Discovery of small molecule isozyme non-specific inhibitors of mammalian acetyl-CoA carboxylase 1 and 2

Screening Pfizer’s compound library resulted in the identification of weak acetyl-CoA carboxylase inhibitors, from which were obtained rACC1 CT-domain co-crystal structures. Utilizing HTS hits and structure-based drug discovery, a more rigid inhibitor was designed and led to the discovery of sub-micromolar, spirochromanone non-specific ACC inhibitors. Low nanomolar, non-specific ACC-isozyme inhibitors that exhibited good rat pharmacokinetics were obtained from this chemotype.     

The ubiquitin ligase NEDD4-2/NEDD4L regulates both sodium homeostasis and fibrotic signaling to prevent end-stage renal disease

Kidney disease progression can be affected by Na⁺ abundance. A key regulator of Na⁺ homeostasis is the ubiquitin ligase NEDD4-2 and its deficiency leads to increased Na⁺ transport activity and salt-sensitive progressive kidney damage. However, the mechanisms responsible for high Na⁺ induced damage remain poorly understood. Here we show that a high Na⁺ diet compromised kidney function in Nedd4-2-deficient mice, indicative of progression toward end-stage renal disease. Injury was characterized by enhanced tubule dilation and extracellular matrix accumulation, together with sustained activation of both Wnt/β-catenin and TGF-β signaling. Nedd4-2 knockout in cortical collecting duct cells also activated these pathways and led to epithelial–mesenchymal transition. Furthermore, low dietary Na⁺ rescued kidney disease in Nedd4-2-deficient mice and silenced Wnt/β-catenin and TGF-β signaling. Our study reveals the important role of NEDD4-2-dependent ubiquitination in Na⁺ homeostasis and protecting against aberrant Wnt/β-catenin/TGF-β signaling in progressive kidney disease.Subject terms: Stress signalling, End-stage renal disease     

Inhibition of liver metastases in murine colon adenocarcinoma by liposomes containing human C-reactive protein or crude lymphokine

Previous studies from our laboratory have shown that liposomes containing LYNK or CRP inhibit lung metastases in mice bearing the malignant fibrosarcoma, T241. We have now extended these observations to the murine colon adenocarcinoma (MCA-38), which metastasizes to the liver. MCA-38 tumor cells (1 X 10(6)) were implanted in the wall of the cecum by orthotopic transplantation. Three-hundred twenty-six mice bearing such tumors were divided into four treatment groups as follows: (1) no treatment (2) liposomes containing control medium (3) liposomes containing LYNK, and (4) liposomes containing CRP. Treatment was started from day 2, day 18, or 34 after tumor implantation and it was administered on 3 days per week. Each treatment, given parenterally, consisted of 4 mumol liposomes (PS-PC, 1:1) containing the appropriate agents. Mice receiving liposomes containing LYNK or CRP had significantly fewer and smaller liver metastases (25%-28%), than those in the two control groups (53%-54%). Also, a significantly better survival was noted in the two treated groups than in the two control groups. The most likely mechanism of tumor inhibition appears to be through macrophage activation. In the Winn tumor neutralization test, peritoneal macrophages harvested from normal mice 24 h after a single injection of liposomes (2.5 mumol) containing LYNK or CRP markedly inhibited tumor growth when a mixture of effector-target cells (40 : 1) was injected in the footpad. These studies further confirm the suggested role of CRP as an 'immunomodulator' or 'biological response modifier' in yet another tumor system.     

Phosphorylation by Aurora B kinase regulates caspase-2 activity and function

Mitotic catastrophe (MC) is an important oncosuppressive mechanism that serves to eliminate cells that become polyploid or aneuploid due to aberrant mitosis. Previous studies have demonstrated that the activation and catalytic function of caspase-2 are key steps in MC to trigger apoptosis and/or cell cycle arrest of mitotically defective cells. However, the molecular mechanisms that regulate caspase-2 activation and its function are unclear. Here, we identify six new phosphorylation sites in caspase-2 and show that a key mitotic kinase, Aurora B kinase (AURKB), phosphorylates caspase-2 at the highly conserved residue S384. We demonstrate that phosphorylation at S384 blocks caspase-2 catalytic activity and apoptosis function in response to mitotic insults, without affecting caspase-2 dimerisation. Moreover, molecular modelling suggests that phosphorylation at S384 may affect substrate binding by caspase-2. We propose that caspase-2 S384 phosphorylation by AURKB is a key mechanism that controls caspase-2 activation during mitosis.Subject terms: Proteases, Proteolysis