SREBP1-Induced Glutamine Synthetase Triggers a Feedforward Loop to Upregulate SREBP1 through Sp1 O-GlcNAcylation and Augments Lipid Droplet Formation in Cancer Cells

Glutamine and lipids are two important components of proliferating cancer cells. Studies have demonstrated that glutamine synthetase (GS) boosts glutamine-dependent anabolic processes for nucleotide and protein synthesis, but the role of GS in regulating lipogenesis remains unclear. This study identified that insulin and glutamine deprivation activated the lipogenic transcription factor sterol regulatory element-binding protein 1 (SREBP1) that bound to the GS promoter and increased its transcription. Notably, GS enhanced the O-linked N-acetylglucosaminylation (O-GlcNAcylation) of the specificity protein 1 (Sp1) that induced SREBP1/acetyl-CoA carboxylase 1 (ACC1) expression resulting in lipid droplet (LD) accumulation upon insulin treatment. Moreover, glutamine deprivation induced LD formation through GS-mediated O-GlcNAc-Sp1/SREBP1/ACC1 signaling and supported cell survival. These findings demonstrate that insulin and glutamine deprivation induces SREBP1 that transcriptionally activates GS, resulting in Sp1 O-GlcNAcylation. Subsequently, O-GlcNAc-Sp1 transcriptionally upregulates the expression of SREBP1, resulting in a feedforward loop that increases lipogenesis and LD formation in liver and breast cancer cells.

Insulin and Metformin Control Cell Proliferation by Regulating TDG-Mediated DNA Demethylation in Liver and Breast Cancer Cells

Type 2 diabetes mellitus (T2DM) is a frequent comorbidity of cancer. Hyperinsulinemia secondary to T2DM promotes cancer progression, whereas antidiabetic agents, such as metformin, have anticancer effects. However, the detailed mechanism for insulin and metformin-regulated cancer cell proliferation remains unclear. This study identified a mechanism by which insulin upregulated the expression of c-Myc, sterol regulatory element-binding protein 1 (SREBP1), and acetyl-coenzyme A (CoA) carboxylase 1 (ACC1), which are important regulators of lipogenesis and cell proliferation. Thymine DNA glycosylase (TDG), a DNA demethylase, was transactivated by c-Myc upon insulin treatment, thereby decreasing 5-carboxylcytosine (5caC) abundance in the SREBP1 promoter. On the other hand, metformin-activated AMP-activated protein kinase (AMPK) increased DNA methyltransferase 3A (DNMT3A) activity to increase 5-methylcytosine (5mC) abundance in the TDG promoter. This resulted in decreased TDG expression and enhanced 5caC abundance in the SREBP1 promoter. These findings demonstrate that c-Myc activates, whereas AMPK inhibits, TDG-mediated DNA demethylation of the SREBP1 promoter in insulin-promoted and metformin-suppressed cancer progression, respectively. This study indicates that TDG is an epigenetic-based therapeutic target for cancers associated with T2DM.

Thermo-responsive magnetic liposomes for hyperthermia-triggered local drug delivery

We prepared and characterised thermo-responsive magnetic liposomes, which were designed to combine features of magnetic targeting and thermo-responsive control release for hyperthermia-triggered local drug delivery. The particle size and zeta-potential of the thermo-responsive magnetic ammonium bicarbonate (MagABC) liposomes were about 210 nm and -14 mV, respectively. The MagABC liposomes showed encapsulation efficiencies of about 15% and 82% for magnetic nanoparticles (mean crystallite size 12 nm) and doxorubicin (DOX), respectively. The morphology of the MagABC liposomes was visualised using transmission electron microscope (TEM). The MagABC liposomes showed desired thermo-responsive release. The MagABC liposomes, when physically targeted to tumour cells in culture by a permanent magnetic field yielded a substantial increase in intracellular accumulation of DOX as compared to non-magnetic ammonium bicarbonate (ABC) liposomes. This resulted in a parallel increase in cytotoxicity for DOX loaded MagABC liposomes over DOX loaded ABC liposomes in tumour cells.

Cloning a novel endo-1,4-β-D-glucanase gene from Trichoderma virens and heterologous expression in E. coli

Endo-1,4-β-d-glucanase (EG), as a key constituent of cellulase taking the responsibility of cutting β-1,4 glycosidic bonds, plays the essential role in the process of degrading cellulose by cellulase. Cloning and expressing the EG gene is important to the cellulase research and application. In this work, a novel EG gene was cloned from Trichoderma virens ZY-01, which was a cellulase secreting microbe isolated by our laboratory. The DNA sequence showed that the length of the cloned EG is 1069 bp, which had 95.2% similarity to the EG IV from T. viride AS 3.3711. Further, the expression vector pET-32a-EG was constructed and was successfully heterologously expressed in Escherichia coli. The expression product was purified with Ni²⁺ affinity chromatography and its enzymatic properties were investigated. The SDS-PAGE showed the target protein is 39 kDa, which is consistent with the translated result from the DNA sequence. The kinetic parameter for the expression product was K_m = 13.71 mg/mL and V_max=0.51 μmol/min·mL. The optimal reaction pH and temperature was pH = 7.0 and T = 40 °C, which is similar to the native EG produced by Trichoderma virens ZY-01. It provides the foundation for the endo-1,4-β-d-glucanase further evolution and application.

[A review on the epidemiologic features of severe fever with thrombocytopenia syndrome]

Severe fever with Thrombocytopenia Syndrome (SFTS) is an emerging hemorrhagic fever disease in the rural areas of east-central China, which is caused by SFTSV-a newly discovered bunyavirus. SFTSV is most likely transmitted by tick bites but can also be transmitted within human beings. The onset of SFTS is sudden and with rapid progress, with main clinical manifestations as fever, thrombocytopenia, leucopenia and gastrointestinal and hepatorenal dysfunctions. Some patients may die from multiple organ failure, and the case fatality rate is approximately 10%. In this paper, we use the method of literature review to summarize the recent research progress of SFTS which includes the epidemic distribution characteristics, medium of transmission, host animals, transmission routes and susceptibility in the general population.

Using molecular markers to identify two major loci controlling carotenoid contents in maize grain

Maize is an important source of pro-vitamin A; beta-carotene, alpha-carotene and beta-cryptoxanthin, and the non-pro-vitamin A carotenoids including lutein and zeaxanthin. In the present study, a recombinant inbred (RI) population with 233 RI lines derived from a cross between By804 and B73 was employed to detect QTL for these nutritionally important components in maize grain. High Performance Liquid Chromatography was used to measure amounts of individual carotenoids over 2 years. A genetic linkage map was constructed with 201 molecular markers. In all, 31 putative QTL including 23 for individual and 8 for total carotenoids were detected on chromosome(s) 1, 3, 5, 6, 7, 8 and 10. The notable aspect of this study was that much of the phenotypic variation in contents of carotenoids could be explained by two loci (y1 and y9), and the QTL for carotenoids elucidated the interrelationships among these compounds at the molecular level. A gene targeted marker (Y1ssr) in the candidate gene phytoene synthase 1 (psy1) tightly linked to a major QTL explaining 6.6-27.2% phenotypic variation for levels of carotenoids was identified, which may prove useful to expedite breeding for higher level of carotenoids in maize grain. This functionally characterized gene (psy1) could also be exploited for further development of functional marker for carotenoids in maize. The QTL cluster located at y9 locus may also be used for pyramiding favorable alleles controlling contents of carotenoids from diverse maize germplasm.

Conservative management of spontaneous ruptured hepatocellular carcinoma

Because most emergent surgical operations for patients with spontaneous ruptured hepatocellular carcinoma (HCC) achieved hemostasis only, a conservative approach was chosen for management of initial bleeding in our institute. Elective surgery was performed in selected patients to attempt resection of the HCC after stabilization of the hemorrhage. From 1971, 68 of 87 patients with ruptured HCC received the conservative treatment, and 19 were treated by emergent surgery during the same period. Overall, one week and one month mortality rates were 26.5 per cent, 48.5 per cent in the conservative group, and 31.6 per cent, 47.4 per cent in the emergent operative group, respectively. Two patients in the emergent operative group underwent partial hepatectomy for a resectability of 10.5 per cent. Fifteen patients in the conservative group received elective laparotomy 1-3 weeks after control of the initial bleeding. Six underwent partial hepatectomy with a resectability of 40.0 per cent. In conclusion, conservative management is an effective approach for control of intraperitoneal hemorrhage in patients with ruptured HCC. Elective surgery on selected patients after hemostasis will increase the cancer resection rate in patients who undergo laparotomy and will give a better life expectancy than emergent laparotomy in patients with ruptured HCC.