Germline Cas9 promoters with improved performance for homing gene drive.

Gene drive systems could be a viable strategy to prevent pathogen transmission or suppress vector populations by propagating drive alleles with super-Mendelian inheritance. CRISPR-based homing gene drives convert wild type alleles into drive alleles in heterozygotes with Cas9 and gRNA. It is thus desirable to identify Cas9 promoters that yield high drive conversion rates, minimize the formation rate of resistance alleles in both the germline and the early embryo, and limit somatic Cas9 expression. In Drosophila, the nanos promoter avoids leaky somatic expression, but at the cost of high embryo resistance from maternally deposited Cas9. To improve drive efficiency, we test eleven Drosophila melanogaster germline promoters. Some achieve higher drive conversion efficiency with minimal embryo resistance, but none completely avoid somatic expression. However, such somatic expression often does not carry detectable fitness costs for a rescue homing drive targeting a haplolethal gene, suggesting somatic drive conversion. Supporting a 4-gRNA suppression drive, one promoter leads to a low drive equilibrium frequency due to fitness costs from somatic expression, but the other outperforms nanos, resulting in successful suppression of the cage population. Overall, these Cas9 promoters hold advantages for homing drives in Drosophila species and may possess valuable homologs in other organisms.

Reducing Effect of Farnesylquinone on Lipid Mass in C. elegans by Modulating Lipid Metabolism.

Bioassay-guided fractionation of marine-derived fungi revealed that the EtOAc fraction from the fermentation broth of a mutated fungal strain Streptomyces nitrosporeus YBH10-5 had lipid-lowering effects in HepG2 cells. Chromatographic separation of the EtOAc fraction resulted in the isolation of 11 PKS-based derivatives, including a structurally unique meroterpenoid namely nitrosporeunol H (1). The structure of compound 1 was determined by the analysis of spectroscopic data. Further bioassay resulted in farnesylquinone (2) and its analogues to exert in vivo fat-reducing effects in C. elegans worm model. The underlying mode of action of compound 2 in the context of live worms was investigated, uncovering that compound 2 enhanced the mitochondrial ß-oxidation rate and changed the transcriptional level of energy metabolism genes. Additional experiments revealed that compound 2 exerted its effects in C. elegans partially through repressing FAT-5, an isoform of stearoyl-CoA desaturase (SCD) which catalyzes the conversion of saturated fatty acids to monounsaturated fatty acids, thereafter leading to the modification of the fatty acid profile. Thus, compound 2 was suggested to be a promising lead for further optimization to treat obesity.

[DREAM: a multifunctional transcriptional regulator].

DREAM (downstream regulatory element antagonist modulator), Calsenilin and KChIP3 (potassium channel interacting protein 3) belong to the neuronal calcium sensor (NCS) superfamily, which transduces the intracellular calcium signaling into a variety of activities. They are encoded by the same gene locus, but have distinct subcellular locations. DREAM was first found to interact with DRE (downstream regulatory element) site in the vicinity of the promoter of prodynorphin gene to suppress gene transcription. Calcium can disassemble this interaction by binding reversibly to DREAM protein on its four EF-hand motifs. Apart from having calcium dependent DRE site binding, DREAM can also interact with other transcription factors, such as cAMP responsive element binding protein (CREB), CREB-binding protein (CBP) and cAMP responsive element modulator (CREM), by this concerted actions, DREAM extends the gene pool under its control. DREAM is predominantly expressed in central nervous system with its highest level in cerebellum, and accumulating evidence demonstrated that DREAM might play important roles in pain sensitivity. Novel findings have shown that DREAM is also involved in learning and memory processes, Alzheimer's disease and stroke. This mini-review provides a brief introduction of its discovery history and protein structure properties, focusing on the mechanism of DREAM nuclear translocation and gene transcription regulation functions.

[Preliminary study on mechanisms of granulocyte macrophage-colony stimulating factor in enhancing impaired colonic anastomotic healing in rats treated with intraperitoneal oxaliplatin].

OBJECTIVE: To investigate the mechanisms of local application of granulocyte macrophage-colony stimulating factor (GM-CSF) on healing of colonic anastomoses impaired by intraperitoneal oxaliplatin in rats. METHODS: Sixty 10-week-old male Wistar rats were made the colonic anastomosis model and randomized into 3 groups, 20 rats in each. The rats received intraperitoneal injection of 5% dextrose in group A, and intraperitoneal injection of 5% dextrose and 10 mL oxaliplatin (25 mg/kg) in group B at 1 day; and 50 microg GM-CSF was injected into the perianastomotic area immediately after operation and 10 mL intraperitoneal oxaliplatin (25 mg/kg) was given at 1 day. The general situation of rats was observed after operation. Anastomotic healing was tested by measuring the bursting pressure in vivo at 2, 3, 5, 7 days. Anastomotic healing score was evaluated by histological staining. Immunohistochemical staining of the anastomotic site was used to determine the amount of collagen type I content. RESULTS: All animals survived to the experiment end. There was no significant difference in the bursting pressure among 3 groups at 2 and 3 days (P > 0.05); the bursting pressure of group B was significantly lower than that of groups A and C (P < 0.05). There was no significant difference in mononuclear cells infiltration, mucosal epithelialization, submucosa-muscle layer connection degree, and granulation tissue formation between groups A and C at different time points (P > 0.05); groups A and C were significantly better than group B in mucosal epithelialization and granulation tissue formation (P < 0.05). Groups A and C were significantly better than group B in mononuclear cells infiltration at 2 and 3 days, and in submucosa-muscle layer connection degree at 5 and 7 days (P < 0.05). There was no significant difference in collagen type I content among 3 groups at 2 and 3 days (P > 0.05); the content of collagen type I in groups A and C were significantly higher than that in group B (P < 0.05) at 5 and 7 days. CONCLUSION: Local administration of GM-CSF may enhance colonic anastomotic healing by early stimulating infiltration of macrophages and increasing collagen deposition.

Decreased energy metabolism extends life span in Caenorhabditis elegans without reducing oxidative damage.

On the basis of the free radical and rate of living theories of aging, it has been proposed that decreased metabolism leads to increased longevity through a decreased production of reactive oxygen species (ROS). In this article, we examine the relationship between mitochondrial energy metabolism and life span by using the Clk mutants in Caenorhabditis elegans. Clk mutants are characterized by slow physiologic rates, delayed development, and increased life span. This phenotype suggests that increased life span may be achieved by decreasing energy expenditure. To test this hypothesis, we identified six novel Clk mutants in a screen for worms that have slow defecation and slow development and that can be maternally rescued. Interestingly, all 11 Clk mutants have increased life span despite the fact that slow physiologic rates were used as the only screening criterion. Although mitochondrial function is decreased in the Clk mutants, ATP levels are normal or increased, suggesting decreased energy utilization. To determine whether the longevity of the Clk mutants results from decreased production of ROS, we examined sensitivity to oxidative stress and oxidative damage. We found no evidence for systematically increased resistance to oxidative stress or decreased oxidative damage in the Clk mutants despite normal or elevated levels of superoxide dismutases. Overall, our findings suggest that decreased energy metabolism can lead to increased life span without decreased production of ROS.

[Caenorhabditis elegans: a powerful tool for drug discovery].

A simple model organism Caenorhabditis elegans has contributed substantially to the fundamental researches in biology. In an era of functional genomics, nematode worm has been developed into a multi-purpose tool that can be exploited to identify disease-causing or disease-associated genes, validate potential drug targets. This, coupled with its genetic amenability, low cost experimental manipulation and compatibility with high throughput screening in an intact physiological condition, makes the model organism into an effective toolbox for drug discovery. This review shows the unique features of C. elegans, how it can play a valuable role in our understanding of the molecular mechanism of human diseases and finding drug leads in drug development process.

Effect of runing II on the growth and metastasis of transplanted tumor in mammary cancer-bearing mice and its mechanism.

OBJECTIVE: To study the effect of Runing II (a Chinese herbal preparation for mammary cancer) on the growth and metastasis of transplanted tumor of mammary cancer MA-891-bearing TA2 mice and its mechanism. METHODS: The model of mammary cancer MA-891 cell strain transplanted tumor of TA2 mice with lung metastasis were developed to observe the effect of Runing II on the growth and metastasis of the transplanted tumor. The immunohistochemical method and image analysis were adopted to detect the levels of vascular endothelial growth factor (VEGF), vascular endothelial growth factor receptor (VEGFR), and micro-vessel count (MVC) and micro-vessel area (MVA). RESULTS: In the Runing II group, the tumor weight inhibition rate and the lung metastasis inhibition rate were 37.3% and 65.4% respectively, the tumor growth and lung metastasis were obviously inhibited; And the levels of VEGF and VEGFR, MVC and MVA were significantly decreased as compared with those in the tumor-bearing control group (P<0.05). CONCLUSION: The Chinese herbal preparation Running II can inhibit the metastasis of tumor through inhibiting the angiogenesis, and the mechanism is possibly related with down-regulation of VEGF and VEGFR expression.