Central to cellular metabolism and cell proliferation are highly conserved signalling pathways controlled by mammalian target of rapamycin (mTOR) and AMP-activated protein kinase (AMPK) 1 , 2 , dysregulation of which are implicated in pathogenesis of major human diseases such as cancer and type 2 diabetes. AMPK pathways leading to reduced cell proliferation are well established and, in part, act through inhibition of TOR complex-1 (TORC1) activity. Here we demonstrate reciprocal regulation, specifically that TORC1 directly down-regulates AMPK signalling by phosphorylating the evolutionarily conserved residue Ser367 in the fission yeast AMPK catalytic subunit Ssp2, and AMPK α1Ser347/α2Ser345 in the mammalian homologs, which is associated with reduced phosphorylation of activation loop Thr172. Genetic or pharmacological inhibition of TORC1 signalling led to AMPK activation in the absence of increased AMP:ATP ratios; under nutrient stress conditions this was associated with growth limitation in both yeast and human cell cultures. Our findings reveal fundamental, bi-directional regulation between two major metabolic signalling networks and uncover new opportunity for cancer treatment strategies aimed at suppressing cell proliferation in the nutrient-poor tumor microenvironment.

Maternal undernutrition around the time of conception is associated with an increased risk of insulin resistance in adulthood. We determined the effect of maternal undernutrition in the periconceptional period (PCUN, i.e., 60 days prior to 6 days after conception) and the preimplantation period (PIUN, i.e., 0-6 days after conception) on mRNA expression and protein abundance of key insulin-signaling molecules as well as the global microRNA expression in quadriceps muscle of singleton and twin fetal sheep in late gestation. In singleton fetuses, exposure to PCUN resulted in lower protein abundance of PIK3CB (P < 0.01), PRKCZ (P < 0.05), and pPRKCZ (Thr410) (P < 0.05) in skeletal muscle compared to controls. In PIUN singletons, there was a higher protein abundance of IRS1 (P < 0.05), PDPK1 (P < 0.05), and SLC2A4 (P < 0.05) compared to controls. In twins, PCUN resulted in higher protein abundance of IRS1 (P < 0.05), AKT2 (P < 0.05), PDPK1 (P < 0.05), and PRKCZ (P < 0.001), while PIUN also resulted in higher protein abundance of IRS1 (P < 0.05), PRKCZ (P < 0.001), and SLC2A4 (P < 0.05) in fetal muscle compared to controls. There were specific patterns of the types and direction of changes in the expression of 22 microRNAs in skeletal muscle after exposure to PCUN or PIUN and clear differences in these patterns between singleton and twin pregnancies. These findings provide evidence that maternal undernutrition around the time of conception induces changes in the expression of microRNAs, which may play a role in altering the abundance of the key insulin-signaling molecules in skeletal muscle and in the association between PCUN undernutrition and insulin resistance in adult life.

There is a need to understand the separate or interdependent contributions of maternal prepregnancy BMI, gestational weight gain, glycaemic control, and macronutrient intake on the metabolic outcomes for the offspring. Experimental studies highlight that there may be separate influences of maternal obesity during the periconceptional period and late gestation on the adiposity of the offspring. While a period of dietary restriction in obese mothers may ablate the programming of obesity, it is associated with an activation of the stress axis in the offspring. Thus, maternal obesity may result in epigenetic changes which predict the need for efficient fat storage in postnatal life, while maternal weight loss may lead to epigenetic changes which predict later adversity. Thus, development of dietary interventions for obese mothers during the periconceptional period requires a greater evidence base which allows the effective weighing up of the metabolic benefits and costs for the offspring.

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-This study aimed to determine whether exposure of the oocyte and/or embryo to maternal undernutrition results in the later programming of insulin action in the liver and factors regulating gluconeogenesis. To do this, we collect livers from singleton and twin fetal sheep that were exposed to periconceptional (PCUN; Ϫ60 to 7 days) or preimplantation (PIUN; 0 -7 days) undernutrition at 136 -138 days of gestation (term ϭ 150 days). The mRNA and protein abundance of insulin signaling and gluconeogenic factors were then quantified using qRT-PCR and Western blotting, respectively, and global microRNA expression was quantified using deep sequencing methodology. We found that hepatic PEPCK-C mRNA (P Ͻ 0.01) and protein abundance and the protein abundance of IRS-1 (P Ͻ 0.01), p110␤ (P Ͻ 0.05), PTEN (P Ͻ 0.05), CREB (P Ͻ 0.01), and pCREB (Ser 133 ; P Ͻ 0.05) were decreased in the PCUN and PIUN singletons. In contrast, hepatic protein abundance of IRS-1 (P Ͻ 0.01), p85 (P Ͻ 0.01), p110␤ (P Ͻ 0.001), PTEN (P Ͻ 0.01), Akt2 (P Ͻ 0.01), p-Akt (Ser 473 ; P Ͻ 0.01), and p-FOXO-1 (Thr24) (P Ͻ 0.01) was increased in twins. There was a decrease in PEPCK-C mRNA (P Ͻ 0.01) but, paradoxically, an increase in PEPCK-C protein (P Ͻ 0.001) in twins. Both PCUN and PIUN altered the hepatic expression of 23 specific microRNAs. We propose that the differential impact of maternal undernutrition in the presence of one or two embryos on mRNAs and proteins involved in the insulin signaling and gluconeogenesis is explained by changes in the expression of a suite of specific candidate microRNAs.pregnancy; nutrition; fetus; epigenetic IT HAS BEEN DEMONSTRATED in a range of epidemiological and experimental studies that exposure of the oocyte, embryo, or fetus to a range of environmental stressors, including poor maternal nutrition, results in poor metabolic and cardiovascular outcomes in postnatal life (8,9,13,22,25,41,42,53,56). In sheep, maternal undernutrition from 60 days before to 30 days after conception resulted in an impairment of the insulin and glucose responses to a glucose tolerance test at 10 mo after birth (49). The effects of exposure to maternal undernutrition during early gestation were also more pronounced in singleton than in twin offspring. However, it is not known whether exposure to maternal undernutrition limited to around the time of conception alone is sufficient to program changes in the insulin-signaling pathway in tissues of metabolic importance such as the liver or whether there is a differential impact of maternal undernutrition in the periconceptional period in singletons and twins.Insulin acts through the insulin receptor (IR), which is stabilized by caveolin-1 (Cav-1), resulting in a series of activations by phosphorylation of the insulin receptor substrate-1 (IRS-1) or -2 (IRS-2), phosphatidylinositol 3-kinase (PI3K), and conversion of phosphatidylinositol 4,5-bisphosphate (PIP2) to phosphatidylinositol 3,4,5-trisphosphate (PIP3). Conversion of PIP2 to PIP3 is negatively regulated by phosphatase and tensin homolog (...