O-glycan structures in apo(a) subunit of human lipoprotein(a) suppresses the pro-angiogenic activity of galectin-1 on human umbilical vein endothelial cells.

Apolipoprotein(a) [apo(a)] is a highly polymorphic O-glycoprotein circulating in human plasma as lipoprotein(a) [Lp(a)]. The O-glycan structures of apo(a) subunit of Lp(a) serve as strong ligands of galectin-1, an O-glycan binding pro-angiogenic lectin abundantly expressed in placental vascular tissues. But the pathophysiological significance of apo(a)-galectin-1 binding is not yet been revealed. Carbohydrate-dependent binding of galectin-1 to another O-glycoprotein, neuropilin-1 (NRP-1) on endothelial cells activates vascular endothelial growth factor receptor 2 (VEGFR2) and mitogen-activated protein kinase (MAPK) signaling. Using apo(a), isolated from human plasma, we demonstrated the potential of the O-glycan structures of apo(a) in Lp(a) to inhibit angiogenic properties such as proliferation, migration, and tube-formation in human umbilical vein endothelial cells (HUVECs) as well as neovascularization in chick chorioallantoic membrane. Further, in vitro protein-protein interaction studies have confirmed apo(a) as a superior ligand to NRP-1 for galectin-1 binding. We also demonstrated that the protein levels of galectin-1, NRP-1, VEGFR2, and downstream proteins in MAPK signaling were reduced in HUVECs in the presence of apo(a) with intact O-glycan structures compared to that of de-O-glycosylated apo(a). In conclusion, our study shows that apo(a)-linked O-glycans prevent the binding of galectin-1 to NRP-1 leading to the inhibition of galectin-1/neuropilin-1/VEGFR2/MAPK-mediated angiogenic signaling pathway in endothelial cells. As higher plasma Lp(a) level in women is an independent risk factor for pre-eclamsia, a pregnancy-associated vascular complication, we propose that apo(a) O-glycans-mediated inhibition of the pro-angiogenic activity of galectin-1 may be one of the underlying molecular mechanism of pathogenesis of Lp(a) in pre-eclampsia.

Adipocytes utilize sucrose as an energy source-Effect of different carbohydrates on adipocyte differentiation.

Adipose tissue is a complex and heterogenic tissue exhibiting high variability and appears to have multiple functions, especially in metabolic regulation. Change in carbohydrate source is reported to have a profound effect in the regular functioning of adipocytes. Here, we analyzed the role of two monosaccharides namely, glucose (5.2 and 25 nM), galactose (25 mM), and two disaccharides namely, lactose and sucrose (both at 25 mM) in the adipocyte differentiation process and its utilization by adipocytes as an energy source. The change in cell morphology, adipocyte-specific gene expression, and protein levels were analyzed at three different time points: 2, 6, and 48 hr. Oil Red O staining at Day 8 of differentiation showed that no other carbohydrates were able to increase lipid content as better as 25 mM glucose. Gene expression pattern was altered by the change in glucose concentration and sucrose was able to mimic the effect of glucose even though, the lipid synthesis was solely promoted by high glucose levels. Galactose and lactose did not show any effect in promoting adipocyte differentiation. The expression of PPAR γ was high in the presence of sucrose and galactose, possibly of adipogenic cocktail in enhancing the expression rather than the effect of carbohydrate. Acarbose, a potent glucosidase inhibitor was able to inhibit the lipid content in adipocytes grown with sucrose as a carbohydrate source and shows the possibility of its direct utilization. Lactate production by cells upon differentiation also proved the possible uptake of glucose after sucrose cleavage.

Time-dependent alterations in mRNA, protein and microRNA during in vitro adipogenesis.

Adipogenesis is a complex biological process involving synchronised interplay of different nuclear receptors. Aberration in the process leads to obesity and associated disorders. Addressing the complexity of molecular mechanisms, we worked on characterising the changes in NR1C3/PPARγ-, NR1H3/LXRα- and NCoAs/SRCs-associated microRNA, genes and proteins during different time points of adipogenesis. Glucose uptake of differentiating cells was checked at selected time points with FACS. Observations on gene expression pattern pointed a correlation in adipogenic-related genes and increased expression of PPARγ, but not LXRα. Western blot experiments also supported the gene expression pattern. MicroRNAs that vary during adipogenesis was selected using bioinformatics tools and database. Real-time PCR-based experiments showed a change in the expression of mmu-mir-23a-3p, 206-3p, 17-3p, 126a-3p and 1a-3p. Mmu-mir-23a-3p showed a gradual decrease in expression corresponding to the progression of adipogenesis. MicroRNA 23a-3p and 1a-3p showed positive association to the mRNA levels of NCoA1 and 3. Overall, the study elaborates time-dependent variations in nucleic acid and protein expression during adipogenesis in accordance to fatty acid and glucose metabolism.

A lysosome targetable luminescent bioprobe based on a europium ß-diketonate complex for cellular imaging applications.

Herein, we report a novel lysosome targetable luminescent bioprobe derived from a europium coordination compound, namely Eu(pfphOCH3IN)3(DDXPO) 4 [where HpfphOCH3IN = 4,4,5,5,5-pentafluoro-3-hydroxy-1-(1-(4-methoxyphenyl)-1H-indol-3-yl)pent-2-en-1-one and DDXPO = 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene oxide]. Notably, the newly designed europium complex exhibits significant quantum yield (Φoverall = 25 ± 3%) and 5D0 excited state lifetime (τ = 398 ± 3 µs) values under physiological pH (7.2) conditions when excited at 405 nm. Hence the developed europium complex has been evaluated for live cell imaging applications using mouse pre-adipocyte cell lines (3T3L1). Colocalization studies of the designed bio-probe with commercial Lysosome-GFP in 3T3L1 cells demonstrated the specific localization of the probe in the lysosome with a high colocalization coefficient (A = 0.83). Most importantly, the developed bioprobe exhibits good cell permeability, photostability and non-cytotoxicity.

Effect on oxidative stress, glucose uptake level and lipid droplet content by Apigenin 7, 4'-dimethyl ether isolated from Piper longum L.

Piper longum L. (Family: Piperaceae), is a widely used herb in several Ayurvedic formulations prescribed for various diseases. Potential of the plant material as an antidiabetic and cardio protective agent has not been evaluated so far. In the study, we designed experiments to evaluate antioxidant, glucose uptake potential and lipid content regulating potential of extracts and compound from P. longum fruits. Solvent extracts from Piper longum fruits using hexane, ethyl acetate, methanol, 70 % methanol-water were taken and apigenin 7, 4'-dimethyl ether (ADE) was isolated from ethyl acetate extract. Antioxidant activity, glucose uptake potential and adipocyte differentiation assay was performed with extract and pure compound. Antioxidant activity in terms of TRP (196.03 µg/mg GAE), DPPH assay (IC50-173.09 µg/mL), hydroxyl radical scavenging assay (IC50-20.42 µg/mL), inhibiting LDL oxidation (IC50-51.99 µg/mL) and to enhance SOD activity (25.3 %) was higher in ethyl acetate extract (EAP). Phenolic and flavonoid content was measured and showed a positive correlation with antioxidant activity. Presence of apigenin 7, 4'-dimethyl ether (ADE) and piperine (Pip) in EAP was determined by HPTLC analysis and was isolated. ADE inhibited α-glucosidase and α-amylase enzymes and enhanced 2-NBDG uptake in L6 cells. Hypolipidemic effect of ADE on mouse pre-adipocyte (3T3L1) cell lines also showed a dose dependent reduction on lipid droplet content and effective concentration range was determined as 1-2.5 µg/mL. The results suggested that Piper longum fruits can provide a natural source of antioxidants with antidiabetic and anti obesity potential.

Zingiber officinale extract exhibits antidiabetic potential via modulating glucose uptake, protein glycation and inhibiting adipocyte differentiation: an in vitro study.

BACKGROUND: Ginger, the rhizome of Zingiber officinale Roscoe (Zingiberaceae), a perennial herbaceous plant is native to Southern Asia. Study was aimed to evaluate antioxidant and antidiabetic potential of ginger extract and its characterization. Possible mode of action to elicit antidiabetic activity was also evaluated. METHODS AND RESULTS: Ethyl acetate extract of ginger (EAG) was evaluated for its antioxidant activity in terms of DPPH radical scavenging potential with an IC50 value of 4.59 µg/ml. Antidiabetic activity of EAG was evaluated by estimating antiglycation potential (IC50 290.84 µg/ml). HPLC profiling of EAG revealed the presence of phenolic components, gingerol and shoagol as major constituents. After determining sub-toxic concentration of EAG (50 µg/ml), efficacy of extract to enhance glucose uptake in cell lines were checked in L6 mouse myoblast and myotubes. EAG was effective at 5 µg/ml concentration in both cases. Antibody based studies in treated cells revealed the effect of EAG in expressing Glut 4 in cell surface membrane compared to control. CONCLUSION: The antidiabetic effect of ginger was experimentally proved in the study and has concluded that the activity is initiated by antioxidant, antiglycation and potential to express or transport Glut4 receptors from internal vesicles.