Maternal obesity during pregnancy leads to adipose tissue ER stress in mice via miR-126-mediated reduction in Lunapark

Abstract

Aims/hypothesis Levels of the microRNA (miRNA) miR-126-3p are programmed cell-autonomously in visceral adipose tissue of adult offspring born to obese female C57BL/6J mice. The spectrum of miR-126-3p targets and thus the consequences of its dysregulation for adipocyte metabolism are unknown. Therefore, the aim of the current study was to identify novel targets of miR-126-3p in vitro and then establish the outcomes of their dysregulation on adipocyte metabolism in vivo using a well-established maternal obesity mouse model. Methods miR-126-3p overexpression in 3T3-L1 pre-adipocytes followed by pulsed stable isotope labelling by amino acids in culture (pSILAC) was performed to identify novel targets of the miRNA. Well-established bioinformatics algorithms and luciferase assays were then employed to confirm those that were direct targets of miR-126-3p. Selected knockdown experiments were performed in vitro to define the consequences of target dysregulation. Quantitative real-time PCR, immunoblotting, histology, euglycaemic–hyperinsulinaemic clamps and glucose tolerance tests were performed to determine the phenotypic and functional outcomes of maternal programmed miR-126-3p levels in offspring adipose tissue. Results The proteomic approach confirmed the identity of known targets of miR-126-3p (including IRS-1) and identified Lunapark, an endoplasmic reticulum (ER) protein, as a novel one. We confirmed by luciferase assay that Lunapark was a direct target of miR-126-3p. Overexpression of miR-126-3p in vitro led to a reduction in Lunapark protein levels and increased Perk (also known as Eif2ak3) mRNA levels and small interference-RNA mediated knockdown of Lunapark led to increased Xbp1, spliced Xbp1, Chop (also known as Ddit3) and Perk mRNA levels and an ER stress transcriptional response in 3T3-L1 pre-adipocytes. Consistent with the results found in vitro, increased miR-126-3p expression in adipose tissue from adult mouse offspring born to obese dams was accompanied by decreased Lunapark and IRS-1 protein levels and increased markers of ER stress. At the whole-body level the animals displayed glucose intolerance. Conclusions/interpretation Concurrently targeting IRS-1 and Lunapark, a nutritionally programmed increase in miR-126-3p causes adipose tissue insulin resistance and an ER stress response, both of which may contribute to impaired glucose tolerance. These findings provide a novel mechanism by which obesity during pregnancy leads to increased risk of type 2 diabetes in the offspring and therefore identify miR-126-3p as a potential therapeutic target. Graphical abstract

Paternal obesity induces placental hypoxia and sex-specific impairments in placental vascularization and offspring metabolism

“…Prenatal stressors, including improper nutrition or hypoxia, induce fetal adaptations in metabolic organs including the liver. Maternal obesity in mice, results in ER stress in offspring liver [ 61 ]. Although paternal obesity leads to impaired glucose tolerance and liver steatosis in murine offspring [ 62 ], few studies have investigated whether changes in the fetal liver contribute to offspring metabolic dysfunction.…”

Developmental programming by maternal obesity: Lessons from animal models

“…Although body weight, fat mass and glucose tolerance were not altered in in 8-week-old male offspring of HFHS-induced obese mouse pregnancy, 22,24 they developed increased adiposity and metabolic abnormalities by 6 months of age. 29 These 6-month-old male offspring showed epididymal fat expansion with adipocyte hypertrophy, altered expression of lipogenic enzymes, endoplasmic reticulum stress, systemic and epididymal fat insulin resistance as well as glucose intolerance during a glucose tolerance test. 29 Few studies have investigated the effects of maternal obesity (rather than gestational HFD feeding) in offspring aged for 12 months or longer.…”

“…29 These 6-month-old male offspring showed epididymal fat expansion with adipocyte hypertrophy, altered expression of lipogenic enzymes, endoplasmic reticulum stress, systemic and epididymal fat insulin resistance as well as glucose intolerance during a glucose tolerance test. 29 Few studies have investigated the effects of maternal obesity (rather than gestational HFD feeding) in offspring aged for 12 months or longer. A study in rats showed that both male and female offspring of obese dams showed excessive age-related adiposity, insulin resistance, hyperinsulinaemia, hyperleptinaemia and fatty liver disease at 12 months of age.…”

Parental obesity-induced changes in developmental programming

“…Altered expression of microRNAs is another epigenetic modification that impacts adipose tissue metabolism in offspring of pregnancies with obesity. For instance, overexpression of miR-126 in adipocytes of male mice offspring targets the downregulation of insulin receptor substrate-1 (IRS-1), modulating insulin signaling (Figure 3) (Fernandez-Twinn et al, 2014;De Almeida-Faria et al, 2021). These epigenetic changes promote premature differentiation, attenuating the expansion of adipocytes and favoring metabolically adverse modes of expansion in adulthood.…”