Cellular effects of everolimus and sirolimus on podocytes.

Everolimus (EVL) and Sirolimus (SRL) are potent immunosuppressant agents belonging to the group of mammalian target of rapamycin (mTOR) inhibitors used to prevent transplant rejection. However, some patients develop proteinuria following a switch from a calcineurin inhibitor regimen to mTOR inhibitors. Whether different mTOR inhibitors show similar effects on podocytes is still unknown.

Transient receptor potential channel 6 (TRPC6) protects podocytes during complement-mediated glomerular disease.

Gain-of-function mutations in the calcium channel TRPC6 lead to autosomal dominant focal segmental glomerulosclerosis and podocyte expression of TRPC6 is increased in some acquired human glomerular diseases, particularly in membranous nephropathy. These observations led to the hypothesis that TRPC6 overactivation is deleterious to podocytes through pathological calcium signaling, both in genetic and acquired diseases. Here, we show that the effects of TRPC6 on podocyte function are context-dependent.

Akt2 relaxes podocytes in chronic kidney disease.

A signaling cascade is activated in podocytes to induce survival and cope with stress during advanced glomerular disease, a new study shows. The findings may also explain why the immunosuppressor sirolimus, an inhibitor of this pathway, can cause proteinuria in a subset of patients with chronic kidney disease (pages 1288–1296).

CD80, suPAR and nephrotic syndrome in a case of NPHS2 mutation.

Background: Podocin mutations are characterized by progression to end stage renal disease and histologic findings of Focal Segmental Glomerulosclerosis (FSGS). CD80 is a podocytes protein that may play a role in proteinuria, particularly in Minimal Change Disease whereas the soluble urokinase receptor (suPAR) is characteristically elevated in the serum of FSGS patients.

Methods: In a patient with nephrotic syndrome and podocin mutation, urinary and serum CD80 as well as suPAR were measured using commercially available kits.

Circulating permeability factor suPAR: from concept to discovery to clinic.

Kidney filtration functions through a hydrostatically driven multicellular barrier that includes visceral epithelial cells termed podocytes. These cells have delicate foot processes by which they ensure proper generation of urine. Most forms of chronic kidney disease start with disruption of podocytes, allowing for a breakdown of kidney barrier function and loss of plasma proteins from the blood into the urine (proteinuria).

Podocyte effacement closely links to suPAR levels at time of posttransplantation focal segmental glomerulosclerosis occurrence and improves with therapy.

Background: Focal segmental glomerulosclerosis (FSGS) recurs after kidney transplantation in more than 30% of cases and can lead to allograft loss. Serum soluble urokinase-type plasminogen activator receptor (suPAR) is implicated in the pathogenesis of native and recurrent FSGS.

Methods: We conducted a retrospective study of 25 adults with posttransplantation FSGS.

Rituximab is a safe and effective long-term treatment for children with steroid and calcineurin inhibitor-dependent idiopathic nephrotic syndrome.

In children with idiopathic nephrotic syndrome, rituximab can maintain short-term remission with withdrawal of prednisone and calcineurin inhibitors. Long-term effects including the number of repeated infusions to maintain remission are unknown. To test this, we treated 46 consecutive children with idiopathic nephrotic syndrome lasting for at least 1 year (mean 6.

C-kit(+) cells isolated from developing kidneys are a novel population of stem cells with regenerative potential.

The presence of tissue specific precursor cells is an emerging concept in organ formation and tissue homeostasis. Several progenitors are described in the kidneys. However, their identity as a true stem cell remains elusive.

Regulated expression of lentivirus-mediated GDNF in human bone marrow-derived mesenchymal stem cells and its neuroprotection on dopaminergic cells in vitro.

Gene regulation remains one of the major challenges for gene therapy in clinical trials. In the present study, we first generated a binary tetracycline-on (Tet-On) system based on two lentivirus vectors, one expressing both human glial cell line-derived neurotrophic factor (hGDNF) and humanized recombinant green fluorescent protein (hrGFP) genes under second-generation tetracycline response element (TRE), and the other expressing the advanced reverse tetracycline-controlled transactivator--rtTA2S-M2 under a human minimal cytomegalovirus immediate early (CMV-IE) promoter. This system allows simultaneous expression of hGDNF and hrGFP genes in the presence of doxycycline (Dox).

Acquired substrate preference for GAB1 protein bestows transforming activity to ERBB2 kinase lung cancer mutants.

Activating mutations in the αC-β4 loop of the ERBB2 kinase domain, such as ERBB2(YVMA) and ERBB2(G776VC), have been identified in human lung cancers and found to drive tumor formation. Here we observe that the docking protein GAB1 is hyper-phosphorylated in carcinomas from transgenic mice and in cell lines expressing these ERBB2 cancer mutants. Using dominant negative GAB1 mutants lacking canonical tyrosine residues for SHP2 and PI3K interactions or lentiviral shRNA that targets GAB1, we demonstrate that GAB1 phosphorylation is required for ERBB2 mutant-induced cell signaling, cell transformation, and tumorigenesis.

Cystic fibrosis transmembrane conductance regulator recruitment to phagosomes in neutrophils.

Optimal microbicidal activity of human polymorphonuclear leukocytes (PMN) relies on the generation of toxic agents such as hypochlorous acid (HOCl) in phagosomes. HOCl formation requires H2O2 produced by the NADPH oxidase, myeloperoxidase derived from azurophilic granules, and chloride ion. Chloride transport from cytoplasm into phagosomes requires chloride channels which include cystic fibrosis transmembrane conductance regulator (CFTR), a cAMP-activated chloride channel.

Management of severe recurrent focal segmental glomerulosclerosis through circulating soluble urokinase receptor modification.

Circulating soluble urokinase receptor (suPAR) was recently identified as one of the causes responsible for native and recurrent focal segmental glomerulosclerosis (FSGS) through overactivation of podocyte β(3) integrin. Here, we discuss the management of a patient with very high suPAR serum levels and FSGS recurrence. The suPAR reduction using plasmapheresis and immunoadsorption allowed for lowering of suPAR and reduced podocyte β(3) integrin activation and proteinuria.

Innate immune defense defines susceptibility of sarcoma cells to measles vaccine virus-based oncolysis.

The oncolytic potential of measles vaccine virus (MeV) has been demonstrated in several tumor entities. Here, we investigated the susceptibility of eight sarcoma cell lines to MeV-mediated oncolysis and found five to be susceptible, whereas three proved to be resistant. In the MeV-resistant cell lines, we often observed an inhibition of viral replication along with a strong upregulation of the intracellular virus-sensing molecule RIG-I and of the interferon (IFN)-stimulated gene IFIT1.

Podocyte biology and pathogenesis of kidney disease.

Proteinuric chronic kidney disease (CKD), once a rare affliction believed to be mainly caused by genetic mutations, has become a global pandemic that severely diminishes the quality of life for millions. Despite the changing face of CKD, treatment options and resources remain woefully antiquated and have failed to arrest or reverse the effects of kidney-related diseases. Histological and genetic data strongly implicate one promising target: the podocyte.

Circulating suPAR in two cohorts of primary FSGS.

Overexpression of soluble urokinase receptor (suPAR) causes pathology in animal models similar to primary FSGS, and one recent study demonstrated elevated levels of serum suPAR in patients with the disease. Here, we analyzed circulating suPAR levels in two cohorts of children and adults with biopsy-proven primary FSGS: 70 patients from the North America-based FSGS clinical trial (CT) and 94 patients from PodoNet, the Europe-based consortium studying steroid-resistant nephrotic syndrome. Circulating suPAR levels were elevated in 84.

Potassium acts as a GTPase-activating element on each nucleotide-binding domain of the essential Bacillus subtilis EngA.

EngA proteins form a unique family of bacterial GTPases with two GTP-binding domains in tandem, namely GD1 and GD2, followed by a KH (K-homology) domain. They have been shown to interact with the bacterial ribosome and to be involved in its biogenesis. Most prokaryotic EngA possess a high GTPase activity in contrast to eukaryotic GTPases that act mainly as molecular switches.

The calcineurin-NFAT pathway allows for urokinase receptor-mediated beta3 integrin signaling to cause podocyte injury.

Circulating and podocyte-bound urokinase receptor (uPAR) is a mediator of podocyte injury, proteinuria, and focal segmental glomerulosclerosis (FSGS) allowing pathological activation of the uPAR-β3 integrin signaling axis. Clinically, calcineurin inhibitors (e.g.

Expression of fgf23 and αklotho in developing embryonic tissues and adult kidney of the zebrafish, Danio rerio.

Fibroblast growth factor 23 (FGF23) is an endocrine hormone that is secreted by bone and acts on the kidney and parathyroid glands to regulate phosphate homeostasis. The effects of FGF23 on phosphate homeostasis are mediated by binding to FGF receptors and their coreceptor, αklotho, which are abundantly expressed in the kidney and parathyroid glands. However, the mechanisms of how FGF23 regulates phosphate handling in the proximal tubule are unclear because αklotho is primarily expressed in the distal nephron in humans and rodents.

Specific targeting of human interleukin (IL)-13 receptor α2-positive cells with lentiviral vectors displaying IL-13.

The ability to selectively and efficiently target transgene delivery to specific cell types in vitro and in vivo remains one of the formidable challenges in gene therapy. Lentiviral vectors have several advantages that make them attractive as gene delivery vehicles and their tropism can be altered through pseudotyping, allowing transgene delivery to specific populations of cells. The human interleukin-13 receptor α2 (IL-13Rα2) is uniquely overexpressed in many different human tumors, making it an attractive target for cancer therapy.

Podocyte GTPases regulate kidney filter dynamics.

Our concept of the kidney filtration barrier is changing from one of a static sieve into one of a highly dynamic structure regulated through the motility of podocyte foot processes. Inactivation of the small GTPase RhoA in vitro causes hypermotility, whereas activation decreases motility. Wang et al.