Yaqun Guan

Background: Ring Finger Protein 40 (RNF40), an E3 ubiquitin ligase, plays context-dependent roles in various cancers, serving as either a tumor suppressor or an oncogene. Critically, RNF40 targets LIM domain and actin-binding protein 1 (LIMA1) for degradation via the ubiquitin-proteasome pathway. LIMA1, which is involved in actin cytoskeleton organization, exerts opposing effects in different cancer types. However, the precise functional relationship between RNF40 and LIMA1 in Hepatocellular Carcinoma (HCC) remains poorly understood. Despite the efficacy of immune checkpoint inhibitors, intrinsic resistance affects 40-60% of patients, necessitating novel epigenetic and ubiquitin-related therapeutic targets. Methods: This study investigated the molecular mechanisms through which RNF40-mediated ubiquitination of LIMA1 influences Hepatocellular Carcinoma (HCC) progression. We utilized an integrative approach combining multi-omics analysis including bulk transcriptomics, single-cell RNA sequencing (scRNA-seq), and spatial transcriptomics with experimental validation using in vitro assays and in vivo mouse models. Differential expression analysis, survival outcome correlation, immune infiltration assessment, and cell-cell communication analyses were performed to characterize the roles of RNF40 and LIMA1 in HCC. Results: LIMA1 was significantly overexpressed in HCC across multiple transcriptomic and proteomic datasets (log2FC>1.5, P < 0.001), and its upregulation correlated with accelerated tumor proliferation, migration, invasion as well as an immunosuppressive checkpoint-enriched TME featured by M2 macrophage infiltration (R = 0.498, P < 0.001) and CD8+ T cell exclusion. Single-cell and spatial transcriptomic analyses indicated predominant LIMA1 enrichment in malignant cells and tumor lesions. LIMA1 overexpression facilitated HCC clonogenicity, migration, invasion and xenograft tumor growth. Conversely, ectopic RNF40 expression suppressed these malignant phenotypes, and such inhibitory effects were fully abolished upon concurrent LIMA1 overexpression both in vitro and in vivo . Re-analysis of TCGA-LIHC revealed that LIMA1 failed to serve as an independent prognostic marker after adjusting for clinicopathological covariates, warranting cautious interpretation of its prognostic implication. Conclusion: Our findings support the biological relevance of a functional RNF40-LIMA1 axis in HCC progression. Together with previously established biochemical evidence of RNF40-mediated LIMA1 ubiquitination and proteasome-dependent degradation, this study provides a rationale for further investigation of the RNF40-LIMA1 axis in HCC. The prognostic and immunotherapy-predictive value of LIMA1 requires validation in independent clinical cohorts and larger ICI-treated HCC datasets.

Long noncoding RNAs (LncRNAs) play critical roles in regulating gene expression and cellular processes, including adipocyte differentiation. LncRNA00602 is upregulated in adipose tissue. Therefore, we aimed to investigate the potential role of LncRNA00602 in adenovirus type 36 (Ad36)-induced adipocyte browning. Human adipose-derived stem cells were induced into adipocytes by Ad36, and were divided into the control and LncRNA00602 knockdown groups. Lipid droplets and mitochondria were stained with BODIPY and Mito Tracker Red, respectively. The binding of LncRNA00602 to upstream frameshift 1 (UPF1) was detected by RNA-immunoprecipitation. We used silver staining, co-immunoprecipitation, and mass spectrometry to detect and identify the protein complexes bound to UPF1. The control and caveolin-1 (CAV-1) knockdown groups were set up. The mRNA and protein levels were detected by real-time quantitative PCR and Western Blot. On days 2 and 4, compared with the control group, the lipid droplet area of adipocytes in the LncRNA00602 knockdown group was larger, whereas the mitochondrial fluorescence intensity was lower. We observed significant reductions in the mRNA and protein expression levels of ATP5O and COX5B in the LncRNA00602 knockdown group. LncRNA00602 could bind to UPF1. The proteins bound to UPF1 were involved in the nonsense-mediated mRNA decay pathway and lipid metabolism. Additionally, we found that CAV-1 mRNA and protein in the LncRNA00602 knockdown group were significantly lower than those in the control group. Furthermore, the mRNA and protein expression levels of UCP1, ATP5O, and COX5B in the CAV-1 knockdown group were significantly lower than those in the control group. In adipocytes induced by Ad36, LncRNA00602 may upregulate the expression of UCP1 and mitochondrial oxidative phosphorylation-related enzyme genes via the complex composed of UPF1 and CAV-1, thus inducing the browning of adipocytes.

RelA, also known as nuclear factor kappa B p65, plays a crucial role in the pathogenesis of various liver diseases. However, the specific role of RelA in hepatocytes during the progression of metabolic dysfunction-associated steatotic liver disease (MASLD) is not well understood. This study explored the relationship between impaired RelA signaling and lipid metabolism disorders in hepatocytes, and how they synergistically contribute to the advancement of MASLD. We assessed the changes, regulatory relationships, and impacts of RelA signaling and lipid metabolism remodeling on disease progression both in vitro and in vivo. During MASLD, there was a decrease in the expression of RelA and hepatocyte nuclear factor 1 alpha (HNF1α), with both factors showing mutual enhancement of each other’s expression under normal conditions. This synergistic effect was absent during hepatocyte steatosis. RelA or HNF1α depletion in hepatocytes intensified MASLD symptoms, whereas overexpression of RELA or treatment with necrostatin-1 (a necroptosis inhibitor) or Z-VAD (a caspase inhibitor) significantly mitigated these effects. Mechanistically, during hepatic steatosis, altered lipid profiles exhibited lipotoxicity, inducing hepatocyte apoptosis and necroptosis, whereas endoplasmic reticulum (ER) stress triggered lipid remodeling processes similar to those observed in MASLD. RelA signaling upregulated the expression of activating transcription factor 4 and glucose-regulated protein 78, thereby alleviating ER stress. Impaired RelA signaling remodeled the ER stress response and lipid metabolism, and enhanced lipid accumulation and lipid toxicity. In conclusion, impaired RelA signaling and disrupted lipid metabolism form a detrimental feedback loop in hepatocytes that promotes MASLD progression. Lipid accumulation suppresses RelA signaling, remodeling the ER stress response and exacerbating lipid metabolism disorder, ultimately leading to hepatocyte apoptosis and necroptosis.

BACKGROUND Bletilla striata polysaccharides (BSP) have antioxidant, immune regulation, and anti-fibrotic activities. However, the therapeutic effect and mechanisms underlying the action of BSP in metabolic dysfunction-associated steatotic liver disease (MASLD) have not been fully understood. AIM To investigate the therapeutic effects and mechanisms of BSP on MASLD by centering on the hepatocyte nuclear factor kappa B p65 (RelA)/hepatocyte nuclear factor-1 alpha (HNF1α) signaling. METHODS A mouse model of MASLD was induced by feeding with a high-fat-diet (HFD) and a hepatocyte model of steatosis was induced by treatment with sodium oleate (SO) and sodium palmitate (SP). The therapeutic effects of BSP on MASLD were examined in vivo and in vitro . The mechanisms underlying the action of BSP were analyzed for their effect on lipid metabolism disorder, endoplasmic reticulum (ER) stress, and the RelA/HNF1α signaling. RESULTS HFD feeding reduced hepatocyte RelA and HNF1α expression, induced ER stress, lipid metabolism disorder, and necroptosis in mice, which were significantly mitigated by treatment with BSP. Furthermore, treatment with BSP or BSP-containing conditional rat serum significantly attenuated the sodium oleate/sodium palmitate (SO/SP)-induced hepatocyte steatosis by decreasing lipid accumulation, and lipid peroxidation, and enhancing the expression of RelA, and HNF1α. The therapeutic effects of BSP on MASLD were partially abrogated by RELA silencing in mice and RELA knockout in hepatocytes. RELA silencing or knockout significantly down-regulated HNF1α expression, and remodeled ER stress and oxidative stress responses during hepatic steatosis. CONCLUSION Treatment with BSP ameliorates MASLD, associated with enhancing the RelA/HNF1α signaling, remodeling ER stress and oxidative stress responses in hepatocytes.

Kazakh people, like many other populations that settled in Central Asia, demonstrate an array of mixed anthropological features of East Eurasian (EEA) and West Eurasian (WEA) populations, indicating a possible scenario of biological admixture between already differentiated EEA and WEA populations. However, their complex biological origin, genomic makeup, and genetic interaction with surrounding populations are not well understood. To decipher their genetic structure and population history, we conducted, to our knowledge, the first whole-genome sequencing study of Kazakhs residing in Xinjiang (KZK). We demonstrated that KZK derived their ancestries from 4 ancestral source populations: East Asian (∼39.7%), West Asian (∼28.6%), Siberian (∼23.6%), and South Asian (∼8.1%). The recognizable interactions of EEA and WEA ancestries in Kazakhs were dated back to the 15th century BCE. Kazakhs were genetically distinctive from the Uyghurs in terms of their overall genomic makeup, although the 2 populations were closely related in genetics, and both showed a substantial admixture of western and eastern peoples. Notably, we identified a considerable sex-biased admixture, with an excess of western males and eastern females contributing to the KZK gene pool. We further identified a set of genes that showed remarkable differentiation in KZK from the surrounding populations, including those associated with skin color (SLC24A5, OCA2), essential hypertension (HLA-DQB1), hypertension (MTHFR, SLC35F3), and neuron development (CNTNAP2). These results advance our understanding of the complex history of contacts between Western and Eastern Eurasians, especially those living or along the old Silk Road.

LIMA1 is a LIM domain and Actin binding 1 protein that acts as a skeleton protein to promote cholesterol absorption, which makes it an ideal target for interfering with lipid metabolism. However, the detailed regulation of LIMA1 remains unclear. Here, we identified that ring finger protein 40 (RNF40), an E3 ubiquitin ligase previously known as an epigenetic modifier to increase H2B ubiquitination, mediated the ubiquitination of LIMA1 and thereby promoted its degradation in a proteasome-dependent manner. Fraction studies revealed that the 1–166aa fragment of LIMA1 was indispensable for the interaction with RNF40, and at least two domains of RNF40 might mediate the association of RNF40 with LIMA1. Notably, treatment with simvastatin dramatically decreased the levels of CHO and TG in control cells rather than cells with overexpressed LIMA1. Moreover, RNF40 significantly decreased lipid content, which could be reversed by LIMA1 overexpression. These findings suggest that E3 ubiquitin ligase RNF40 could directly target LIMA1 and promote its protein degradation in cytoplasm, leading to the suppression of lipid accumulation mediated by LIMA1. Collectively, this study unveils that RNF40 is a novel E3 ubiquitin ligase of LIMA1, which underpins its high therapeutic value to combat dysregulation of lipid metabolism.

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by synovial inflammation, cartilage destruction, pannus formation and bone erosion. Various immune cells, including macrophages, are involved in RA pathogenesis. The heterogeneity and plasticity of macrophages render them pivotal regulators of both the induction and resolution of the inflammatory response. Predominantly, two different phenotypes of macrophages have been identified: classically activated M1 macrophages exacerbate inflammation via the production of cytokines, chemokines and other inflammatory mediators, while alternatively activated M2 macrophages inhibit inflammation and facilitate tissue repair. An imbalance in the M1/M2 macrophage ratio is critical during the initiation and progression of RA. Macrophage polarization is modulated by various transcription factors, epigenetic elements and metabolic reprogramming. Curcumin, an active component of turmeric, exhibits potent immunomodulatory effects and is administered in the treatment of multiple autoimmune diseases, including RA. The regulation of macrophage polarization and subsequent cytokine production as well as macrophage migration is involved in the mechanisms underlying the therapeutic effect of curcumin on RA. In this review, we summarize the underlying mechanisms by which curcumin modulates macrophage function and polarization in the context of RA to provide evidence for the clinical application of curcumin in RA treatment.

Background: Impaired glucose regulation (IGR) represents the prediabetic state and is associated with gut microbiota (GM) dysbiosis and chronic inflammation. Tangning Ziyabitusi Tablet (TZT) is a Chinese Uyghur herbal medicine with preventative and therapeutic effects on diabetes, but its hypoglycemic mechanisms are unclear. Methods: Thirty-six male Wistar rats were divided into the normal diet (ND) and IGR groups. The IGR group was given a high-fat diet (HFD). After the IGR model establishment, the ND group was divided into ND and ND+TZT groups, and the IGR group into IGR and IGR+TZT groups. After 8 weeks of TZT administration, 16S rRNA sequencing and untargeted metabolomics were performed on fecal samples. Mesenteric lymph nodes were also collected, and T lymphocytes separated after rats were sacrificed. Flow cytometry was used to characterize different CD4+ T cell subsets in mesenteric lymph nodes. Finally, we analyzed the correlation between GM and characteristic fecal metabolites. Results: Impaired glucose tolerance and insulin resistance were improved in the IGR+TZT group when compared with the IGR group. Bacterial 16S rRNA sequencing results showed that Sobs and Chao1 indices in the IGR group were significantly decreased, but were increased in the IGR+TZT group. The relative abundance of Bacteroidetes was decreased while the relative abundance of Firmicutes was increased in the IGR group. Adlercreutzia abundance was decreased after TZT administration, while the abundance of Christensenellaceae_R-7_group, norank_f_norank_o_Clostridia_UCG-014, UCG-005, and Eubacterium_nodatum_group was increased in the IGR+TZT group. Lymph node CD4+ T cell proportions in the IGR group were significantly increased, while they were significantly decreased in the IGR+TZT group. Correlation analysis showed that tumor necrosis factor-α, interleukin-6, T helper cells (Th1, Th2, Treg), and insulin had a greater impact on GM community structure. Conclusions: TZT improved glucose tolerance and ameliorated GM dysbiosis in IGR rats. Additionally, TZT significantly modulated CD4+ T cell subset proportions in rat mesenteric lymph nodes and fecal metabolism. Moreover, correlation analysis showed that key microbiota was closely related to IGR indices. Thus, TZT modulated GM composition and immune functions of the intestinal mucosa. We provide useful information for the investigation of active mechanisms and the clinical application of TZT.