Glyoxalase 1 expression is downregulated in preimplantation blastocysts of diabetic rabbits

Elimination of apoptotic cells by non-professional embryonic phagocytes can be stimulated or inhibited by external stimuli

Active elimination of apoptotic cells is very important for maintaining homeostasis of early embryos. Recent observations on mouse blastocysts freshly isolated from healthy dams have shown that the majority of incidentally occurring apoptotic cells is eliminated by neighbouring embryonic cells. Some apoptotic cells escape phagocytosis, but the frequency of such processes usually does not exceed 10%. The aim of the current study was to evaluate whether the non-professional embryonic phagocytes can respond to experimentally induced increase in apoptosis by increasing the frequency of efferocytosis and whether their activity can be decreased by selective inhibition of specific component of efferoctosis machinery. Experiments were performed in vitro on cultured mouse blastocysts with a differentiated trophectoderm and inner cell mass and on the human trophoblast cell line Ac-1M88. Samples were assessed using fluorescence immunostaining: Apoptotic cells (TUNEL) internalised within the cytoplasm of non-professional embryonic phagocytes (phalloidin T membrane staining) were considered ingested; apoptotic cells co-localised with acidified phagosomes (LysoTracker) were considered digested. First, we tested the ability of embryonic phagocytes to respond to elevated incidence of apoptosis induced by actinomycin D (4 nM). The results showed that the increase in apoptosis was accompanied by a significant elevation of the phagocytosis and digestion of dead cells in both mouse blastocysts and human trophoblast cells. We then assessed the effect of selective inhibition of lysosomal acidification in embryonic phagocytes using a specific V-ATPase inhibitor bafilomycin A1. The results showed that the inhibitor at 0.1 and 0.2 nM was able to negatively affect the execution of both initiative and terminal phases of efferocytosis in mouse blastocysts, although the decrease was not as profound as expected. When compared to mouse trophectoderm cells, human hybrid cells displayed a very low sensitivity to bafilomycin A1. Higher concentrations of bafilomycin A1 had a more harmful impact on overall cell viability than on digestive activity. The results show that the ability of non-professional embryonic phagocytes to successfully execute all stages of efferocytosis is not limited by the frequency of apoptosis and is preserved even at elevated rates of the apoptotic process. The effectiveness of embryonic phagocytes can be partially decreased by selective inhibition of lysosomal acidification conducted via V-ATPase.

Post-Translational Modifications and Diabetes

Diabetes and its associated complications have increasingly become major challenges for global healthcare. The current therapeutic strategies involve insulin replacement therapy for type 1 diabetes (T1D) and small-molecule drugs for type 2 diabetes (T2D). Despite these advances, the complex nature of diabetes necessitates innovative clinical interventions for effective treatment and complication prevention. Accumulative evidence suggests that protein post-translational modifications (PTMs), including glycosylation, phosphorylation, acetylation, and SUMOylation, play important roles in diabetes and its pathological consequences. Therefore, the investigation of these PTMs not only sheds important light on the mechanistic regulation of diabetes but also opens new avenues for targeted therapies. Here, we offer a comprehensive overview of the role of several PTMs in diabetes, focusing on the most recent advances in understanding their functions and regulatory mechanisms. Additionally, we summarize the pharmacological interventions targeting PTMs that have advanced into clinical trials for the treatment of diabetes. Current challenges and future perspectives are also provided.

Advanced maternal age leads to changes within the insulin/IGF system and lipid metabolism in the reproductive tract and preimplantation embryo: insights from the rabbit model

Reproductive potential in women declines with age. The impact of ageing on embryo-maternal interactions is still unclear. Rabbits were used as a reproductive model to investigate maternal age-related alterations in reproductive organs and embryos on Day 6 of pregnancy. Blood, ovaries, endometrium, and blastocysts from young (16-20 weeks) and advanced maternal age phase (>108 weeks, old) rabbits were analysed at the mRNA and protein levels to investigate the insulin-like growth factor (IGF) system, lipid metabolism, and stress defence system. Older rabbits had lower numbers of embryos at Day 6 of pregnancy. Plasma insulin and IGF levels were reduced, which was accompanied by paracrine regulation of IGFs and their receptors in ovaries and endometrium. Embryos adapted to hormonal changes as indicated by reduced embryonic IGF1 and 2 levels. Aged reproductive organs increased energy generation from the degradation of fatty acids, leading to higher oxidative stress. Stress markers, including catalase, superoxide dismutase 2, and receptor for advanced glycation end products were elevated in ovaries and endometrium from aged rabbits. Embryonic fatty acid uptake and β-oxidation were increased in both embryonic compartments (embryoblast and trophoblast) in old rabbits, associated with minor changes in the oxidative and glycative stress defence systems. In summary, the insulin/IGF system, lipid metabolism, and stress defence were dysregulated in reproductive tissues of older rabbits, which is consistent with changes in embryonic metabolism and stress defence. These data highlight the crucial influence of maternal age on uterine adaptability and embryo development.

Ectopic Lipid Accumulation Correlates with Cellular Stress in Rabbit Blastocysts from Diabetic Mothers

Maternal diabetes mellitus in early pregnancy leads to hyperlipidemia in reproductive tract organs and an altered embryonic environment. To investigate the consequences on embryonic metabolism, the effect of high environmental-lipid levels was studied in rabbit blastocysts cultured with a lipid mixture in vitro and in blastocysts from diabetic, hyperlipidemic rabbits in vivo. The gene and protein expression of marker molecules involved in lipid metabolism and stress response were analyzed. In diabetic rabbits, the expression of embryoblast genes encoding carnitine palmityl transferase 1 and peroxisome proliferator-activated receptors α and γ increased, whereas trophoblast genes encoding for proteins associated with fatty acid synthesis and β-oxidation decreased. Markers for endoplasmic (activating transcription factor 4) and oxidative stress (nuclear factor erythroid 2-related factor 2) were increased in embryoblasts, while markers for cellular redox status (superoxide dismutase 2) and stress (heat shock protein 70) were increased in trophoblasts from diabetic rabbits. The observed regulation pattern in vivo was consistent with an adaptation response to the hyperlipidemic environment, suggesting that maternal lipids have an impact on the intracellular metabolism of the preimplantation embryo in diabetic pregnancy and that embryoblasts are particularly vulnerable to metabolic stress.