The Mechanism of Dehydrating Bimodules in trans-Acyltransferase Polyketide Biosynthesis: A Showcase Study on Hepatoprotective Hangtaimycin.

A bioassay-guided fractionation led to the isolation of hangtaimycin (HTM) from Streptomyces spectabilis CCTCC M2017417 and the discovery of its hepatoprotective properties. Structure elucidation by NMR suggested the need for a structural revision. A putative HTM degradation product was also isolated and its structure was confirmed by total synthesis. The biosynthetic gene cluster was identified and resembles a hybrid trans-AT PKS/NRPS biosynthetic machinery whose first PKS enzyme contains an internal dehydrating bimodule, which is usually found split in other trans-AT PKSs. The mechanisms of such dehydrating bimodules have often been proposed, but have never been deeply investigated. Here we present in vivo mutations and in vitro enzymatic experiments that give first and detailed mechanistic insights into catalysis by dehydrating bimodules.

YAP mediates the positive regulation of hnRNPK on the lung adenocarcinoma H1299 cell growth.

Lung cancer is the leading cause of cancer death worldwide, and non-small cell lung cancer (NSCLC) accounts for 80%-85% of diagnostic cases. The molecular mechanisms of NSCLC pathogenesis are not well understood. Heterogeneous nuclear ribonucleoprotein K (hnRNPK) is a multifunctional protein that regulates gene expression and signal transduction and closely associated with tumorigenesis, but its mechanism of action in the pathogenesis of NSCLC is unclear. In this study, we observed that the expression pattern of hnRNPK in H1299 lung adenocarcinoma cells varied depending on the cell density in culture. Moreover, hnRNPK stimulated the ability of proliferation and colony formation of H1299 cells, which is important for the multilayered cell growth in culture. We further investigated whether there is an association between hnRNPK and the elements involved in the cell contact inhibition pathway. By using quantitative reverse transcriptase-polymerase chain reaction assay and a YAP activity reporter system, we found that hnRNPK upregulated the mRNA and protein levels and transcriptional activity of Yes-associated protein 1 (YAP), a master negative regulator of Hippo contact inhibition pathway. Furthermore, YAP knockdown with siRNA abolished the stimulatory effect of hnRNPK on H1299 cell proliferation. These results suggested that YAP could be one of the effectors of hnRNPK. Our data may provide new clues for further understanding the biological functions of hnRNPK, particularly in the context of lung adenocarcinoma oncogenesis.

The efficacy and safety of local 5-aminolevulinic acid-based photodynamic therapy in the treatment of cervical high-grade squamous intraepithelial lesion: a single center retrospective observational study.

Background: Typical treatments for cervical high-grade squamous intraepithelial lesion (HSIL) are invasive procedures. However, these procedures often come with several severe side effects, despite their positive effects on cervical HSIL. 5-aminolevulinic acid photodynamic therapy (ALA-PDT) is a non-invasive treatment that has been successfully used to treat cervical low-grade squamous intraepithelial lesion (LSIL). In this study, we aimed to further investigate the clinical efficacy and safety of ALA-PDT in the treatment of patients with cervical HSIL. Methods: A total of 40 patients aged 20 - 41 years with cervical HSIL and high-risk Human Papilloma Virus (HR-HPV) infections were enrolled in this retrospective study from January 2019 to December 2022. Patients were treated with six times of ALA-PDT at intervals of 7-14 days. Three months after the treatment, the efficacy was evaluated through HPV genotyping and cervical cytology examination. If the cytological result was worse than ASC -US, the patient underwent colposcopy-directed biopsy immediately. Otherwise, patients would receive rigorous follow-up observation. Results: Three months after receiving ALA-PDT treatment, 65% (26/40) of cervical HSIL patients at our center showed complete regression (cytological result: normal; HR-HPV: negative). This rate increased to 82.5% (33/40) at the 12-month follow-up. None of the patients experienced disease progression after ALA-PDT therapy. The risk of persistent HR-HPV infection was 32.5% (13/40) at the 3-month follow-up after ALA-PDT. Multivariate analyses identified cervical canal involvement as an independent risk factor for persistent HR-HPV infection at the 3-month follow-up after ALA-PDT treatment. During the treatment of the 40 patients with ALA-PDT, there were no reports of severe adverse reactions. Only a limited number of patients experienced slight discomfort symptoms. Conclusion: ALA-PDT is safe and effective noninvasive therapy for patients with cervical HSIL and HR-HPV infections. It is particularly suitable for young women, who have been confirmed with cervical HSIL and have demand for fertility protection. Three months after ALA-PDT treatment, if a patient still has either ASC-US cervical cytological result and/or HR-HPV infection, rigorous observation is considered safe for her. Cervical canal involvement is an independent risk factor for persistent HR-HPV infection at the 3-month follow-up after ALA-PDT treatment.

The neuroprotective effect of YaoYi-moxibustion on ischemic stroke by attenuating NK-κB expression in rats.

Background: Traditional Chinese medicine (TCM) has become a crucial direction for ischemic stroke treatment. This study sought to explore the underlying roles of YaoYi-moxibustion (YY-moxi) in ischemic stroke. Methods: A total of 75 Sprague-Dawley rats were randomly divided into the following 5 groups: (I) the sham-operated group; (II) the middle cerebral artery occlusion model (MCAO) group; (III) the YY-moxi group; (IV) the antioxidant (N-acetylcysteine, NAC) group; and (V) the NAC + YY-moxi group. After the model had been established, the NAC group received intracerebroventricular injections of NAC, the YY-moxi group received YY-moxi, and the NAC + YY-moxi group received a combination of these 2 interventions. The neurological deficit score was confirmed, and the cerebral infarction was examined by triphenyl tetrazolium chloride (TTC) staining. In the ischemia site of stroke, terminal deoxynucleotidyl transferase-mediated Dutp nick end labeling staining was applied to examine the apoptotic cells. Additionally, the apoptosis-associated genes and protein expressions in the ischemic brains were investigated by the reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR), immunohistochemistry, and western blot analysis. Results: YY-moxi alone and YY-moxi combined with NAC significantly reduced the neurological scores and cerebral infarction area of the MCAO rats. Additionally, YY-moxi alone and the combined application of YY-moxi and NAC improved the pathological status of ischemic brain tissues. Further, we found that YY-moxi alone and YY-moxi in combination with NAC could enhanced the antioxidation ability and reduced the inflammatory response of the MCAO model rats. We also proved that YY-moxi alone and YY-moxi combined with NAC significantly suppressed apoptosis-related proteins in the MCAO model rats. Conclusions: These findings indicate that YY-moxi exerts a protective effect on cerebral ischemic injury by reducing apoptosis. The study suggests that the mechanism may be related to its downregulating the expression of nuclear factor kappa B (NK-κB).

TRIM21-regulated Annexin A2 plasma membrane trafficking facilitates osteosarcoma cell differentiation through the TFEB-mediated autophagy.

Osteosarcoma (OS) is the most common primary malignant bone tumor in children and adolescents, which is characterized by dysfunctional autophagy and poor differentiation. Our recent studies have suggested that the tripartite motif containing-21 (TRIM21) plays a crucial role in regulating OS cell senescence and proliferation via interactions with several proteins. Yet, its implication in autophagy and differentiation in OS is largely unknown. In the present study, we first showed that TRIM21 could promote OS cell autophagy, as determined by the accumulation of LC3-II, and the degradation of cargo receptor p62. Further, we were able to identify that Annexin A2 (ANXA2), as a novel interacting partner of TRIM21, was critical for TIRM21-induced OS cell autophagy. Although TRIM21 had a negligible effect on the mRNA and protein expressions of ANXA2, we did find that TRIM21 facilitated the translocation of ANXA2 toward plasma membrane (PM) in OS cells through a manner relying on TRIM21-mediated cell autophagy. This functional link has been confirmed by observing a nice co-expression of TRIM21 and ANXA2 (at the PM) in the OS tissues. Mechanistically, we demonstrated that TRIM21, via facilitating the ANXA2 trafficking at the PM, enabled to release the transcription factor EB (TFEB, a master regulator of autophagy) from the ANXA2-TFEB complex, which in turn entered into the nucleus for the regulation of OS cell autophagy. In accord with previous findings that autophagy plays a critical role in the control of differentiation, we also demonstrated that autophagy inhibited OS cell differentiation, and that the TRIM21/ANXA2/TFEB axis is implicated in OS cell differentiation through the coordination with autophagy. Taken together, our results suggest that the TRIM21/ANXA2/TFEB axis is involved in OS cell autophagy and subsequent differentiation, indicating that targeting this signaling axis might lead to a new clue for OS treatment.

Musk Ketone Induces Neural Stem Cell Proliferation and Differentiation in Cerebral Ischemia via Activation of the PI3K/Akt Signaling Pathway.

Traditional Chinese medicine has been reported to influence the proliferation and differentiation of neural stem cells (NSCs) that may be protective against nervous system diseases. Recent evidence indicates the importance of musk ketone in nerve recovery and preventing secondary damage after cerebral ischemic injury. A middle cerebral artery occlusion (MCAO) rat model was established by a transient filament model, and rats were treated with musk ketone (0.9 or 1.8 µM). Next, an in vitro oxygen-glucose deprivation (OGD) cell model was established to study the effect of musk ketone on the proliferation and differentiation of NSCs. To determine the potential mechanisms of musk ketone involved in activities of NSCs, the effect of musk ketone on the PI3K/Akt signaling pathway activation was assessed. Furthermore, NSCs were treated with musk ketone in the presence of PI3K/Akt inhibitor Akti-1/2 to examine their roles on NSC proliferation and differentiation. Musk ketone reduced cerebral ischemic injury in a dose-dependent manner in rats. In addition, NSCs treated with musk ketone showed enhanced proliferation and differentiation along with increased PI3K/Akt signaling pathway activation. The effects of muck ketone were reversed by Akti-1/2. Altogether, musk ketone promoted NSC proliferation and differentiation and protected against cerebral ischemia by activating the PI3K/Akt signaling pathway, highlighting the potential of musk ketone as a physiologically validated approach for the treatment of cerebral ischemia.

PRMT5-TRIM21 interaction regulates the senescence of osteosarcoma cells by targeting the TXNIP/p21 axis.

Osteosarcoma (OS) is the most common bone malignancy in adolescents and has poor clinical outcomes. Protein arginine methyltransferase 5 (PRMT5) has recently been shown to be aberrantly expressed in various cancers, yet its role in OS remains elusive. Here, we found that PRMT5 was overexpressed in OS and its overexpression predicted poor clinical outcomes. PRMT5 knockdown significantly triggered pronounced senescence in OS cells, as evidenced by the increase in senescence-associated ß-galactosidase (SA-ß-gal)-stained cells, induction of p21 expression, and upregulation of senescence-associated secretory phenotype (SASP) gene expression. In addition, we found that PRMT5 plays a key role in regulating DNA damaging agents-induced OS cell senescence, possibly, via affecting the repair of DNA damage. Furthermore, we found that TXNIP acts as a key factor mediating PRMT5 depletion-induced DNA damage and cellular senescence. Mechanistically, TRIM21, which interacts with PRMT5, was essential for the regulation of TXNIP/p21 expression. In summary, we propose a model in which PRMT5, by interaction with TRIM21, plays a key role in regulating the TXNIP/p21 axis during senescence in OS cells. The present findings suggest that PRMT5 overexpression in OS cells might confer resistance to chemotherapy and that targeting the PRMT5/TRIM21/TXNIP signaling may enhance the therapeutic efficacy in OS.