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The aim of this research was to determine the effects of Momordica charantia (MC) fruit aqueous extract on pancreatic histopathological changes in neonatal STZ-induced type-II diabetic rats. Diabetes mellitus was induced in one day Sprague-Dawley neonatal rats using a single intrapretoneal injection of streptozotocin (STZ) (85 mg/kg body weight) and monitored for 12 weeks thereafter. The diabetic rats were separated into three groups, as follows: the diabetic control group (i.e. nSTZ), the diabetic group (i.e. nSTZ/M) - which was orally given 20 mg/kg of MC fruit extract, and the diabetic group (i.e. nSTZ/G) - that was treated with glibenclamide, 0.1 mg/kg for a period of four weeks. At the end of treatment, the animals were sacrificed and blood samples were collected from the saphenous vein to measure the blood glucose and serum insulin level. The pancreatic specimens were removed and processed for light microscopy, electron microscopy examination and immunohistochemical study. The results of this study showed that MC fruit aqueous extract reduced the blood glucose level as well as glibenclamide and increased the serum insulin level in the treated diabetic rats (P<0.05). The fruit extract of MC alleviated pancreatic damage and increased the number of β-cells in the diabetic treated rats (P<0.05). Our results suggest that oral feeding of MC fruit extract may have a significant role in the renewal of pancreatic β-cells in the nSTZ rats. 相似文献
225.
Gunaratne J Goh MX Swa HL Lee FY Sanford E Wong LM Hogue KA Blackstock WP Okumura K 《The Journal of biological chemistry》2011,286(20):18093-18103
The tumor suppressor PTEN (phosphatase and tensin homologue) negatively regulates the PI3K pathway through its lipid phosphatase activity and is one of the most commonly lost tumor suppressors in human cancers. Though the tumor suppressive function involves the lipid phosphatase-dependent and -independent activities of PTEN, the mechanism leading to the phosphatase-independent function of PTEN is understood poorly. Some PTEN mutants have lipid phosphatase activity but fail to suppress cell growth. Here, we use a cancer-associated mutant, G20E, to gain insight into the phosphatase-independent function of PTEN by investigating protein-protein interactions using MS-based stable isotope labeling by amino acids in cell culture (SILAC). A strategy named parallel affinity purification (PAP) and SILAC has been developed to prioritize interactors and to compare the interactions between wild-type and G20E PTEN. Clustering of the prioritized interactors acquired by the PAP-SILAC approach shows three distinct clusters: 1) wild-type-specific interactors, 2) interactors unique to the G20E mutant, and 3) proteins common to wild-type and mutant. These interactors are involved mainly in cell migration and apoptosis pathways. We further demonstrate that the wild-type-specific interactor, NUDTL16L1, is required for the regulatory function of wild-type PTEN in cell migration. These findings contribute to a better understanding of the mechanisms of the phosphatase-dependent and -independent functions of PTEN. 相似文献
226.
Brooke M. Ahern Andrea Sebastian Bryana M. Levitan Jensen Goh Douglas A. Andres Jonathan Satin 《The Journal of general physiology》2021,153(9)
The L-type Ca2+ channel (LTCC) provides trigger calcium to initiate cardiac contraction in a graded fashion that is regulated by L-type calcium current (ICa,L) amplitude and kinetics. Inactivation of LTCC is controlled to fine-tune calcium flux and is governed by voltage-dependent inactivation (VDI) and calcium-dependent inactivation (CDI). Rad is a monomeric G protein that regulates ICa,L and has recently been shown to be critical to β-adrenergic receptor (β-AR) modulation of ICa,L. Our previous work showed that cardiomyocyte-specific Rad knockout (cRadKO) resulted in elevated systolic function, underpinned by an increase in peak ICa,L, but without pathological remodeling. Here, we sought to test whether Rad-depleted LTCC contributes to the fight-or-flight response independently of β-AR function, resulting in ICa,L kinetic modifications to homeostatically balance cardiomyocyte function. We recorded whole-cell ICa,L from ventricular cardiomyocytes from inducible cRadKO and control (CTRL) mice. The kinetics of ICa,L stimulated with isoproterenol in CTRL cardiomyocytes were indistinguishable from those of unstimulated cRadKO cardiomyocytes. CDI and VDI are both enhanced in cRadKO cardiomyocytes without differences in action potential duration or QT interval. To confirm that Rad loss modulates LTCC independently of β-AR stimulation, we crossed a β1,β2-AR double-knockout mouse with cRadKO, resulting in a Rad-inducible triple-knockout mouse. Deletion of Rad in cardiomyocytes that do not express β1,β2-AR still yielded modulated ICa,L and elevated basal heart function. Thus, in the absence of Rad, increased Ca2+ influx is homeostatically balanced by accelerated CDI and VDI. Our results indicate that the absence of Rad can modulate the LTCC without contribution of β1,β2-AR signaling and that Rad deletion supersedes β-AR signaling to the LTCC to enhance in vivo heart function. 相似文献
227.
Bai J Lai L Yeo HC Goh BC Tan TM 《The international journal of biochemistry & cell biology》2004,36(2):247-257
Multidrug resistance proteins (MRPs) are ATP-dependent export pumps that mediate the export of organic anions. ABCC1 (MRP1), ABCC2 (MRP2) and ABCC3 (MRP3) are all able to facilitate the efflux of anionic conjugates including glutathione (GSH), glucuronide and sulfate conjugates of xenobiotics and endogenous molecules. Earlier studies showed that ABCC4 functions as an ATP-driven export pump for cyclic AMP and cyclic GMP, as well as estradiol-17-beta-D-glucuronide. However, it was unclear if other conjugated metabolites can be transported by ABCC4. Hence in this study, a fluorescent substrate, bimane-glutathione (bimane-GS) was used to further examine the transport activity of ABCC4. Using cells stably overexpressing ABCC4, this study shows that ABCC4 can facilitate the efflux of the glutathione conjugate, bimane-glutathione. Bimane-glutathione efflux increased with time and >85% of the conjugate was exported after 15min. This transport was abolished in the presence of 2.5microM carbonylcyanide m-chlorophenylhydrasone (CCCP), an uncoupler of oxidative phosphorylation. Inhibition was also observed with known inhibitors of MRP transporters including benzbromarone, verapamil and indomethacin. In addition, 100microM methotrexate, an ABCC4 substrate or 100microM 6-thioguanine (6-TG), a compound whose monophosphate metabolite is an ABCC4 substrate, reduced efflux by >40%. A concentration-dependent inhibition of bimane-glutathione efflux was observed with 1-chloro-2,4-dinitrobenzene (CDNB) which is metabolized intracellularly to the glutathione conjugate, 2,4-dinitrophenyl-glutathione (DNP-GS). The determination that ABCC4 can mediate the transport of glucuronide and glutathione conjugates indicates that ABCC4 may play a role in the cellular extrusion of Phase II detoxification metabolites. 相似文献
228.
The terminal step of cytokinesis in animal cells is the abscission of the midbody, a cytoplasmic bridge that connects the two prospective daughter cells. Here we show that two members of the SNARE membrane fusion machinery, syntaxin 2 and endobrevin/VAMP-8, specifically localize to the midbody during cytokinesis in mammalian cells. Inhibition of their function by overexpression of nonmembrane-anchored mutants causes failure of cytokinesis leading to the formation of binucleated cells. Time-lapse microscopy shows that only midbody abscission but not further upstream events, such as furrowing, are affected. These results indicate that successful completion of cytokinesis requires a SNARE-mediated membrane fusion event and that this requirement is distinct from exocytic events that may be involved in prior ingression of the plasma membrane. 相似文献
229.
Garrett B. Goh Benjamin S. Hulbert Huiqing Zhou Charles L. Brooks III 《Proteins》2014,82(7):1319-1331
pH is a ubiquitous regulator of biological activity, including protein‐folding, protein‐protein interactions, and enzymatic activity. Existing constant pH molecular dynamics (CPHMD) models that were developed to address questions related to the pH‐dependent properties of proteins are largely based on implicit solvent models. However, implicit solvent models are known to underestimate the desolvation energy of buried charged residues, increasing the error associated with predictions that involve internal ionizable residue that are important in processes like hydrogen transport and electron transfer. Furthermore, discrete water and ions cannot be modeled in implicit solvent, which are important in systems like membrane proteins and ion channels. We report on an explicit solvent constant pH molecular dynamics framework based on multi‐site λ‐dynamics (CPHMDMSλD). In the CPHMDMSλD framework, we performed seamless alchemical transitions between protonation and tautomeric states using multi‐site λ‐dynamics, and designed novel biasing potentials to ensure that the physical end‐states are predominantly sampled. We show that explicit solvent CPHMDMSλD simulations model realistic pH‐dependent properties of proteins such as the Hen‐Egg White Lysozyme (HEWL), binding domain of 2‐oxoglutarate dehydrogenase (BBL) and N‐terminal domain of ribosomal protein L9 (NTL9), and the pKa predictions are in excellent agreement with experimental values, with a RMSE ranging from 0.72 to 0.84 pKa units. With the recent development of the explicit solvent CPHMDMSλD framework for nucleic acids, accurate modeling of pH‐dependent properties of both major class of biomolecules—proteins and nucleic acids is now possible. Proteins 2014; 82:1319–1331. © 2013 Wiley Periodicals, Inc. 相似文献
230.
Hui Chyn Wong Charng Choon Wong Sreenivasa Rao Sagineedu Seng Cheong Loke Nordin Haji Lajis Johnson Stanslas 《Cell biology and toxicology》2014,30(5):269-288