Renal Lipid Metabolism Abnormalities in Obesity and Clear Cell Renal Cell Carcinoma.

Clear cell renal cell carcinoma is the most common and deadly type of cancer affecting the kidney, and is characterized histologically by large intracellular lipid deposits. These deposits are thought to result from lipid metabolic reprogramming occurring in tumor cells, but the exact mechanisms and implications of these metabolic alterations are incompletely understood. Obesity is an independent risk factor for clear cell renal cell carcinoma, and is also associated with lipid accumulation in noncancerous epithelial cells of the proximal tubule, where clear cell renal cell carcinoma originates. This article explores the potential link between obesity-associated renal lipid metabolic disturbances and lipid metabolic reprogramming in clear cell renal cell carcinoma, and discusses potential implications for future research.

Chronic whipworm infection exacerbates Schistosoma mansoni egg-induced hepatopathology in non-human primates.

BACKGROUND: Schistosomiasis continues to inflict significant morbidity and mortality in the tropical and subtropical regions of the world. The disease endemicity overlaps with the transmission of other parasitic diseases. Despite the ubiquity of polyparasitism in tropical regions, particularly in rural communities, little is known about the impact of multiple helminth infections on disease progression. In this pilot study, we describe the influence of chronic Trichuris trichiura infection on Schistosoma mansoni egg-induced hepatopathology in infected baboons. METHODS: Baboons with or without underlying whipworm infection were challenged with S. mansoni cercariae to establish schistosomiasis. Adult S. mansoni worms were recovered by perfusion and enumerated, hepatic granulomas were quantified via light microscopy, and transcriptional profiling of tissues were completed using RNA sequencing technologies. RESULTS: Co-infection with both S. mansoni and T. trichiura resulted in higher female schistosome worm burden and significantly larger liver granuloma sizes. Systems biology analyses of peripheral blood mononuclear cells (PBMC) revealed pathways associated with increased liver damage in co-infected baboons. CONCLUSIONS: Underlying chronic whipworm infection intensified schistosome egg-induced liver pathology in infected baboons. RNA-Seq analysis provided insight into pathways associated with increased liver damage, corroborating histological findings.

Mechanism of inhibition of PP2A activity and abnormal hyperphosphorylation of tau by I2(PP2A)/SET.

Protein phosphatase-2A (PP2A) activity, which is compromised in Alzheimer disease brain, is regulated by two endogenous inhibitors, one of them being I(2)(PP2A), a 277 amino acid long protein also known as SET. Here we report that both the amino terminal fragment (I(2NTF); aa 1-175) and the carboxy terminal fragment (I(2CTF); aa 176-277) of I(2)(PP2A) inhibit PP2A by binding to its catalytic subunit PP2Ac and cause hyperphosphorylation of tau. The C-terminal acidic region in I(2CTF) and Val 92 in I(2NTF) are essential for their association with PP2Ac and inhibition of the phosphatase activity.

Involvement of I2PP2A in the abnormal hyperphosphorylation of tau and its reversal by Memantine.

The activity of protein phosphatase (PP)-2A, which regulates tau phosphorylation, is compromised in Alzheimer disease brain. Here we show that the transient transfection of PC12 cells with inhibitor-2 (I2PP2A) of PP2A causes abnormal hyperphosphorylation of tau at Ser396/Ser404 and Ser262/Ser356. This hyperphosphorylation of tau is observed only when a sub-cellular shift of I2PP2A takes place from the nucleus to the cytoplasm and is accompanied by cleavage of I2PP2A into a 20 kDa fragment. Memantine, an un-competitive inhibitor of N-methyl-D-aspartate receptors, inhibits this abnormal phosphorylation of tau and cell death and prevents the I2PP2A-induced inhibition of PP2A activity in vitro. These findings demonstrate novel mechanisms by which I2PP2A regulates the intracellular activity of PP2A and phosphorylation of tau, and by which Memantine modulates PP2A signaling and inhibits neurofibrillary degeneration.

Role of protein kinase B in Alzheimer's neurofibrillary pathology.

Protein kinase B (PKB) is an important intermediate in the phosphatidylinositol-3 kinase signaling cascade that acts to phosphorylate glycogen synthase kinase-3 (GSK-3) at its serine 9 residue, thereby inactivating it. Activated GSK-3 has been previously shown to be preferentially associated with neurofibrillary tangles (NFTs) in Alzheimer's disease (AD) brain. In the present study, we performed immunohistochemistry with an antibody to the active form of PKB in brains with different stages of neurofibrillary degeneration. We found that the amount of activated PKB (p-Thr308) increased in correlation to the progressive sequence of AT8 immunoreactivity and neurofibrillary changes assessed according to Braak's criteria. By confocal microscopy, activated PKB (p-Thr308) was found to appear in particular in neurons that are known to later develop NFTs in AD. Western blotting showed that activated PKB was increased by more than 50% in the 16,000- g supernatants of AD brains as compared with normal aged and Huntington's disease controls. This increase in PKB levels corresponded with a several-fold increase in the levels of total tau and abnormally hyperphosphorylated tau at the Tau-1 site. These studies suggest the involvement of PKB/GSK-3 signaling in Alzheimer neurofibrillary degeneration.