Use of pregnancy‐associated plasma protein‐A during oocyte in vitro maturation increases IGF‐1 and affects the transcriptional profile of cumulus cells and embryos from Nelore cows

Abstract

Insulin‐like growth factor 1 (IGF‐1) activity is established by the regulation of IGF binding protein activity, which blocks IGF‐1 functions, whereas pregnancy‐associated plasma protein‐A (PAPP‐A) improves IGF‐1 bioavailability and facilitates binding to IGF receptors. To further extend our understanding of the effect of exogenous PAPP‐A on bovine embryo production, we added this protein during in vitro maturation of cumulus‐oocyte complexes (COCs); moreover, we assessed its effects on IGF‐1 quantity in the maturation medium, embryonic yield and postwarming survival, blastocyst quality, and transcript abundance. Bovine COCs were matured in a serum‐free medium, either with PAPP‐A supplementation (100 ng/ml) or without (control). The treatment group produced higher IGF‐1 concentrations in the maturation medium; however, showed no difference on cleavage, blastocysts rates, and embryonic survival 3 and 24 hr postcryopreservation. Regarding gene expression, VNN1 was upregulated, whereas AGPAT9, FASN, EGFR, HAS2, and IMPDH1 were downregulated in PAPP‐A treated. PAPP‐A treated, CPT2, DNMT3A, and TFAM were upregulated, whereas ATF4 and IFITM3 were downregulated. We concluded that although the addition of PAPP‐A did not affect embryo yield and blastocyst survival, higher IGF‐1 levels may affect embryo competence through differential expression of genes involved in lipid metabolism, oocyte competence, and mitochondrial function.

Señales embrionarias y hormonas placentarias: bases moleculares y potencial uso para el diagnóstico y el seguimiento de la gestación en animales de interés productivo

“…En tal sentido, IGF2, IGFR1, IGFR2 e IR están presentes en ovocitos humanos y de ratón, implicados en la regulación del desarrollo de gametos (Ipsa et al, 2019). Esta regulación difiere entre especies observándose que los ovocitos bovinos expresan dos receptores, IGFR1 e IGFR2, e IGF1 pero no IGF2 (Giroto et al, 2019). La expresión y localización de los IGF al inicio de la gestación ha sido estudiada en diferentes especies de rumiantes (cuadro 2).…”

Pluripotency and Growth Factors in Early Embryonic Development of Mammals: A Comparative Approach

“…In fact, IGF-2 , IGFR-1 , IGFR-2 , and IR are present in human and mouse oocytes, where an IGF/insulin axis regulates gamete development [ 118 , 119 ]. This regulation differs between species, e.g., rat oocytes only express IGF-1 but not its receptor IGFR-1 [ 120 ], bovine oocytes express two receptors, IGFR-1 and IGFR-2 , and IGF-1 but not IGF-2 [ 121 , 122 ], and in dog, corpus luteum presents a similar amount of IGFR-1 , but expression of IGF-1 diminishes during embryonic development [ 123 ]. In vitro studies have shown that the addition of IGF-1 in culture oocyte medium improves maturation rate and embryonic development in sheep by the PI3/AKT pathways, but the blastocyst development rate is not affected in sheep and mice [ 124 , 125 , 126 ].…”