Background::Steroid receptor-associated and regulated protein (SRARP) suppresses tumor progression and modulates steroid receptor signaling by interacting with estrogen receptors and androgen receptors in breast cancer. In endometrial cancer (EC), progesterone receptor (PR) signaling is crucial for responsiveness to progestin therapy. The aim of this study was to investigate the role of SRARP in tumor progression and PR signaling in EC. Methods::Ribonucleic acid sequencing data from the Cancer Genome Atlas, Clinical Proteomic Tumor Analysis Consortium, and Gene Expression Omnibus were used to analyze the clinical significance of SRARP and its correlation with PR expression in EC. The correlation between SRARP and PR expression was validated in EC samples obtained from Peking University People’s Hospital. SRARP function was investigated by lentivirus-mediated overexpression in Ishikawa and HEC-50B cells. Cell Counting Kit-8 assays, cell cycle analyses, wound healing assays, and Transwell assays were used to evaluate cell proliferation, migration, and invasion. Western blotting and quantitative real-time polymerase chain reaction were used to evaluate gene expression. The effects of SRARP on the regulation of PR signaling were determined by co-immunoprecipitation, PR response element (PRE) luciferase reporter assay, and PR downstream gene detection. Results::Higher SRARP expression was significantly associated with better overall survival and disease-free survival and less aggressive EC types. SRARP overexpression suppressed growth, migration, and invasion in EC cells, increased E-cadherin expression, and decreased N-cadherin and Wnt family member 7A ( WNT7A) expression. SRARP expression was positively correlated with PR expression in EC tissues. In SRARP-overexpressing cells, PR isoform B (PRB) was upregulated and SRARP bound to PRB. Significant increases in PRE-based luciferase activity and expression levels of PR target genes were observed in response to medroxyprogesterone acetate. Conclusions::This study illustrates that SRARP exerts a tumor-suppressive effect by inhibiting the epithelial-mesenchymal transition via Wnt signaling in EC. In addition, SRARP positively modulates PR expression and interacts with PR to regulate PR downstream target genes.

B淋巴细胞瘤/白血病因子3(B cell CLL/lymphoma 3,BCL3)是一个转录辅调节因子,通过结合转录因子对基因表达起激活或抑制作用,维持细胞存活,但其机制尚不清楚.该研究采用 CRISPR/Cas9技术建立BCL3基因敲除的人宫颈癌HeLa细胞,实时荧光定量PCR和Western blot验证敲除情况.使用特异性荧光探针法、萤火虫荧光素酶法、活细胞能量代谢动态分析法等技术手段检测基因敲除(BCL3-KO)对细胞内活性氧类(reactive oxygen species,ROS)水平、线粒体膜电位、线粒体呼吸作用以及ATP生成的影响.结果发现,BCL3-KO细胞内的相对ROS水平上升约50％,采用转染的方式恢复细胞内表达BCL3基因则可抑制ROS水平的上升;与野生型HeLa细胞相比,BCL3-KO细胞的线粒体膜电位明显降低(P<0.001);BCL3敲除不影响细胞基础有氧呼吸速率,但引起碳酰氰4-(三氟甲氧基)笨腙[carbomyl cyanide 4-(trifluorometyocy)phenylhydrazone,FCCP]诱导的最大(极限)呼吸速率显著上升(P<0.001);相比野生型细胞,BCL3-KO细胞中的ATP的浓度下降40％.该研究揭示了BCL3对线粒体功能的调控作用,可能是其维护癌细胞存活的原因之一.

The nuclear receptors(NRs)are an evolutionarily related family of transcription factors,which share certain common structural characteristics and regulate the expressions of various genes by recognizing different response elements.NRs play important roles in cell differentiation,proliferation,survival and apoptosis,rendering them indispensable in many physiological activities including growth and metabolism.As a result,dysfunctions of NRs are closely related to a variety of diseases,such as diabetes,obesity,infertility,inflammation,the Alzheimer's disease,cardiovascular diseases,prostate and breast cancers.Meanwhile,small-molecule drugs directly targeting NRs have been widely used in the treatment of above diseases.Here we summarize recent progress in the structural biology studies of NR family proteins.Compared with the dozens of structures of isolated DNA-binding domains(DBDs)and the striking more than a thousand of structures of isolated ligand-binding domains(LBDs)accumulated in the Protein Data Bank(PDB)over thirty years,by now there are only a small number of multi-domain NR complex structures,which reveal the integration of different NR domains capable of the allosteric signal transduction,or the detailed interactions between NR and various coregulator proteins.On the other hand,the structural information about several orphan NRs is still totally unavailable,hindering the further understanding of their functions.The fast development of new technologies in structural biology will certainly help us gain more comprehensive information of NR structures,inspiring the discovery of novel NR-targeting drugs with a new binding site beyond the classic LBD pockets and/or a new mechanism of action.

RIPK1 is a master regulator of multiple cell death pathways,including apoptosis and necroptosis,and inflammation.Importantly,activation of RIPK1 has also been shown to promote the transcriptional induction of proinflammatory cytokines in cells undergoing necroptosis,in animal models of amyotrophic lateral sclerosis(ALS)and Alzheimer's disease(AD),and in human ALS and AD.Rare human genetic carriers of non-cleavable RIPK1 variants(D324V and D324H)exhibit distinct symptoms of recurrent fevers and increased transcription of proinflammatory cytokines.Multiple RIPK1 inhibitors have been advanced into human clinical trials as new therapeutics for human inflammatory and neurodegenerative diseases,such as ALS and AD.However,it is unclear whether and how RIPK1 kinase activity directly mediates inflammation independent of cell death as the nuclear function of RIPK1 has not yet been explored.Here we show that nuclear RIPK1 is physically associated with the BAF complex.Upon RIPK1 activation,the RIPK1/BAF complex is recruited by specific transcription factors to active enhancers and promoters marked by H3K4me1 and H3K27ac.Activated nuclear RIPK1 mediates the phosphorylation of SMARCC2,a key component of the BAF complex,to promote chromatin remodeling and the transcription of specific proinflammatory genes.Increased nuclear RIPK1 activation and RIPK1/BAF-mediated chromatin-remodeling activity were found in cells expressing non-cleavable RIPK1,and increased enrichment of activated RIPK1 on active enhancers and promoters was found in an animal model and human pathological samples of ALS.Our results suggest that RIPK1 kinase serves as a transcriptional coregulator in nucleus that can transmit extracellular stimuli to the BAF complex to modulate chromatin accessibility and directly regulate the transcription of specific genes involved in mediating inflammatory responses.

RIPK1 is a multifaceted kinase with roles in diverse cellular processes,including cell death,innate immunity,and inflam-matory signaling.RIPK1 can also facilitate inflammatory diseases,like amyotrophic lateral sclerosis(ALS)and Alzhei-mer's disease(AD),independent of its cell death functions;in a recent Cell Research paper,Li et al.show that this results from RIPK1 acting as a transcriptional coregulator,forming a nuclear complex with the BAF complex through direct interactions with BRG1 and SMARCC2,mediating phosphor-ylation of SMARCC2,and promoting chromatin remodeling and transcription of proinflammatory genes.