonstrated that the formation of SUMO2/3 conjugates was significantly increased following HCC cells being exposed to isoflurane for 0.5 h, and continued to increase for 48 h, even after the drug had been withdrawn. Furthermore, isoflurane-exposed HCC cells exhibited increased proliferation and invasion activity during the subsequent observation period. SUMO specific protease 3 (SENP3), which inhibits the binding of SUMO2/3 to its target proteins, was overexpressed and it was discovered that isoflurane-induced SUMOylation was significantly inhibited, and accordingly, the proliferation and invasion abilities of HCC cells were decreased to a certain extent. These findings indicated that SUMO2/3 is involved in the progression of HCC cells, at least in the Hep3B cell line, induced by the anesthetic isoflurane, and that inhibition of SUMO2/3 may antagonize the response. These results provided a novel target for decreasing the adverse reactions occurring in patients with HCC during anesthesia, particularly those who are exposed to isoflurane for long periods of time.

HIF-1α is a Potential Molecular Target for Herbal Medicine to Treat Diseases

HIF-1α is an important factor regulating oxygen balance in mammals, and its expression is closely related to various physiological and pathological conditions of the body. Because HIF-1α plays an important role in the occurrence and development of cancer and other diseases, it has become an enduring research hotspot. At the same time, natural medicines and traditional Chinese medicine compounds have amazing curative effects in various diseases related to HIF-1 subtype due to their unique pharmacological effects and more effective ingredients. Therefore, in this article, we first outline the structure of HIF-1α and the regulation related to its expression, then introduce various diseases closely related to HIF-1α, and finally focus on the regulation of natural medicines and compound Chinese medicines through various pathways. This will help us understand HIF-1α systematically, and use HIF-1α as a target to discover more natural medicines and traditional Chinese medicines that can treat related diseases.

Post-translational Modifications of IκBα: The State of the Art

The nuclear factor-kappa B (NF-κB) signaling pathway regulates a variety of biological functions in the body, and its abnormal activation contributes to the pathogenesis of many diseases, such as cardiovascular and respiratory diseases and cancers. Therefore, to ensure physiological homeostasis of body systems, this pathway is strictly regulated by IκBα transcription, IκBα synthesis, and the IκBα-dependent nuclear transport of NF-κB. Particularly, the post-translational modifications of IκBα including phosphorylation, ubiquitination, SUMOylation, glutathionylation and hydroxylation are crucial in the abovementioned regulatory process. Because of the importance of the NF-κB pathway in maintaining body homeostasis, understanding the post-translational modifications of IκBα can not only provide deeper insights into the regulation of NF-κB pathway but also contribute to the development of new drug targets and biomarkers for the diseases.

The Function of SUMOylation and Its Role in the Development of Cancer Cells under Stress Conditions: A Systematic Review

Malignant tumors still pose serious threats to human health due to their high morbidity and mortality. Recurrence and metastasis are the most important factors affecting patient prognosis. Chemotherapeutic drugs and radiation used to treat these tumors mainly interfere with tumor metabolism, destroy DNA integrity, and inhibit protein synthesis. The upregulation of small ubiquitin-like modifier (SUMO) is a prevalent posttranslational modification (PTM) in various cancers and plays a critical role in tumor development. The dysregulation of SUMOylation can protect cancer cells from stresses exerted by external or internal stimuli. SUMOylation is a dynamic process finely regulated by SUMOylation enzymes and proteases to maintain a balance between SUMOylation and deSUMOylation. An increasing number of studies have reported that SUMOylation imbalance may contribute to cancer development, including metastasis, angiogenesis, invasion, and proliferation. High level of SUMOylation is required for cancer cells to survive internal or external stresses. Downregulation of SUMOylation may inhibit the development of cancer, making it an important potential clinical therapeutic target. Some studies have already begun to treat tumors by inhibiting the expression of SUMOylation family members, including SUMO E1 or E2. The tumor cells become more aggressive under internal and external stresses. The prevention of tumor development, metastasis, recurrence, and radiochemotherapy resistance by attenuating SUMOylation requires further exploration. This review focused on SUMOylation in tumor cells to discuss its effects on tumor suppressor proteins and oncoproteins as well as classical tumor pathways to identify new insights for cancer clinical therapy.

Mass Spectrometry-Based Metabolic Fingerprinting Contributes to Unveil the Role of RSUME in Renal Cell Carcinoma Cell Metabolism

Clear cell renal cell carcinoma (ccRCC) is a heterogeneous disease with 50-80% patients exhibiting mutations in the von Hippel-Lindau (VHL) gene. RSUME (RWD domain (termed after three major RWD-containing proteins: RING finger-containing proteins, WD-repeat-containing proteins, and yeast DEAD (DEXD)-like helicases)-containing protein small ubiquitin-related modifier (SUMO) enhancer) acts as a negative regulator of VHL function in normoxia. A discovery-based metabolomics approach was developed by means of ultraperformance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (MS) for fingerprinting the endometabolome of a human ccRCC cell line 786-O and three other transformed cell systems (n = 102) with different expressions of RSUME and VHL. Cross-validated orthogonal projection to latent structures discriminant analysis models were built on positive, negative, and a combination of positive- and negative-ion mode MS data sets. Discriminant feature panels selected by an iterative multivariate classification allowed differentiating cells with different expressions of RSUME and VHL. Fifteen identified discriminant metabolites with level 1, including glutathione, butyrylcarnitine, and acetylcarnitine, contributed to understand the role of RSUME in ccRCC. Altered pathways associated with the RSUME expression were validated by biological and bioinformatics analyses. Combined results showed that in the absence of VHL, RSUME is involved in the downregulation of the antioxidant defense system, whereas in the presence of VHL, it acts in rerouting energy-related pathways, negatively modulating the lipid utilization, and positively modulating the fatty acid synthesis, which may promote deposition in droplets.

The Role of Sumoylation in the Response to Hypoxia: An Overview

Sumoylation is the covalent attachment of the small ubiquitin-related modifier (SUMO) to a vast variety of proteins in order to modulate their function. Sumoylation has emerged as an important modification with a regulatory role in the cellular response to different types of stress including osmotic, hypoxic and oxidative stress. Hypoxia can occur under physiological or pathological conditions, such as ischemia and cancer, as a result of an oxygen imbalance caused by low supply and/or increased consumption. The hypoxia inducible factors (HIFs), and the proteins that regulate their fate, are critical molecular mediators of the response to hypoxia and modulate procedures such as glucose and lipid metabolism, angiogenesis, erythropoiesis and, in the case of cancer, tumor progression and metastasis. Here, we provide an overview of the sumoylation-dependent mechanisms that are activated under hypoxia and the way they influence key players of the hypoxic response pathway. As hypoxia is a hallmark of many diseases, understanding the interrelated connections between the SUMO and the hypoxic signaling pathways can open the way for future molecular therapeutic interventions.

SUMO: From Bench to Bedside

Sentrin/small ubiquitin-like modifier (SUMO) is protein modification pathway that regulates multiple biological processes, including cell division, DNA replication/repair, signal transduction, and cellular metabolism. In this review, we will focus on recent advances in the mechanisms of disease pathogenesis, such as cancer, diabetes, seizure, and heart failure, which have been linked to the SUMO pathway. SUMO is conjugated to lysine residues in target proteins through an isopeptide linkage catalyzed by SUMO-specific activating (E1), conjugating (E2), and ligating (E3) enzymes. In steady state, the quantity of SUMO-modified substrates is usually a small fraction of unmodified substrates due to the deconjugation activity of the family Sentrin/SUMO-specific proteases (SENPs). In contrast to the complexity of the ubiquitination/deubiquitination machinery, the biochemistry of SUMOylation and de-SUMOylation is relatively modest. Specificity of the SUMO pathway is achieved through redox regulation, acetylation, phosphorylation, or other posttranslational protein modification of the SUMOylation and de-SUMOylation enzymes. There are three major SUMOs. SUMO-1 usually modifies a substrate as a monomer; however, SUMO-2/3 can form poly-SUMO chains. The monomeric SUMO-1 or poly-SUMO chains can interact with other proteins through SUMO-interactive motif (SIM). Thus SUMO modification provides a platform to enhance protein-protein interaction. The consequence of SUMOylation includes changes in cellular localization, protein activity, or protein stability. Furthermore, SUMO may join force with ubiquitin to degrade proteins through SUMO-targeted ubiquitin ligases (STUbL). After 20 yr of research, SUMO has been shown to play critical roles in most, if not all, biological pathways. Thus the SUMO enzymes could be targets for drug development to treat human diseases.

Toll like Receptor signalling by Prevotella histicola activates alternative NF-κB signalling in Cystic Fibrosis bronchial epithelial cells compared to P. aeruginosa

Cystic Fibrosis (CF), caused by mutations affecting the CFTR gene, is characterised by viscid secretions in multiple organ systems. CF airways contain thick mucus, creating a gradient of hypoxia, which promotes the establishment of polymicrobial infection. Such inflammation predisposes to further infection, a self-perpetuating cycle in mediated by NF-κB. Anaerobic Gram-negative Prevotella spp. are found in sputum from healthy volunteers and CF patients and in CF lungs correlate with reduced levels of inflammation. Prevotella histicola (P. histicola) can suppress murine lung inflammation, however, no studies have examined the role of P. histicola in modulating infection and inflammation in the CF airways. We investigated innate immune signalling and NF-kB activation in CF epithelial cells CFBE41o- in response to clinical stains of P. histicola and Pseudomonas aeruginosa (P. aeruginosa). Toll-Like Receptor (TLR) expressing HEK-293 cells and siRNA assays for TLRs and IKKα were used to confirm signalling pathways. We show that P. histicola infection activated the alternative NF-kB signalling pathway in CF bronchial epithelial cells inducing HIF-1α protein. TLR5 signalling was responsible for the induction of the alternative NF-kB pathway through phosphorylation of IKKα. The induction of transcription factor HIF-1α was inversely associated with the induction of the alternative NF-kB pathway and knockdown of IKKα partially restored canonical NF-kB activation in response to P. histicola. This study demonstrates that different bacterial species in the respiratory microbiome can contribute differently to inflammation, either by activating inflammatory cascades (P. aeruginosa) or by muting the inflammatory response by modulating similar or related pathways (P. histicola). Further work is required to assess the complex interactions of the lung microbiome in response to mixed bacterial infections and their effects in people with CF.