RETRACTED: MLL1 promotes migration and invasion of fibroblast-like synoviocytes in rheumatoid arthritis by activating the TRIF/NF-κB signaling pathway via H3K4me3 enrichment in the TLR4 promoter region

The inflammatory and oxidative phenotype of gestational diabetes is epigenetically transmitted to the offspring: role of methyltransferase MLL1-induced H3K4me3

BACKGROUND AND AIMS

Hyperglycaemia during gestational diabetes (GD) predisposes women and their offspring to later cardiometabolic disease. The hyperglycaemia-mediated epigenetic changes remain to be elucidated. Methyltransferase MLL1-induced trimethylation of histone 3 at lysine 4 (H3K4me3) activates inflammatory and oxidative phenotype. This epigenetic mark in GD women and its transmission to the offspring were investigated.

METHODS

Peripheral blood mononuclear cells (PBMC) were collected from GD and control (C) women and also from adolescents born to women of both groups. Endothelial human umbilical vein endothelial cells (HUVEC) and cord blood mononuclear cells (CBMC) were from umbilical cords. The NF-κBp65 and NOX4 expressions were investigated by reverse transcription quantitative polymerase chain reaction and immunofluorescence (IF). MLL1 and H3K4me3 were investigated by immunoblotting and IF. H3K4me3 on NF-κBp65 and NOX4 promoters was studied by chromatin immunoprecipitation. Superoxide anion generation was measured by electron spin resonance spectroscopy. Plasma cytokines were measured by enzyme-linked immunosorbent assay. To investigate the role of MLL1, HUVEC were exposed to inhibitor MM102 or siRNA transfection.

RESULTS

PBMC, CBMC, and HUVEC showed an increase of NF-κBp65, IL-6, ICAM-1, MCP-1, and VCAM-1 mRNAs. These findings were associated with H3K4me3 enrichment in the promoter of NF-κBp65. Elevated H3K4me3 and cytokine levels were observed in GD adolescents. MLL1 drives H3K4me3 not only on NF-kB p65, but also on NOX4 promoter. Inhibition of MLL1 blunted NF-κBp65 and NOX4 by modulating inflammatory and oxidative phenotype.

CONCLUSIONS

Such proof-of-concept study shows persistence of MLL1-dependent H3K4me3 in offspring born to GD women, suggesting an epigenetic-driven transmission of maternal phenotype. These findings may pave the way for pharmacological reprogramming of adverse histone modifications to mitigate abnormal phenotypes underlying early ASCVD.

To stay in shape and keep moving: MLL emerges as a new transcriptional regulator of Rho GTPases

RhoA, Rac1 and CDC42 are small G proteins that play a crucial role in regulating various cellular processes, such as the formation of actin cytoskeleton, cell shape and cell migration. Our recent results suggest that MLL is responsible for maintaining the balance of these small Rho GTPases. MLL depletion affects the stability of Rho GTPases, leading to a decrease in their protein levels and loss of activity. These changes manifest in the form of abnormal cell shape and disrupted actin cytoskeleton, resulting in reduced cell spreading and migration. Interestingly, their chaperone protein RhoGDI1 but not the Rho GTPases, is under the direct transcriptional regulation of MLL. Here, we comment on the possible implications of these observations on the signalling by Rho GTPases protein network.

Epigenetic Regulations in Autoimmunity and Cancer: from Basic Science to Translational Medicine

Epigenetics, as a discipline that aims to explain the differential expression of phenotypes arising from the same gene sequence and the heritability of epigenetic expression, has received much attention in medicine. Epigenetic mechanisms are constantly being discovered, including DNA methylation, histone modifications, noncoding RNAs and m6A. The immune system mainly achieves an immune response through the differentiation and functional expression of immune cells, in which epigenetic modification will have an important impact. Because of immune infiltration in the tumor microenvironment, immunotherapy has become a research hotspot in tumor therapy. Epigenetics plays an important role in autoimmune diseases and cancers through immunology. An increasing number of drugs targeting epigenetic mechanisms, such as DNA methyltransferase inhibitors, histone deacetylase inhibitors, and drug combinations, are being evaluated in clinical trials for the treatment of various cancers (including leukemia and osteosarcoma) and autoimmune diseases (systemic lupus erythematosus, rheumatoid arthritis, systemic sclerosis). This review summarizes the progress of epigenetic regulation for cancers and autoimmune diseases to date, shedding light on potential therapeutic strategies.

MLL regulates the actin cytoskeleton and cell migration by stabilising Rho GTPases via the expression of RhoGDI1

Attainment of proper cell shape and the regulation of cell migration are essential processes in the development of an organism. The mixed lineage leukemia (MLL or KMT2A) protein, a histone 3 lysine 4 (H3K4) methyltransferase, plays a critical role in cell-fate decisions during skeletal development and haematopoiesis in higher vertebrates. Rho GTPases - RhoA, Rac1 and CDC42 - are small G proteins that regulate various key cellular processes, such as actin cytoskeleton formation, the maintenance of cell shape and cell migration. Here, we report that MLL regulates the homeostasis of these small Rho GTPases. Loss of MLL resulted in an abnormal cell shape and a disrupted actin cytoskeleton, which lead to diminished cell spreading and migration. MLL depletion affected the stability and activity of Rho GTPases in a SET domain-dependent manner, but these Rho GTPases were not direct transcriptional targets of MLL. Instead, MLL regulated the transcript levels of their chaperone protein RhoGDI1 (also known as ARHGDIA). Using MDA-MB-231, a triple-negative breast cancer cell line with high RhoGDI1 expression, we show that MLL depletion or inhibition by small molecules reduces tumour progression in nude mice. Our studies highlight the central regulatory role of MLL in Rho/Rac/CDC42 signalling pathways. This article has an associated First Person interview with the first author of the paper.

Anti-proliferation and anti-inflammation effects of corilagin in rheumatoid arthritis by downregulating NF-κB and MAPK signaling pathways

ETHNOPHARMACOLOGICAL RELEVANCE

The dried aboveground part of Geranium Wilfordii Maxim. (G. Wilfordii) is a traditional Chinese herbal medicine named lao-guan-cao. It has long been used for dispelling wind-dampness, unblocking meridians, and stopping diarrhea and dysentery. Previous investigations have revealed that 50% ethanolic extract of G. Wilfordii has anti-inflammatory and anti-proliferation activities on TNF-α induced murine fibrosarcoma L929 cells. Corilagin (COR) is a main compound in G. Wilfordii with the content up to 1.69 mg/g. Pharmacology study showed that COR has anti-inflammatory, anti-tumor, anti-microorganism, anti-oxidant, and hepatoprotective effects. However, there is no any investigation on its anti-proliferation and anti-inflammation effects in rheumatoid arthritis (RA).

AIM OF THE STUDY

The present study aimed to evaluate the potential pharmacological mechanisms of anti-proliferation and anti-inflammation effects of COR in RA.

MATERIALS AND METHODS

In vitro, MH7A cells model induced by IL-1β was used. The anti-proliferation activity of COR was assessed by Cell Counting Kit-8 (CCK-8) assay, and the anti-migration and anti-invasion activity of COR was determined by wound healing assay and transwell assay, respectively. Furthermore, apoptosis assay by flow cytometer was used to measure the pro-apoptotic effect of COR. The mRNA expressions of Bax, Bcl-2, IL-6, IL-8, MMP-1, MMP-2, MMP-3, MMP-9, COX-2, and iNOS were measured by qRT-PCR, and related protein were further verified by ELISA kits or Western blot. Moreover, protein levels associated with NF-κB and MAPK signaling pathways of p65, P-p65, IκBα, P-IκBα, ERK1/2, P-ERK1/2, JNK, P-JNK1/2/3, p38, and P-p38 were determined by Western blot. The nuclear translocation of NF-κB-p65 was detected by immunofluorescent staining. In vivo, adjuvant-induced arthritis (AIA) rat model was used, and the body weight, paw swelling, and arthritis score during the entire period were measured. Histopathological analysis of joints of synovial tissues was also determined. The expression of pro-inflammatory cytokines in serum including IL-6, TNF-α, IL-1β, and IL-17 were measured.

RESULTS

The in vitro results showed that COR could dose-dependently inhibit the proliferation, migration, and invasion of IL-1β-induced MH7A cells, as well as promote its apoptosis. Moreover, it also suppressed the over-expression of Bcl-2, IL-6, IL-8, MMP-1, MMP-2, MMP-3, MMP-9, COX-2, and iNOS while up-regulated the level of Bax. Besides, the ratios of P-p65/p65, P-IκBα/IκBα, P-ERK/ERK, P-JNK/JNK, and P-p38/p38 were decreased, and the nuclear translocation of p65 induced by IL-1β was blocked by COR. In vivo results indicated that COR significantly reduced the paw swelling and arthritis score in AIA rats, and inhibited synovial tissue hyperplasia and erosion, as well as inflammatory cells infiltration. It also decreased the serum pro-inflammatory cytokines (IL-6, TNF-α, IL-1β, and IL-17) production.

CONCLUSION

These results revealed that COR exerted anti-rheumatoid arthritis effect, and its underlying mechanisms may be related to inhibiting the proliferation, migration, and invasion of synovial fibroblasts, enhancing cell apoptosis, and suppressing inflammatory responses via downregulating NF-κB and MAPK signaling pathways.

Contribution of Toll-Like Receptors and the NLRP3 Inflammasome in Rheumatoid Arthritis Pathophysiology

Rheumatoid arthritis (RA) is a progressive autoimmune disease that is characterized by inflammation of the synovial joints leading to cartilage and bone damage. The pathogenesis is sustained by the production of pro-inflammatory cytokines including tumor necrosis factor (TNF), interleukin (IL)-1 and IL-6, which can be targeted therapeutically to alleviate disease severity. Several innate immune receptors are suggested to contribute to the chronic inflammation in RA, through the production of pro-inflammatory factors in response to endogenous danger signals. Much research has focused on toll-like receptors and more recently the nucleotide-binding domain and leucine-rich repeat pyrin containing protein-3 (NLRP3) inflammasome, which is required for the processing and release of IL-1β. This review summarizes the current understanding of the potential involvement of these receptors in the initiation and maintenance of inflammation and tissue damage in RA and experimental arthritis models.

Baicalein alleviates osteoarthritis by protecting subchondral bone, inhibiting angiogenesis and synovial proliferation

Osteoarthritis (OA) is one of the most frequent chronic joint diseases with the increasing life expectancy. The main characteristics of the disease are loss of articular cartilage, subchondral bone sclerosis and synovium inflammation. Physical measures, drug therapy and surgery are the mainstay of treatments for OA, whereas drug therapies are mainly limited to analgesics, glucocorticoids, hyaluronic acids and some alternative therapies because of single therapeutic target of OA joints. Baicalein, a traditional Chinese medicine extracted from Scutellaria baicalensis Georgi, has been widely used in anti‐inflammatory therapies. Previous studies revealed that baicalein could alleviate cartilage degeneration effectively by acting on articular chondrocytes. However, the mechanisms involved in baicalein‐mediated protection of the OA are not completely understood in consideration of integrality of arthrosis. In this study, we found that intra‐articular injection of baicalein ameliorated subchondral bone remodelling. Further studies showed that baicalein could decrease the number of differentiated osteoblasts by inhibiting pre‐osteoblasts proliferation and promoting pre‐osteoblasts apoptosis. In addition, baicalein impaired angiogenesis of endothelial cells and inhibited proliferation of synovial cells. Taken together, these results implicated that baicalein might be an effective medicine for treating OA by regulating multiple targets.