Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P42345 (mTOR)
 26,049 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Polycystic kidney diseases (autosomal dominant and autosomal recessive) are progressive renal tubular cystic diseases, which are characterised by cyst expansion and loss of normal kidney structure and function. Autosomal dominant polycystic kidney disease (ADPKD) is the most common life- threatening, hereditary disease. ADPKD is more prevalent than Huntington's disease, haemophilia, sickle cell disease, cystic fibrosis, myotonic dystrophy and Down's syndrome combined. Early diagnosis and treatment of hypertension with inhibitors of the renin-angiotensin-aldosterone system (RAAS) and its potential protective effect on left ventricular hypertrophy has been one of the major therapeutic goals to decrease cardiac complications and contribute to improved prognosis of the disease. Advances in the understanding of the genetics, molecular biology and pathophysiology of the disease are likely to facilitate the improvement of treatments for these diseases. Developments in describing the role of intracellular calcium ([Ca(2+)](i)) and its correlation with cellular signalling systems, Ras/Raf/mitogen extracellular kinase (MEK)/extracellular signal-regulated protein kinase (ERK), and interaction of these pathways with cyclic adenosine monophosphate (cAMP) levels, provide new insights on treatment strategies. Blocking the vasopressin V(2) receptor, a major adenylyl cyclase agonist, demonstrated significant improvements in inhibiting cytogenesis in animal models. Because of activation of the mammalian target of rapamycin (mTOR) pathway, the use of sirolimus (rapamycin) an mTOR inhibitor, markedly reduced cyst formation and decreased polycystic kidney size in several animal models. Caspase inhibitors have been shown to decrease cytogenesis and renal failure in rats with cystic disease. Cystic fluid secretion results in cyst enlargement and somatostatin analogues have been shown to decrease renal cyst progression in patients with ADPKD. The safety and efficacy of these classes of drugs provide potential interventions for experimental and clinical trials.
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PMID:Potential pharmacological interventions in polycystic kidney disease. 1803 88

Autosomal dominant polycystic kidney disease (ADPKD) is one of the most common hereditary disorders. It accounts for 6% of the incidence of end-stage renal disease in Europe. Over the last decade, knowledge of the pathology underlying this disease has increased rapidly. Attributing important roles to tubular cell ciliary functioning, cell proliferation and fluid secretion, subsequent alterations in levels of intracellular calcium, adenosine 3',5'-cyclic monophosphate (cAMP) and activation of a variety of cellular kinases, including mammalian target of rapamycin (mTOR), has laid out the foundations for development of potentially effective treatments. In this editorial, the possible therapeutic roles for vasopressin antagonists, rapamycin, somatostatin and roscovitine are discussed. Clinical trials have been started to investigate the efficacy and safety of these agents for treating ADPKD in humans.
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PMID:Better understanding of ADPKD results in potential new treatment options: ready for the cure? 1844 6

Autosomal dominant polycystic kidney disease (ADPKD) is a common genetic disease characterized by bilateral renal cyst formation. Both hyperproliferation and hypertrophy have been previously observed in ADPKD kidneys. Polycystin-1 (PC-1), a large orphan receptor encoded by the PKD1 gene and mutated in 85% of all cases, is able to inhibit proliferation and apoptosis. Here we show that overexpression of PC-1 in renal epithelial cells inhibits cell growth (size) in a cell cycle-independent manner due to the downregulation of mTOR, S6K1, and 4EBP1. Upregulation of the same pathway leads to increased cell size, as found in mouse embryonic fibroblasts derived from Pkd1-/- mice. We show that PC-1 controls the mTOR pathway in a Tsc2-dependent manner, by inhibiting the extracellular signal-regulated kinase (ERK)-mediated phosphorylation of tuberin in Ser664. We provide a detailed molecular mechanism by which PC-1 can inhibit the mTOR pathway and regulate cell size.
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PMID:Polycystin-1 regulates extracellular signal-regulated kinase-dependent phosphorylation of tuberin to control cell size through mTOR and its downstream effectors S6K and 4EBP1. 1925 43

Because the size of renal cysts in the native kidneys of patients with ADPKD who have been transplanted was found to be reduced when rapamycin was the immunosuppressant, we tested the involvement of the mTOR pathway in cyst enlargement. Here, male pcy mice, with mutation in one of the nephronophthisis genes, were treated with rapamycin at an early (6 to 12 weeks of age) or a later (20 to 30 weeks of age) disease stage by means of slow-release pellets containing placebo or rapamycin. Effectiveness of the rapamycin dose and delivery was shown by the inhibition of insulin-stimulated phosphorylation of p70S6K, a marker of mTOR activity, in skeletal muscle. Early treatment did not affect initial cyst development but when started late, there was a significant reduction in the rate of cyst enlargement, kidney fibrosis, and the progressive loss of renal function as measured by blood urea nitrogen. Kidneys of the mice treated through 30 weeks of age tended to be smaller and have less fibrosis compared with those of untreated or placebo-treated pcy/pcy mice at 20 weeks when treatment was initiated. Our study shows that rapamycin can prevent the late- but not the early-stage progression of renal pathology and deterioration of renal functional in this model of nephronophthisis, presumably by inhibiting mTOR activity.
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PMID:Late progression of renal pathology and cyst enlargement is reduced by rapamycin in a mouse model of nephronophthisis. 1942 Nov 90

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by the progressive development of innumerable cysts in both kidneys, which distort the normal kidney architecture, leading to a loss of renal function that may necessitate renal replacement therapy and/or kidney transplantation. In experimental animal models for dominant and recessive forms of polycystic kidney disease, mammalian target of rapamycin (mTOR)-inhibitors such as rapamycin effectively reduced cyst growth and loss of renal function. Furthermore, an analysis of sirolimus-treated renal transplant ADPKD patients showed that cystic kidney volumes regressed. An interventional study has been initiated to investigate whether sirolimus retards cyst growth and slows renal functional deterioration in patients with ADPKD. This prospective study is an 18-month, controlled, open label clinical trial with 2 parallel groups of patients with ADPKD. The aim of the study is to investigate whether sirolimus used at a low dose (2 mg/d) retards cyst growth and slows renal functional deterioration in patients with ADPKD. It is anticipated that the inhibition of mTOR with sirolimus can slow disease progression and delay the need for chronic renal replacement therapy. Preliminary study results are expected in 2010.
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PMID:Mammalian target of rapamycin and autosomal dominant polycystic kidney disease. 1965 Dec 90

Autosomal dominant polycystic kidney disease (ADPKD) is the most common of the inherited renal cystic diseases and constitutes 10% of the end stage kidney disease population. ADPKD is caused by PKD1 and PKD2 gene mutations in 85% and 15% of the cases respectively. Its high prevalence and negative impact on health outcomes fostered efforts to explain pathophysiologic pathways of cyst formation in kidneys. Among these are increased apoptosis, unopposed proliferation of tubule cells, impaired polarization and planar cell polarity, impaired cAMP pathway, cilier dysfunction, activated mTOR pathway, increased tumor necrosis factor-alpha (TNF-alpha) production. Many drugs have been tried in an attempt to halt cystogenesis in some point. Despite success to some extent in experimental studies, none reached clinical armamentarium yet. Colchicine, originally extracted from Colchicum autunale, is an anti-inflammatory drug that has been in continuous use for more than 3000 years. It has been used successfully to prevent attacks of familial mediterranien fever and amyloidosis, to treat gout and pseudogout attacks for a few decades. Colchicine principally is a microtubule inhibitor, thus prevents cell migration, division, and polarization. It also has anti-apoptotic, anti-proliferative and anti-inflammatory effects and down-regulates (TNF-alpha) receptors. As can easily be seen, many of the effects of colchicine have pathophysiologic counterparts in ADPKD. Thus, we hypothesized that colchicine would be beneficial to prevent or at least delay cyst formation in ADPKD patients. Indirect evidence also support our hypothesis, in which taxol and paclitaxel, other two microtubule inhibitors, were shown to delay cyst formation in experimental models of ADPKD. To our opinion, despite its narrow therapeutic index, widespread experience makes colchicine a suitable candidate for prolonged clinical use, should experimental studies show any benefit in ADPKD.
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PMID:Colchicine treatment in autosomal dominant polycystic kidney disease: many points in common. 1976 12

Autosomal dominant polycystic kidney disease (ADPKD) is a genetic disease characterized by the formation of renal cysts. This disease can be caused by mutations in two genes, PKD1 and PKD2, which encode polycystin-1 (PC-1) and -2 (PC-2), respectively.PC-1 is a large plasma membrane receptor involved in the regulation of several biological functions and signaling pathways, and PC-2 is a calcium channel of the TRP family. The two proteins associate in a complex to prevent cyst formation, but the precise mechanism(s) involved remain largely unknown.This review will focus on recent advances in our understanding of the functions of polycystins and their role in signal transduction.Increased activity of the mammalian target of rapamycin (mTOR) kinase has been observed in cysts found in ADPKD tissues. Rapamycin has been shown to have beneficial effects in rodent models of polycystic kidney disease, prompting the initiation of pilot clinical trials with human patients. Furthermore, a direct role for PC-1 in the regulation of cell growth (size) via mTOR has recently been demonstrated.Major advancements in the study of mTOR biology have highlighted that this kinase exists in association with two different complexes, mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2). The mTORC1 complex regulates cell growth (size), proliferation, translation and autophagy, and mTORC2 regulates the actin cytoskeleton and apoptosis. Interestingly, mTORC2 has been shown to contain the kinase responsible for the phosphorylation of Akt at Serine 473. Previous studies have shown that PC-1 controls the PI 3-kinase/Akt cascade to regulate apoptosis and the actin cytoskeleton, suggesting that this receptor might regulate mTOR at several levels.This review aims to discuss three different, inter-related themes emerging from the literature: (i) studies performed in our and other laboratories collectively suggest that PC-1 might be able to differentially regulate the two mTOR complexes; (ii) several studies point to genetic and functional cross-talk between the PKD and TSC genes, although the molecular details remain obscure; and (iii) studies performed in mammals and in the unicellular algae Chlamidomonas Reinhardtii might highlight a link between cilia, regulation of cell size and regulation of the cell cycle.
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PMID:Emerging evidence of a link between the polycystins and the mTOR pathways. 1986 83

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by the massive enlargement of both kidneys caused by numerous cysts. The cyst formation begins in utero and the continuous growth of cysts leads to compression and destruction of non-cystic renal parenchyma, so that finally a kidney replacement in the 5th to 6th decade of life is necessary. So far there is no therapy that halts disease progression. Animal data show that pharmacological inhibition of a central regulator of cell proliferation, the so-called mammalian target of rapamycin (mTOR), slows disease progression. This overview provides an insight into the disease and the specific mTOR inhibitor sirolimus, which is currently tested in clinical trials.
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PMID:[Autosomal dominant polycystic kidney disease (ADPKD): rapamycin as a new treatment option]. 2001 87

Autosomal dominant polycystic kidney disease (ADPKD) is a commonly inherited renal disorder caused by defects in the PKD1 or PKD2 genes. ADPKD is associated with significant morbidity, and is a major underlying cause of end-stage renal failure (ESRF). Commonly, treatment options are limited to the management of hypertension, cardiovascular risk factors, dialysis, and transplantation when ESRF develops, although several new pharmacotherapies, including rapamycin, have shown early promise in animal and human studies. Evidence implicates polycystin-1 (PC-1), the gene product of the PKD1 gene, in regulation of the mTOR pathway. Here we demonstrate a mechanism by which the intracellular, carboxy-terminal tail of polycystin-1 (CP1) regulates mTOR signaling by altering the subcellular localization of the tuberous sclerosis complex 2 (TSC2) tumor suppressor, a gatekeeper for mTOR activity. Phosphorylation of TSC2 at S939 by AKT causes partitioning of TSC2 away from the membrane, its GAP target Rheb, and its activating partner TSC1 to the cytosol via 14-3-3 protein binding. We found that TSC2 and a C-terminal polycystin-1 peptide (CP1) directly interact and that a membrane-tethered CP1 protects TSC2 from AKT phosphorylation at S939, retaining TSC2 at the membrane to inhibit the mTOR pathway. CP1 decreased binding of 14-3-3 proteins to TSC2 and increased the interaction between TSC2 and its activating partner TSC1. Interestingly, while membrane tethering of CP1 was required to activate TSC2 and repress mTOR, the ability of CP1 to inhibit mTOR signaling did not require primary cilia and was independent of AMPK activation. These data identify a unique mechanism for modulation of TSC2 repression of mTOR signaling via membrane retention of this tumor suppressor, and identify PC-1 as a regulator of this downstream component of the PI3K signaling cascade.
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PMID:Carboxy terminal tail of polycystin-1 regulates localization of TSC2 to repress mTOR. 2016 78

Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited renal disease, and sirolimus, a mammalian target of rapamycin (mTOR) inhibitor, has been shown to significantly retard cyst expansion in animal models. The optimal therapeutic dose of sirolimus is not yet defined. Here, we report the history of a previously unknown ADPKD deceased donor whose kidneys were engrafted in two different recipients. One of the two received an immunosuppressive regimen based on sirolimus for 5 years while the other did not. After transplantation, both patients developed severe transplant cystic disease. Donor DNA sequence identified a new hypomorphic mutation in PKD1. The rate of cyst growth was identical in the two patients regardless of the treatment. While sirolimus treatment reduced the activation of mTOR in peripheral blood mononuclear cells, it failed to prevent mTOR activation in kidney tubular cells, this could account for the inefficiency of treatment on cyst growth. Together, our results suggest that the dose of sirolimus required to inhibit mTOR varies according to the tissue.
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PMID:Therapeutic mTOR inhibition in autosomal dominant polycystic kidney disease: What is the appropriate serum level? 2064 92


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