Tumor Progression Locus 2 in Hepatocytes Potentiates Both Liver and Systemic Metabolic Disorders in Mice

Luteolin and its analog luteolin-7-methylether from Leonurus japonicus Houtt suppress aromatase-mediated estrogen biosynthesis to alleviate polycystic ovary syndrome by the inhibition of tumor progression locus 2

ETHNOPHARMACOLOGICAL RELEVANCE

Leonurus japonicus Houtt (L. japonicus, Chinese motherwort), known as Yi Mu Cao which means "good for women", has long been widely used in China and other Asian countries to alleviate gynecological disorders, often characterized by estrogen dysregulation. It has been used for the treatment of polycystic ovary syndrome (PCOS), a common endocrine disorder in women but the underlying mechanism remains unknown.

AIM OF THE STUDY

The present study was designed to investigate the effect and mechanism of flavonoid luteolin and its analog luteolin-7-methylether contained in L. japonicus on aromatase, a rate-limiting enzyme that catalyzes the conversion of androgens to estrogens and a drug target to induce ovulation in PCOS patients.

MATERIALS AND METHODS

Estrogen biosynthesis in human ovarian granulosa cells was examined using ELISA. Western blots were used to explore the signaling pathways in the regulation of aromatase expression. Transcriptomic analysis was conducted to elucidate the potential mechanisms of action of compounds. Finally, animal models were used to assess the therapeutic potential of these compounds in PCOS.

RESULTS

Luteolin potently inhibited estrogen biosynthesis in human ovarian granulosa cells stimulated by follicle-stimulating hormone. This effect was achieved by decreasing cAMP response element-binding protein (CREB)-mediated expression of aromatase. Mechanistically, luteolin and luteolin-7-methylether targeted tumor progression locus 2 (TPL2) to suppress mitogen-activated protein kinase 3/6 (MKK3/6)-p38 MAPK-CREB pathway signaling. Transcriptional analysis showed that these compounds regulated the expression of different genes, with the MAPK signaling pathway being the most significantly affected. Furthermore, luteolin and luteolin-7-methylether effectively alleviated the symptoms of PCOS in mice.

CONCLUSIONS

This study demonstrates a previously unrecognized role of TPL2 in estrogen biosynthesis and suggests that luteolin and luteolin-7-methylether have potential as novel therapeutic agents for the treatment of PCOS. The results provide a foundation for further development of these compounds as effective and safe therapies for women with PCOS.

Molecular mechanism and therapeutic significance of essential amino acids in metabolically associated fatty liver disease

Non-alcoholic fatty liver disease (NAFLD), also known as metabolically associated fatty liver disease (MAFLD), is a systemic metabolic disease characterized by lipid accumulation in the liver, lipid toxicity, insulin resistance, intestinal dysbiosis, and inflammation that can progress from simple steatosis to nonalcoholic steatohepatitis (NASH) and even cirrhosis or cancer. It is the most prevalent illness threatening world health. Currently, there are almost no approved drug interventions for MAFLD, mainly dietary changes and exercise to control weight and regulate metabolic disorders. Meanwhile, the metabolic pathway involved in amino acid metabolism also influences the onset and development of MAFLD in the body, and most amino acid metabolism takes place in the liver. Essential amino acids are those amino acids that must be supplemented from outside the diet and that cannot be synthesized in the body or cannot be synthesized at a rate sufficient to meet the body's needs, including leucine, isoleucine, valine (collectively known as branched-chain amino acids), tryptophan, phenylalanine (which are aromatic amino acids), histidine, methionine, threonine and lysine. The metabolic balance of the body is closely linked to these essential amino acids, and essential amino acids are closely linked to the pathophysiological process of MAFLD. In this paper, we will focus on the metabolism of essential amino acids in the body and further explore the therapeutic strategies for MAFLD based on the studies conducted in recent years.

Astragaloside Ⅳ negatively regulates Gpr97-TPL2 signaling to protect against hyperhomocysteine-exacerbated sepsis associated acute kidney injury

BACKGROUND

Hyperhomocysteine (HHcy) plays an important role in promoting inflammation and cell death of tubular epithelial cells. However, the role of HHcy and Astragaloside IV (AS-IV) in sepsis associated acute kidney injury (S-AKI) remain unclear.

PURPOSE

A significant aspect of this study aimed to elucidate the effect of AS-Ⅳ treatment on HHcy-exacerbated S-AKI and reveal its potential mechanism.

METHODS

Male C57BL/6 J mice fed with specific diet containing 2% methionine were established as in vivo models, and AS-Ⅳ was orally administrated continuously for 3 weeks, and then LPS (10 mg·kg-1 bodyweight) was given by a single intraperitoneal injection. The renal morphological changes were evaluated by HE and PAS staining. RNA-sequencing analysis was applied to select key signaling. The NRK-52E cells exposed to Hcy or combined with LPS were used as in vitro models. The mRNA and protein expression levels of Gpr97-TPL2 signaling were examined by qRT-PCR and western blotting assays.

RESULTS

In vivo, HHcy mice developed more severe renal injury and prevalent tubular inflammation after LPS injection. In vitro, the levels of NGAL, Gpr97 and TPL2 were significantly increased in NRK-52E cells induced by Hcy (1.6 mM) or in combination with LPS. Notably, the effects of Hcy on TPL2 signaling was abolished by transfecting TPL2 siRNA or treating TPL2 inhibitor, without alterations in Gpr97. However, the enhancement of Gpr97-TPL2 signaling induced by Hcy was counteracted by Gpr97 siRNA. Subsequently, our findings demonstrated that AS-Ⅳ treatment can improve renal function in HHcy-exacerbated S-AKI mice. Mechanistically, AS-Ⅳ alleviated renal tubular damage characterized by abnormal increases in KIM-1, NGAL, TPL2, Gpr97, Sema3A and TNF-α, and decreases in survivin in vivo and in vitro mainly through suppressing the activation of Gpr97-TPL2 signaling.

CONCLUSION

The present study suggested that HHcy-exacerbated S-AKI was mediated mechanically by activation of Gpr97-TPL2 signaling for the first time. Furthermore, our research also illustrated that AS-Ⅳ protected against HHcy-exacerbated S-AKI by attenuating renal tubular epithelial cells damage through negatively regulating Gpr97-TPL2 signaling, proposing a natural product treatment strategy for HHcy-exacerbated S-AKI.

A genomics perspective of personalized prevention and management of obesity

This review discusses the landscape of personalized prevention and management of obesity from a nutrigenetics perspective. Focusing on macronutrient tailoring, we discuss the impact of genetic variation on responses to carbohydrate, lipid, protein, and fiber consumption. Our bioinformatic analysis of genomic variants guiding macronutrient intake revealed enrichment of pathways associated with circadian rhythm, melatonin metabolism, cholesterol and lipoprotein remodeling and PPAR signaling as potential targets of macronutrients for the management of obesity in relevant genetic backgrounds. Notably, our data-based in silico predictions suggest the potential of repurposing the SYK inhibitor fostamatinib for obesity treatment in relevant genetic profiles. In addition to dietary considerations, we address genetic variations guiding lifestyle changes in weight management, including exercise and chrononutrition. Finally, we emphasize the need for a refined understanding and expanded research into the complex genetic landscape underlying obesity and its management.

Porcine β-Defensin 114: Creating a Dichotomous Response to Inflammation

The immunity-related functions of defensins seem to be dependent on environmental stimuli, the cell type, and the concentration of peptides. However, the function and mechanism of porcine β-defensin 114 (pBD114) in regulating the inflammatory response to macrophages are unclear. Therefore, the modulatory effects of porcine pBD114 on the inflammatory response were investigated by treating the mouse monocyte macrophage cell line RAW264.7 with different concentrations of pBD114 with or without lipopolysaccharide (LPS). RNA-seq analysis was performed to investigate the mechanisms underlying pBD114's regulation of inflammatory responses in macrophages. In addition, the inflammatory response-modulating effects of pBD114 were also further verified with a mouse assay. The results showed that 100 μg/mL of pBD114 significantly promoted the secretion of TNF-α and IL-10 in RAW264.7. However, the LPS-induced increase in TNFα in the RAW264.7 cell cultures was significantly decreased with 10 μg/mL of pBD114. These results suggest that pBD114 can exhibit pro-inflammatory activities under normal physiological conditions with 100 μg/mL of pBD114, and anti-inflammatory activities during an excessive inflammatory response with 10 μg/mL of pBD114. RNA-seq analysis was performed to gain further insights into the effects of pBD114 on the inflammatory response. Among the pBD114-promoting RAW264.7 pro-inflammatory responses, pBD114 significantly up-regulated 1170 genes and down-regulated 724 genes. KEGG enrichment showed that the differentially expressed genes (DEGs) were significantly enriched in the immune- and signal-transduction-related signaling pathways. Protein-Protein Interaction (PPI) and key driver analysis (KDA) analyses revealed that Bcl10 and Bcl3 were the key genes. In addition, pBD114 significantly up-regulated 12 genes and down-regulated 38 genes in the anti-inflammatory response. KEGG enrichment analysis revealed that the DEGs were mainly enriched in the "Cytokine-cytokine receptor interaction" signaling pathway, and PPI and KDA analyses showed that Stat1 and Csf2 were the key genes. The results of qRT-PCR verified those of RNA-seq. In vivo mouse tests also confirmed the pro- or anti-inflammatory activities of pBD114. Although the inflammatory response is a rapid and complex physiological reaction to noxious stimuli, this study found that pBD114 plays an essential role mainly by acting on the genes related to immunity, signal transduction, signaling molecules, and interactions. In conclusion, this study provides a certain theoretical basis for the research and application of defensins.

Tumor progression locus 2 (TPL2): A Cot-plicated progression from inflammation to chronic liver disease

The cytoplasmic protein tumor progression locus 2 (TPL2), also known as cancer Osaka thyroid (Cot), or MAP3K8, is thought to have a significant role in a variety of cancers and illnesses and it is a key component in the activation pathway for the expression of inflammatory mediators. Despite the tight connection between inflammation and TPL2, its function has not been extensively studied in chronic liver disease (CLD), a major cause of morbidity and mortality worldwide. Here, we analyze more in detail the significance of TPL2 in CLD to shed light on the pathological and molecular transduction pattern of TPL2 during the progression of CLD. This might result in important advancements and enable progress in the diagnosis and treatment of CLD.

Breviscapine alleviates NASH by inhibiting TGF-β-activated kinase 1-dependent signaling

BACKGROUND AND AIMS

NAFLD is a key component of metabolic syndrome, ranging from nonalcoholic fatty liver to NASH, and is now becoming the leading cause of cirrhosis and HCC worldwide. However, due to the complex and unclear pathophysiological mechanism, there are no specific approved agents for treating NASH. Breviscapine, a natural flavonoid prescription drug isolated from the traditional Chinese herb Erigeron breviscapus, exhibits a wide range of pharmacological properties, including effects on metabolism. However, the anti-NASH efficacy and mechanisms of breviscapine have not yet been characterized.

APPROACH AND RESULTS

We evaluated the effects of breviscapine on the development of hepatic steatosis, inflammation, and fibrosis in vivo and in vitro under metabolic stress. Breviscapine treatment significantly reduced lipid accumulation, inflammatory cell infiltration, liver injury, and fibrosis in mice fed a high-fat diet, a high-fat/high-cholesterol diet, or a methionine- and choline-deficient diet. In addition, breviscapine attenuated lipid accumulation, inflammation, and lipotoxicity in hepatocytes undergoing metabolic stress. RNA-sequencing and multiomics analyses further indicated that the key mechanism linking the anti-NASH effects of breviscapine was inhibition of TGF-β-activated kinase 1 (TAK1) phosphorylation and the subsequent mitogen-activated protein kinase signaling cascade. Treatment with the TAK1 inhibitor 5Z-7-oxozeaenol abrogated breviscapine-mediated hepatoprotection under metabolic stress. Molecular docking illustrated that breviscapine directly bound to TAK1.

CONCLUSION

Breviscapine prevents metabolic stress-induced NASH progression through direct inhibition of TAK1 signaling. Breviscapine might be a therapeutic candidate for the treatment of NASH.

Exploring the Changes of Peroxisomal Polarity in the Liver of Mice with Nonalcoholic Fatty Liver Disease

Peroxisome proliferator-activated receptor alpha (PPAR-a) is a crucial nuclear transcription regulator of lipid metabolism, which is closely associated with the initiation and development of nonalcoholic fatty liver disease (NAFLD). Because PPAR-a can directly decide the level of peroxisomal metabolic enzymes, its changes might directly cause variations in peroxisomal polarity. Therefore, we developed a new two-photon fluorescence imaging probe, PX-P, in which the triphenylamine and cyanide moieties can real-time sense peroxisomal polarity changes. Using PX-P, we observed a prominent decrease in the peroxisomal polarity in the liver of mice with NAFLD for the first time. More importantly, we discovered that intracellular excessive peroxynitrite (ONOO^-) and hydrogen peroxide (H₂O₂) underwent nitrification and oxidation, respectively, with various sites of PPAR-a. Interestingly, the key site of PPAR-a was nitrated by a low concentration of ONOO^- rather than being oxidized by the high level of H₂O₂. These drastically reduced the activity of PPAR-a, accelerating the occurrence of NAFLD. Moreover, through activating PPARs with pioglitazone, peroxisomal polarity markedly increased compared with that of NAFLD. Altogether, our work presents a new approach for the early diagnosis of NAFLD and identifies potential therapeutic targets.

Tpl2 kinase regulates inflammation but not tumorigenesis in mice

Tumor progression locus 2 (Tpl2, gene name MAP3K8), a mitogen-activated protein kinase, is widely expressed in immune and non-immune cells to integrate tumor necrosis factor (TNF), toll-like receptors (TLRs), and interleukin-1 (IL1) receptor signaling to regulate inflammatory response. Given its central role in inflammatory response, Tpl2 is an attractive small molecule drug target. However, the role of Tpl2 as an oncogene or tumor suppressor gene remains controversial, and its function outside immune cells is not understood. We therefore utilized a Tpl2 kinase dead (Tpl2-KD) mouse model in an 18-month aging study to further elucidate Tpl2 effects on lifespan and chronic disease. Histopathological studies revealed the incidence and severity of spontaneous tumors and non-neoplastic lesions were comparable between wild type and Tpl2-KD mice. The only finding was that male Tpl2-KD mice had higher bodyweight and an increased incidence of liver steatosis, suggesting a sex-specific role for Tpl2 in hepatic lipid metabolism. In conclusion, loss of Tpl2 kinase activity did not lead to increased tumorigenesis over aging in mice but affected likely alterations in lipid metabolism in male animals.

Her2 promotes early dissemination of breast cancer by suppressing the p38 pathway through Skp2-mediated proteasomal degradation of Tpl2

While mechanisms for metastasis were extensively studied in cancer cells from patients with detectable tumors, pathways underlying metastatic dissemination from early lesions before primary tumors appear are poorly understood. Her2 promotes breast cancer early dissemination by suppressing p38, but how Her2 downregulates p38 is unclear. Here, we demonstrate that in early lesion breast cancer models, Her2 inhibits p38 by inducing Skp2 through Akt-mediated phosphorylation, which promotes ubiquitination and proteasomal degradation of Tpl2, a p38 MAP3K. The early disseminating cells are Her2⁺Skp2^highTpl2^lowp-p38^lowE-cadherin^low in the MMTV-Her2 breast cancer model. In human breast carcinoma, high Skp2 and low Tpl2 expression are associated with the Her2⁺ status; Tpl2 expression positively correlates with that of activated p38; Skp2 expression negatively correlates with that of Tpl2 and activated p38. Moreover, the Her2-Akt-Skp2-Tpl2-p38 axis plays a key role in the disseminating phenotypes in early lesion breast cancer cells; inhibition of Tpl2 enhances early dissemination in vivo. These findings identify the Her2-Akt-Skp2-Tpl2-p38 cascade as a novel mechanism mediating breast cancer early dissemination and a potential target for novel therapies targeting early metastatic dissemination.

Green tea polyphenols attenuate hepatic steatosis, and reduce insulin resistance and inflammation in high-fat diet-induced rats

Non‑alcoholic fatty liver disease (NAFLD) is characterized by hepatic steatosis, insulin resistance and inflammation; however, the exact pathogenesis of NAFLD is not fully understood. Green tea polyphenols (GTP) exhibit beneficial effects against metabolic syndrome. However, the effect of GTP on NAFLD remains largely unknown. The aim of the present study was to investigate the effects of GTP on NAFLD in high‑fat diet (HFD)‑induced rats. The NAFLD rat model was induced with a HFD for 8 weeks. A total of 30 adult male Sprague Dawley rats were randomly divided into three groups: i) Normal control group; ii) HFD group; and iii) HFD with GTP group. Hematoxylin and eosin and Oil Red O analyses were performed. The levels of alanine aminotransferase (ALT), aspartate amino-transferase (AST) and inflammatory cytokines in the serum, as well as oxidative stress markers and hepatic lipids in the liver were measured. In addition, parameters associated with glucose metabolism were also assessed. Western blotting and RT‑qPCR were used to determine the expression levels of 5' adenosine monophosphate‑activated protein kinase (AMPK). HFD‑induced rats exhibited features associated with NAFLD. GTP intervention significantly reduced serum ALT and AST levels. Fasting serum glucose, insulin resistance and hepatic lipid levels were all decreased in the GTP‑treated rats. GTP also significantly decreased the levels of TNF‑α, IL‑6 and malondialdehyde. In contrast, superoxide dismutase levels were increased in the liver. Furthermore, GTP also significantly increased phosphorylation of AMPK and attenuated histopathological changes indicative of injury in liver tissue. GTP has a protective effect on HFD‑induced hepatic steatosis, insulin resistance and inflammation, and the underlying mechanism may involve the AMPK pathway.

Ubiquitin-Specific Peptidase 10 (USP10) Inhibits Hepatic Steatosis, Insulin Resistance, and Inflammation Through Sirt6

Nonalcoholic fatty liver disease (NAFLD) is characterized by hepatic steatosis, insulin resistance and inflammation, and the pathogenic mechanism of NAFLD is poorly understood. Ubiquitin-specific peptidase 10 (USP10), a member of the ubiquitin-specific protease family, is involved in environmental stress responses, tumor growth, inflammation, and cellular metabolism. However, the role of USP10 in hepatic steatosis, insulin resistance, and inflammation remains largely unexplored. USP10 expression was detected in livers of patients with NAFLD, mice with high-fat diet (HFD)-induced obesity, and genetically obese (ob/ob) mice, as well as in palmitate-induced hepatocytes. The function of USP10 in hepatic steatosis, insulin resistance, and inflammation was investigated using hepatocyte-specific USP10 deficiency or overexpression in mice induced by HFD treatment or genetic defect. The molecular mechanisms underlying USP10-regulated hepatic steatosis were further investigated in HFD-treated mice. USP10 expression was significantly decreased in the fatty livers of NAFLD patients and obese mice and in palmitate-treated hepatocytes. USP10 deficiency exacerbated the metabolic dysfunction induced by HFD treatment for 12 weeks. Conversely, USP10 overexpression significantly suppressed metabolic dysfunction in mice after HFD treatment and inhibited the development of NAFLD in ob/ob mice. Further investigation indicated that USP10 regulates hepatic steatosis by interacting with Sirt6 and inhibiting its ubiquitination and degradation. Sirt6 overexpression markedly ameliorated the effects of USP10 deficiency in hepatic steatosis, insulin resistance, and inflammation. Conversely, Sirt6 deficiency decreased the ameliorative effects of USP10 overexpression in response to HFD treatment. Conclusion: USP10 inhibits hepatic steatosis, insulin resistance, and inflammation through Sirt6.