Ataxia telangiectasia mutated impacts insulin-like growth factor 1 signalling in skeletal muscle.

Reports that ataxia telangiectasia mutated (ATM) is required for full activation of Akt raise the hypothesis that ATM plays a role in insulin-like growth factor 1 (IGF-1) signalling through the Akt/mammalian target of rapamycin (mTOR) pathway. Differentiated C2C12 cells harbouring either ATM-targeting short hairpin RNA (shRNA) or non-targeting shRNA and myotubes from a C2C12 lineage previously exposed to empty vector lentivirus were incubated in the presence or absence of 10 nm IGF-1 followed by Western blot analysis. Parallel experiments were performed in isolated soleus muscles from mice expressing only one functional ATM allele (ATM(+/-)) compared with muscles from wild-type (ATM(+/+)) mice. Insulin-like growth factor 1 increased phosphorylation of Akt S473, Akt T308 and p70 S6 kinase (S6K) in myotubes expressing non-targeting shRNA and in empty vector controls, but the IGF-1 effects were significantly reduced in myotubes with shRNA-mediated ATM knockdown. Likewise, IGF-1-stimulated phosphorylation of Akt S473, Akt T308, mTOR and S6K was lower in isolated soleus muscles from ATM(+/-) mice compared with muscles from ATM(+/+) mice. The ATM inhibitor KU55933 prevented stimulation of S6K phosphorylation in C2C12 myotubes exposed to IGF-1, suggesting that decreased IGF-1 action is not limited to chronic conditions of decreased ATM function. Stimulation of insulin receptor substrate 1 tyrosine 612 phosphorylation by IGF-1 was unaffected by ATM deficiency, though IGF-1 phosphatidylinositol 3-kinase activity tended to be lower in muscle from ATM haploinsufficient mice compared with wild-type muscle. The data suggest that ATM is a modulator of IGF-1 signalling downstream of insulin receptor substrate 1 in skeletal muscle.

Fabrication and characterization of a water purification system using activated carbon and graphene nanoplatelets: Toward the development of a nanofiltration matrix.

Researchers are trying to tackle water scarcity in numerous ways. One of those ways is the use of nanotechnology in water processing and purification. The current work involves the fabrication and optimization of activated carbon and graphene-based hybrid water purification system. Five different concentrations of methylene blue and deionized water (DI) dye solutions were used, and they were filtered in three different cycles. For the potential usage on the consumer side, a small-scale, low-cost water filter is developed using activated carbon, commercial filter paper, and graphene nanoplatelets. The filter paper is used to hold mixtures of the activated carbon and graphene nanoplatelets within the water filter. The conductivity, TDS, and pH are measured for the feed water and the processed water using an Oakton EcoTestr and Apera Instruments PH60 Premium Pocket pH meter, respectively. A UV-Vis spectrometer is used to measure the absorption of solutions. The distribution and adsorption of the dye particles were observed by scanning electron microscopy. PRACTITIONER POINTS: These results show the effectiveness of the system in the removal of dye particles above a given particle size. The concentration of the dye solution decreased after every cycle. The GnPs filtration system more effectively dye particles as compared to the filtration system containing only Activated carbon. UV-Vis spectroscopy results showed that the methylene blue dye particles decreased after every cycle. This research can open a broad area of projects toward waste/wastewater practice for particles above a certain particle size.

A role for AMPK in increased insulin action after serum starvation.

Serum starvation is a common cell culture procedure for increasing cellular response to insulin, though the mechanism for the serum starvation effect is not understood. We hypothesized that factors known to potentiate insulin action [e.g., AMP-activated protein kinase (AMPK) and p38] or to be involved in insulin signaling leading to glucose transport [e.g., Akt, PKCζ, AS160, and ataxia telangiectasia mutated (ATM)] would be phosphorylated during serum starvation and would be responsible for increased insulin action after serum starvation. L6 myotubes were incubated in serum-containing or serum-free medium for 3 h. Levels of phosphorylated AMPK, Akt, and ATM were greater in serum-starved cells than in control cells. Serum starvation did not affect p38, PKCζ, or AS160 phosphorylation or insulin-stimulated Akt or AS160 phosphorylation. Insulin had no effect on glucose transport in control cells but caused an increase in glucose uptake for serum-starved cells that was preventable by compound C (an AMPK inhibitor), by expression of dominant negative AMPK (AMPK-DN), and by KU55933 (an ATM inhibitor). ATM protein levels increased during serum starvation, and this increase in ATM was prevented by compound C and AMPK-DN. Thus, it appears that AMPK is required for the serum starvation-related increase in insulin-stimulated glucose transport, with ATM as a possible downstream effector.