Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Activation of RAS proteins can lead to multiple outcomes by virtue of regulated signal traffic through alternate effector pathways. We demonstrate that the RAS effector protein RIN1 binds to activated RAS with an affinity (K(d), 22 nM) similar to that observed for RAF1. At concentrations close to their equilibrium dissociation constant values, RIN1 and RAF1 compete directly for RAS binding. RIN1 was also observed to inhibit cellular transformation by activated mutant RAS. This distinguishes RIN1 from other RAS effectors, which are transformation enhancing. Blockade of transformation was mediated by the RAS binding domain but required membrane localization. RIN1 recognizes endogenous RAS following transient activation by epidermal growth factor, and a portion of RIN1 fractionates to the cell membrane in a manner consistent with a reversible interaction. RIN1 also binds to 14-3-3 proteins through a sequence including serine 351. Mutation of this residue abolished the 14-3-3 binding capacity of RIN1 and led to more efficient blockade of RAS-mediated transformation. The mutant protein, RIN1(S351A), showed a shift in localization to the plasma membrane. Serine 351 is a substrate for protein kinase D (PKD [also known as PKCmu]) in vitro and in vivo. These data suggest that the normal localization and function of RIN1, as well as its ability to compete with RAF, are regulated in part by 14-3-3 binding, which in turn is controlled by PKD phosphorylation.
Mol Cell Biol 2002 Feb
PMID:The RAS effector RIN1 directly competes with RAF and is regulated by 14-3-3 proteins. 1178 66

A significant phenotypical variability is observed in autosomal dominant polycystic kidney disease (ADPKD). ADPKD is associated with altered endothelial-dependent vasodilation and decreased vascular production of nitric oxide (NO). Thus, ENOS, the gene coding for the endothelial nitric oxide synthase (eNOS), could have a modifier effect in ADPKD. In order to test this hypothesis, we genotyped 173 unrelated ADPKD patients from Belgium and the north of France for the Glu298Asp, intron 4 VNTR and T-786C polymorphisms of ENOS and looked for their influence on the age at end-stage renal disease (ESRD). In males (n = 93), the Glu298Asp polymorphism was associated with a lower age at ESRD (Glu/Asp + Asp/Asp: 49.0 +/- 1.2 years, n = 53; Glu/Glu: 53.5 +/- 1.5 years, n = 40; simple regression, P = 0.02; multiple regression, P = 0.006). This effect was confirmed in a subset of males linked to PKD1 and reaching ESRD before age 45, and by a cumulative renal survival analysis in PKD1-linked families. Further studies demonstrated that NO synthase (NOS) activity was decreased in renal artery samples from ADPKD males harbouring the Asp298 allele, in association with post-translational modifications and partial cleavage of eNOS. No significant effect of the other polymorphisms was found in males, and no polymorphism influenced the age at ESRD in females. In conclusion, the frequent Glu298Asp polymorphism of ENOS is associated with a 5 year lower mean age at ESRD in this subset of ADPKD males. This effect could be due to a decreased NOS activity and a partial cleavage of eNOS, leading to a further decrease in the vascular production of NO.
Hum Mol Genet 2002 Feb 01
PMID:Modifier effect of ENOS in autosomal dominant polycystic kidney disease. 1182 42

The tuberous sclerosis (TSC) 2 tumor suppressor gene encodes the protein tuberin, which has recently been shown to play a crucial role in the intracellular trafficking of polycystin-1, the product of the polycystic kidney disease (PDK) 1 gene. PKD1 is responsible for most cases of autosomal dominant polycystic kidney disease, which has been described as "neoplasia in disguise." Polycystin-1 is a membrane protein localized to adherens junctions in a complex containing E-cadherin and alpha-, beta-, and gamma-catenins. To determine whether loss of membrane localization of polycystin-1 and E-cadherin affects the function of beta-catenin, beta-catenin localization and signaling were characterized in tuberin-null EKT2 and ERC15 cells and in tuberin-positive TRKE2 cells derived from polycystic, neoplastic, and normal rat kidney epithelial cells, respectively. EKT2 cells lacking tuberin because of inactivation of the Tsc2 gene fail to localize polycystin-1 and E-cadherin appropriately to these junctions. However, beta-catenin was retained at lateral cell membranes in both tuberin-null and tuberin-positive cells. Moreover, gene transcription mediated by beta-catenin T-cell--specific transcription factor complexes showed no differences among EKT2, ERC15, and TRKE2 cells. Thus, beta-catenin was stably retained at the lateral cell membrane in tuberin-null renal cells lacking membrane-localized polycystin-1 and E-cadherin. These data suggest that, although loss of Tsc2 tumor suppressor gene function disrupts normal polycystin-1 function and membrane localization of E-cadherin, normal beta-catenin signaling is retained in tuberin-null cells.
Mol Carcinog 2002 Mar
PMID:Retention of membrane-localized beta-catenin in cells lacking functional polycystin-1 and tuberin. 1187 Aug 78

Polycystin-1 is a protein mutated in the majority of cases of autosomal dominant polycystic kidney disease (ADPKD), but its role in the molecular pathway of tubulogenesis and cystogenesis is not understood. To define the role of polycystin-1 during dynamic changes in formation of intercellular contacts and cell polarity accompanying epithelial morphogenesis, we have utilized a 3D MDCK in vitro model of tubulogenesis and cystogenesis. Here we demonstrate that polycystin-1 is a novel component of desmosomal junctions of epithelial cells. A striking downregulation of polycystin-1 mRNA was detected in cysts as compared to tubules, leading to altered protein expression and localization. While polycystin-1 is localized to basolateral membranes of MDCK tubules, it is only detected in cytoplasmic pools in cystic cells. Furthermore, the expression of polycystin-1 is modulated during distinct stages of HGF-induced tubulogenesis from MDCK cysts. Thus, polycystin-1 is not detected in intercellular contacts at early steps of tubulogenesis, but assumes its basolateral localization at the time of cell polarization and lumen formation. An important role of polycystin-1 is further demonstrated using the pancreatic ductal epithelial cell line SU.86.86 which undergoes in vitro differentiation resulting in the formation of domes. Dome formation is thought to parallel tubular differentiation and morphogenesis in vivo. Our data reveal significant upregulation of polycystin-1 mRNA and protein levels in domes. Collectively, our results demonstrate a critical importance of controlled level of polycystin-1 expression for proper tubular differentiation and maturation. We suggest that the loss of polycystin-1 from its basolateral location in tubular epithelium may alter critical pathways controlling normal tubulogenesis leading to cystic transformation.
Hum Mol Genet 2002 Apr 15
PMID:Functional polycystin-1 expression is developmentally regulated during epithelial morphogenesis in vitro: downregulation and loss of membrane localization during cystogenesis. 1197 74

Autosomal-dominant polycystic kidney disease (ADPKD) is one of the most common monogenetic diseases in humans. The discovery that mutations in the PKD1 and PKD2 genes are responsible for ADPKD has sparked extensive research efforts into the physiological and pathogenetic role of polycystin-1 and polycystin-2, the proteins encoded by these two genes. While polycystin-1 may mediate the contact among cells or between cells and the extracellular matrix, a lot of evidence suggests that polycystin-2 represents an endoplasmic reticulum-bound cation channel. Cyst development has been compared to the growth of benign tumors and this view is highlighted by the model that a somatic mutation in addition to the germline mutation is responsible for cystogenesis (two-hit model of cyst formation). Since in vitro polycystin-1 and polycystin-2 interact through their COOH termini, the two proteins possibly act in a common pathway, which controls the width of renal tubules. The loss of one protein may lead to a disruption of this pathway and to the uncontrolled expansion of tubules. Our increasing knowledge of the molecular events in ADPKD has also started to be useful in designing novel diagnostic and therapeutic strategies.
Cell Mol Life Sci 2002 Apr
PMID:Molecular basis of autosomal-dominant polycystic kidney disease. 1202 74

Mutations of either PKD1 or PKD2 are associated with autosomal dominant polycystic kidney disease (ADPKD). The molecular function of the gene product of PKD1, polycystin-1, in vitro has been elucidated recently, but the molecular pathological consequences of the loss of polycystin-1 in vivo have remained unclear. We have generated a mouse with a targeted deletion of exons 2-6 of Pkd1 to study the molecular defects in Pkd1 mutants. Homozygote embryos (Pkd1(-/-)) developed hydrops, cardiac conotruncal defects and renal cystogenesis. Total protein levels of beta-catenin in heart and kidney and c-MYC in heart were decreased in Pkd1(-/-) embryos. In the kidneys of Pkd1(-/-), the expression of E-cadherin and PECAM in basolateral membranes of renal tubules was attenuated, and tyrosine phosphorylation of epidermal growth factor receptor and Gab1 were constitutively enhanced when cystogenesis started on embryonic day (E) 15.5-16.5. Maternally administered pioglitazone, a thiazolidinedione compound, resolved these molecular defects of Pkd1(-/-). Treatment with pioglitazone improved survival of Pkd1(-/-) embryos and ameliorated the cardiac defects and the degree of renal cystogenesis. Long-term treatment with pioglitazone improved the endothelial function of adult Pkd1(+/-). These data indicated that molecular defects observed in Pkd1(-/-) embryos contributed to the pathogenesis of ADPKD and that thiazolidinediones had a compensatory effect on the pathway affected by the loss of polycystin-1. Pathways activated by thiazolidinediones may provide new therapeutic targets in ADPKD.
Hum Mol Genet 2002 Jul 15
PMID:Pioglitazone improves the phenotype and molecular defects of a targeted Pkd1 mutant. 1209 15

Autosomal dominant polycystic kidney disease (ADPKD) occurs by germline mutation in PKD1 or PKD2. Evidence of homozygous inactivation of either gene in human cyst lining cells as well as in mouse knockout models strongly supports a two-hit mechanism for cyst formation. Discovery of trans-heterozygous mutations in PKD1 and PKD2 in a minority of human renal cysts has led to the proposal that such mutations also can play a role in cyst formation. In the current study, we investigated the role of trans-heterozygous mutations in mouse models of polycystic kidney disease. In Pkd1(+/-), Pkd2 (+/-) and Pkd1(+/-) : Pkd2 (+/-) mice, the renal cystic lesion was mild and variable with no adverse effect on survival at 1 year. In keeping with the two-hit mechanism of cyst formation, approximately 70% of kidney cysts in Pkd2 (+/-) mice exhibited uniform loss of polycystin-2 expression. Cystic disease in trans-heterozygous Pkd1(+/-) : Pkd2 (+/-) mice, however, was notable for severity in excess of that predicted by a simple additive effect based on cyst formation in singly heterozygous mice. The data suggest a modifier role for the 'trans' polycystin gene in cystic kidney disease, and support a contribution from threshold effects to cyst formation and growth.
Hum Mol Genet 2002 Aug 01
PMID:Trans-heterozygous Pkd1 and Pkd2 mutations modify expression of polycystic kidney disease. 1214 Jan 87

The genetic analysis of rodent disease models provides a powerful tool to investigate how modifier loci cause variation in the phenotypic expression of a disease. In order to test the existence of modifier loci influencing polycystic kidney disease (PKD) phenotypes, we derived a backcross between PKD susceptible Han:SPRD(cy/+) and control Brown Norway (BN) rats, and performed a whole-genome scan in 182 PKD affected hybrids showing different grades of disease severity. The genetic dissection of PKD in the cross allowed us to detect a modifier locus, Modpkdr1, on rat chromosome 8 that controls PKD severity, kidney mass and plasma urea concentration. Results from database searches and computational analyses demonstrated that the Modpkdr1 locus shows strong evidence of synteny conservation with human and mouse chromosomal regions controlling kidney diseases, including disease progression of Alport syndrome. Comparative genome mapping also provided an inventory of potential candidate genes for modifier(s) of PKD. Analyses of the coding regions for four strong candidates (Ctsh, Bcl2a1, Trpc1 and Slc21a2) in (cy/+), BN and Lewis rat strains did not reveal sequence variants that could be associated with PKD. The characterization of Modpkdr1 may provide new insights into modulating mechanisms involved in the pathogenesis of PKD that could delay disease progression in humans. It may also have strong implications in the identification of pathophysiological factors common to different renal disorders.
Hum Mol Genet 2002 Sep 01
PMID:Characterization of a major modifier locus for polycystic kidney disease (Modpkdr1) in the Han:SPRD(cy/+) rat in a region conserved with a mouse modifier locus for Alport syndrome. 1218 69

Nephrogenesis starts with the reciprocal induction of two embryonically distinct analages, metanephric mesenchyme and ureteric bud. This complex process requires the refined and coordinated expression of numerous developmental genes, such as inv. Mice that are homozygous for a mutation in the inv gene (inv/inv) develop renal cysts resembling autosomal-recessive polycystic kidney disease. The gene locus containing inv has been proposed to serve as a common modifier for some human and rodent polycystic kidney disease phenotypes. We generated polyclonal antibodies to inversin to study its subcellular distribution, potential binding partners, and functional aspects in cultured murine proximal tubule cells. A 125-kDa inversin protein isoform was found at cell-cell junctions. Two inversin isoforms, 140- and 90-kDa, were identified in the nuclear and perinuclear compartments. Plasma membrane allocation of inversin is dependent upon cell-cell contacts and was redistributed when cell adhesion was disrupted after incubation of the cell monolayer with low-calcium/EGTA medium. We further show that the membrane-associated 125-kDa inversin forms a complex with N-cadherin and the catenins. The 90-kDa nuclear inversin complexes with beta-catenin. These findings indicate that the inv gene product functions in several cellular compartments, including the nucleus and cell-cell adhesion sites.
Mol Biol Cell 2002 Sep
PMID:Inversin forms a complex with catenins and N-cadherin in polarized epithelial cells. 1222 Nov 18

Polycystin-2 (PC2) is the product of the second cloned gene (PKD2) responsible for autosomal dominant polycystic kidney disease and has recently been shown to be a calcium-permeable cation channel. PC2 has been shown to connect indirectly with the actin microfilament. Here, we report a direct association between PC2 and the actin microfilament. Using a yeast two-hybrid screen, we identified a specific interaction between the PC2 cytoplasmic C-terminal domain and tropomyosin-1 (TM-1), a component of the actin microfilament complex. Tropomyosins constitute a protein family of more than 20 isoforms arising mainly from alternative splicing and are present in muscle as well as non-muscle cells. We identified a new TM-1 splicing isoform in kidney and heart (TM-1a) that differs from TM-1 in the C terminus and interacted with PC2. In vitro biochemical methods, including GST pull-down, blot overlay and microtiter binding assays, confirmed the interaction between PC2 and the two TM-1 isoforms. Further experiments targeted the interacting domains to G821-R878 of PC2 and A152-E196, a common segment of TM-1 and TM-1a. Indirect double immunofluorescence experiments showed partial co-localization of PC2 and TM-1 in transfected mouse fibroblast NIH 3T3 cells. Co-immunoprecipitation (co-IP) studies using 3T3 cells and Xenopus oocytes co-expressing PC2 and TM-1 (or TM-1a) revealed in vivo association between the protein pairs. Furthermore, the in vivo interaction between the endogenous PC2 and TM-1 was demonstrated also by reciprocal co-IP using native human embryonic kidney cells and human adult kidney. Considering previous reports that TM-1 acts as a suppressor of neoplastic growth of transformed cells, it is possible that TM-1 contributes to cyst formation/growth when the anchorage of PC2 to the actin microfilament via TM-1 is altered.
J Mol Biol 2003 Jan 31
PMID:Polycystin-2 associates with tropomyosin-1, an actin microfilament component. 1252 1


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