Stable oil bodies sheltered by a unique oleosin in lily pollen

Stable oil bodies were purified from mature lily (Lilium longiflorum Thunb.) pollen. The integrity of pollen oil bodies was maintained via electronegative repulsion and steric hindrance possibly provided by their surface proteins. Immunodetection revealed that a major protein of 18 kDa was exclusively present in pollen oil bodies and massively accumulated in late stages of pollen maturation. According to mass spectrometric analyses, this oil body protein possessed a tryptic fragment of 13 residues matching that of a theoretical rice oleosin. A complete cDNA fragment encoding this putative oleosin was obtained by PCR cloning with primers derived from its known 13-residue sequence. Sequence analysis as well as immunological non-cross-reactivity suggests that this pollen oleosin represents a distinct class in comparison with oleosins found in seed oil bodies and tapetum. In pollen cells observed by electron microscopy, oil bodies were presumably surrounded by tubular membrane structures, and encapsulated in the vacuoles after germination. It seems that pollen oil bodies are mobilized via a different route from that of glyoxysomal mobilization of seed oil bodies after germination.     

Synergistic effect of prostaglandin F2alpha and cyclic AMP on glucose transport in 3T3-L1 adipocytes

The combined effect of prostaglandin F2alpha (PGF2alpha) and cAMP on glucose transport in 3T3-L1 adipocytes was examined. In cells pretreated with PGF2alpha and 8-bromo cAMP for 8 h, a synergy between these two agents on glucose uptake was found. Insulin-stimulated glucose transport, on the other hand, was only slightly affected. The synergistic effect of these two agents was suppressed in the presence of cycloheximide and actinomycin D. In concord, immunoblot and Northern blot analyses revealed that GLUT1 protein and mRNA levels were both increased in cells pretreated with both PGF2alpha and 8-bromo cAMP, greater than the additive effect of each agent alone. The synergistic action of PGF2alpha with 8-bromo cAMP to enhance glucose transport was inhibited by GF109203X, a selective protein kinase C (PKC) inhibitor. In addition, in cells depleted of diacylglycerol-sensitive PKC by prolonged treatment with 4beta-phorbol 12beta-myristate 13alpha-acetate, a PKC activator, the synergistic effects of PGF2alpha and 8-bromo cAMP on glucose transport and GLUT1 mRNA accumulation were both abolished. Taken together, these results indicate that PGF2alpha may act with cAMP in a synergistic way to increase glucose transport, probably through enhanced GLUT1 expression by a PKC-dependent mechanism.     

A novel mechanism of coenzyme Q10 protects against human endothelial cells from oxidative stress-induced injury by modulating NO-related pathways

BackgroundAtherosclerosis is a chronic inflammatory disease of the vessel wall associated with oxidized low-density lipoprotein (oxLDL)-induced apoptosis of endothelial cells. Coenzyme Q10 (CoQ10), a potent antioxidant and a critical intermediate of the electron transport chain, has been reported to inhibit LDL oxidation and thus the progression of atherosclerosis. However, its molecular mechanisms on endothelial cells remain still unclarified.MethodsIn this study, primary human umbilical vein endothelial cell cultures treated with oxLDL were used to explore the protective effects of CoQ10.ResultsOur results showed that CoQ10 attenuated the oxLDL-induced generation of reactive oxygen species and improved the antioxidant capacity. CoQ10 also attenuated the oxLDL-mediated down-regulation of endothelial nitric oxide synthase (eNOS) and up-regulation of inducible nitric oxide synthase (iNOS). In addition, CoQ10 suppressed oxLDL-activated NF-κB and downstream inflammatory mediators, including expression of adhesion molecules, release of proinflammatory cytokines and the adherence of monocytic THP-1 cells. Moreover, CoQ10 attenuated oxLDL-altered proapoptotic responses. The inhibitor of eNOS (l-NIO 10 μM) and iNOS (1400W 10 μM) as well as NO enhancer (SNP 10 μM) were used to clean up the mechanism.ConclusionThese results provide new insight into the possible molecular mechanisms by which CoQ10 protects against atherogenesis by NO-related pathways.     

Movement of the tube cell in the lily style in the absence of the pollen grain and the spent pollen tube

Our model proposes that pollen tube growth is a form of cell movement where the tube tip can be considered analogous to a migrating cell which leaves a trail of extracellular matrix (the spent pollen tube) behind. We demonstrate that the tube cell can convey the sperm cells to the ovule and effect fertilization even in the absence of the pollen grain and the spent pollen tube. Adhesion is an integral part of cell attachment and movement in animal systems. We show that in vivo-grown pollen tubes grow beneath the cuticle of the stylar transmitting tract epidermis and directly adhere to one another and the outer wall of the epidermal cells. A fibrous wall material is found to cover the tip of the pollen tube cell wall and the surface of the transmitting tract cells where the two adhere. Fixation methods to preserve adhesive compounds were used. The pollen-tubes grown in vivo, but not in vitro, show star-shaped clusters of F-actin microfilaments in the region back from the tip, as seen by rhodamine-phalloidin staining. These configurations are similar to focal adhesions seen in moving animal cells.     

Characterization of porcine arterial endothelial cells cultured on amniotic membrane, a potential matrix for vascular tissue engineering

The existing of basement membrane improves the development of endothelium while constructing blood vessel equivalent. The amniotic membrane (AM) provides a natural basement membrane and has been used in ocular surface reconstruction. This study evaluated the molecular and cellular characteristics of porcine vascular endothelial cells (ECs) cultured on AM. ECs cultured on AM expressed the endothelial marker vWF and exhibited normal endothelial morphology. Here, we demonstrated that AM enhanced the expression of intercellular molecules, platelet-endothelial cell adhesion molecule-1 (PECAM-1), and adhesion molecule VE-cadherin at the intercellular junctions. The expression level of integrin was markedly higher in ECs cultured on AM than on plastic dish. Furthermore, the AM downregulated the expression of E-selectin and P-selectin in both LPS-activated and non-activated ECs. Consistently, adhesion of leukocytes to both activated and non-activated cells was decreased in ECs cultured on AM. Our results suggest that AM is an ideal matrix to develop a functional endothelium in blood vessel equivalent construction.     

A unique caleosin in oil bodies of lily pollen

In view of the recent isolation of stable oil bodies as well as a unique oleosin from lily pollen, this study examined whether other minor proteins were present in this lipid-storage organelle. Immunological cross-recognition using antibodies against three minor oil-body proteins from sesame suggested that a putative caleosin was specifically detected in the oil-body fraction of pollen extract. A cDNA fragment encoding this putative pollen caleosin, obtained by PCR cloning, was confirmed by immunodetection and MALDI-MS analyses of the recombinant protein over-expressed in Escherichia coli and the native form. Caleosin in lily pollen oil bodies seemed to be a unique isoform distinct from that in lily seed oil bodies.