血管生成素在造血系统恶性肿瘤中的作用及机制

促血管生成因子不仅参与实体肿瘤的发生和进展,而且与非实体瘤(如白血病等)的发生和发展进程密切相关.在众多促血管生成因子中,血管生成素(angiogenin, ANG)可以促进实体瘤细胞的生长和血管生成,然而其引起血管生成异常的详细机制目前还不完全清楚.本文就近年来在非实体瘤中血管生成素的功能及其潜在的治疗作用的研究进展进行综述.     

Small molecule AKAP-protein kinase A (PKA) interaction disruptors that activate PKA interfere with compartmentalized cAMP signaling in cardiac myocytes

A-kinase anchoring proteins (AKAPs) tether protein kinase A (PKA) and other signaling proteins to defined intracellular sites, thereby establishing compartmentalized cAMP signaling. AKAP-PKA interactions play key roles in various cellular processes, including the regulation of cardiac myocyte contractility. We discovered small molecules, 3,3'-diamino-4,4'-dihydroxydiphenylmethane (FMP-API-1) and its derivatives, which inhibit AKAP-PKA interactions in vitro and in cultured cardiac myocytes. The molecules bind to an allosteric site of regulatory subunits of PKA identifying a hitherto unrecognized region that controls AKAP-PKA interactions. FMP-API-1 also activates PKA. The net effect of FMP-API-1 is a selective interference with compartmentalized cAMP signaling. In cardiac myocytes, FMP-API-1 reveals a novel mechanism involved in terminating β-adrenoreceptor-induced cAMP synthesis. In addition, FMP-API-1 leads to an increase in contractility of cultured rat cardiac myocytes and intact hearts. Thus, FMP-API-1 represents not only a novel means to study compartmentalized cAMP/PKA signaling but, due to its effects on cardiac myocytes and intact hearts, provides the basis for a new concept in the treatment of chronic heart failure.     

Global Invasion of Lantana camara: Has the Climatic Niche Been Conserved across Continents?

Lantana camara, a native plant from tropical America, is considered one of the most harmful invasive species worldwide. Several studies have identified potentially invasible areas under scenarios of global change, on the assumption that niche is conserved during the invasion process. Recent studies, however, suggest that many invasive plants do not conserve their niches. Using Principal Components Analyses (PCA), we tested the hypothesis of niche conservatism for L. camara by comparing its native niche in South America with its expressed niche in Africa, Australia and India. Using MaxEnt, the estimated niche for the native region was projected onto each invaded region to generate potential distributions there. Our results demonstrate that while L. camara occupied subsets of its original native niche in Africa and Australia, in India its niche shifted significantly. There, 34% of the occurrences were detected in warmer habitats nonexistent in its native range. The estimated niche for India was also projected onto Africa and Australia to identify other vulnerable areas predicted from the observed niche shift detected in India. As a result, new potentially invasible areas were identified in central Africa and southern Australia. Our findings do not support the hypothesis of niche conservatism for the invasion of L. camara. The mechanisms that allow this species to expand its niche need to be investigated in order to improve our capacity to predict long-term geographic changes in the face of global climatic changes.     

The 2-Oxoacid Dehydrogenase Complexes in Mitochondria Can Produce Superoxide/Hydrogen Peroxide at Much Higher Rates Than Complex I

Several flavin-dependent enzymes of the mitochondrial matrix utilize NAD⁺ or NADH at about the same operating redox potential as the NADH/NAD⁺ pool and comprise the NADH/NAD⁺ isopotential enzyme group. Complex I (specifically the flavin, site I_F) is often regarded as the major source of matrix superoxide/H₂O₂ production at this redox potential. However, the 2-oxoglutarate dehydrogenase (OGDH), branched-chain 2-oxoacid dehydrogenase (BCKDH), and pyruvate dehydrogenase (PDH) complexes are also capable of considerable superoxide/H₂O₂ production. To differentiate the superoxide/H₂O₂-producing capacities of these different mitochondrial sites in situ, we compared the observed rates of H₂O₂ production over a range of different NAD(P)H reduction levels in isolated skeletal muscle mitochondria under conditions that favored superoxide/H₂O₂ production from complex I, the OGDH complex, the BCKDH complex, or the PDH complex. The rates from all four complexes increased at higher NAD(P)H/NAD(P)⁺ ratios, although the 2-oxoacid dehydrogenase complexes produced superoxide/H₂O₂ at high rates only when oxidizing their specific 2-oxoacid substrates and not in the reverse reaction from NADH. At optimal conditions for each system, superoxide/H₂O₂ was produced by the OGDH complex at about twice the rate from the PDH complex, four times the rate from the BCKDH complex, and eight times the rate from site I_F of complex I. Depending on the substrates present, the dominant sites of superoxide/H₂O₂ production at the level of NADH may be the OGDH and PDH complexes, but these activities may often be misattributed to complex I.     

<Emphasis Type="Italic">BRCA1</Emphasis> and <Emphasis Type="Italic">BRCA2</Emphasis> mutations and clinical interpretation in 398 ovarian cancer patients: comparison with breast cancer variants in a similar population

Background

Ovarian cancer is the leading cause of death worldwide among gynecologic malignancies. The recent approval of inhibitors of poly (ADP-ribose) polymerase (iPARP) in the treatment of ovarian cancer in the presence of a BRCA1/2 mutation has sparked the analysis of women with such diagnosis, which can further benefit from the detection of carriers in the family. Germline sequence and large rearrangements for BRCA1/2 were tested in 398 consecutive epithelial ovarian cancer (EOC) patients.The aim of this study was to identify the frequency and spectrum of germline BRCA1/2 pathogenic alterations in a cohort of patients with ovarian serous carcinoma, with a view to adequately selecting patients for prevention through family counseling and correlating this frequency with platinum sensitivity as a guidance to identify patients eligible for iPARP in our population.

Results

A total of 96 patients carried a pathogenic germline mutation, accounting for an overall 24.1% mutation incidence. Among mutation carriers, BRCA1 showed 62.5% incidence, BRCA2 rendered 36.5%, and one patient exhibited a mutation in both genes. Three pathogenic mutations were recurrent mutations detected five, three, and four times and represented 12.5% of the mutated samples. Worth highlighting, a 50% mutation incidence was detected when breast and ovarian cancer coexisted in the same patient. Novel mutations amounted to 9.4% of the total mutations, as compared to 4.7% in breast cancer. Forty out of 60 BRCA1 mutations were beyond the ovarian cancer cluster region (OCCR), in stark contrast with 22 out of 36 BRCA2 mutations being inside the OCCR. Taken together, germline BRCA1/2 mutations in EOC patients showed a distinct mutational spectrum compared to our previously published data on breast cancer patients.

Conclusions

In sum, our study provides novel data on ovarian BRCA1/2 mutation prevalence worldwide, enhances adequate patient selection for family counseling and prevention, and sheds light on the benefits of iPARP treatment.

     

Biological activity of human immunodeficiency virus type 1 Vif requires membrane targeting by C-terminal basic domains.

Human immunodeficiency virus type 1 (HIV-1) encodes a Vif protein which is important for virus replication and infectivity. Vif is a cytoplasmic protein which exists in both membrane-associated and soluble forms. The membrane-associated form is an extrinsic membrane protein which is tightly associated with the cytoplasmic side of membranes. We have analyzed the mechanism of membrane targeting of Vif and its role in HIV-1 replication. Mutagenesis studies demonstrate that C-terminal basic domains are required for membrane association. Vif mutations which disrupt membrane association also inhibit HIV-1 replication, indicating that membrane localization of Vif is likely to be required for its biological activity in vivo. Membrane binding of Vif is almost completely abolished by trypsin treatment of membranes. These results demonstrate that membrane localization of Vif requires C-terminal basic domains and interaction with a membrane-associated protein(s). This interaction may serve to direct Vif to a specific cellular site, since immunofluorescence staining and plasma membrane fractionation studies show that Vif is localized predominantly to an internal cytoplasmic compartment rather than to the plasma membrane. The mechanism of membrane targeting of Vif is different in some respects from that of other extrinsic membrane proteins, such as Ras, Src, and MARCKS, which utilize a basic domain together with a lipid modification for membrane targeting. Membrane targeting of Vif is likely to play an important role in HIV-1 replication and thus may be a therapeutic target.     

The mouse Igh-1 a and Igh-1 b H chain constant regions are derived from two distinct isotypic genes

Genetic and structural analyses of the mouse genes encoding constant region of immunoglobulin subclasses (Igh-C) have shown that recombination is rare within this cluster which is inherited as a set designated the Igh haplotype. Recent molecular analyses have demonstrated that either DNA exchanges or gene duplications have probably occurred during the evolution of this set of genes. In order to assess the generality of the duplication processes, the presence and expression of two allelic forms of the Igh-1 (2a) gene (Igh-1 ^a and Igh-1 ^b) were examined in a large panel of wild mice belonging to Mus musculus domesticus and Mus musculus musculus species. Our data indicate that certain M. m. domesticus animals and most animals in the M. m. musculus group coexpress the two allelic forms of Igh-1. Moreover, genetic studies show that these two immunoglobulin types are encoded by tandemly arranged genes. We propose that wild mice, from which laboratory mice are derived, carry three isotypic 2 genes (Igh-1 ^a, Igh-1^b, Igh-3), and these have given rise to the two isotypes seen in laboratory strains by a deletion/insertion mechanism.     

Leptin modulates dose‐dependently the metabolic and cytolytic activities of NK‐92 cells

Leptin, a hormone‐cytokine produced primarily in the adipose tissue, has pleiotropic effects on many biological systems and in several cell types, including immune cells. Hyperleptinemia is associated with immune dysfunction and carcinogenesis. Natural killer (NK) cells are critical mediators of anti‐tumor immunity, and leptin receptor deficiency in mice leads to impaired NK function. It was thus decided to explore the in vitro effects of leptin on human NK cell function. NK‐92 cells were cultured during 48 h with different leptin concentrations [absence, 10 (physiological), 100 (obesity), or 200 ng/ml (pharmacology)]. Their metabolic activity was assessed using the resazurin test. NK‐92 cell cytotoxicity and intracellular IFN‐γ production were analyzed by flow cytometry. NK‐92 cell mRNA and protein expression levels of cytotoxic effectors were determined by RT‐qPCR and Western blot. In our conditions, leptin exerted a dose‐dependent stimulatory effect on NK‐92 cell metabolic activity. In addition, high leptin concentrations enhanced NK‐92 cell cytotoxicity against K562‐EGFP and MDA‐MB‐231‐EGFP target cells and inversely reduced cytotoxicity against the MCF‐7‐EGFP target. At 100 ng/ml, leptin up‐regulated both NK cell granzyme B and TRAIL protein expressions and concomitantly down‐regulated perforin expression without affecting Fas‐L expression. In response to PMA/ionomycin stimulation, the proportion of IFN‐γ expressing NK‐92 cells increased with 100 and 200 ng/ml of leptin. In conclusion, leptin concentration, at obesity level, variably increased NK‐92 cell metabolic activity and modulated NK cell cytotoxicity according to the target cells. The underlying mechanisms are partly due to an up‐regulation of TRAIL and IFN‐γ expression and a down‐regulation of perforin. J. Cell. Physiol. 228: 1202–1209, 2013. © 2012 Wiley Periodicals, Inc.