Nephronophthisis-associated FBW7 mediates cyst-dependent decline of renal function in ADPKD.

Nephronophthisis (NPHP) and autosomal dominant Polycystic Kidney Disease (ADPKD) are two genetically distinct forms of Polycystic Kidney Disease (PKD), yet both diseases present with kidney cysts and a gradual decline in renal function. Prevailing dogma in PKD is that changes in kidney architecture account for the decline in kidney function, but the molecular/cellular basis of such coupling is unknown. To address this question, we induced a form of proteome reprogramming by deleting Fbxw7 encoding FBW7, the recognition receptor of the SCF FBW7 E3 ubiquitin ligase in different segments of the kidney tubular system. Deletion of Fbxw7 in the medulla led to a juvenile-adult NPHP-like phenotype, where the decline in renal function was due to SOX9-mediated interstitial fibrosis rather than cystogenesis. In contrast, the decline of renal function in ADPKD is coupled to cystic expansion via the abnormal accumulation of FBW7 in the proximal tubules and other cell types in the renal cortex. We propose that FBW7 functions at the apex of a protein network that determines renal function in ADPKD by sensing architectural changes induced by cystic expansion.

Gold Nanoparticles Inhibit Macropinocytosis by Decreasing KRAS Activation.

The RAS-transformed cells utilize macropinocytosis to acquire amino acids to support their uncontrolled growth. However, targeting RAS to inhibit macropinocytosis remains a challenge. Here, we report that gold nanoparticles (GNP) inhibit macropinocytosis by decreasing KRAS activation. Using surface-modified and unmodified GNP, we showed that unmodified GNP specifically sequestered both wild-type and mutant KRAS and inhibited its activation, irrespective of growth factor stimulation, while surface-passivated GNP had no effect. Alteration of KRAS activation is reflected on downstream signaling cascades, macropinocytosis and tumor cell growth in vitro, and two independent preclinical human xenograft models of pancreatic cancer in vivo. The current study demonstrates NP-mediated inhibition of macropinocytosis and KRAS activation and provides translational opportunities to inhibit tumor growth in a number of cancers where activation of KRAS plays a major role.

Inhibition of complement C5 protects against organ failure and reduces mortality in a baboon model of Escherichia coli sepsis.

Bacterial sepsis triggers robust activation of the complement system with subsequent generation of anaphylatoxins (C3a, C5a) and the terminal complement complex (TCC) that together contribute to organ failure and death. Here we tested the effect of RA101295, a 2-kDa macrocyclic peptide inhibitor of C5 cleavage, using in vitro whole-blood assays and an in vivo baboon model of Escherichia coli sepsis. RA101295 strongly inhibited E. coli-induced complement activation both in vitro and in vivo by blocking the generation of C5a and the soluble form of TCC, sC5b-9. RA101295 reduced the E. coli-induced "oxidative burst," as well as leukocyte activation, without affecting host phagocytosis of E. coli RA101295 treatment reduced plasma LPS content in E. coli-challenged baboons, implying reduced complement-mediated bacteriolysis, whereas treated animals showed slightly improved bacterial clearance during the bacteremic stage compared with controls. Treatment with RA101295 also improved consumptive coagulopathy and preserved endothelial anticoagulant and vascular barrier functions. RA101295 abolished sepsis-induced surges in proinflammatory cytokines and attenuated systemic circulatory and febrile responses, likely reflecting decreased systemic levels of LPS and C5a. Overall, RA101295 treatment was associated with significant organ protection and markedly reduced mortality compared with nontreated controls (four of five animals survived in a 100% lethal model). We therefore conclude that inhibition of C5 cleavage during the bacteremic stage of sepsis could be an important therapeutic approach to prevent sepsis-induced inflammation, consumptive coagulopathy, and subsequent organ failure and death.