1,721,044 research outputs found
The regulation of NKCC2 cotransporter in animal models of hypertension and renal epithelial cell lines
No full textIntramolecular and intermolecular fluorescence resonance energy transfer in fluorescent protein-tagged Na-K-Cl cotransporter (NKCC1): sensitivity to regulatory conformational change and cell volume.
No full textApical membrane expression of NKCC2 is directed by a domain within its cytoplasmic C-terminus
No full textHistamine-induced AQP4 internalization in gastric cells is paralleled to an increase in AQP4 phosphorylation
No full textCell Stress: Survival and Apoptosis
No full textThe multifunctional polydnavirus ANK1 protein: new insights for apoptotis pathway. Mammalians and insects, although phylogenetically distant, share some conserved pathways.
One of these is the apoptosis involved in physiological and pathological conditions. The induction
of apoptosis is one of the most common strategies adopted by various polydnaviruses (PDVs) to
suppress the immune response of insect hosts. PDVs are obligate symbionts of parasitoid wasps
attacking exclusively larval stages of their lepidopteran hosts. PDVs DNA is integrated into the
genome of the parasitoid and vertically transmitted through the germline. The PDVs particles
selectively infect host tissues expressing their genes without undergoing any replication events. In
this work we studied the model system host-parasitoid, Heliothis virescens/Toxoneuron nigriceps,
focusing on the role of the viral gene T. nigriceps Bracovirus ank 1(TnBVank1) in the apoptosis.
TnBVank1 encodes an ankyrin motif protein similar to the mammalian IkB, an inhibitor of the
transcription nuclear factor kB.
The role of TnBVank1 was investigated in H. virescens haemocytes, by in vivo transient expression
and, in vitro, in Drosophila Schneider’s S2 cells which stably expressed TnBVank1. Apoptosis
was detected by caspase-3 activity and Tunel staining. ANK1 interactor proteins were reveled
by coimmunoprecipitation experiments which indicated that ANK1 bound Alix, an interactor
of apoptosis-linked gene protein 2 (ALG-2). Alix was silenced by RNAi to study the function of
ANK1-Alix interaction.
Here we show that when ANK1 was stably expressed in S2 cells stimulated caspase-3 activity.
Furthermore we get the same results into H. virescens haemocytes by in vivo transient expression
of TnBVank1. Silencing Alix, ANK1 was no longer able to cause apoptosis in S2 cells and
into H. virescens haemocytes. Collectively, these results indicate that ANK1 induces apoptosis
by interacting with Alix, suggesting that this role could be relevant in the suppression of host
immune response observed in larvae parasitized by T. nigriceps
β3 adrenergic receptor in the kidney may be a new player in sympathetic regulation of renal function
No full textTo date, the study of the sympathetic regulation of renal function has been restricted to the important contribution of β1- and β2-adrenergic receptors (ARs). Here we investigate the expression and the possible physiologic role of β3-adrenergic receptor (β3-AR) in mouse kidney. The β3-AR is expressed in most of the nephron segments that also express the type 2 vasopressin receptor (AVPR2), including the thick ascending limb and the cortical and outer medullary collecting duct. Ex vivo experiments in mouse kidney tubules showed that β3-AR stimulation with the selective agonist BRL37344 increased intracellular cAMP levels and promoted 2 key processes in the urine concentrating mechanism. These are accumulation of the water channel aquaporin 2 at the apical plasma membrane in the collecting duct and activation of the Na-K-2Cl symporter in the thick ascending limb. Both effects were prevented by the β3-AR antagonist L748,337 or by the protein kinase A inhibitor H89. Interestingly, genetic inactivation of β3-AR in mice was associated with significantly increased urine excretion of water, sodium, potassium, and chloride. Stimulation of β3-AR significantly reduced urine excretion of water and the same electrolytes. Moreover, BRL37344 promoted a potent antidiuretic effect in AVPR2-null mice. Thus, our findings are of potential physiologic importance as they uncover the antidiuretic effect of β3-AR stimulation in the kidney. Hence, β3-AR agonism might be useful to bypass AVPR2-inactivating mutations.To date, the study of the sympathetic regulation of renal function has been restricted to the important contribution of β1- and β2-adrenergic receptors (ARs). Here we investigate the expression and the possible physiologic role of β3-adrenergic receptor (β3-AR) in mouse kidney. The β3-AR is expressed in most of the nephron segments that also express the type 2 vasopressin receptor (AVPR2), including the thick ascending limb and the cortical and outer medullary collecting duct. Ex vivo experiments in mouse kidney tubules showed that β3-AR stimulation with the selective agonist BRL37344 increased intracellular cAMP levels and promoted 2 key processes in the urine concentrating mechanism. These are accumulation of the water channel aquaporin 2 at the apical plasma membrane in the collecting duct and activation of the Na-K-2Cl symporter in the thick ascending limb. Both effects were prevented by the β3-AR antagonist L748,337 or by the protein kinase A inhibitor H89. Interestingly, genetic inactivation of β3-AR in mice was associated with significantly increased urine excretion of water, sodium, potassium, and chloride. Stimulation of β3-AR significantly reduced urine excretion of water and the same electrolytes. Moreover, BRL37344 promoted a potent antidiuretic effect in AVPR2-null mice. Thus, our findings are of potential physiologic importance as they uncover the antidiuretic effect of β3-AR stimulation in the kidney. Hence, β3-AR agonism might be useful to bypass AVPR2-inactivating mutations
Exon loss accounts for differential sorting of Na-K-Cl cotransporters in polarized epithelial cells.
Full text linkHigh-throughput fluorescent-based NKCC functional assay in adherent epithelial cells
Full text linkBackground: The kidney-specific NKCC cotransporter isoform NKCC2 is involved in the Na+ reabsorption in the Thich Ascending Limb (TAL) cells and in the regulation of body fluid volume. In contrast, the isoform NKCC1 represents the major pathway for Cl- entry in endothelial cells, playing a crucial role in cell volume regulation and vascular tone. Importantly, both NKCC isoforms are involved in the regulation of blood pressure and represent important potential drug targets for the treatment of hypertension. Results: Taking advantage of an existing Thallium (Tl+)-based kit, we set up a Tl+ influx-based fluorescent assay, that can accurately and rapidly measure NKCC transporter activity in adherent epithelial cells using the high-throughput Flex station device. We assessed the feasibility of this assay in the renal epithelial LLC-PK1 cells stably transfected with a previously characterized chimeric NKCC2 construct (c-NKCC2). We demonstrated that the assay is highly reproducible, offers high temporal resolution of NKCC-mediated ion flux profiles and, importantly, being a continuous assay, it offers improved sensitivity over previous endpoint NKCC functional assays. Conclusions: So far the screening of NKCC transporters activity has been done by 86Rb+ influx assays. Indeed, a fluorescence-based high-throughput screening method for testing NKCC inhibitors would be extremely useful in the development and characterization of new anti-hypertensive drugs
Role of Lamin A/C Gene Mutations in the signaling defects leading to cardiomyopathies
Full text linkNuclear lamin A/C are crucial components of the intricate protein mesh that underlies the inner nuclear membrane and confers mainly nuclear and cytosolic rigidity. However, throughout the years a number of other key physiological processes have been associated with lamins such as modulation of both genes expression and the activity of signaling mediators. To further solidify its importance in cell physiology, mutations in the lamin A/C gene (LMNA) have been associated to diverse pathological phenotypes with skeletal muscles and the heart being the most affected systems. When affected, the heart develops a wide array of phenotypes spanning from dilated cardiomyopathy with conduction defects to arrhythmogenic right ventricular cardiomyopathy. The surprising large number of cardiac phenotypes reflects the equally large number of specific mutations identified in the LMNA gene. In this review, we underlie how mutations in LMNA can impact the activity and the spatial/temporal organization of signaling mediators and transcription factors. We analyzed the ever-increasing amount of findings collected in LmnaH222P/H222P mice whose cardiomyopathy resemble the most important features of the disease in humans and a number of key evidences from other experimental models. With this mini review, we attempt to combine the newest insights regarding both the pathogenic effects of LMNA mutations in terms of signaling abnormalities and cardiac laminopathies
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