The roles of HMGB1-produced DNA gaps in DNA protection and aging biomarker reversal

Impact of HMGB1 on cancer development and therapeutic insights focused on CNS malignancy

The present study explores the complex roles of High Mobility Group Box 1 (HMGB1) in the context of cancer development, emphasizing glioblastoma (GBM) and other central nervous system (CNS) cancers. HMGB1, primarily known for its involvement in inflammation and angiogenesis, emerges as a multifaceted player in the tumorigenesis of GBM. The overexpression of HMGB1 correlates with glioma malignancy, influencing key pathways like RAGE/MEK/ERK and RAGE/Rac1. Additionally, HMGB1 secretion is linked to the maintenance of glioma stem cells (GSCs) and contributes to the tumor microenvironment's (TME) vascular leakiness. Henceforth, our review discusses the bidirectional impact of HMGB1, acting as both a promoter of tumor progression and a mediator of anti-tumor immune responses. Notably, HMGB1 exhibits tumor-suppressive roles by inducing apoptosis, limiting cellular proliferation, and enhancing the sensitivity of GBM to therapeutic interventions. This dualistic nature of HMGB1 calls for a nuanced understanding of its implications in GBM pathogenesis, offering potential avenues for more effective and personalized treatment strategies. The findings underscore the need to explore HMGB1 as a prognostic marker, therapeutic target, and a promising tool for stimulating anti-tumor immunity in GBM.

Box A of HMGB1 Maintains the DNA Gap and Prevents DDR-induced Kidney Injury in D-galactose Induction Rats

BACKGROUND/AIM

Disability and mortality rates for renal failure are still increasing. DNA damage and oxidative stress intoxication from body metabolism, high blood glucose, or the environment cause significant kidney damage. Recently, we reported that Box A of HMGB1 (Box A) acts as molecular scissors, producing DNA gaps that prevent DNA damage in kidney cell lines and ultimately reverse aging phenotypes in aging rat models. The present study aimed to demonstrate the potency of Box A in preventing D-galactose (D-gal)-induced kidney injury.

MATERIALS AND METHODS

A Box A expression plasmid was constructed and administered to a rat model. D-gal was injected subcutaneously for eight weeks. Serum was collected to study renal function, and white blood cells were collected for DNA gap measurement. Kidney tissue was also collected for γ-H2AX and NF-κB immunostaining; Senescence-associated (SA)-beta-gal staining; and analysis of the mRNA expression of p16INK4A, TNF-α, and IL-6. Moreover, histopathology analysis was performed using hematoxylin & eosin and Masson trichome staining.

RESULTS

Pretreatment with Box A administration prevented the reduction of DNA gaps and the consequences of the DNA damage response, which include elevated serum creatinine; high serum BUN; an increased positive SA-beta-gal staining area; overexpression of p16INK4A, NF-κB and senescence-associated secretory phenotype molecules, including IL-6, TNF-α; and histological alterations, including tubular dilation and collagen accumulation.

CONCLUSION

Box A effectively prevents DNA gap reduction and all D-gal-induced kidney pathological changes at the molecular, histological, and physiological levels. Therefore, Box A administration is a promising novel therapeutic strategy to prevent DNA-damaging agent-induced kidney failure.

Targeting Neutrophil Extracellular Traps in Gouty Arthritis: Insights into Pathogenesis and Therapeutic Potential

Gouty arthritis (GA) is an immune-mediated disorder characterized by severe inflammation due to the deposition of monosodium urate (MSU) crystals in the joints. The pathophysiological mechanisms of GA are not yet fully understood, and therefore, the identification of effective therapeutic targets is of paramount importance. Neutrophil extracellular traps (NETs), an intricate structure of DNA scaffold, encompassing myeloperoxidase, histones, and elastases - have gained significant attention as a prospective therapeutic target for gouty arthritis, due to their innate antimicrobial and immunomodulatory properties. Hence, exploring the therapeutic potential of NETs in gouty arthritis remains an enticing avenue for further investigation. During the process of gouty arthritis, the formation of NETs triggers the release of inflammatory cytokines, thereby contributing to the inflammatory response, while MSU crystals and cytokines are sequestered and degraded by the aggregation of NETs. Here, we provide a concise summary of the inflammatory processes underlying the initiation and resolution of gouty arthritis mediated by NETs. Furthermore, this review presents an overview of the current pharmacological approaches for treating gouty arthritis and summarizes the potential of natural and synthetic product-based inhibitors that target NET formation as novel therapeutic options, alongside elucidating the intrinsic challenges of these inhibitors in NETs research. Lastly, the limitations of HL-60 cell as a suitable substitute of neutrophils in NETs research are summarized and discussed. Series of recommendations are provided, strategically oriented towards guiding future investigations to effectively address these concerns. These findings will contribute to an enhanced comprehension of the interplay between NETs and GA, facilitating the proposition of innovative therapeutic strategies and novel approaches for the management of GA.

The inverse association between DNA gaps and HbA1c levels in type 2 diabetes mellitus

Naturally occurring DNA gaps have been observed in eukaryotic DNA, including DNA in nondividing cells. These DNA gaps are found less frequently in chronologically aging yeast, chemically induced senescence cells, naturally aged rats, D-galactose-induced aging model rats, and older people. These gaps function to protect DNA from damage, so we named them youth-associated genomic stabilization DNA gaps (youth-DNA-gaps). Type 2 diabetes mellitus (type 2 DM) is characterized by an early aging phenotype. Here, we explored the correlation between youth-DNA-gaps and the severity of type 2 DM. Here, we investigated youth-DNA-gaps in white blood cells from normal controls, pre-DM, and type 2 DM patients. We found significantly decreased youth-DNA-gap numbers in the type 2 DM patients compared to normal controls (P = 0.0377, P = 0.0018 adjusted age). In the type 2 DM group, youth-DNA-gaps correlate directly with HbA1c levels. (r = - 0.3027, P = 0.0023). Decreased youth-DNA-gap numbers were observed in patients with type 2 DM and associated with increased HbA1c levels. Therefore, the decrease in youth-DNA-gaps is associated with the molecular pathogenesis of high blood glucose levels. Furthermore, youth-DNA-gap number is another marker that could be used to determine the severity of type 2 DM.

Targeting HMGB1: A Potential Therapeutic Strategy for Chronic Kidney Disease

High-mobility group protein box 1 (HMGB1) is a member of a highly conserved high-mobility group protein present in all cell types. HMGB1 plays multiple roles both inside and outside the cell, depending on its subcellular localization, context, and post-translational modifications. HMGB1 is also associated with the progression of various diseases. Particularly, HMGB1 plays a critical role in CKD progression and prognosis. HMGB1 participates in multiple key events in CKD progression by activating downstream signals, including renal inflammation, the onset of persistent fibrosis, renal aging, AKI-to-CKD transition, and important cardiovascular complications. More importantly, HMGB1 plays a distinct role in the chronic pathophysiology of kidney disease, which differs from that in acute lesions. This review describes the regulatory role of HMGB1 in renal homeostasis and summarizes how HMGB1 affects CKD progression and prognosis. Finally, some promising therapeutic strategies for the targeted inhibition of HMGB1 in improving CKD are summarized. Although the application of HMGB1 as a therapeutic target in CKD faces some challenges, a more in-depth understanding of the intracellular and extracellular regulatory mechanisms of HMGB1 that underly the occurrence and progression of CKD might render HMGB1 an attractive therapeutic target for CKD.

The Role of Box A of HMGB1 in Enhancing Stem Cell Properties of Human Mesenchymal Cells: A Novel Approach for the Pursuit of Anti-aging Therapy

BACKGROUND/AIM

Box A is a highly conserved DNA-binding domain of high-mobility group box 1 (HMGB1) and has been shown to reverse senescence and aging features in many cell models. We investigated whether the activation of box A can influence stem cell properties.

MATERIALS AND METHODS

Human dermal papilla (DP) cells and primary human white pre-adipocytes (HWPc) were employed as mesenchymal cell models. Box A-overexpressing plasmids were used to induce cellular box A expression. mRNA and protein levels of stemness markers POU class 5 homeobox 1 pseudogene 5 (OCT4, HGNC: 9221), Nanog homeobox (NANOG, HGNC: 20857), and SRY-box transcription factor 2 (SOX2, HGNC:11195) in DP cells and HWPc were measured by real-time polymerase chain reaction and immunofluorescence analysis, respectively.

RESULTS

Transfection efficiency of box A-overexpressing plasmid was 80% and 50% in DP cells and HWPc, respectively. The proliferative rate of both cell types significantly increased 72 h after transfection. Levels of OCT4, NANOG and SOX2 mRNA and protein expression were significantly increased in box A-transfected DP cells and HWPc compared to empty plasmid-transfected cells. Immunofluorescence analysis confirmed the induction of OCT4, NANOG and SOX2 protein expression in response to box A in DP cells and HWPc. OCT4 and SOX2 were expressed in both the nuclear and cytoplasmic compartments, while NANOG was intensely located in the nucleus of box A-transfected cells.

CONCLUSION

Our findings suggest that box A may potentially enhance stemness, which may have significant benefits in improving stem cell function due to aging processes and disease. This research may have implications for regenerative medicine applications.

The Redox Protein High-Mobility Group Box 1 in Cell Death and Cancer

Significance: As a redox-sensitive protein, high-mobility group box 1 (HMGB1) is implicated in regulating stress responses to oxidative damage and cell death, which are closely related to the pathology of inflammatory diseases, including cancer. Recent Advances: HMGB1 is a nonhistone nuclear protein that acts as a deoxyribonucleic acid chaperone to control chromosomal structure and function. HMGB1 can also be released into the extracellular space and function as a damage-associated molecular pattern protein during cell death, including during apoptosis, necrosis, necroptosis, pyroptosis, ferroptosis, alkaliptosis, and cuproptosis. Once released, HMGB1 binds to membrane receptors to shape immune and metabolic responses. In addition to subcellular localization, the function and activity of HMGB1 also depend on its redox state and protein posttranslational modifications. Abnormal HMGB1 plays a dual role in tumorigenesis and anticancer therapy (e.g., chemotherapy, radiation therapy, and immunotherapy) depending on the tumor types and stages. Critical Issues: A comprehensive understanding of the role of HMGB1 in cellular redox homeostasis is important for deciphering normal cellular functions and pathological manifestations. In this review, we discuss compartmental-defined roles of HMGB1 in regulating cell death and cancer. Understanding these advances may help us develop potential HMGB1-targeting drugs or approaches to treat oxidative stress-related diseases or pathological conditions. Future Directions: Further studies are required to dissect the mechanism by which HMGB1 maintains redox homeostasis under different stress conditions. A multidisciplinary effort is also required to evaluate the potential applications of precisely targeting the HMGB1 pathway in human health and disease. Antioxid. Redox Signal. 39, 569-590.

Decreased Alu methylation in type 2 diabetes mellitus patients increases HbA1c levels

INTRODUCTION

Alu hypomethylation is a common epigenetic process that promotes genomic instability with aging phenotypes, which leads to type 2 diabetes mellitus (type 2 DM). Previously, our results showed significantly decreased Alu methylation levels in type 2 DM patients. In this study, we aimed to investigate the longitudinal changes in Alu methylation levels in these patients.

RESULTS

We observed significantly decreased Alu methylation levels in type 2 DM patients compared with normal (p = 0.0462). Moreover, our findings demonstrated changes in Alu hypomethylation over a follow-up period within the same individuals (p < 0.0001). A reduction in Alu methylation was found in patients with increasing HbA1c levels (p = 0.0013) and directly correlated with increased HbA1c levels in type 2 DM patients (r = -0.2273, p = 0.0387).

CONCLUSIONS

Alu methylation in type 2 DM patients progressively decreases with increasing HbA1c levels. This observation suggests a potential association between Alu hypomethylation and the underlying molecular mechanisms of elevated blood glucose. Furthermore, monitoring Alu methylation levels may serve as a valuable biomarker for assessing the clinical outcomes of type 2 DM.

The redox protein HMGB1 in cell death and cancer

SIGNIFICANCE

As a redox-sensitive protein, high-mobility group box 1 (HMGB1) is implicated in regulating stress responses to oxidative damage and cell death, which are closely related to the pathology of inflammatory diseases, including cancer.

RECENT ADVANCES

HMGB1 is a non-histone nuclear protein that acts as a DNA chaperone to control chromosomal structure and function. HMGB1 can also be released into the extracellular space and function as a damage-associated molecular pattern protein during cell death, including during apoptosis, necrosis, necroptosis, pyroptosis, ferroptosis, alkaliptosis, and cuproptosis. Once released, HMGB1 binds to membrane receptors to shape immune and metabolic responses. In addition to subcellular localization, the function and activity of HMGB1 also depends on its redox state and protein posttranslational modifications. Abnormal HMGB1 plays a dual role in tumorigenesis and anticancer therapy (e.g., chemotherapy, radiation therapy, and immunotherapy) depending on tumor types and stages.

CRITICAL ISSUES

A comprehensive understanding of the role of HMGB1 in cellular redox homeostasis is important for deciphering normal cellular functions and pathological manifestations. In this review, we discuss compartmental-defined roles of HMGB1 in regulating cell death and cancer. Understanding these advances may help us develop potential HMGB1-targeting drugs or approaches to treat oxidative stress-related diseases or pathological conditions.

FUTURE DIRECTIONS

Further studies are required to dissect the mechanism by which HMGB1 maintains redox homeostasis under different stress conditions. A multidisciplinary effort is also required to evaluate the potential applications of precisely targeting the HMGB1 pathway in human health and disease.

The landscape of histone modifications in epigenomics since 2020

Histone proteins are a primary component of chromatin; therefore, any modifications to their structure are anticipated to affect the behavior of our genetic material, which is manifested in the form of phenotypic changes at a molecular, cellular or organic level. The majority of histone modifications are of either methylation or acetylation type that regulate gene expression. Though, not all of these modifications are concerned with the direct regulation of gene transcription. Throughout its 13-year run, Epigenomics has never ceased to cover these most gripping epigenetic stories, a significant proportion of which is in the matter of histones and their modifications. As such, the current perspective piece is intended to highlight original histone-oriented contributions published in Epigenomics since 2020.

Magnetic bioassembly platforms for establishing craniofacial exocrine gland organoids as aging in vitro models

A multitude of aging-related factors and systemic conditions can cause lacrimal gland (LG) or salivary gland (SG) hypofunction leading to degenerative dry eye disease (DED) or dry mouth syndrome, respectively. Currently, there are no effective regenerative therapies that can fully reverse such gland hypofunction due to the lack of reproducible in vitro aging models or organoids required to develop novel treatments for multi-omic profiling. Previously, our research group successful developed three-dimensional (3D) bioassembly nanotechnologies towards the generation of functional exocrine gland organoids via magnetic 3D bioprinting platforms (M3DB). To meet the needs of our aging Asian societies, a next step was taken to design consistent M3DB protocols to engineer LG and SG organoid models with aging molecular and pathological features. Herein, a feasible step-by-step protocol was provided for producing both LG and SG organoids using M3DB platforms. Such protocol provided reproducible outcomes with final organoid products resembling LG or SG native parenchymal epithelial tissues. Both acinar and ductal epithelial compartments were prominent (21 ± 4.32% versus 42 ± 6.72%, respectively), and could be clearly identified in these organoids. Meanwhile, these can be further developed into aging signature models by inducing cellular senescence via chemical mutagenesis. The generation of senescence-like organoids will be our ultimate milestone aiming towards high throughput applications for drug screening and discovery, and for gene therapy investigations to reverse aging.

Human RNA-directed DNA methylation methylates high-mobility group box 1 protein-produced DNA gaps

Background: DNA sequences around HMGB1-produced DNA gaps are hypermethylates. DNA methylation of interspersed repetitive sequences (IRS) such as Alu elements can be established through AGO4-mediating, RNA-directed DNA methylation (RdDM). HMGB1 depletion, DNA gap reduction and global hypomethylation promote genomic instability. Methods: HMGB1, SIRT1, AGO4 and DNA gap colocalizations were evaluated. Then, Alu methylation was analyzed in HMGB1-deficient or HMGB1-overexpressing cells and Alu siRNA-transfected HMGB1-deficient cells. Results: HMGB1, SIRT1, AGO4 and DNA gap are colocalized in the nucleus. Moreover, HMGB1 or Alu siRNA increased Alu methylation, whereas Alu siRNA could not methylate HMGB1-deficient cells. Conclusion: AGO4 play a role in methylating DNA sequence around HMGB1-produced DNA gaps and localize DNA gap in IRS, and loss of intranuclear HMGB1 causes global hypomethylation.