Targeting the transcription factor HES1 by L-menthol restores protein phosphatase 6 in keratinocytes in models of psoriasis

Defactinib inhibits FAK phosphorylation and regulates psoriasis via attenuating hyperproliferation of keratinocytes

Excessive proliferation of keratinocytes is a crucial pathological risk feature of psoriasis. Focal adhesion kinase (FAK) is a non-receptor protein that primarily regulates cell proliferation and migration. However, the expression and regulatory mechanism of FAK in psoriasis remains unclear. This study aimed to investigate the regulation of FAK in psoriasis and examined the potential impact of FAK inhibitor on psoriasis. A small molecular selective FAK inhibitor, defactinib, was used to evaluate the effect of FAK on psoriasis in in vitro and in vivo functional assays. In our experiments, imiquimod (IMQ)-induced psoriasis mice and human keratinocytes cells were used to study the potential roles and mechanisms of FAK in psoriasis. FAK phosphorylation has been weakly detected in normal intact skin and is markedly elevated upon IMQ treatment. By reducing FAK phosphorylation (p-FAK), defactinib treatment could attenuate psoriasiform inflammation and epidermal hyperplasia in IMQ-treated mice compared with IMQ-induced mice treated with the vehicle. In in vitro studies, resiquimod (R848) increased (p-FAK) and promoted cell proliferation in human keratinocytes cells, while defactinib reversed this effect. Mechanistically, defactinib can alleviate the proliferation via JNK/YB1 pathway in vitro and in vivo. Defactinib significantly attenuates psoriasiform inflammation and epidermal hyperproliferation through the inhibition of the FAK-mediated axis. The downregulation of phosphorylated FAK then suppressed the activation of JNK/YB1 protein signaling pathway in psoriasis. Our work highlights targeting FAK as a potentially effective strategy for the treatment of psoriasis.

Protein phosphatase 6 promotes stemness of colorectal cancer cells

Colorectal cancer (CRC) remains a significant global health concern, demanding a more profound comprehension of its molecular foundations for the development of improved therapeutic strategies. This study aimed to elucidate the role of protein phosphatase 6 (PP6), a member of the type 2A protein phosphatase family, in CRC. Protein phosphatase 6 functions as a heterotrimer with a catalytic subunit (PP6c), regulatory subunits (PP6Rs; PP6R1, PP6R2, and PP6R3), and scaffold subunits (ANKRD28, ANKRD44, and ANKRD52). Elevated PP6c expression has been identified in CRC tissues compared to normal mucosa, aligning with its potential involvement in CRC pathogenesis. PP6c knockdown resulted in decreased colony-forming ability and in vivo proliferation of various CRC cell lines. Transcriptome analysis revealed that PP6c knockdown resulted in altered expression of genes associated with cancer stemness. Notably, the PP6c-PP6R3 complex is a key player in regulating cancer stem cell (CSC) markers. Additionally, increased PP6c expression was observed in CSC-like cells induced by sphere formation, implicating the role of PP6c in CSC maintenance. This study highlights the role of PP6c in CRC and suggests that it is a potential therapeutic target disrupting a pathway critical for CRC progression and stem cell maintenance.

Fibroblast: A Novel Target for Autoimmune and Inflammatory Skin Diseases Therapeutics

Fibroblasts are crucial components of the skin structure. They were traditionally believed to maintain the skin's structure by producing extracellular matrix and other elements. Recent research illuminated that fibroblasts can respond to external stimuli and exhibit diverse functions, such as the secretion of pro-inflammatory factors, adipogenesis, and antigen presentation, exhibiting remarkable heterogeneity and plasticity. This revelation positions fibroblasts as active contributors to the pathogenesis of skin diseases, challenging the traditional perspective that views fibroblasts solely as structural entities. Based on their diverse functions, fibroblasts can be categorized into six subtypes: pro-inflammatory fibroblasts, myofibroblasts, adipogenic fibroblasts, angiogenic fibroblasts, mesenchymal fibroblasts, and antigen-presenting fibroblasts. Cytokines, metabolism, and epigenetics regulate functional abnormalities in fibroblasts. The dynamic changes fibroblasts exhibit in different diseases and disease states warrant a comprehensive discussion. We focus on dermal fibroblasts' aberrant manifestations and pivotal roles in inflammatory and autoimmune skin diseases, including psoriasis, vitiligo, lupus erythematosus, scleroderma, and atopic dermatitis, and propose targeting aberrantly activated fibroblasts as a potential therapeutic strategy for inflammatory and autoimmune skin diseases.

Ubiquitin-specific protease 54 regulates GLUT1-mediated aerobic glycolysis to inhibit lung adenocarcinoma progression by modifying p53 degradation

Lung adenocarcinoma (LUAD) is one of the most prevalent types of cancer. Ubiquitination is crucial in modulating cell proliferation and aerobic glycolysis in cancer. The frequency of TP53 mutations in LUAD is approximately 50%. Currently, therapeutic targets for wild-type (WT) p53-expressing LUAD are limited. In the present study, we systemically explored the expression of ubiquitin-specific protease genes using public datasets. Then, we focused on ubiquitin-specific protease 54 (USP54), and explored its prognostic significance in LUAD patients using public datasets, analyses, and an independent cohort from our center. We found that the expression of USP54 was lower in LUAD tissues compared with that in the paracancerous tissues. Low USP54 expression levels were linked to a malignant phenotype and worse survival in patients with LUAD. The results of functional experiments revealed that up-regulation of USP54 suppressed LUAD cell proliferation in vivo and in vitro. USP54 directly interacted with p53 protein and the levels of ubiquitinated p53 were inversely related to USP54 levels, consistent with a role of USP54 in deubiquitinating p53 in p53-WT LUAD cells. Moreover, up-regulation of the USP54 expression inhibited aerobic glycolysis in LUAD cells. Importantly, we confirmed that USP54 inhibited aerobic glycolysis and the growth of tumor cells by a p53-mediated decrease in glucose transporter 1 (GLUT1) expression in p53-WT LUAD cells. Altogether, we determined a novel mechanism of survival in the p53-WT LUAD cells to endure the malnourished tumor microenvironment and provided insights into the role of USP54 in the adaptation of p53-WT LUAD cells to metabolic stress.

CPT-11 mitigates autoimmune diseases by suppressing effector T cells without affecting long-term anti-tumor immunity

The incidence of autoimmune diseases has significantly increased over the past 20 years. Excessive host immunoreactions and disordered immunoregulation are at the core of the pathogenesis of autoimmune diseases. The traditional anti-tumor chemotherapy drug CPT-11 is associated with leukopenia. Considering that CPT-11 induces leukopenia, we believe that it is a promising drug for the control of autoimmune diseases. Here, we show that CPT-11 suppresses T cell proliferation and pro-inflammatory cytokine production in healthy C57BL/6 mice and in complete Freund's adjuvant-challenged mice. We found that CPT-11 effectively inhibited T cell proliferation and Th1 and Th17 cell differentiation by inhibiting glycolysis in T cells. We also assessed CPT-11 efficacy in treating autoimmune diseases in models of experimental autoimmune encephalomyelitis and psoriasis. Finally, we proved that treatment of autoimmune diseases with CPT-11 did not suppress long-term immune surveillance for cancer. Taken together, these results show that CPT-11 is a promising immunosuppressive drug for autoimmune disease treatment.

NU6300 covalently reacts with cysteine-191 of gasdermin D to block its cleavage and palmitoylation

Gasdermin D (GSDMD) serves as a vital mediator of inflammasome-driven pyroptosis. In our study, we have identified NU6300 as a specific GSDMD inhibitor that covalently interacts with cysteine-191 of GSDMD, effectively blocking its cleavage while not affecting earlier steps such as ASC oligomerization and caspase-1 processing in AIM2- and NLRC4-mediated inflammation. On the contrary, NU6300 robustly inhibits these earlier steps in NLRP3 inflammasome, confirming a unique feedback inhibition effect in the NLRP3-GSDMD pathway upon GSDMD targeting. Our study reveals a previously undefined mechanism of GSDMD inhibitors: NU6300 impairs the palmitoylation of both full-length and N-terminal GSDMD, impeding the membrane localization and oligomerization of N-terminal GSDMD. In vivo studies further demonstrate the efficacy of NU6300 in ameliorating dextran sodium sulfate-induced colitis and improving survival in lipopolysaccharide-induced sepsis. Overall, these findings highlight the potential of NU6300 as a promising lead compound for the treatment of inflammatory diseases.

The associations between gut microbiota and inflammatory skin diseases: a bi-directional two-sample Mendelian randomization study

Background

Accumulating evidence shows that dysregulation of intestinal flora is associated with inflammatory skin diseases, specifically atopic dermatitis (AD), psoriasis (PSO), and rosacea (ROS). However, the causality is still unclear.

Objectives

To study the underlying causality between gut microbiota (GM) and AD, PSO, and ROS, a bi-directional two-sample Mendelian randomization (2SMR) analysis was conducted.

Methods

Summary statistics of gut microbiota, AD, PSO, and ROS were extracted from large-scale genome-wide association studies (GWASs). In 2SMR analysis, in addition to the inverse variance weighted as the principal method for evaluating causal association, four different methods were also used. Sensitivity analysis and reverse 2SMR study were implemented to evaluate the robustness of 2SMR results or reverse causal relationship, respectively.

Results

A total of 24 specific gut microbiota species related to AD, PSO, and ROS were identified by 2SMR analysis. After using the Bonferroni method for multiple testing correction, family FamilyXIII (ID: 1957) [OR = 1.28 (1.13, 1.45), p = 9.26e-05] and genus Eubacteriumfissicatenagroup (ID: 14373) [OR = 1.20 (1.09, 1.33), p = 1.65e-04] were associated with an increased risk for AD and PSO, respectively. The genus Dialister showed a negative association, suggesting a protective role against both atopic dermatitis and rosacea. Our reverse 2SMR analysis indicated no reverse causality between these inflammatory skin diseases and the identified gut microbiota.

Conclusions

In summary, this study provided evidence for the causality between GM and inflammatory skin diseases. These findings suggested that supplementing specific bacterial taxa may be an effective therapy for AD, PSO, and ROS.

Protein phosphatase 6 promotes transforming growth factor-β signaling in mouse embryonic fibroblasts

Transforming growth factor-beta (TGF-β) is a multifunctional cytokine that controls various cellular processes. Protein phosphatase 6 (PP6) is an evolutionarily conserved serine/threonine protein phosphatase with diverse functions in cell signaling. However, it has not been linked to TGF-β signaling. We found that TGF-β treatment increased PP6 protein levels via transcriptional and post-translational regulation. Loss of the Ppp6c gene suppressed TGF-β-induced canonical Smad3 phosphorylation and its transcriptional activity. PP6 knockout also inhibited non-canonical p38 mitogen-activated protein kinase (MAPK) pathway. Moreover, PP6 depletion suppressed cell migration induced by TGF-β. These findings uncovered the role of PP6 as a positive regulator for TGF-β signaling.

Liraglutide intervention improves high-glucose-induced reactive gliosis of Müller cells and ECM dysregulation

Reactive gliosis of Müller cells plays an important role in the pathogenesis of diabetic retinopathy (DR). Liraglutide, a glucagon-like peptide-1 receptor (GLP-1R) agonist, has been shown to improve DR by inhibiting reactive gliosis. However, the mechanism of inhibition has yet to be elucidated. This study investigated the effects of liraglutide on Müller glia reactivity in the early stages of DR and the underlying mechanisms. Proteomics combined with bioinformatics analysis, HE staining, and immunofluorescence staining revealed ganglion cell loss, reactive gliosis of Müller cells, and extracellular matrix (ECM) imbalance in rats with early stages of DR. High glucose (HG) exposure up-regulated GFAP and TNF-α expression and down-regulated ITGB1 expression and FN1 content in extracellular fluid in rMC1 cells, thereby promoting reactive gliosis. GLP-1R knockdown and HG+DAPT inhibition experiments show that liraglutide balances ECM levels by inhibiting activation of the Notch1/Hes1 pathway and ameliorates high-glucose-induced Müller glia reactivity. Thus, the study provides new targets and ideas for improvement of DR in early stages.