Hyperglycemia Slows Embryonic Growth and Suppresses Cell Cycle via Cyclin D1 and p21

Abstract

In pregnant women, the diabetic condition results in a three- to fivefold increased risk for fetal cardiac malformations as a result of elevated glucose concentrations and the resultant osmotic stress in the developing embryo and fetus. Heart development before septation in the chick embryo was studied under two hyperglycemic conditions. Pulsed hyperglycemia induced by daily administration of glucose during 3 days of development caused daily spikes in plasma glucose concentration. In a second model, sustained hyperglycemia was induced with a single injection of glucose into the yolk on day 0. The sustained model raised the average plasma glucose concentration from 70 mg/dL to 180 mg/dL and led to decreased gene expression of glucose transporter GLUT1. Both models of hyperglycemia reduced embryo size, increased mortality, and delayed development. Within the heart outflow tract, reduced proliferation of myocardial and endocardial cells resulted from the sustained hyperglycemia and hyperosmolarity. The cell cycle inhibitor p21 was significantly increased, whereas cyclin D1, a cell cycle promoter, decreased in sustained hyperglycemia compared with controls. The evidence suggests that hyperglycemia-induced developmental delays are associated with slowed cell cycle progression, leading to reduced cellular proliferation. The suppression of critical developmental steps may underlie the cardiac defects observed during late gestation under hyperglycemic conditions.

ASK1 mediates the teratogenicity of diabetes in the developing heart by inducing ER stress and inhibiting critical factors essential for cardiac development

“…This differential regulation has been reported in the liver (31). Downregulation of cyclin D1 by diabetes is in agreement with a recent study in the chick model (38). Cyclin D2 is a GATA4 cofactor in cardiogenesis (54); however, we did not observe any changes in cyclin D2 expression.…”

“…Compound deletion of all three cyclin Ds results in VSD (14), a common type of CHD in diabetic pregnancies (15). A recent study reports that high glucose suppresses cyclin D1 and increases p21Cip in the chick embryo (38). Because the ASK1-JNK1/2 or p38 MAPK pathway critically regulates cell proliferation, it is possible that ASK1 mediates the inhibitory effect of maternal diabetes on cell proliferation by modulating cyclin Ds and cell cycle inhibitors.…”

Effects of High Salt-Exposure on the Development of Retina and Lens in 5.5-Day Chick Embryo

“…Following reverse transcription, PCR amplification of the cDNA was performed as described previously [21,22]. The following primers were used: NGF: CGACATCAAAGGCAAAGAG and GTCGATCCGGATAAATCTC [23]; CyclinD1: TCGGTGTCCTACTTCAAGTG and GGAGTTGTCGGTGTAAATGC [24]; GAPDH: GTCAACGGATTTGGCCGTAT and AATGCCAAAGTTGTCATGGATG [25]. PCR reactions were performed in a Bio-Rad S1000TM Thermal cycler (Bio-Rad, USA).…”

The impact of high salt exposure on cardiovascular development in the early chick embryo

“…Following reverse transcription, PCR amplification of the cDNA was performed as described previously (Dugaiczyk et al, 1983;Maroto et al, 1997). The primers were as follows: PPIA, TGACAAGGTGCCCATAACAG and GCGTAAAGTCACCACCCTGA; cyclin D1, TCGGTGTCCTACTTCA-AGTG and GGAGTTGTCGGTGTAAATGC (Scott-Drechsel et al, 2013); VMHC, GCTACAAACACCAAGCAGAG and TCTTATATCTGGGAG-CCAGG (Schlueter et al, 2006); Nkx2.5, GGATCCCTCCTCGTTGCTC-TCG and CCTTGACACGCCGCTCTGACTT (Schlueter et al, 2006); GATA4, CCACACGACCACAACCACACTCTG and AAAGCTTCAGG-GCTGAAATTGCAG (Zhang et al, 2003); BMP2, AGCGTCAAGCGA-AACACAAACAG and GGGCAACAATCCAGTCATTCCAC (Endo et al, 2012); HIF2, CCGAGCGTGACTTCTTCATGAGG and GCTCATCGT-CAACAGGTGTGGCT (Larger et al, 2004); FGF2, TTCTTCCTGCGC-ATCAAC and GGATAGCTTTCTGTCCAG (Larger et al, 2004); VEGFR, GGTCGCATGAACATGAAGAA and TTGGTAGGGTTTGTAAGGAC; SOD1, AGGAGTGGCAGAAGTAG and CACGGAAGAGCAAGTA; SOD2, CTTCCTGACCTGCCTTAC and CGTCCCTGCTCCTTATT; Gpx, GCCACCTCCATCTACGAC and TGCTCCTTCAGCCACTTC. PCR reactions were performed in a Bio-Rad S1000TM thermal cycler (Bio-Rad, USA).…”