Serum S-adenosylhomocysteine, rather than homocysteine, is associated with hepatocellular carcinoma survival: a prospective cohort study.

BACKGROUND: Emerging evidence suggested that S-adenosylhomocysteine (SAH) may be a better serum biomarker for cardiovascular disease than homocysteine (Hcy). However, the role of SAH in hepatocellular carcinoma (HCC) prognosis remains unclear. OBJECTIVES: We aimed to prospectively explore the relationships between serum SAH and related metabolites (Hcy, S-adenosylmethionine [SAM]) with HCC survival, and to evaluate the effect modifications by gene polymorphisms in one-carbon metabolism key enzymes. METHODS: We included 1,080 newly diagnosed HCC patients from the Guangdong Liver Cancer Cohort. Serum SAH, Hcy, and SAM were measured utilizing HPLC-MS/MS. Gene polymorphisms in one-carbon metabolism key enzymes were identified using competitive allele-specific PCR (KASP). Primary outcomes were liver cancer-specific survival (LCSS) and overall survival (OS). Hazard ratios (HRs) and 95% confidence intervals (CIs) were computed using multivariate Cox proportional hazards models. RESULTS: After a median follow-up of 3.6 years, 601 deaths occurred, with 552 (92%) attributed to HCC. Multivariable analysis revealed that patients in the highest quartile of serum SAH concentrations were significantly associated with worse survival compared to those in the lowest quartile, with HRs of 1.58 (95% CI: 1.19, 2.10; P-trend = 0.002) for LCSS and 1.54 (95% CI: 1.18, 2.02; P-trend = 0.001) for OS. There were no significant interactions between serum SAH concentrations and genetic variants of one-carbon metabolism key enzymes. No significant associations were found between serum Hcy, SAM concentrations and SAM/SAH ratio with LCSS or OS. CONCLUSIONS: Higher serum SAH concentrations, rather than homocysteine, were independently associated with worse survival in HCC patients, regardless of the genetic variants of one-carbon metabolism key enzymes. These findings suggesting that SAH may serve as a novel metabolism-related prognostic biomarker for HCC.

Rapid aggregation of amyloid-like protein enhanced by mTGase to prepare functional wool fabrics for efficient and sustainable remove heavy metals from wastewater.

To counteract the increasing severity of water pollution and purify water sources, wastewater treatment materials are essential. In particular, it is necessary to improve the bonding strength between the adsorption material and the substrate in a long-term humid environment, and resist the invasion of microorganisms to prolong the service life. In this study, an amyloid-like aggregation method of lysozyme catalyzed by microbial transglutaminase (mTGase). Lysozyme self-assembles into an amyloid-like phase-transited lysozyme (PTL) in the presence of a reducing agent. Simultaneously, mTGase catalyzes acyl transfer reactions within lysozyme molecules or between lysozyme and keratin molecules, and driving PTL assembly on the wool fiber (TG-PTL@wool). This process enhances the grafting amount and fastness of PTL on the wool. Moreover, the tensile strength of wool fabric increased to 523 N. TG-PTL@wool achieves a 97.32 % removal rate of heavy metals, maintaining a removal rate of over 95 % after 5 cycles. TG-PTL@wool has excellent antibacterial property (99 %), and it remains above 90 % after 50 times of circulating washing. This study proved that mTGase can enhance the amyloid aggregation of lysozyme and enhance the bonding strength between PTL coating and substrate. Moreover, TG-PTL@wool provides a sustainable, efficient and cleaner solution for removing heavy metals from water.

Recent advances in injectable hydrogel therapies for periodontitis.

Periodontitis is an immune-inflammatory disease caused by dental plaque, and deteriorates the periodontal ligament, causes alveolar bone loss, and may lead to tooth loss. To treat periodontitis, antibacterial and anti-inflammation approaches are required to reduce bone loss. Thus, appropriate drug administration methods are significant. Due to their "syringeability", biocompatibility, and convenience, injectable hydrogels and associated methods have been extensively studied and used for periodontitis therapy. Such hydrogels are made from natural and synthetic polymer materials using physical and/or chemical cross-linking approaches. Interestingly, some injectable hydrogels are stimuli-responsive hydrogels, which respond to the local microenvironment and form hydrogels that release drugs. Therefore, as injectable hydrogels are different and highly varied, we systematically reviewed the periodontal treatment field from three perspectives: raw material sources, cross-linking methods, and stimuli-responsive methods. We then discussed current challenges and opportunities for the translation of hydrogels to clinic, which may guide further injectable hydrogel designs for periodontitis.

Interaction between the gut microbiota and colonic enteroendocrine cells regulates host metabolism.

Nutrient handling is an essential function of the gastrointestinal tract. Hormonal responses of small intestinal enteroendocrine cells (EECs) have been extensively studied but much less is known about the role of colonic EECs in metabolic regulation. To address this core question, we investigated a mouse model deficient in colonic EECs. Here we show that colonic EEC deficiency leads to hyperphagia and obesity. Furthermore, colonic EEC deficiency results in altered microbiota composition and metabolism, which we found through antibiotic treatment, germ-free rederivation and transfer to germ-free recipients, to be both necessary and sufficient for the development of obesity. Moreover, studying stool and blood metabolomes, we show that differential glutamate production by intestinal microbiota corresponds to increased appetite and that colonic glutamate administration can directly increase food intake. These observations shed light on an unanticipated host-microbiota axis in the colon, part of a larger gut-brain axis, that regulates host metabolism and body weight.

Follicular fluid meiosis-activating sterol prevents porcine ovarian granulosa cells from hypoxia-induced apoptosis via inhibiting STAT4 expression.

Follicular fluid meiosis-activating sterol (FF-MAS) is a small molecule compound found in FF, named for its ability to induce oocyte resumption of meiosis. Granulosa cells (GCs) within the follicle are typically located in a hypoxic environment under physiologic conditions due to limited vascular distribution. Previous research suggests that hypoxia-induced cell cycle arrest and apoptosis in GCs may be crucial triggering factors in porcine follicular atresia. However, the impact of FF-MAS on GCs within follicles has not been explored so far. In this study, we uncovered a novel role of FF-MAS in facilitating GC survival under hypoxic conditions by inhibiting STAT4 expression. We found that STAT4 expression was upregulated in porcine GCs exposed to 1% O2. Both gain and loss of function assays confirmed that STAT4 was required for cell apoptosis under hypoxia conditions, and that the GC apoptosis caused by hypoxia was markedly attenuated following FF-MAS treatment through inhibition of STAT4 expression. Correlation analysis in vivo revealed that GC apoptosis was associated with increased STAT4 expression, while the FF-MAS content in follicular fluid was negatively correlated with STAT4 mRNA levels and cell apoptosis. These findings elucidate a novel role of FF-MAS-mediated protection of GCs by inhibiting STAT4 expression under hypoxia, which might contribute to the mechanistic understanding of follicular development.

Granulosa cells (GCs) influence follicle growth and development, with their proliferation and differentiation promoting follicle development and ovulation, while their programmed cell death and degeneration trigger follicular atresia. In this study, to investigate the effect of FF-MAS on GCs of follicles, we performed gene expression profiling in the domestic pig (Sus scrofa). We discovered STAT4 is required for GC apoptosis under hypoxia conditions both in vitro and in vivo and FF-MAS prevents porcine ovarian granulosa cells from hypoxia-induced apoptosis via inhibiting STAT4 expression.

Collagen type X expression and chondrocyte hypertrophic differentiation during OA and OS development.

Chondrocyte hypertrophy and the expression of its specific marker, the collagen type X gene (COL10A1), constitute key terminal differentiation stages during endochondral ossification in long bone development. Mutations in the COL10A1 gene are known to cause schmid type metaphyseal chondrodysplasia (SMCD) and spondyloepiphyseal dyschondrodysplasia (SMD). Moreover, abnormal COL10A1 expression and aberrant chondrocyte hypertrophy are strongly correlated with skeletal diseases, notably osteoarthritis (OA) and osteosarcoma (OS). Throughout the progression of OA, articular chondrocytes undergo substantial changes in gene expression and phenotype, including a transition to a hypertrophic-like state characterized by the expression of collagen type X, matrix metalloproteinase-13, and alkaline phosphatase. This state is similar to the process of endochondral ossification during cartilage development. OS, the most common pediatric bone cancer, exhibits characteristics of abnormal bone formation alongside the presence of tumor tissue containing cartilaginous components. This observation suggests a potential role for chondrogenesis in the development of OS. A deeper understanding of the shifts in collagen X expression and chondrocyte hypertrophy phenotypes in OA or OS may offer novel insights into their pathogenesis, thereby paving the way for potential therapeutic interventions. This review systematically summarizes the findings from multiple OA models (e.g., transgenic, surgically-induced, mechanically-loaded, and chemically-induced OA models), with a particular focus on their chondrogenic and/or hypertrophic phenotypes and possible signaling pathways. The OS phenotypes and pathogenesis in relation to chondrogenesis, collagen X expression, chondrocyte (hypertrophic) differentiation, and their regulatory mechanisms were also discussed. Together, this review provides novel insights into OA and OS therapeutics, possibly by intervening the process of abnormal endochondral-like pathway with altered collagen type X expression.

Ddx5 participates in regulation of Col10a1 expression and chondrocyte hypertrophic differentiation in vitro.

BACKGROUND AND AIMS: The type X collagen gene (Col10a1), is a specific molecular marker of hypertrophic chondrocytes during endochondral ossification. Col10a1 expression is known to be influenced by many regulators. In this study, we aim to investigate how DEAD-box helicase 5 (DDX5), a potential binding factor for Col10a1 enhancer, may play a role in Col10a1 expression and chondrocyte hypertrophic differentiation in vitro. METHODS: The potential binding factors of the 150-bp Col10a1 cis-enhancer were identified with the hTFtarget database. The expression of DDX5 and COL10A1 was detected by quantitative real-time PCR (qRT-PCR) and Western blot in chondrogenic ATDC5 and MCT cell models with or without Ddx5 knockdown or overexpression. Dual-luciferase reporter assay and chromatin immunoprecipitation (ChIP) were performed to determine the interaction between DDX5 and the Col10a1 enhancer. The effect and mechanism of DDX5 on chondrocyte differentiation and maturation was evaluated by alcian blue, alkaline phosphatase (ALP), and alizarin red staining in ATDC5 cell lines with stable knockdown of Ddx5. RESULTS: DDX5 was identified as a potential binding factor for the Col10a1 enhancer. The expression of DDX5 in hypertrophic chondrocytes was higher than that in proliferative chondrocytes. Knockdown of Ddx5 decreased, while overexpression of Ddx5 slightly increased COL10A1 expression. DDX5 promotes the enhancer activity of Col10a1 as demonstrated by dual-luciferase reporter assay, and the ChIP experiment suggests a direct interaction between DDX5 and the Col10a1 enhancer. Compared to the control (NC) group, we observed weaker alcian blue and ALP staining intensity in the Ddx5 knockdown group of ATDC5 cells cultured both for 7 and 14 days. Whereas weaker alizarin red staining intensity was only found in the Ddx5 knockdown group of cells cultured for 7 days. Meanwhile, knockdown of Ddx5 significantly reduced the level of runt-related transcription factor 2 (RUNX2) in related ATDC5 cells examined. CONCLUSIONS: Our results suggest that DDX5 acts as a positive regulator for Col10a1 expression and may cooperate with RUNX2 together to control Col10a1 expression and promote the proliferation and maturation of chondrocytes.

The impact of metabolic disorders on management of periodontal health in children.

Periodontitis is a chronic inflammatory disease caused by plaque biofilm which shares risk factors with systemic chronic diseases such as diabetes, cardiovascular disease, and osteoporosis. Many studies have found increased prevalence and rate of progression of periodontal disease in children with common metabolic disorders. Although the causal relationship and specific mechanism between them has not been determined yet. The aim of this paper is to progress on the impact of metabolic disorders on periodontal health in children and the underlying mechanisms, which provides new evidences for the prevention and intervention of metabolic disorders and periodontitis in children.

[Occurrence Characteristic and Risk Assessment of Microplastics in Sishui River (Xingyang Section)].

Urban rivers are the main receptors and transporters of microplastic pollution. Understanding the occurrence and environmental risk of microplastics in urban rivers can provide theoretical basis for further control of microplastic pollution. The Sishui River, a tributary of the Yellow River, was selected as the research object. A total of nine water samples were collected from sewage outlets of the Sishui River (Xingyang section). The microplastics in the collected samples were characterized by their sizes, shapes, and colors using a microscope. It was found that microplastics were mostly in the form of transparent fibers and fragments in the water body of sewage outlets, of which the size below 500 µm was relatively high. In addition, PET and PE polymers were identified as the main types using a laser infrared imager. The correlation analysis showed that there was a significant correlation between the PET and PE, indicating that they were similar in origin. The results of the environmental risk assessment showed that the type of microplastics was the main factor affecting the assessment results, whereas the risk values of six sewage samples containing PVC were high. However, the value of pollution load index revealed a low risk level of pollutants in the study area.

Adipose-derived mesenchymal stem cells (MSCs) are a superior cell source for bone tissue engineering.

Effective bone regeneration through tissue engineering requires a combination of osteogenic progenitors, osteoinductive biofactors and biocompatible scaffold materials. Mesenchymal stem cells (MSCs) represent the most promising seed cells for bone tissue engineering. As multipotent stem cells that can self-renew and differentiate into multiple lineages including bone and fat, MSCs can be isolated from numerous tissues and exhibit varied differentiation potential. To identify an optimal progenitor cell source for bone tissue engineering, we analyzed the proliferative activity and osteogenic potential of four commonly-used mouse MSC sources, including immortalized mouse embryonic fibroblasts (iMEF), immortalized mouse bone marrow stromal stem cells (imBMSC), immortalized mouse calvarial mesenchymal progenitors (iCAL), and immortalized mouse adipose-derived mesenchymal stem cells (iMAD). We found that iMAD exhibited highest osteogenic and adipogenic capabilities upon BMP9 stimulation in vitro, whereas iMAD and iCAL exhibited highest osteogenic capability in BMP9-induced ectopic osteogenesis and critical-sized calvarial defect repair. Transcriptomic analysis revealed that, while each MSC line regulated a distinct set of target genes upon BMP9 stimulation, all MSC lines underwent osteogenic differentiation by regulating osteogenesis-related signaling including Wnt, TGF-ß, PI3K/AKT, MAPK, Hippo and JAK-STAT pathways. Collectively, our results demonstrate that adipose-derived MSCs represent optimal progenitor sources for cell-based bone tissue engineering.

Betaine alleviates cognitive impairment induced by homocysteine through attenuating NLRP3-mediated microglial pyroptosis in an m6A-YTHDF2-dependent manner.

Dementia, with homocysteine (Hcy) as an important risk factor, is a severe public health problem in the aging society. Betaine serves as a methyl donor and plays an important role in reducing Hcy. However, the effects and mechanisms of betaine on Hcy-induced cognitive impairment remain unclear. Firstly, SD rats were injected with Hcy (400 µg/kg) through vena caudalis, and betaine (2.5 % w/v) was supplemented via drinking water for 14 days. Betaine supplementation could attenuate Hcy-induced cognitive impairment in the Y maze and novel object recognition tests by repairing brain injury. Meanwhile, microglial activation was observed to be inhibited by betaine supplementation using immunofluorescence and sholl analysis. Secondly, HMC3 cells were treated with betaine, which was found to decrease the ROS level, ameliorate cell membrane rupture, reduce the release of LDH, IL-18 and IL-1ß, and attenuate the damage of microglia to neurons. Mechanistically, betaine alleviates cognitive impairment by inhibiting microglial pyroptosis via reducing the expressions of NLRP3, ASC, pro-caspase-1, cleaved-caspase-1, GSDMD, GSDMD-N, IL-18 and IL-1ß. Betaine treatment can increase SAM/SAH ratio, confirming its enhancement on methylation capacity. Furthermore, betaine treatment was found to enhance N6-methyladenosine (m6A) modification of NLRP3 mRNA, and reduced the NLRP3 mRNA stability through increasing the expression of the m6A reader YTH N6-methyladenosine RNA binding protein 2 (YTHDF2). Finally, silencing YTHDF2 could reverse the inhibitory effect of betaine on pyroptosis. Our data demonstrated that betaine attenuated Hcy-induced cognitive impairment by suppressing microglia pyroptosis via inhibiting the NLRP3/caspase-1/GSDMD pathway in an m6A-YTHDF2-dependent manner.

The evolving roles of Wnt signaling in stem cell proliferation and differentiation, the development of human diseases, and therapeutic opportunities.

The evolutionarily conserved Wnt signaling pathway plays a central role in development and adult tissue homeostasis across species. Wnt proteins are secreted, lipid-modified signaling molecules that activate the canonical (ß-catenin dependent) and non-canonical (ß-catenin independent) Wnt signaling pathways. Cellular behaviors such as proliferation, differentiation, maturation, and proper body-axis specification are carried out by the canonical pathway, which is the best characterized of the known Wnt signaling paths. Wnt signaling has emerged as an important factor in stem cell biology and is known to affect the self-renewal of stem cells in various tissues. This includes but is not limited to embryonic, hematopoietic, mesenchymal, gut, neural, and epidermal stem cells. Wnt signaling has also been implicated in tumor cells that exhibit stem cell-like properties. Wnt signaling is crucial for bone formation and presents a potential target for the development of therapeutics for bone disorders. Not surprisingly, aberrant Wnt signaling is also associated with a wide variety of diseases, including cancer. Mutations of Wnt pathway members in cancer can lead to unchecked cell proliferation, epithelial-mesenchymal transition, and metastasis. Altogether, advances in the understanding of dysregulated Wnt signaling in disease have paved the way for the development of novel therapeutics that target components of the Wnt pathway. Beginning with a brief overview of the mechanisms of canonical and non-canonical Wnt, this review aims to summarize the current knowledge of Wnt signaling in stem cells, aberrations to the Wnt pathway associated with diseases, and novel therapeutics targeting the Wnt pathway in preclinical and clinical studies.

Alkali-Metal-Assisted Green-Solvent Synthesis for In Situ Growth of Perovskite Nanocrystals in Porous Materials.

Inorganic metal halide perovskite CsPbX3 (X = I, Br, and Cl) nanocrystals (NCs) are rapidly developed due to their excellent photophysical properties and potential applications in lighting, lasers, and scintillators. However, the materials for growing perovskite NCs are insoluble or hydrolyzed in most green solvents, limiting their further development. Based on rational chemical analysis, an alkali-metal-assisted green-solvent synthesis method for in situ growth of CsPbBr3 NCs within SAPO-34 zeolite with bright luminescence is developed. Water is the only solvent used in the whole process. Surprisingly, by the synergistic effect of the channel structure of SAPO-34 and alkali-metal ions crystallization regulation, the CsPbBr3 NCs embedded in SAPO-34 assisted by Na+ emit bright blue light under ultraviolet illumination, with a 30 nm blue shift comparing to the CsPbBr3 NCs assisted by K+. Moreover, CsPbBr3 NCs can also be grown in mesoporous SiO2 SBA-15 and zeolites including ZSM-5, AlPO-5, and SOD, indicating that the method is universal for in situ growth of luminescent perovskite NCs in porous materials. This alkali-metal-assisted green-solvent synthesis provides a new strategy for developing high-quantum-yield, tunable-emission, and stable perovskite luminescent materials.

Experimental investigation of biostimulatory effects after polydioxanone thread insertion in a pig model.

BACKGROUND: Polydioxanone (PDO) threads have been widely used to tighten and lift the facial soft tissue. OBJECTIVE: This research aims to determine the collagenation and inflammation changes that occur in the adipose tissue over time when different types of threads are implanted. METHODS & MATERIALS: Three threads types, PDO, poly glycolic-co-lactic acid (PGLA), and nylon, were inserted in the subcutaneous fat of 12-month-old Bama miniature pigs. Collagen production and inflammatory response were evaluated by hematoxylin and eosin and Masson trichrome staining at 1, 4, 12, 24, and 48 weeks. RESULTS: The integrity of the PDO thread lasted up to 24 weeks with mild inflammation and collagen production. The PGLA thread integrity lasted until 12 weeks and had a strong inflammatory response. The nylon thread's integrity was maintained for 48 weeks and showed minor inflammation and collagen production. CONCLUSION: Our data suggest that PDO thread is the best choice for clinicians, as it has a mild action process with minimal irritation, moderate collagen production, a reasonable explanation time, with obvious bridging fibrous tissue, and thickening action for the superficial fascia.

Systematic Review of Nonsyndromic Craniosynostosis: Genomic Alterations and Impacted Signaling Pathways.

BACKGROUND: Genetic research in nonsyndromic craniosynostosis remains limited compared with syndromic craniosynostosis. This systematic review aimed to comprehensively summarize the genetic literature of nonsyndromic craniosynostosis and highlight key signaling pathways. METHODS: The authors performed a systematic literature search of PubMed, Ovid, and Google Scholar databases from inception until December of 2021 using search terms related to nonsyndromic craniosynostosis and genetics. Two reviewers screened titles and abstract for relevance, and three reviewers independently extracted study characteristics and genetic data. Gene networks were constructed using Search Tool for Retrieval of Interacting Genes/Proteins (version 11) analysis. RESULTS: Thirty-three articles published between 2001 and 2020 met inclusion criteria. Studies were further classified into candidate gene screening and variant identification studies ( n = 16), genetic expression studies ( n = 13), and common and rare variant association studies ( n = 4). Most studies were good quality. Using our curated list of 116 genes extracted from the studies, two main networks were constructed. CONCLUSIONS: This systematic review concerns the genetics of nonsyndromic craniosynostosis, with network construction revealing TGF-ß/BMP, Wnt, and NF-κB/RANKL as important signaling pathways. Future studies should focus on rare rather than common variants to examine the missing heritability in this defect and, going forward, adopt a standard definition.

Variability of rare earth and heavy metal elements in a representative alluvial depositional system.

Heavy metals (Ni, Cr, W, Cd, and Pb) and rare earth elements (REE) were investigated in the flood plain sediments of an island of the lower Yangtze River near Nanjing to determine how the vertical distribution of heavy metals could be affected by natural sedimentation processes and anthropogenic contamination. Stratigraphic analyses of magnetic susceptibility and the mean grain size distribution of the deposits enabled us to identify layers associated with a relatively high influx of suspended sediments that resulted in sudden changes in the concentrations of heavy metals. The results show that layers associated with high sediment influx (0.8 m depth) displayed low concentrations of Cr, Ni, W, and Cd that were mainly lithogenic in origin. The Post Archean Australian Shale (PAAS) normalized REE patterns in the flood plain cores were enrichment in Ce and Eu relative to PAAS, indicating that the sediments were most likely derived from a mixture of sediments and not from an anthropogenic source. Sharp increases in Y/Ho ratios, as well as heavy metal (Cd, Cr, Ni, and W) and Y concentrations were observed in the uppermost layer that could have been deposited from the rapid transport of sediment-laden, contaminated waters. The temporal (vertical) trends in Pb concentrations may be strongly influenced by coal burning. Elevated Pb concentrations (350 ppm and 1000 ppm) correlate with high magnetic susceptibility (> 200 m3 × kg-1) and the history of thermal power plant (1910-2002) activity. The anthropogenic inputs of Pb were, however, not diluted by high suspended sediment loads, which supports the argument that Pb was derived from fly ash.

FSH preserves the viability of hypoxic granulosa cells via activating the HIF-1α-GAS6-Axl-Akt pathway.

The developmental fate of ovarian follicles is primarily determined by the survival status (proliferation or apoptosis) of granulosa cells (GCs). Owing to the avascular environment within follicles, GCs are believed to live in a hypoxic niche. Follicle-stimulating hormone (FSH) has been reported to improve GCs survival by governing hypoxia-inducible factor-1α (HIF-1α)-dependent hypoxia response, but the underlying mechanisms remain poorly understood. Growth arrest-specific gene 6 (GAS6) is a secreted ligand of tyrosine kinase receptors, and has been documented to facilitate tumor growth. Here, we showed that the level of GAS6 was markedly increased in mouse ovarian GCs after the injection of FSH. Specifically, FSH-induced GAS6 expression was accompanied by HIF-1α accumulation under conditions of hypoxia both in vivo and in vitro, whereas inhibition of HIF-1α with small interfering RNAs/antagonist repressed both expression and secretion of GAS6. As such, Luciferase reporter assay and chromatin immunoprecipitation assay showed that HIF-1α directly bound to a hypoxia response element site within the Gas6 promoter and contributed to the regulation of GAS6 expression in response to FSH. Notably, blockage of GAS6 and/or its receptor Axl abrogated the pro-survival effects of FSH under hypoxia. Moreover, phosphorylation of Axl by GAS6 is required for FSH-mediated Akt activation and the resultant pro-survival phenotypes. Finally, the in vitro findings were verified in vivo, which showed that FSH-induced proliferative and antiapoptotic effects in ovarian GCs were diminished after blocking GAS6/Axl using HIF-1α antagonist. These findings highlight a novel function of FSH in preserving GCs viability against hypoxic stress by activating the HIF-1a-GAS6-Axl-Akt pathway.

IGF-I protects porcine granulosa cells from hypoxia-induced apoptosis by promoting homologous recombination repair through the PI3K/AKT/E2F8/RAD51 pathway.

Severe hypoxia induced by vascular compromise (ovarian torsion, surgery), obliteration of vessels (aging, chemotherapy, particularly platinum drugs) can cause massive follicle atresia. On the other hand, hypoxia increases the occurrence of DNA double-strand breaks (DSBs) and triggers cellular damage repair mechanisms; however, if the damage is not promptly repaired, it can also induce the apoptosis program. Insulin-like growth factor-I (IGF-I) is a polypeptide hormone that plays essential roles in stimulating mammalian follicular development. Here, we report a novel role for IGF-I in protecting hypoxic GCs from apoptosis by promoting DNA repair through the homologous recombination (HR) process. Indeed, the hypoxic environment within follicles significantly inhibited the efficiency of HR-directed DNA repair. The presence of IGF-I-induced HR pathway to alleviate hypoxia-induced DNA damage and apoptosis primarily through upregulating the expression of the RAD51 recombinase. Importantly, we identified a new transcriptional regulator of RAD51, namely E2F8, which mediates the protective effects of IGF-I on hypoxic GCs by facilitating the transcriptional activation of RAD51. Furthermore, we demonstrated that the PI3K/AKT pathway is crucial for IGF-I-induced E2F8 expression, resulting in increased RAD51 expression and enhanced HR activity, which mitigates hypoxia-induced DNA damage and thereby protects against GCs apoptosis. Together, these findings define a novel mechanism of IGF-I-mediated GCs protection by activating the HR repair through the PI3K/AKT/E2F8/RAD51 pathway under hypoxia.

Autophagy regulates tumor growth and metastasis.

The role of autophagy in tumorigenesis and tumor metastasis remains poorly understood. Here we show that inhibition of autophagy stabilizes the transcription factor Twist1 through Sequestosome-1 (SQSTM1, also known as p62) and thus increases cell proliferation, migration, and epithelial-mesenchymal transition (EMT) in tumor development and metastasis. Inhibition of autophagy or p62 overexpression blocks Twist1 protein degradation in the proteasomes, while p62 inhibition enhances it. SQSTM1/p62 interacts with Twist1 via the UBA domain of p62, in a Twist1-ubiquitination-dependent manner. Lysine 175 in Twist1 is critical for Twist1 ubiquitination, degradation, and SQSTM1/p62 interaction. For squamous skin cancer and melanoma cells that express Twist1, SQSTM1/p62 increases tumor growth and metastasis in mice. Together, our results identified Twist1 as a key downstream protein for autophagy and suggest a critical role of the autophagy/p62/Twist1 axis in cancer development and metastasis.