Maternal diabetes promotes mTORC1 downstream signalling in rabbit preimplantation embryos

Abstract

The mammalian target of rapamycin complex 1 (mTORC1) is known to be a central cellular nutrient sensor and master regulator of protein metabolism; therefore, it is indispensable for normal embryonic development. We showed previously in a diabetic pregnancy that embryonic mTORC1 phosphorylation is increased in case of maternal hyperglycaemia and hypoinsulinaemia. Further, the preimplantation embryo is exposed to increased L-leucine levels during a diabetic pregnancy. To understand how mTOR signalling is regulated in preimplantation embryos, we examined consequences of L-leucine and glucose stimulation on mTORC1 signalling and downstream targets in in vitro cultured preimplantation rabbit blastocysts and in vivo. High levels of L-leucine and glucose lead to higher phosphorylation of mTORC1 and its downstream target ribosomal S6 kinase 1 (S6K1) in these embryos. Further, L-leucine supplementation resulted in higher embryonic expression of genes involved in cell cycle (cyclin D1; CCND1), translation initiation (eukaryotic translation initiation factor 4E; EIF4E), amino acid transport (large neutral amino acid transporter 2; Lat2: gene SLC7A8) and proliferation (proliferating cell nuclear antigen; PCNA) in a mTORC1-dependent manner. Phosphorylation of S6K1 and expression patterns of CCND1 and EIF4E were increased in embryos from diabetic rabbits, while the expression of proliferation marker PCNA was decreased. In these embryos, protein synthesis was increased and autophagic activity was decreased. We conclude that mammalian preimplantation embryos sense changes in nutrient supply via mTORC1 signalling. Therefore, mTORC1 may be a decisive mediator of metabolic programming in a diabetic pregnancy.

Protein O-GlcNAcylation Promotes Trophoblast Differentiation at Implantation

“…Embryos are acutely sensitive to nutrient imbalances or deprivation. Signalling through adenosine monophosphate-activated kinase (AMPK) and mammalian target of rapamycin (mTOR) mediates responses to nutritive stress in embryos [ 12 , 13 ], leading to increased endocytosis and autophagy [ 14 , 15 ], altered trophoblast differentiation [ 16 ], and ultimately offspring health consequences [ 17 , 18 ]. However, unlike these pathways which transduce signals through protein phosphorylation, post-translational modification with O-linked β-N-acetylglucosamine (O-GlcNAcylation) is recognised as an important cellular response to a wide range of environmental stressors, including osmotic, oxidative, temperature and genotoxic stresses [ 19 ].…”

Impact of gestational low-protein intake on embryonic kidney microRNA expression and in the nephron progenitor cells of the male offspring fetus

“…Among the top 10 deregulated miRNAs, the study selected 7 miRNAs, which its biological targets were related to proliferation, differentiation, and cellular apoptosis processes. As could be The mammalian target of rapamycin complex 1 (mTORC1) is known to be indispensable for healthy embryonic development, has how to function to regulate the balance between growth and autophagy in physiological conditions and environmental stress (Gürke et al, 2016). It has been suggested that mTOR signaling plays a central role in the perception and response to intracellular nutrient availability (Xiang et al, 2016).…”

Glyoxalase 1 expression is downregulated in preimplantation blastocysts of diabetic rabbits

“…The mRNA from single blastocysts, embryoblasts and trophoblasts was extracted with Dynabeads ® Oligo (dT)25 (Invitrogen) and used for cDNA synthesis as described previously (Gürke et al., ). cDNAs were adjusted to total volumes of 100 μl and 80 μl for single blastocyst and embryoblasts or trophoblasts, respectively.…”