Visceral adipose tissue alteration of PI3KR1 expression is associated with gestational diabetes but not promoter DNA methylation

Figures & data

Table 1. Maternal and birth characteristics of study cohort according to groups (NGT and GDM).

	NGT	GDM
n	22	20	P-value*
Maternal age (years)	32.0 ± 1.1	33.0 ± 1.0	0.55
Prepregnancy BMI (kg/m^2)	26.8 ± 1.7	28.4 ± 1.5	0.20
BMI at delivery (kg/m^2)	33.1 ± 1.9	33.5 ± 1.5	0.40
Blood glucose at oGTT (mg/dL)
Fasting	79.5 ± 1.7	100 ± 6.7	<0.0002
1-h	121 ± 6.3	213 ± 8.0	<0.0001
2-h	90.3 ± 4.2	166 ± 10.8	<0.0001
Area under the curve (mg/dL*h)	206 ± 8.2	346 ± 15.6	<0.0001
Maternal fasting plasma levels at delivery:
Glucose (mg/dL)	71.1 ± 2.3	85.0 ± 1.2	<0.0001
Insulin (µU/mL)	21.5 ± 3.4	40 ± 8.0	0.04
HOMA-IR	3.2 ± 0.3	8.2 ± 1.6	0.004
C-peptide (ng/mL)	2.0 ± 0.2	4.8 ± 0.6	<0.0001
Infant data:
Birth weight (g)	3365 ± 106.0	3581 ± 98.9	0.059
Relative Birth weight (g/cm)	66.4 ± 1.5	70.31 ± 1.7	0.075

Data are means ± SEM.

Abbreviations: NGT: Normal glucose tolerance, GDM: gestational diabetes mellitus, BMI: Body-mass-index, oGTT: Oral glucose tolerance test, HOMA-IR: Homoeostatic model assessment of insulin resistance

*Statistical significant (P-value<0.05).

Figure 1. Relative mRNA levels of IRS1, IRS2, PI3KCA and PI3KR1 in SAT (a) and VAT (b) of women with GDM vs. NGT. Relative gene expression of insulin receptor substrate 1 and 2 (IRS1, IRS2), phosphoinositide-3-kinase alpha (PI3KCA) and phosphoinositide-3-kinase regulatory subunit p85 (PI3KR1) was normalized to peptidylprolyl isomerase A (PPIA) in abdominal subcutaneous (SAT- a) and visceral omental adipose tissues (VAT – b), of women with gestational diabetes mellitus (GDM; black; n = 20) vs. normal glucose tolerant women (NGT; white; n = 22). Sum expression values of IRS1 + 2 and PI3KCA+R1 were also included. Data are means ± SEM, shown as percentage to NGT levels. A.U., arbitrary units.* P< 0.05 (Mann-Whitney-U test). PI3KR1-VAT P = 0.012, Sum PI3KCA+R1-VAT P = 0.014.

Figure 2. DNA Methylation analysis in the PI3KR1 promoter region. CpG site-specific DNA methylation analyses at the phosphoinositide-3-kinase regulatory subunit p85 (PI3KR1) at the CpG island within the promoter region in the visceral omental adipose tissue from mothers with NGT vs. GDM. Schematic illustration of the DNA methylation assay for the PI3KR1 promoter region, including a characterized transcription factor binding site for PPARgamma (a). Percent DNA methylation at each individual CpG site investigated (12 CpG sites) in the VAT for normal glucose tolerant (NGT; white; n = 22) vs. gestational diabetes mellitus group (GDM; black; n = 20). (b) CpG site number is location distance from transcriptional start site (TSS). Overall mean across CpG sites is also included. Data are means ± SEM.

Table 2. Summary of PI3KR1 (p85) molecular findings in studies involving metabolic health e.g. GDM and adiposity.

Author and Year ^(Reference)	Model system/Study Design	Sample size	Samples-Tissue	Method: Molecular analysis/assay	Findings/Main results
Catalano et al. 2002^[14]	Human	GDM; n = 5, pregnant-Control; n = 4	Abdominal SAT	Expression: Protein (Western-blot)	PI3Kp85α protein higher in GDM
Colomiere et al 2009^[31]	Human, Clinical Study	GDM insulin- or diet-controlled, Control; n = 6–7 per group	Placenta	Expression: mRNA (RT-PCR), Protein (Western-blot)	Decreased mRNA and protein expression in GDM insulin-controlled group
Chu et al. 2010^[30]	Human, cohort	GDM, Control; n = 50 per group	Blood, Adipose tissue (type not specified)	Expression: mRNA (RT-PCR), Protein (Western-blot)	No differences
				PI3K activity (immunoprecipitation)	Decreased activity in GDM
Veenendall et al. 2012^[33]	Human, cohort	Prenatal famine exposure, unexposed n = 757	Blood	DNA Methylation (Methylation sensitive PCR)	No differences
Zhang et al. 2014^[34]	Human, cohort	GDM, Control; n = 45 per group	Skeletal muscle	Expression: Protein (Immunohistological staining)	Protein higher in GDM
				PI3K activity (ELISA)	Decreased activity in GDM
Xu et al. 2015^[24]	Human, cohort	PCOS; n = 22, Control; n = 13	Abdominal SAT	Expression: mRNA (quantitative RT-PCR)	No differences
Zhang et al. 2016^[32]	Human, cohort	GDM, Control; n = 45 per group	Placenta	Expression: mRNA (RT-PCR), Protein (Western-blot)	No differences

Abbreviations: GDM: gestational diabetes mellitus, SAT: Subcutaneous adipose tissue, PCOS: Polycystic ovary syndrome

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