Browsing by Subject "Autosomal dominant polycystic kidney disease (ADPKD)"

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    A novel 9 kDa phosphoprotein is a component of the primary cilium and interacts with polycystin-1
    (Springer Nature, 2012-11-16) Osborn, D. P. S.; Boucher, C.; Wilson, P.; Gattone, V.; Beales, P. L.; Drummond, I.; Sandford, R.; Anatomy, Cell Biology and Physiology, School of Medicine
    Polycystin-1 (PKD1) forms a mechanosensitive cation channel complex with polycystin-2 (PKD2) in the primary cilium. Functional defects in this complex caused by mutation of PKD1 and PKD2 result in autosomal dominant polycystic kidney disease (ADPKD). The mechanisms by which this complex regulates normal cell physiology remain elusive. In particular the proteins that interact directly with polycystin-1 remain poorly characterised. A Y-2H screen using the C-terminus of polycystin-1 as bait identified a novel binding partner that we have called PIP9 (polycystin interacting protein 9). PIP9 is evolutionary conserved, ubiquitously expressed, and predicted to be a 9KDa phosphoprotein containing a single coiled-coil domain that interacts with the coiled-coil domain of PC-1. Specific anti-PIP9 antisera confirmed the widespread and developmentally regulated expression of PIP9 and identified phosphorylated isoforms. PIP9 co-localised to the renal primary cilium with PC1 and immuno-EM studies revealed localisation to IFT particles. Knockdown of zPip9, using morpholino oligonucleotides, resulted in developmental defects in gastrulation movements. In addition, evidence of cell detachment was observed, common to the phenotype described for double bbs4;bbs10 morphant zebrafish which suggests pip9 may act in the same genetic pathway. zpip9 morphants also displayed variable head and eye degeneration, including coloboma and hydrocephalus, pronephric cysts and shortening of the body axis. Loss of Pip9 function in mice is lethal before embryonic day E11.5. This preliminary analysis suggests that PIP9 plays a central role in mediating polycystin-1 dependant signalling.
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    Renal Cyst Fluid From Human Polycystic Kidney Disease Patients Stimulates Cl- Transport: Active Factor and Cl- Channels
    (Office of the Vice Chancellor for Research, 2011-04-08) Blazer-Yost, Bonnie L.; Blacklock, Brenda; Bacallao, Robert L.; Gattone, Vincent H.
    Autosomal dominant polycystic kidney disease (ADPKD) is characterized by the slow growth of fluid-filled cysts predominately in the kidney and in liver bile ducts. The factors involved in modifying the rate of cyst growth through epithelial proliferation or secretion are critical to understanding the progression of the disease. In addition, elucidation of mechanisms that potentiate the normal progression to renal failure will provide the basis for therapeutic intervention. Of note are the observations that the decline in renal function in middle age is precipitous and that renal injury results in an exacerbation of cyst growth. Using electrophysiological and biochemical techniques, we identified LPA (lysophosphatic acid) as a component of cyst fluid that stimulates secretory Cl- transport via two anion channels, CFTR and TMEM16a, in the mpkCCDcl4 model of renal principal cells. The LPA effect is manifested through receptors located on the basolateral membrane of polarized renal cells resulting in stimulation of channel activity in the apical membrane. Concentrations of LPA measured in ADPKD cyst fluid and in normal serum are sufficient to maximally stimulate ion transport. Thus, cyst fluid seepage into the interstitial space and/or leakage of vascular LPA are capable of stimulating epithelial cell secretion resulting in cyst enlargement. Research Support: IUPUI Membrane Biosciences Signature Center Grant
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    Virtual-tissue computer simulations define the roles of cell adhesion and proliferation in the onset of kidney cystic disease
    (The American Society for Cell Biology, 2016-11-07) Belmonte, Julio M.; Clendenon, Sherry G.; Oliveira, Guilherme M.; Swat, Maciej H.; Greene, Evan V.; Jeyaraman, Srividhya; Glazier, James A.; Bacallao, Robert L.; Department of Medicine, IU School of Medicine
    In autosomal dominant polycystic kidney disease (ADPKD), cysts accumulate and progressively impair renal function. Mutations in PKD1 and PKD2 genes are causally linked to ADPKD, but how these mutations drive cell behaviors that underlie ADPKD pathogenesis is unknown. Human ADPKD cysts frequently express cadherin-8 (cad8), and expression of cad8 ectopically in vitro suffices to initiate cystogenesis. To explore cell behavioral mechanisms of cad8-driven cyst initiation, we developed a virtual-tissue computer model. Our simulations predicted that either reduced cell-cell adhesion or reduced contact inhibition of proliferation triggers cyst induction. To reproduce the full range of cyst morphologies observed in vivo, changes in both cell adhesion and proliferation are required. However, only loss-of-adhesion simulations produced morphologies matching in vitro cad8-induced cysts. Conversely, the saccular cysts described by others arise predominantly by decreased contact inhibition, that is, increased proliferation. In vitro experiments confirmed that cell-cell adhesion was reduced and proliferation was increased by ectopic cad8 expression. We conclude that adhesion loss due to cadherin type switching in ADPKD suffices to drive cystogenesis. Thus, control of cadherin type switching provides a new target for therapeutic intervention.