ORP4L Extracts and Presents PIP2 from Plasma Membrane for PLC beta 3 Catalysis : Targeting It Eradicates Leukemia Stem Cells

Leukemia stem cells (LSCs) are a rare subpopulation of abnormal hematopoietic stem cells (HSCs) that propagates leukemia and are responsible for the high frequency of relapse in therapies. Detailed insights into LSCs' survival will facilitate the identification of targets for therapeutic approaches. Here, we develop an inhibitor, LYZ-81, which targets ORP4L with high affinity and specificity and selectively eradicates LCSs in vitro and in vivo. ORP4L is expressed in LSCs but not in normal HSCs and is essential for LSC bioenergetics and survival. It extracts PIP2 from the plasma membrane and presents it to PLC beta 3, enabling IP3 generation and subsequentCa(2+)-dependent bioenergetics. LYZ-81 binds ORP4L competitively with PIP2 and blocks PIP2 hydrolysis, resulting in defective Ca2+ signaling. The results provide evidence that LSCs can be eradicated through the inhibition of ORP4L by LYZ-81, which may serve as a starting point of drug development for the elimination of LSCs to eventually cure leukemia.Peer reviewe

Molecular diagnosis and vegetative compatibility group analysis of Fusarium Wilt of banana in Nepal

Fusarium wilt of banana (FWB), caused by Fusarium oxysporum f. sp. cubense (Foc), is the most important constraint of the banana industry globally. In Nepal, epidemics resembling FWB have been increasingly observed on the Malbhog cultivar in the past several years. However, the disease has not been officially reported yet, and consequently, little is known about the pathogen present across the country. In this study, we characterized 13 fungal strains isolated from banana plants of the Malbhog cultivar (Silk, AAB) showing symptoms similar to FWB in banana plantations in Nepal. All of the strains were typed as belonging to the F. oxysporum and caused FWB symptoms when inoculated in the Malbhog and Cachaco (Bluggoe, ABB) cultivars. No symptoms were observed in the Williams cultivar (Cavendish, AAA). Vegetative compatibility group (VCG) analysis classified the strains as VCG 0124 or VCG 0125. PCR analyses conducted with primers specific for Foc race 1 (Foc R1) or Foc tropical race 4 (TR4) revealed that all the strains reacted positively for Foc R1 and none for TR4. Altogether, our results demonstrated that the pathogen populations causing FWB of the Malbhog cultivar in Nepal were Foc R1. This work reported, for the first time, the occurrence of FWB in Nepal. Further studies with larger Foc populations are needed to better understand disease epidemiology to design sustainable disease management strategies

Effects of Layer-Charge Distribution of 2:1 Clay Minerals on Methane Hydrate Formation: A Molecular Dynamics Simulation Study

Molecular dynamics simulations were used to investigate the effects of the external surface of a 2:1 clay mineral with different charge amounts and charge locations on CH4 hydrate formation. The results showed that 5(12), 5(12)6(2), 5(12)6(3), and 5(12)6(4) were formed away from the clay mineral surface. The surface of the clay mineral with high-and low-charge layers was occupied by Na+ to form various distributions of outer-and inner-sphere hydration structures, respectively. The adsorbed Na+ on the high-charge layer surface reduced the H2O activity by disturbing the hydrogen bond network, resulting in low tetrahedral arrangement of H2O molecules near the layer surface, which inhibited CH4 hydrate formation. However, more CH4 molecules were adsorbed onto the vacancy in the Si-O rings of a neutral-charge layer to form semicage structures. Thus, the order parameter of H2O molecules near this surface indicated that the arrangement of H2O molecules resulted in a more optimal tetrahedral structure for CH4 hydrate formation than that near the negatively charged layer surface. Different nucleation mechanisms of the CH4 hydrate on external surfaces of clay mineral models were observed. For clay minerals with negatively charged layers (i.e., high and low charge), the homogeneous nucleation of the CH4 hydrate occurred away from the surface. For a clay mineral with a neutralcharge layer, the CH4 hydrate could nucleate either in the bulk-like solution homogeneously or at the clay mineral-H2O interface heterogeneously

Structures of human mGlu2 and mGlu7 homo- and heterodimers

International audienceThe metabotropic glutamate receptors (mGlus) are involved in the modulation of synaptic transmission and neuronal excitability in the central nervous system1. These receptors probably exist as both homo- and heterodimers that have unique pharmacological and functional properties2-4. Here we report four cryo-electron microscopy structures of the human mGlu subtypes mGlu2 and mGlu7, including inactive mGlu2 and mGlu7 homodimers; mGlu2 homodimer bound to an agonist and a positive allosteric modulator; and inactive mGlu2-mGlu7 heterodimer. We observed a subtype-dependent dimerization mode for these mGlus, as a unique dimer interface that is mediated by helix IV (and that is important for limiting receptor activity) exists only in the inactive mGlu2 structure. The structures provide molecular details of the inter- and intra-subunit conformational changes that are required for receptor activation, which distinguish class C G-protein-coupled receptors from those in classes A and B. Furthermore, our structure and functional studies of the mGlu2-mGlu7 heterodimer suggest that the mGlu7 subunit has a dominant role in controlling dimeric association and G-protein activation in the heterodimer. These insights into mGlu homo- and heterodimers highlight the complex landscape of mGlu dimerization and activation

Predictors of Hemodynamic Instability During Surgery for Pheochromocytoma

BACKGROUND: Resection of pheochromocytoma is often associated with hemodynamic instability (HDI). We examined patient and tumor factors that may influence HDI. The effect of pre-treatment with non-selective alpha-blockade phenoxybenzamine (PXB) vs. selective alpha-blockade on HDI and outcomes was also evaluated. METHODS: The records of 91 patients who underwent adrenalectomy between 2002 and 2013 were retrospectively reviewed. HDI was determined by: number of intraoperative episodes of systolic blood pressure (SBP) >200mmHg, those greater than or less than 30% of baseline, heart rate >110 and the need for postoperative vasopressors. Fishers exact, t-test and regressions were performed. RESULTS: Among the 91 patients, 78% received PXB, 18% selective alpha-blockade and 4% no adrenergic blockade. Patient demographics, tumor factors and surgical approach were similar among the blockade groups. On multivariate analysis increasing tumor size was associated with a significant rise in the number of episodes of SBP >30% (RR 1.40) and an increased postoperative vasopressor requirement (OR 1.23). Open adrenalectomy and use of selective blockade were associated with an increased number of episodes of SBP >200mmHg (RR 27.8 and RR 20.9, respectively). Open adrenalectomy was also associated with increased readmissions (OR 12.3), complications (OR 5.6), use of postoperative vasopressors (OR 4.4) and hospital stay (4.6 days longer). There were no differences in other HDI measurements or postoperative outcomes among the blockade groups. CONCLUSIONS: Tumor size, open adrenalectomy and type of alpha-blockade were associated with intraoperative HDI during pheochromocytoma resection. Selective blockade was associated with significantly more episodes of intraoperative hypertension but no perioperative adverse outcomes