Hypoxia-induced fatty acid transporter translocation increases fatty acid transport and contributes to lipid accumulation in the heart

AbstractProtein-mediated LCFA transport across plasma membranes is highly regulated by the fatty acid transporters FAT/CD36 and FABPpm. Physiologic stimuli (insulin stimulation, AMP kinase activation) induce the translocation of one or both transporters to the plasma membrane and increase the rate of LCFA transport. In the hypoxic/ischemic heart, intramyocardial lipid accumulation has been attributed to a reduced rate of fatty acid oxidation. However, since acute hypoxia (15min) activates AMPK, we examined whether an increased accumulation of intramyocardial lipid during hypoxia was also attributable to an increased rate of LCFA uptake as a result AMPK-induced translocation of FAT/CD36 and FABPpm. In cardiac myocytes, hypoxia (15min) induced the redistribution of FAT/CD36 from an intracellular pool (LDM) (−25%, P<0.05) to the plasma membranes (PM) (+54%, P<0.05). Hypoxia also induced an increase in FABPpm at the PM (+56%, P<0.05) and a concomitant FABPpm reduction in the LDM (−24%, P<0.05). Similarly, in intact, Langendorff perfused hearts, hypoxia induced the translocation of a both FAT/CD36 and FABPpm to the PM (+66% and +61%, respectively, P<0.05), with a concomitant decline in FAT/CD36 and FABPpm in the LDM (−24% and −23%, respectively, P<0.05). Importantly, the increased plasmalemmal content of these transporters was associated with increases in the initial rates of palmitate uptake into cardiac myocytes (+40%, P<0.05). Acute hypoxia also redirected palmitate into intracellular lipid pools, mainly to PL and TG (+48% and +28%, respectively, P<0.05), while fatty acid oxidation was reduced (−35%, P<0.05). Thus, our data indicate that the increased intracellular lipid accumulation in hypoxic hearts is attributable to both: (a) a reduced rate of fatty acid oxidation and (b) an increased rate of fatty acid transport into the heart, the latter being attributable to a hypoxia-induced translocation of fatty acid transporters

Gene Targeting Implicates Cdc42 GTPase in GPVI and Non-GPVI Mediated Platelet Filopodia Formation, Secretion and Aggregation

Background: Cdc42 and Rac1, members of the Rho family of small GTPases, play critical roles in actin cytoskeleton regulation. We have shown previously that Rac1 is involved in regulation of platelet secretion and aggregation. However, the role of Cdc42 in platelet activation remains controversial. This study was undertaken to better understand the role of Cdc42 in platelet activation. Methodology/Principal Findings: We utilized the Mx-cre;Cdc42 lox/lox inducible mice with transient Cdc42 deletion to investigate the involvement of Cdc42 in platelet function. The Cdc42-deficient mice exhibited a significantly reduced platelet count than the matching Cdc42 +/+ mice. Platelets isolated from Cdc42 2/2, as compared to Cdc42 +/+, mice exhibited (a) diminished phosphorylation of PAK1/2, an effector molecule of Cdc42, (b) inhibition of filopodia formation on immobilized CRP or fibrinogen, (c) inhibition of CRP- or thrombin-induced secretion of ATP and release of P-selectin, (d) inhibition of CRP, collagen or thrombin induced platelet aggregation, and (e) minimal phosphorylation of Akt upon stimulation with CRP or thrombin. The bleeding times were significantly prolonged in Cdc42 2/2 mice compared with Cdc42 +/+ mice. Conclusion/Significance: Our data demonstrate that Cdc42 is required for platelet filopodia formation, secretion an

Kinetics of Binary Ion Exchange on Titanium Vanadophosphate

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Kinetics of Exchange of Rb(I) & Cs(I) Ions with Hydrogen Ion on Tin(IV) Antimonate- A Radiochemical Study

524-52

Platelet Agglutinating Protein p37 Causes Platelet Agglutination through its Binding to Membrane Glycoprotein IV

SummaryA 37 kDa platelet agglutinating protein (PAP p37) has previously been shown to be present in a subset of patients with thrombotic thrombocytopenic purpura and has been purified from their plasma. Using solubilized platelet membrane proteins from normal donors, it was shown by Western blotting that r2sI-p37 bound to a membrane protein of 97 kDa (red/unred). Furthernore, the same protein was identified by reverse immunoblotting in which purified p37 was electrophoresed, transferred to the nitrocellulose sheet and incubated with solubilized normal platelet membrane proteins. The complex formed between p37 and the membrane protein was identified by autoradiography using polyclonal and monoclonal (OKM5) anti- GPIV antibodies, but was not detected by polyclonal antibody to GPIIIa. Similar studies with purified platelet GPIV under both reducing and non-reducing conditions demonstrated the binding of 125I-p37. Polyclonal and monoclonal antibodies to GPIV completely inhibited the platelet agglutination induced by TTP plasma containing p37, however, normal rabbit IgG, rabbit anti- GPIIIa IgG, and murine monoclonal anti-GPIIb/IIIa (10E5) antibodies had no effect. These data indicate that platelet GPIV is the receptor site for PAP p37