Expression of recombinant classical swine fever virus E2 glycoprotein by endogenous Txnip promoter in stable transgenic CHO cells

As the main immunogen that could stimulate neutralized antibody in pigs, recombinant E2 protein of CSFV was expressed in CHO‐dhfr^?cells driven by endogenous Txnip promoter from Chinese hamster. Different fragments of Txnip promoter were amplified by PCR from isolated genomic DNA of CHO cells and cloned into different expression vectors. Compared with CMV promoter, CHO‐pTxnip‐4‐rE2 (F12) cell clone with the highest yield of rE2 protein was established by random insertion of the expression cassette driven by 860 bp sequences of Txnip promoter. In combination with treatment of 800 nM MTX for copy amplification of inserted expression cassette, the dynamic expression profile of rE2 protein was observed. Then inducible expression strategy of balance between viable cell density and product yield was conducted by mixed addition of 0.1 mM NADH and 0.1 mM ATP in culture medium at day 3 of batch‐wise culture. It could be concluded that Txnip promoter would be a promising alternative promoter for recombinant antigen protein expression in transgenic cells.     

G Protein-Coupled Receptors in and on the Cell Nucleus: A New Signaling Paradigm?

Signaling from internalizing and endosomal receptors has almost become a classic GPCR paradigm in the last several years. However, it has become clear in recent years that GPCRs also elicit signals when resident at other subcellular sites including the endoplasmic reticulum, Golgi apparatus, and the nucleus. In this review we discuss the nature, function, and trafficking of nuclear GPCR signaling complexes, as well as potential sources of endogenous and exogenous ligands. Finally, we pose a series of questions that will need to be answered in the coming years to confirm and extend this as a new paradigm for GPCR signaling.     

Osa modulates the expression of Apterous target genes in the Drosophila wing

The establishment of the dorsal-ventral axis of the Drosophila wing depends on the activity of the LIM-homeodomain protein Apterous. Apterous activity depends on the formation of a higher order complex with its cofactor Chip to induce the expression of its target genes. Apterous activity levels are modulated during development by dLMO. Expression of dLMO in the Drosophila wing is regulated by two distinct Chip dependent mechanisms. Early in development, Chip bridges two molecules of Apterous to induce expression of dLMO in the dorsal compartment. Later in development, Chip, independently of Apterous, is required for expression of dLMO in the wing pouch. We have conducted a modular P-element based EP (enhancer/promoter) misexpression screen to look for genes involved in Apterous activity. We have found Osa, a member of the Brahma chromatin-remodeling complex, as a positive modulator of Apterous activity in the Drosophila wing. Osa mediates activation of some Apterous target genes and repression of others, including dLMO. Osa has been shown to bind Chip. We propose that Chip recruits Osa to the Apterous target genes, thus mediating activation or repression of their expression.     

Brg1 regulates pro-lipogenic transcription by modulating SREBP activity in hepatocytes

Alteration of hepatic lipid metabolism contributes to a range of human diseases including steatosis. Sterol response element binding protein (SREBP) is the master regulator of lipid metabolism. The epigenetic mechanism whereby SREBP activity is regulated remains incompletely understood. We have previously shown that systemic knockdown of brahma-related gene 1 (Brg1), a chromatin remodeling protein, attenuates steatosis in mice by down-regulating the synthesis of pro-inflammatory mediators. Here we show that hepatocyte conditional Brg1 knockout (HepcKO) mice were largely protected from high-fat diet (HFD) induced steatosis as evidenced by decelerated weight gains, improved insulin sensitivity, ameliorated steatotic injuries, and diminished hepatic inflammation. Brg1 contributed to lipid metabolism by trans-activating the genes involved in fatty acid esterification. Mechanistically, Brg1 interacted with and was recruited by sterol response element binding protein (SREBP1c) to the promoters of SREBP target genes and optimized the chromatin structure to facilitate SREBP1c binding. Therefore, our data have identified a previously unrecognized role for Brg1 in hepatic lipid metabolism by portraying Brg1 as an essential epigenetic co-factor for SREBP1c.     

Understanding the mechanistic regulation of ferroptosis in cancer: the gene matters

Ferroptosis has emerged as a crucial regulated cell death involved in a variety of physiological processes or pathological diseases, such as tumor suppression. Though initially being found from anticancer drug screening and considered not essential as apoptosis for growth and development, numerous studies have demonstrated that ferroptosis is tightly regulated by key genetic pathways and/or genes, including several tumor suppressors and oncogenes. In this review, we introduce the basic concepts of ferroptosis, characterized by the features of non-apoptotic, iron-dependent, and overwhelmed accumulation of lipid peroxides, and the underlying regulated circuits are considered to be pro-ferroptotic pathways. Then, we discuss several established lipid peroxidation defending systems within cells, including SLC7A11/GPX4, FSP1/CoQ, GCH1/BH4, and mitochondria DHODH/CoQ, all of which serve as anti-ferroptotic pathways to prevent ferroptosis. Moreover, we provide a comprehensive summary of the genetic regulation of ferroptosis via targeting the above-mentioned pro-ferroptotic or anti-ferroptotic pathways. The regulation of pro- and anti-ferroptotic pathways gives rise to more specific responses to the tumor cells in a context-dependent manner, highlighting the unceasing study and deeper understanding of mechanistic regulation of ferroptosis for the purpose of applying ferroptosis induction in cancer therapy.     

Characterization and expression analysis of seven selenoprotein genes in yellow catfish Pelteobagrus fulvidraco to dietary selenium levels

BackgroundSelenium (Se) appears in the selenoproteins in the form of selenocysteine (Sec) and is important for the growth and development of vertebrates. The present study characterized seven selenoproteins, consisting of the GPX1, GPX3, GPX4, SELENOW, SELENOP, TXNRD2 and TXNRD3 cDNAs in various tissues of yellow catfish, explored their regulation to dietary Se addition.Methods3′ and 5′ RACE PCR were used to clone full-length cDNA sequences of seven selenoprotein genes (GPX1, GPX3, GPX4, SELENOW, SELENOP, TXNRD2 and TXNRD3). Their molecular characterizations were analyzed, including conservative motifs and the SECIS elements. The phylogenetic trees were generated through neighbor-joining (NJ) method with MEGA 6.0 with 1000 bootstrap replications. Quantitative real-time PCR was used to explore their mRNA tissue distribution in the heart, anterior intestine, dorsal muscle, head kidney, gill, liver, brain, spleen and mesenteric fat. Yellow catfish (mixed sex) were fed diets with dietary Se contents at 0.03 (low Se), 0.25 (adequate Se) and 6.39 (high Se) mg Se/kg, respectively, for 12 weeks, and their spleen, kidney, testis and brain were used for the determination of the mRNA levels of the seven selenoproteins.ResultsThe seven selenoproteins had similar domains to their corresponding members of other vertebrates. They were widely expressed in nine tissues, including heart, liver, brain, spleen, head kidney, dorsal muscle, mesenteric fat, anterior intestine and gill, but showed tissue-dependent expression patterns. Dietary Se addition affected the expression of the seven genes in spleen, kidney, testis and brain tissues of yellow catfish.ConclusionTaken together, our study demonstrated the characterization, expression and regulation of seven selenoproteins, which increased our understanding of the biological functions of Se and selenoproteins in fish.