Amino acid modified gadofullerene protects against insulin resistance induced by oxidative stress in 3T3-L1 adipocytes

GF-Ala afforded a significant protection against insulin resistance induced by oxidative stress in 3T3-L1 adipocytes. It could reverse the increase of JNK activation and decreases of insulin-stimulated PI3K, Akt, p70S6K activation and GLUT4 translocation.

CNTO 530 functions as a potent EPO mimetic via unique sustained effects on bone marrow proerythroblast pools

Anemia as associated with numerous clinical conditions can be debilitating, but frequently can be treated via administration of epoetin-alfa, darbepoietin-alfa, or methoxy-PEG epoetin-beta. Despite the complexity of EPO-EPO receptor interactions, the development of interesting EPO mimetic peptides (EMPs) also has been possible. CNTO 530 is one such novel MIMETIBODY Fc-domain dimeric EMP fusion protein. In a mouse model, single-dose CNTO 530 (unlike epoetin-alfa or darbepoietin-alfa) bolstered red cell production for up to 1 month. In 5-fluorouracil and carboplatin-paclitaxel models, CNTO 530 also protected against anemia with unique efficiency. These actions were not fully accounted for by half-life estimates, and CNTO 530 signaling events therefore were studied. Within primary bone marrow erythroblasts, kinetics of STAT5, ERK, and AKT activation were similar for CNTO 530 and epoetin-alfa. p70S6K activation by CNTO 530, however, was selectively sustained. In vivo, CNTO 530 uniquely stimulated the enhanced formation of PODXLhighCD71high (pro)erythroblasts at frequencies multifold above epoetin-alfa or darbepoietin-alfa. CNTO 530 moreover supported the sustained expansion of a bone marrow–resident KitnegCD71highTer119neg progenitor pool. Based on these distinct erythropoietic and EPOR signaling properties, CNTO 530 holds excellent promise as a new EPO mimetic.

Inhibition of stretch-activated channels during eccentric muscle contraction attenuates p70S6K activation

Eccentric contractions (EC) are known to result in muscle hypertrophy, potentially through activation of the Akt-mammalian target of rapamycin-p70 S6 kinase (p70S6K) signaling pathway. Previous work has also demonstrated that EC result in the opening of stretch-activated channels (SAC), and inhibition of these channels resulted in an attenuation of EC-induced muscle hypertrophy. The purpose of this study was to test the hypothesis that a known intracellular pathway directly associated with muscle hypertrophy is coupled to the opening of SAC. Specifically, we measured the activation of the Akt, GSK-3β, p70S6K, and ribosomal protein S6 following a single bout of EC in the rat tibialis anterior (TA) muscle. The TA muscles performed four sets of six repetitions of EC. In vivo blockade of SAC was performed by a continuous oral treatment with streptomycin in the drinking water (4 g/l) or by intravenous infusion of 80 μmol/kg gadolinium (Gd3+). EC increased the degree of Akt and p70S6K phosphorylation in the TA muscle, whereas in animals in which SAC had been inhibited, there was a reduced capacity for EC to induce Akt or p70S6K phosphorylation. Accompanying this reduced activation of Akt and p70S6K was a failure to phosphorylate GSK-3β or S6 when SAC were inhibited. The results from these data indicate the necessity of functional SAC for the complete activation of Akt and p70S6K pathway in response to EC.