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61.
Wei YJ Sun HQ Yamamoto M Wlodarski P Kunii K Martinez M Barylko B Albanesi JP Yin HL 《The Journal of biological chemistry》2002,277(48):46586-46593
Phosphoinositides have a pivotal role as precursors to important second messengers and as bona fide signaling and scaffold targeting molecules. Phosphatidylinositol 4-kinases (PtdIns 4-kinases or PI4Ks) are at the apex of the phosphoinsitide cascade. Sequence analysis revealed that mammalian cells contain two type II PtdIns 4-kinase isoforms, now termed PI4KIIalpha and PI4KIIbeta. PI4KIIalpha was cloned first. It is tightly membrane-associated and behaves as an integral membrane protein. In this study, we cloned PI4KIIbeta and compared the two isoforms by monitoring the distribution of endogenous and overexpressed proteins, their modes of association with membranes, their response to growth factor stimulation or Rac-GTP activation, and their kinetic properties. We find that the two kinases have different properties. PI4KIIbeta is primarily cytosolic, and it associates peripherally with plasma membranes, endoplasmic reticulum, and the Golgi. In contrast, PI4KIIalpha is primarily Golgi-associated. Platelet-derived growth factor promotes PI4KIIbeta recruitment to membrane ruffles. This effect is potentially mediated through Rac; overexpression of the constitutively active RacV12 induces membrane ruffling, increases PI4KIIbeta translocation to the plasma membrane, and stimulates its activity. The dominant-negative RacN17 blocks plasma membrane association and inhibits activity. RacV12 does not boost the catalytic activity of PI4KIIalpha further, probably because it is constitutively membrane-bound and already activated. Membrane recruitment is an important mechanism for PI4KIIbeta activation, because microsome-bound PI4KIIbeta is 16 times more active than cytosolic PI4KIIbeta. Membrane-associated PI4KIIbeta is as active as membrane-associated PI4KIIalpha and has essentially identical kinetic properties. We conclude that PI4KIIalpha and PI4KIIbeta may have partially overlapping, but not identical, functions. PI4KIIbeta is activated strongly by membrane association to stimulate phosphatidylinositol 4,5-bisphosphate synthesis at the plasma membrane. These findings provide new insight into how phosphoinositide cascades are propagated in cells. 相似文献
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63.
One of the most fundamental questions for understanding the origin of species is why genes that function to cause fertility in a pure-species genetic background fail to produce fertility in a hybrid genetic background. A related question is why the sex that is most often sterile or inviable in hybrids is the heterogametic (usually male) sex. In this survey, we have examined the extent and nature of differences in gene expression between fertile adult males of two Drosophila species and sterile hybrid males produced from crosses between these species. Using oligonucleotide microarrays and real-time quantitative polymerase chain reaction, we have identified and confirmed that differences in gene expression exist between pure species and hybrid males, and many of these differences are quantitative rather than qualitative. Furthermore, genes that are expressed primarily or exclusively in males, including several involved in spermatogenesis, are disproportionately misexpressed in hybrids, suggesting a possible genetic cause for their sterility. 相似文献
64.
The effects of some metal ions on amidolytic and fibrinogenolytic activities of highly purified human plasmin were investigated
in vitro. In the presence of Zn2+, Cu2+, Cd2+, and Au+ in the incubation mixture at the concentrations of 1×10−5−1×10−3
M, the anidolytic plasmin activity was strongly inhibited, whereas Ca2+ and Mg2+ at the same concentrations were not effective. The analysis of the kinetic study has shown that Zn2+ or Cu2+ acts as mixed-type inhibitors of plasmin activity. The inhibition of amidolytic plasmin activity by Zn2+ and Cu2+ was reduced in the presence of EDTA, histidine, or albumin. Incubation of plasmin with Zn2+ or Cu2+ (at the concentration of 5×10−4
M) resulted in complete loss of its proteolytic action on fibrinogen, whereas Cd2+ and Au+ under the same conditions only partially inhibited this process. 相似文献
65.
Ghrelin stimulates feeding when administered centrally and peripherally. The lateral hypothalamus (LH) is thought to mediate ghrelin-induced hyperphagia. Thus, we examined central mechanisms underlying feeding generated by LH ghrelin. We determined that 0.3nmol of LH-injected ghrelin was the lowest dose increasing food consumption and it induced Fos immunoreactivity (IR; a marker of neuronal activation) in feeding-related brain areas, including the hypothalamic paraventricular, arcuate, and dorsomedial nuclei, amygdala, and nucleus of the solitary tract. Also, LH ghrelin induced Fos IR in LH orexin neurons. We conclude that the LH, as part of larger central circuitry, integrates orexigenic properties of ghrelin. 相似文献
66.
Transcriptome analysis of root transporters reveals participation of multiple gene families in the response to cation stress 总被引:31,自引:4,他引:27
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68.
Marita Westhrin Minli Xie Magnus ?. Older?y Pawel Sikorski Berit L. Strand Therese Standal 《PloS one》2015,10(3)
Mineralized biomaterials are promising for use in bone tissue engineering. Culturing osteogenic cells in such materials will potentially generate biological bone grafts that may even further augment bone healing. Here, we studied osteogenic differentiation of human mesenchymal stem cells (MSC) in an alginate hydrogel system where the cells were co-immobilized with alkaline phosphatase (ALP) for gradual mineralization of the microenvironment. MSC were embedded in unmodified alginate beads and alginate beads mineralized with ALP to generate a polymer/hydroxyapatite scaffold mimicking the composition of bone. The initial scaffold mineralization induced further mineralization of the beads with nanosized particles, and scanning electron micrographs demonstrated presence of collagen in the mineralized and unmineralized alginate beads cultured in osteogenic medium. Cells in both types of beads sustained high viability and metabolic activity for the duration of the study (21 days) as evaluated by live/dead staining and alamar blue assay. MSC in beads induced to differentiate in osteogenic direction expressed higher mRNA levels of osteoblast-specific genes (RUNX2, COL1AI, SP7, BGLAP) than MSC in traditional cell cultures. Furthermore, cells differentiated in beads expressed both sclerostin (SOST) and dental matrix protein-1 (DMP1), markers for late osteoblasts/osteocytes. In conclusion, Both ALP-modified and unmodified alginate beads provide an environment that enhance osteogenic differentiation compared with traditional 2D culture. Also, the ALP-modified alginate beads showed profound mineralization and thus have the potential to serve as a bone substitute in tissue engineering. 相似文献
69.
Supriya D. Mehta Brock Donovan Kathleen M. Weber Mardge Cohen Jacques Ravel Pawel Gajer Douglas Gilbert Derick Burgad Greg T. Spear 《PloS one》2015,10(2)
BackgroundWe identified predominant vaginal microbiota communities, changes over time, and how this varied by HIV status and other factors in a cohort of 64 women.MethodsBacterial DNA was extracted from reposited cervicovaginal lavage samples collected annually over an 8–10 year period from Chicago Women’s Interagency HIV Study participants: 22 HIV-negative, 22 HIV-positive with stable infection, 20 HIV-positive with progressive infection. The vaginal microbiota was defined by pyrosequencing of the V1/V2 region of the 16S rRNA gene. Scheduled visits included Bacterial vaginsosis (BV) screening; clinically detected cases were referred for treatment. Hierarchical clustering identified bacterial community state types (CST). Multinomial mixed effects modeling determined trends over time in CST, by HIV status and other factors.ResultsThe median follow-up time was 8.1 years (range 5.5–15.3). Six CSTs were identified. The mean relative abundance (RA) of Lactobacillus spp. by CST (with median number of bacterial taxa) was: CST-1–25.7% (10), CST-2–27.1% (11), CST-3–34.6% (9), CST-4–46.8% (9), CST-5–57.9% (4), CST-6–69.4% (2). The two CSTs representing the highest RA of Lactobacillus and lowest diversity increased with each additional year of follow-up (CST-5, adjusted odds ratio (aOR) = 1.62 [95% CI: 1.34–1.94]; CST-6, aOR = 1.57 [95 CI: 1.31–1.89]), while the two CSTs representing lowest RA of Lactobacillus and higher diversity decreased with each additional year (CST-1, aOR = 0.89 [95% CI: 0.80–1.00]; CST-2, aOR = 0.86 [95% CI: 0.75–0.99]). There was no association between HIV status and CST at baseline or over time. CSTs representing lower RA of Lactobacillus were associated with current cigarette smoking.ConclusionsThe vaginal microbial community significantly improved over time in this cohort of women with HIV and at high risk for HIV who had regular detection and treatment referral for BV. 相似文献
70.
Aleksandra Delplanque Dominika Wawrzynczyk Pawel Jaworski Katarzyna Matczyszyn Krzysztof Pawlik Malcolm Buckle Marcin Nyk Claude Nogues Marek Samoc 《PloS one》2015,10(3)
Lanthanide-doped nanoparticles are of considerable interest for biodetection and bioimaging techniques thanks to their unique chemical and optical properties. As a sensitive luminescence material, they can be used as (bio) probes in Förster Resonance Energy Transfer (FRET) where trivalent lanthanide ions (La3+) act as energy donors. In this paper we present an efficient method to transfer ultrasmall (ca. 8 nm) NaYF4 nanoparticles dispersed in organic solvent to an aqueous solution via oxidation of the oleic acid ligand. Nanoparticles were then functionalized with single strand DNA oligomers (ssDNA) by inducing covalent bonds between surface carboxylic groups and a 5’ amine modified-ssDNA. Hybridization with the 5’ fluorophore (Cy5) modified complementary ssDNA strand demonstrated the specificity of binding and allowed the fine control over the distance between Eu3+ ions doped nanoparticle and the fluorophore by varying the number of the dsDNA base pairs. First, our results confirmed nonradiative resonance energy transfer and demonstrate the dependence of its efficiency on the distance between the donor (Eu3+) and the acceptor (Cy5) with sensitivity at a nanometre scale. 相似文献