We report the discovery of a new monomeric peptide that reduces body weight and diabetic complications in rodent models of obesity by acting as an agonist at three key metabolically-related peptide hormone receptors: glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP) and glucagon receptors. This triple agonist demonstrates supraphysiological potency and equally aligned constituent activities at each receptor, all without cross-reactivity at other related receptors. Such balanced unimolecular triple agonism proved superior to any existing dual coagonists and best-in-class monoagonists to reduce body weight, enhance glycemic control and reverse hepatic steatosis in relevant rodent models. Various loss-of-function models, including genetic knockout, pharmacological blockade and selective chemical knockout, confirmed contributions of each constituent activity in vivo. We demonstrate that these individual constituent activities harmonize to govern the overall metabolic efficacy, which predominantly results from synergistic glucagon action to increase energy expenditure, GLP-1 action to reduce caloric intake and improve glucose control, and GIP action to potentiate the incretin effect and buffer against the diabetogenic effect of inherent glucagon activity. These preclinical studies suggest that, so far, this unimolecular, polypharmaceutical strategy has potential to be the most effective pharmacological approach to reversing obesity and related metabolic disorders.

The normal plasma protein serum amyloid P component (SAP) binds to fibrils in all types of amyloid deposits, and contributes to the pathogenesis of amyloidosis. In order to intervene in this process we have developed a drug, R-1-[6-[R-2-carboxy-pyrrolidin-1-yl]-6-oxo-hexanoyl]pyrrolidine-2-carboxylic acid, that is a competitive inhibitor of SAP binding to amyloid fibrils. This palindromic compound also crosslinks and dimerizes SAP molecules, leading to their very rapid clearance by the liver, and thus produces a marked depletion of circulating human SAP. This mechanism of drug action potently removes SAP from human amyloid deposits in the tissues and may provide a new therapeutic approach to both systemic amyloidosis and diseases associated with local amyloid, including Alzheimer's disease and type 2 diabetes.

The accumulation of ␤-amyloid peptides (A␤) into senile plaques is one of the hallmarks of Alzheimer disease. Aggregated A␤ is toxic to cells in culture and this has been considered to be the cause of neurodegeneration that occurs in the Alzheimer disease brain. The discovery of compounds that prevent A␤ toxicity may lead to a better understanding of the processes involved and ultimately to possible therapeutic drugs. Low nanomolar concentrations of A␤1-42 and the toxic fragment A␤25-35 have been demonstrated to render cells more sensitive to subsequent insults as manifested by an increased sensitivity to formazan crystals following MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) reduction. Formation of the toxic ␤-sheet conformation by A␤ peptides is increased by negatively charged membranes. Here we demonstrate that phloretin and exifone, dipolar compounds that decrease the effective negative charge of membranes, prevent association of A␤1-40 and A␤25-35 to negatively charged lipid vesicles and A␤ induced cell toxicity. These results suggest that A␤ toxicity is mediated through a nonspecific physicochemical interaction with cell membranes.␤-amyloid, the major constituent of senile plaques in Alzheimer disease patients (1) has been proposed to be the cause of the neurodegeneration that occurs in Alzheimer disease brains. A␤1-42, A␤1-40, and certain fragments, notably A␤25-35, are directly toxic to neuronal cell cultures at high micromolar concentrations (2-5). The observed cell death has been correlated with an effect of amyloid peptides on the membrane integrity as determined by lipid peroxidation (2). Furthermore, it has recently been shown that low nanomolar concentrations of A␤ peptides increase the susceptibility of the plasma membrane to additional insults (6).Substantial evidence has been provided suggesting that a crucial step for the formation of toxic A␤ is the transition of random coil to ␤-sheet conformation that is necessary for fibril aggregation. Those fibrils have been demonstrated to cause cell death (7-9). On the other hand studies with lipid vesicles demonstrated that formation of ␤-sheet structures is enhanced in the presence of negatively charged lipid vesicles (10-12). Decreasing the negative charge of a membrane may, therefore, result in a decrease in membrane association of A␤ peptides. Such a decrease in the negative charge of lipid membranes by a decrease in the membrane dipole potential has been demonstrated for phloretin, a lipophilic dipolar substance shown to decrease the membrane dipole potential (13-15).Here we demonstrate that phloretin and a structural analogue, exifone, not only reduce the association of toxic A␤ peptides with the membrane but also prevent A␤ toxicity to neuron-like PC12 cells. These results suggest that a physicochemical interaction of A␤ peptides with negatively charged membranes might be responsible for the toxic effect of A␤ to neuronal cells. MATERIALS AND METHODSMaterials. Rat PC12 pheochromocytoma cells were a gift from E. Sho...

Amyloid beta peptide (Abeta), a proteolytic fragment of the amyloid precursor protein (APP), is a major component of the plaques found in the brain of Alzheimer's disease (AD) patients. These plaques are thought to cause the observed loss of cholinergic neurons in the basal forebrain of AD patients. In these neurons, particularly those of the nucleus basalis of Meynert, an up-regulation of 75kD-neurotrophin receptor (p75NTR), a nonselective neurotrophin receptor belonging to the death receptor family, has been reported. p75NTR expression has been described to correlate with beta-amyloid sensitivity in vivo and in vitro, suggesting a possible role for p75NTR as a receptor for Abeta. Here we used a human neuroblastoma cell line to investigate the involvement of p75NTR in Abeta-induced cell death. Abeta peptides were found to bind to p75NTR resulting in activation of NFKB in a time- and dose-dependent manner. Blocking the interaction of Abeta with p75NTR using NGF or inhibition of NFKB activation by curcumin or NFKB SN50 attenuated or abolished Abeta-induced apoptotic cell death. The present results suggest that p75NTR might be a death receptor for Abeta, thus being a possible drug target for treatment of AD.