Bicaudal C mutation causes myc and TOR pathway up-regulation and polycystic kidney disease-like phenotypes in Drosophila.
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ABSTRACT:
SUBMITTER: Gamberi C
PROVIDER: S-EPMC5390980 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Polycystic kidney disease (PKD) is one of the leading causes of end-stage renal disease in humans and is characterized by progressive cyst formation, renal enlargement, and abnormal tubular development. Currently, there is no cure for PKD. Although a number of PKD genes have been identified, their precise role in cystogenesis remains unclear. In the jcpk mouse model of PKD, mutations in the bicaudal C gene (Bicc1) are responsible for the cystic phenotype; however, the function of Bicc1 is unknown. In this study, we establish an alternative, nonmammalian zebrafish model to study the role of Bicc1 in PKD pathogenesis. Antisense morpholinos were used to evaluate loss of Bicc1 function in zebrafish. The resulting morphants were examined histologically for kidney cysts and structural abnormalities. Immunostaining and fluorescent dye injection were used to evaluate pronephric cilia and kidney morphogenesis. Knockdown of zebrafish Bicc1 expression resulted in the formation of kidney cysts; however, defects in kidney structure or pronephric cilia were not observed. Importantly, expression of mouse Bicc1 rescues the cystic phenotype of the morphants. These results demonstrate that the function of Bicc1 in the kidney is evolutionarily conserved, thus supporting the use of zebrafish as an alternative in vivo model to study the role of mammalian Bicc1 in renal cyst formation.
| S-EPMC2855035 | biostudies-literature
Project description:BackgroundPolycystic kidney disease with hyperinsulinaemic hypoglycaemia (HIPKD) is a recently described disease caused by a single nucleotide variant, c.-167G>T, in the promoter region of PMM2 (encoding phosphomannomutase 2), either in homozygosity or compound heterozygosity with a pathogenic coding variant in trans. All patients identified so far are of European descent, suggesting a possible founder effect.MethodsWe generated high density genotyping data from 11 patients from seven unrelated families, and used this information to identify a common haplotype that included the promoter variant. We estimated the age of the promoter mutation with DMLE+ software, using demographic parameters corresponding to the European population.ResultsAll patients shared a 0.312 Mb haplotype which was absent in 503 European controls available in the 1000 Genomes Project. The age of this mutation was estimated as 105-110 generations, indicating its occurrence around 600 BC, a time of intense migration, which might explain the presence of the same mutations in Europeans around the globe.ConclusionThe shared unique haplotype among seemingly unrelated patients is consistent with a founder effect in Europeans.
| S-EPMC8683636 | biostudies-literature
Project description:The pathogenetic mechanisms underlying autosomal dominant polycystic kidney disease (ADPKD) remain to be elucidated. While there is evidence that Pkd1 gene haploinsufficiency and loss of heterozygosity can cause cyst formation in mice, paradoxically high levels of Pkd1 expression have been detected in the kidneys of ADPKD patients. To determine whether Pkd1 gain of function can be a pathogenetic process, a Pkd1 bacterial artificial chromosome (Pkd1-BAC) was modified by homologous recombination to solely target a sustained Pkd1 expression preferentially to the adult kidney. Several transgenic lines were generated that specifically overexpressed the Pkd1 transgene in the kidneys 2- to 15-fold over Pkd1 endogenous levels. All transgenic mice reproducibly developed tubular and glomerular cysts and renal insufficiency and died of renal failure. This model demonstrates that overexpression of wild-type Pkd1 alone is sufficient to trigger cystogenesis resembling human ADPKD. Our results also uncovered a striking increased renal c-myc expression in mice from all transgenic lines, indicating that c-myc is a critical in vivo downstream effector of Pkd1 molecular pathways. This study not only produced an invaluable and first PKD model to evaluate molecular pathogenesis and therapies but also provides evidence that gain of function could be a pathogenetic mechanism in ADPKD.
| S-EPMC1367205 | biostudies-literature
Project description:BackgroundA major difference between autosomal recessive polycystic kidney disease (ARPKD) and autosomal dominant polycystic kidney disease (ADPKD) lies in the pattern of inheritance, and the resultant timing and focality of cyst formation. In both diseases, cysts form in the kidney and liver as a consequence of the cellular recessive genotype of the respective disease gene, but this occurs by germline inheritance in ARPKD and somatic second hit mutations to the one normal allele in ADPKD. The fibrocystic liver phenotype in ARPKD is attributed to abnormal ductal plate formation because of the absence of PKHD1 expression during embryogenesis and organ development. The finding of polycystic liver disease in a subset of adult PKHD1 heterozygous carriers raises the question of whether somatic second hit mutations in PKHD1 in adults may also result in bile duct-derived cyst formation.MethodsWe used an adult-inducible Pkhd1 mouse model to examine whether Pkhd1 has a functional role in maintaining bile duct homeostasis after normal liver development.ResultsInactivation of Pkhd1 beginning at 4 weeks of age resulted in a polycystic liver phenotype with minimal fibrosis at 17 weeks. Increased biliary epithelium, which lines these liver cysts, was most pronounced in female mice. We assessed genetic interaction of this phenotype with either reduced or increased copies of Pkd1, and found no significant effects on the Pkhd1 phenotype in the liver or kidney from altered Pkd1 expression.ConclusionsSomatic adult inactivation of Pkhd1 results in a polycystic liver phenotype. Pkhd1 is a required gene in adulthood for biliary structural homeostasis independent of Pkd1. This suggests that PKHD1 heterozygous carrier patients can develop liver cysts after somatic mutations in their normal copy of PKHD1.
| S-EPMC7861569 | biostudies-literature
Project description:Autosomal-dominant polycystic kidney disease (ADPKD) is characterized by bilateral kidney cysts that ultimately lead to end-stage kidney disease. While the major causative genes of ADPKD are PKD1 and PKD2, other genes are also thought to be involved. Fifty ADPKD patients were analyzed by exome sequencing or multiplex ligation-dependent probe amplification (MLPA), followed by long polymerase chain reaction and Sanger sequencing. Variants in PKD1 or PKD2 or GANAB were detected in 35 patients (70%). Exome sequencing identified 24, 7, and 1 variants in PKD1, PKD2, and GANAB, respectively, in 30 patients. MLPA analyses identified large deletions in PKD1 in three patients and PKD2 in two patients. We searched 90 cyst-associated genes in 15 patients who were negative by exome sequencing and MLPA analyses, and identified 17 rare variants. Four of them were considered "likely pathogenic" or "pathogenic" variants according to the American College of Medical Genetics and Genomics guidelines. Of the 11 patients without a family history, four, two, and four variants were found in PKD1, PKD2, and other genes, respectively, while no causative gene was identified in one patient. While the pathogenicity of each variant in these genes should be carefully assessed, a comprehensive genetic analysis may be useful in cases of atypical ADPKD.
| S-EPMC9956291 | biostudies-literature
Project description:Dietary restriction promotes health and longevity across taxa through mechanisms that are largely unknown. Here, we show that acute yeast restriction significantly improves the ability of adult female Drosophila melanogaster to resist pathogenic bacterial infections through an immune pathway involving downregulation of target of rapamycin (TOR) signaling, which stabilizes the transcription factor Myc by increasing the steady-state level of its phosphorylated forms through decreased activity of protein phosphatase 2A. Upregulation of Myc through genetic and pharmacological means mimicked the effects of yeast restriction in fully fed flies, identifying Myc as a pro-immune molecule. Short-term dietary or pharmacological interventions that modulate TOR-PP2A-Myc signaling may provide an effective method to enhance immunity in vulnerable human populations.
| S-EPMC5560489 | biostudies-literature
Project description:BackgroundGenetic studies in Drosophila melanogaster reveal an important role for Myc in controlling growth. Similar studies have also shown how components of the insulin and target of rapamycin (TOR) pathways are key regulators of growth. Despite a few suggestions that Myc transcriptional activity lies downstream of these pathways, a molecular mechanism linking these signaling pathways to Myc has not been clearly described. Using biochemical and genetic approaches we tried to identify novel mechanisms that control Myc activity upon activation of insulin and TOR signaling pathways.ResultsOur biochemical studies show that insulin induces Myc protein accumulation in Drosophila S2 cells, which correlates with a decrease in the activity of glycogen synthase kinase 3-beta (GSK3β ) a kinase that is responsible for Myc protein degradation. Induction of Myc by insulin is inhibited by the presence of the TOR inhibitor rapamycin, suggesting that insulin-induced Myc protein accumulation depends on the activation of TOR complex 1. Treatment with amino acids that directly activate the TOR pathway results in Myc protein accumulation, which also depends on the ability of S6K kinase to inhibit GSK3β activity. Myc upregulation by insulin and TOR pathways is a mechanism conserved in cells from the wing imaginal disc, where expression of Dp110 and Rheb also induces Myc protein accumulation, while inhibition of insulin and TOR pathways result in the opposite effect. Our functional analysis, aimed at quantifying the relative contribution of Myc to ommatidial growth downstream of insulin and TOR pathways, revealed that Myc activity is necessary to sustain the proliferation of cells from the ommatidia upon Dp110 expression, while its contribution downstream of TOR is significant to control the size of the ommatidia.ConclusionsOur study presents novel evidence that Myc activity acts downstream of insulin and TOR pathways to control growth in Drosophila. At the biochemical level we found that both these pathways converge at GSK3β to control Myc protein stability, while our genetic analysis shows that insulin and TOR pathways have different requirements for Myc activity during development of the eye, suggesting that Myc might be differentially induced by these pathways during growth or proliferation of cells that make up the ommatidia.
| S-EPMC3235970 | biostudies-literature
Project description:Autosomal-dominant polycystic kidney disease (ADPKD) is the most common genetic renal disease, primarily caused by germline mutation of PKD1 or PKD2, leading to end-stage renal disease. The Hippo signaling pathway regulates organ growth and cell proliferation. Herein, we demonstrate the regulatory mechanism of cystogenesis in ADPKD by transcriptional coactivator with PDZ-binding motif (TAZ), a Hippo signaling effector. TAZ was highly expressed around the renal cyst-lining epithelial cells of Pkd1-deficient mice. Loss of Taz in Pkd1-deficient mice reduced cyst formation. In wild type, TAZ interacted with PKD1, which inactivated β-catenin. In contrast, in PKD1-deficient cells, TAZ interacted with AXIN1, thus increasing β-catenin activity. Interaction of TAZ with AXIN1 in PKD1-deficient cells resulted in nuclear accumulation of TAZ together with β-catenin, which up-regulated c-MYC expression. Our findings suggest that the PKD1-TAZ-Wnt-β-catenin-c-MYC signaling axis plays a critical role in cystogenesis and might be a potential therapeutic target against ADPKD.
| S-EPMC7682393 | biostudies-literature
Project description:BackgroundNutrient availability is a key determinant of eukaryotic cell growth. In unicellular organisms many signaling and transcriptional networks link nutrient availability to the expression of metabolic genes required for growth. However, less is known about the corresponding mechanisms that operate in metazoans. We used gene expression profiling to explore this issue in developing Drosophila larvae.ResultsWe found that starvation for dietary amino acids (AA's) leads to dynamic changes in transcript levels of many metabolic genes. The conserved insulin/PI3K and TOR signaling pathways mediate nutrition-dependent growth in Drosophila and other animals. We found that many AA starvation-responsive transcripts were also altered in TOR mutants. In contrast, although PI3K overexpression induced robust changes in the expression of many metabolic genes, these changes showed limited overlap with the AA starvation expression profile. We did however identify a strong overlap between genes regulated by the transcription factor, Myc, and AA starvation-responsive genes, particularly those involved in ribosome biogenesis, protein synthesis and mitochondrial function. The consensus Myc DNA binding site is enriched in promoters of these AA starvation genes, and we found that Myc overexpression could bypass dietary AA to induce expression of these genes. We also identified another sequence motif (Motif 1) enriched in the promoters of AA starvation-responsive genes. We showed that Motif 1 was both necessary and sufficient to mediate transcriptional responses to dietary AA in larvae.ConclusionsOur data suggest that many of the transcriptional effects of amino acids are mediated via signaling through the TOR pathway in Drosophila larvae. We also find that these transcriptional effects are mediated through at least two mechanisms: via the transcription factor Myc, and via the Motif 1 cis-regulatory element. These studies begin to elucidate a nutrient-responsive signaling network that controls metabolic gene transcription in Drosophila.
| S-EPMC2827378 | biostudies-literature
Project description:BACKGROUND:Autosomal dominant polycystic kidney disease (ADPKD) is the most common monogenic renal disorder in humans, affecting 1 in 400 to 1000 individuals. Mutations PKD1 (which accounts for 85% of ADPKD and produces polycystin-1) and PKD2 (produces polycystin-2) are responsible for this disease. These two polycystins are critical for maintaining normal renal tubular structures during kidney development. CASE PRESENTATION:We performed genetic analysis on a family with ADPKD. DNA samples extracted from ADPKD patient blood were subject to targeted Next generation sequencing for human a panel of renal disease-related genes. A splicing mutation, c.2854-3C?>?G (also known as IVS11-3C?>?G), in the PKD1 gene was found in the 3 patients from the family, but was not found in four unaffected relatives and 100 normal control samples. Reverse transcription-PCR (RT-PCR) was performed to analyse the relative mRNA expression in the patient samples. mRNA sequencing showed that 29 bases inserted into the 3'-end of exon 11 in the PKD1 gene lead to a frameshift mutation. CONCLUSIONS:The PKD1 c.2854-3C?>?G mutation leads to a frameshift mutation during translation of the polycystin-1 protein, which eventually led to ADPKD in the Chinese family.
| S-EPMC6234645 | biostudies-literature