TTYH2, a human homologue of the Drosophila melanogaster gene tweety, is located on 17q24 and upregulated in renal cell carcinoma

Using differential display PCR, we identified a novel gene upregulated in renal cell carcinoma. Characterization of the full-length cDNA and gene revealed that the encoded protein is a human homologue of the Drosophila melanogaster Tweety protein, and so we have termed the novel protein TTYH2. The orthologous mouse cDNA was also identified and the predicted mouse protein is 81% identical to the human protein. The encoded human TTYH2 protein is 534 amino acids and, like the other members of the tweety-related protein family, is a putative cell surface protein with five transmembrane regions. TTYH2 is located at 17q24; it is expressed most highly in brain and testis and at lower levels in heart, ovary, spleen, and peripheral blood leukocytes. Expression of this gene is upregulated in 13 of 16 (81%) renal cell carcinoma samples examined. In addition to a putative role in brain and testis, the overexpression of TTYH2 in renal cell carcinoma suggests that it may have an important role in kidney tumorigenesis.

Vascular smooth muscle cell phenotypic modulation in culture is associated with reorganisation of contractile and cytoskeletal proteins

Smooth muscle cells (SMC) exhibit a functional plasticity, modulating from the mature phenotype in which the primary function is contraction, to a less differentiated state with increased capacities for motility, protein synthesis, and proliferation. The present study determined, using Western analysis, double-label immunofluorescence and confocal microscopy, whether changes in phenotypic expression of rabbit aortic SMC in culture could be correlated with alterations in expression and distribution of structural proteins. Contractile state SMC (days 1 and 3 of primary culture) showed distinct sorting of proteins into subcellular domains, consistent with the theory that the SMC structural machinery is compartmentalised within the cell. Proteins specialised for contraction (alpha -SM actin, SM-MHC, and calponin) were highly expressed in these cells and concentrated in the upper central region of the cell. Vimentin was confined to the body of the cell, providing support for the contractile apparatus but not co-localising with it. In line with its role in cell attachment and motility, beta -NM actin was localised to the cell periphery and basal cortex. The dense body protein alpha -actinin was concentrated at the cell periphery, possibly stabilising both contractile and motile apparatus. Vinculin-containing focal adhesions were well developed, indicating the cells' strong adhesion to substrate. In synthetic state SMC (passages 2-3 of culture), there was decreased expression of contractile and adhesion (vinculin) proteins with a concomitant increase in cytoskeletal proteins (beta -non-muscle [NM] actin and vimentin). These quantitative changes in structural proteins were associated with dramatic chan-es in their distribution. The distinct compartmentalisation of structural proteins observed in contractile state SMC was no longer obvious, with proteins more evenly distributed throughout die cytoplasm to accommodate altered cell function. Thus, SMC phenotypic modulation involves not only quantitative changes in contractile and cytoskeletal proteins, but also reorganisation of these proteins. Since the cytoskeleton acts as a spatial regulator of intracellular signalling, reorganisation of the cytoskeleton may lead to realignment of signalling molecules, which, in turn, may mediate the changes in function associated with SMC phenotypic modulation. (C) 2001 Wiley-Liss, Inc.

An ATP-sensitive K+ conductance in dissociated neurones from adult rat intracardiac ganglia

1. An ATP-sensitive K+ (K-ATP) conductance has been identified using the perforated patch recording configuration in a population (52%) of dissociated neurones from adult rat intracardiac ganglia. The presence of the sulphonylurea receptor in approximately half of the intracardiac neurones was confirmed by labelling with fluorescent glibenclamide-BODIPY. 2. Under current clamp conditions in physiological solutions, leveromakalim (10 muM) evoked a hyperpolarization, which was inhibited by the sulphonylurea drugs glibenclamide and tolbutamide. 3. Under voltage clamp conditions in symmetrical (140 mM) K+ solutions, hath application of levcromakalim evoked an inward current with a density of similar to8 pA pF(-1) at -50 mV and a slope conductance of similar to9 nS, which reversed close to the potassium equilibrium potential (E-K). Cell dialysis with an ATP-free intracellular solution also evoked an inward current, which was inhibited by tolbutamide. 4. Bath application of either glibenclamide (10 muM) or tolbutamide (100 muM) depolarized adult intracardiac neurones by 3-5 mV, suggesting that a K-ATP conductance is activated under resting conditions and contributes to the resting membrane potential. 5. Activation of a membrane current by levcromakalim leas concentration dependent, with an EC50 of 1.6 muM. Inhibition of the levcromakalim-activated current by glibenclamide leas also concentration dependent, with an IC50 of 55 nM. 6. Metabolic inhibition with 2,4-dinitrophenol and iodoacetic acid or superfusion with hypoxic solution (P-O2 similar to 16 mmHg) also activated a membrane current. These currents exhibited similar I-P characteristics to the levcroinakalim-induced current and were inhibited by glibenclamide. 7. Activation of K-ATP channels in mammalian intracardiac neurones may contribute to changes in neural regulation of the mature heart and. cardiac function during ischaemia-reperfusion.

Large-conductance calcium-activated potassium channels in neonatal rat intracardiac ganglion neurons

The properties of single Ca2+-activated K+ (BK) channels in neonatal rat intracardiac neurons were investigated using the patch-clamp recording technique. In symmetrical 140 mM K+, the single-channel slope conductance was linear in the voltage range -60/+60 mV. and was 207+/-19 pS. Na+ ions were not measurably permeant through the open channel. Channel activity increased with the cytoplasmic free Ca2+ concentration ([Ca2+],) with a Hill plot giving a half-saturating [Ca2+] (K-0.5) of 1.35 muM and slope of congruent to3. The BK channel was inhibited reversibly by external tetraethylammonium (TEA) ions, charybdotoxin, and quinine and was resistant to block by 4-aminopyridine and apamin. Ionomycin (1-10 muM) increased BK channel activity in the cell-attached recording configuration. The resting activity was consistent with a [Ca2+](i)

Targets to trials in diabetic complications

Diabetes is now the leading cause of end-stage renal disease, blindness, lower-extremity amputations and impotence. In addition, the risk of death from cardiovascular disease such as myocardial infarction and stroke is more than doubled in diabetics. In September 2001, scientists from around the world met in Melbourne to discuss the mechanisms underlying neuronal and vascular changes in diabetic complications. This report summarizes the meeting and attempts to identify potential targets for drug intervention in diabetic complications. (C) 2001 Prous Science. All rights reserved.

Vascular endothelial growth factor-B-deficient mice show impaired development of hypoxic pulmonary hypertension

To test the hypothesis that Vegf-B contributes to the pulmonary vascular remodelling, and the associated pulmonary hypertension, induced by exposure of mice to chronic hypoxia. Methods: Right ventricular systolic pressure, the ratio of right ventricle/[left ventricle+septum] (RV/[LV+S]) and the thickness of the media (relative to vessel diameter) of intralobar pulmonary arteries (o.d. 50-150 and 151-420 mum) were determined in Vegfb knockout mice (Vegfb(-/-); n=17) and corresponding wild-type mice (Vegfb(+/+); n=17) exposed to chronic hypoxia (10% oxygen) or housed in room air (normoxia) for 4 weeks. Results: In Vegfb(+/+) mice hypoxia caused (i) pulmonary hypertension (a 70% increase in right ventricular systolic pressure compared with normoxic Vegfb(+/+) mice; P

Apoptosis in the pathogenesis of renal disease with a focus on tubulointerstitial injury

Renal cell apoptosis is important not only in normal physiological conditions of the kidney but also in pathological processes. In normal renal development, it removes unwanted, damaged or harmful cells, and in the healthy adult kidney, it maintains cellular homeostasis by regulating the balance between cell proliferation and cell loss. The apoptotic process has now been described in the pathogenesis and prognosis of certain renal diseases with both beneficial and detrimental roles. It causes deletion of cells intrinsic to the kidney after, for example, toxic, ischaemic, immune or radiation damage, and this loss can be destructive and can cause significant reduction of renal function. In contrast, it can control and limit inflammatory processes in both the acute and chronic phases of renal disease. Information on the positive and negative outcomes of renal cell apoptosis, plus the thousands of publications on more general aspects of apoptosis mechanisms, have now presented real opportunities for the development of therapies that selectively delete or protect certain renal cell populations. This review will discuss some of the more general aspects of renal cell apoptosis and then concentrate on the detrimental or beneficial roles of apoptosis in the initiation, progression or resolution of selected, mainly tubulointerstitial, renal diseases.

Interacting roles of myofibroblasts, apoptosis and fibrogenic growth factors in the pathogenesis of renal tubulo-interstitial fibrosis

The interrelationship between myofibroblasts and fibrogenic growth factors in the pathogenesis of renal fibrosis is poorly defined. A temporal and spatial analysis of myofibroblasts, their proliferation and death, and presence of transforming growth factor-beta1 (TGF-beta1) and platelet-derived growth factor-B (PDGF-B) was carried out in an established rodent model in which chronic renal scarring and fibrosis occurs after healed renal papillary necrosis (RPN), similar to that seen with analgesic nephropathy. Treated and control groups (N = 6 and 4, respectively) were compared at 2, 4, 8 and 12 weeks. A positive relationship was found between presence of tubulo-interstitial myofibroblasts and development of fibrosis. Apoptotic myofibroblasts were identified in the interstitium and their incidence peaked 2 weeks after treatment. Levels of interstitial cell apoptosis and fibrosis were negatively correlated over time (r = -0.57, p < 0.01 ), suggesting that as apoptosis progressively failed to limit myofibroblast numbers, fibrosis increased. In comparison with the diminishing apoptosis in the interstitium, the tubular epithelium had progressively increasing levels of apoptosis over time, indicative of developing atrophy of nephrons. TGF-beta1 protein expression had a close spatial and temporal association with fibrosis and myofibroblasts, whilst PDGF-B appeared to have a closer link with populations of other chronic inflammatory cells such as infiltrating lymphocytes. Peritubular myofibroblasts were often seen near apoptotic cells in the tubular epithelium, suggestive of a paracrine toxic effect of factor/s secreted by the myofibroblasts. In vitro , TGF-beta1 was found to be toxic to renal tubular epithelial cells. These findings suggest an interaction between myofibroblasts, their deletion by apoptosis, and the presence of the fibrogenic growth factor TGF-beta1 in renal fibrosis, whereby apoptotic deletion of myofibroblasts could act as a controlling factor in progression of fibrosis.

Vascular dysfunction and heart failure: Epiphenomenon or etiologic agent?

Endothelial function plays a key role in the local regulation of vascular tone. Alterations in endothelial function may result in impaired release of endothelium-derived relaxing factors or increased release of endothelium-derived contracting factors. Heart failure may impair endothelial function by means of reduced synthesis and release of nitric oxide (NO) or by increased degradation of NO and increased production of endothelin-1. Endothelial dysfunction may worsen heart function by means of peripheral effects, causing increased afterload and central effects such as myocardial ischemia and inducible nitric oxide synthase (iNOS)-induced detrimental effects. Evidence from clinical studies has suggested that there is a correlation between decreased endothelial function and increasing severity of congestive heart failure (CHF). Treatments that improve heart function may also improve endothelial dysfunction. The relationship between endothelial dysfunction and heart failure may be masked by the stage of endothelial dysfunction, the location of vessels being tested, and the state of endothelial-dependent vasodilatation response.

Neutrophil dysplasia characterised by a pseudo-Pelger-Huet anomaly occurring with the use of mycophenolate mofetil and ganciclovir following renal transplantation: a report of five cases

Aim: The pseudo-Pelger-Huet (PH) anomaly has been associated with a variety of primary haematological disorders, infections and drugs. Recently, the development of dysgranulopoiesis characterised by a pseudo-PH anomaly has been reported in two patients with the use of mycophenolate mofetil (MMF) in the setting of heart and/or lung transplantation. We present a further five cases of MMF-related dysgranulopoiesis characterised by a pseudo-PH anomaly occurring after renal transplantation. Methods: All patients were receiving standard immunosuppression protocols for renal transplantation, including a combination of MMF, steroids and either cyclosporin or tacrolimus. Oral ganciclovir was also used for cytomegalovirus prophylaxis in each case. Results: Development of dysplastic granulopoiesis occurred a median of 96 days (range 66-196 days) after transplantation. Moderate or severe neutropaenia (

Renal pathology of polycystic kidney disease and concurrent hereditary nephritis in Bull Terriers

Objective To describe the renal lesions in Bull Terrier polycystic kidney disease (BTPKD), to confirm that the renal cysts in BTPKD arise from the nephron or collecting tubule, an to identify lesions consistent with concurrent BTPKD and Bull Terrier hereditary nephritis (BTHN). Design Renal tissue from five Bull Terriers with BTPKD and eight control dogs was examined by light and transmission electron microscopy. Clinical data were collected from all dogs, and family history of BTPKD and BTHN for all Bull Terriers. Results In BTPKD the renal cysts were lined by epithelial cells of nephron or collecting duct origin that were usually squamous or cuboidal, with few organelles. They had normal junctional complexes, and basal laminae of varying thicknesses. Glomeruli with small, atrophic tufts and dilated Bowman's capsules, tubular loss and dilation, and interstitial inflammation and fibrosis were common. Whereas the lesions seen in BTHN by light microscope were nonspecific, the presence of characteristic ultrastructural glomerular basement membrane (GMB) lesions and a family history of this disease indicated concurrent BTHN was likely in three of five cases of BTPKD. Conclusion This paper provides evidence that renal cysts in BTPKD are of nephron or collecting duct origin. In addition, GBM lesions are described that strongly suggest that BTPKD and BTHN may occur simultaneously.