Fibroblast growth factor 21 is regulated by the IRE1α-XBP1 branch of the unfolded protein response and counteracts endoplasmic reticulum stress-induced hepatic steatosis.

Endoplasmic reticulum (ER) stress activates the adaptive unfolded protein response (UPR) and represents a critical mechanism that underlies metabolic dysfunctions. Fibroblast growth factor 21 (FGF21), a hormone that is predominantly secreted by the liver, exerts a broad range of effects upon the metabolism of carbohydrates and lipids. Although increased circulating levels of FGF21 have been documented in animal models and human subjects with obesity and nonalcoholic fatty liver disease, the functional interconnections between metabolic ER stress and FGF21 are incompletely understood. Here, we report that increased ER stress along with the simultaneous elevation of FGF21 expression were associated with the occurrence of nonalcoholic fatty liver disease both in diet-induced obese mice and human patients. Intraperitoneal administration of the ER stressor tunicamycin in mice resulted in hepatic steatosis, accompanied by activation of the three canonical UPR branches and increased the expression of FGF21. Furthermore, the IRE1α-XBP1 pathway of the UPR could directly activate the transcriptional expression of Fgf21. Administration of recombinant FGF21 in mice alleviated tunicamycin-induced liver steatosis, in parallel with reduced eIF2α-ATF4-CHOP signaling. Taken together, these results suggest that FGF21 is an integral physiological component of the cellular UPR program, which exerts beneficial feedback effects upon lipid metabolism through counteracting ER stress.

[Inhibitory effect of the recombinant adenovirus pre-miR-10a on K562 cell proliferation].

AIM: To investigate the changes of proliferation and apoptosis in K562 cells over-expressing miR-10a. METHODS: K562 cells were infected with pAd-pre-miR-10a virus, and then the levels of miR-10a and bcr/abl in transfected K562 cells was detected using RT-PCR and the level of BCR/ABL using Western blotting. The methylthiazolyl tetrazolium (MTT) assay and flow cytometry (FCM) were used to monitor the changes of proliferation and apoptosis of K562 cells after transfection. RESULTS: Compared with the control groups, K562 cells transfected with pAd-pre-miR-10a presented the significantly increased level of miR-10a, the significantly decreased expressions of bcr/abl fusion gene and BCR/ABL fusion protein, the inhibited proliferation ability and the promoted apoptosis (P<0.05). CONCLUSION: The recombinant adenovirus of pAd-pre-miR-10a can inhibit the proliferation of K562 cells and promote cell apoptosis significantly.

Enhancement of specific cellular immune response induced by glycosyl-phosphatidylinositol-anchored BCR/ABL and mIL-12.

bcr/abl fusion gene is thought to be a promising target for chronic myelogenous leukemia (CML) patients to enhance immune response after attaining complete remission. In this study, we sought to enhance cellular immunity by co-expression of BCR/ABL and murine IL-12 gene on the tumor cell surface as a glycosyl-phosphatidylinositol (GPI)-form. The successfully constructed plasmid pBudCE4.1-BCR/ABL-GPI-mIL12 resulted in high levels of splenocyte proliferative responses, significant levels of IL-2 and IFNγ, and strong cytotoxic T-lymphocyte (CTL) responses in vitro. In a murine transplant model, the vaccinated mice showed decreased infiltration of leukemia cells and reduced expression of BCR/ABL transcripts and protein in bone marrow cells. Results of the present study indicated that this novel immunization strategy is useful in enhancing immune protection in mice, which would provide new insights into the development of effective vaccines for treating CML.

[MT1-MMP up-regulates VEGF expression in human breast carcinoma MCF-7 cells and induces tumor angiogenesis].

OBJECTIVE: To study the function of MT1-MMP in tumor angiogenesis and elucidate the possible way of action that MT1-MMP contributes to angiogenesis. METHODS: MT1-MMP was transfected into human breast carcinoma cell line MCF-7 cells. Semi-quantitative RT-PCR and immunofluorescence staining were employed to detect the expression of VEGF in the transfected and non-transfected MCF-7 cells. Tumor growth, microvessel density and expression of VEGF in nude mice were detected through in vivo tumorigenicity assay. RESULTS: In MT1-MMP stable transfected MCF-7 cells, mRNA expression of VEGF(189), VEGF(165), and VEGF(121) and immunofluorescence intensity were significantly elevated (P < 0.001). In vivo tumorigenicity assay in the nude mice showed that MT1-MMP promoted tumor growth. The MVD in the MT1-MMP-transfected cells-transplanted tumor tissue was significantly elevated (P < 0.05). Immunohistochemical assay showed that there was a strong immunostaining of VEGF in those tumor tissues. CONCLUSION: MT1-MMP can induce tumor angiogenesis through up-regulation of VEGF expression. This function of MT1-MMP may open a new approach for clinical anti-tumor research and anti-tumor drug development.

The effect of transformation on the virulence of Streptococcus pneumoniae.

Although pneumococcus is one of the most frequently encountered opportunistic pathogen in the world, the mechanisms responsible for its infectiveness have not yet been fully understood. In this paper, we have attempted to characterize the effects of pneumococcal transformation on the pathogenesis of the organism. We constructed three transformation-deficient pneumococcal strains, which were designated as Nos. 1d, 2d, and 22d. The construction of these altered strains was achieved via the insertion of the inactivated gene, comE, to strains 1, 2 and 22. We then conducted a comparison between the virulence of the transformation-deficient strains and that of the wild-type strains, via an evaluation of the ability of each strain to adhere to endothelial cells, and also assessed psaA mRNA expression, and the survival of hosts after bacterial challenge. Compared to what was observed with the wild-type strains, our results indicated that the ability of all of the transformation-deficient strains to adhere to the ECV304 cells had been significantly reduced (p < 0.05), the expression of psaA mRNA was reduced significantly (p < 0.05) in strains 2d and 22d, and the median survival time of mice infected with strains 1d and 2d was increased significantly after intraperitoneal bacterial challenge (p < 0.05). The results of our study also clearly indicated that transformation exerts significant effects on the virulence characteristics of S. pneumoniae, although the degree to which this effect is noted appears to depend primarily on the genetic background of the bacteria.