Developmental programming of neonatal pancreatic β-cells by a maternal low-protein diet in rats involves a switch from proliferation to differentiation

Maternal low-protein diets (LP) impair pancreatic β-cell development, resulting in later-life failure and susceptibility to type 2 diabetes (T2D). We hypothesized that intrauterine and/or postnatal developmental programming seen in this situation involve altered β-cell structure and relative time course of expression of genes critical to β-cell differentiation and growth. Pregnant Wistar rats were fed either control (C) 20% or restricted (R) 6% protein diets during pregnancy (1st letter) and/or lactation (2nd letter) in four groups: CC, RR, RC, and CR. At postnatal days 7 and 21, we measured male offspring β-cell fraction, mass, proliferation, aggregate number, and size as well as mRNA level for 13 key genes regulating β-cell development and function in isolated islets. Compared with CC, pre- and postnatal LP (RR) decreased β-cell fraction, mass, proliferation, aggregate size, and number and increased Hnf1a, Hnf4a, Pdx1, Isl1, Rfx6, and Slc2a2 mRNA levels. LP only in pregnancy (RC) also decreased β-cell fraction, mass, proliferation, aggregate size, and number and increased Hnf1a, Hnf4a, Pdx1, Rfx6, and Ins mRNA levels. Postnatal LP offspring (CR) showed decreased β-cell mass but increased β-cell fraction, aggregate number, and Hnf1a, Hnf4a, Rfx6, and Slc2a2 mRNA levels. We conclude that LP in pregnancy sets the trajectory of postnatal β-cell growth and differentiation, whereas LP in lactation has smaller effects. We propose that LP promotes differentiation through upregulation of transcription factors that stimulate differentiation at the expense of proliferation. This results in a decreased β-cell reserve, which can contribute to later-life predisposition to T2D.

LOC387761 polymorphism is associated with type 2 diabetes in the Mexican population

Worldwide researchers have invested time, effort, and money during the last years to find new genes associated with diabetes susceptibility, such as LOC387761, HHEX, EXT2, and SLC30A8. The aim of the present study was to evaluate whether single-nucleotide polymorphisms (SNPs) of these genes are associated with type 2 diabetes (T2D) and metabolic traits in the Mexican population. We also assessed these SNPs in Mexican indigenous groups to identify a possible inherited susceptibility. Seven SNPs were analyzed in 789 Mexicans (234 control subjects, 455 type 2 diabetic patients, and 100 of indigenous origin), using the KASPar assay (KBioscience Company). Analysis of the data showed an association of the LOC387761 SNP rs7480010 with T2D (p = 0.019). The risk allele A of rs7480010 increased body mass index in diabetic patients (p = 0.01). In addition, there was no association between T2D and the SNPs of HHEX, EXT2, and SLC30A8. Our findings suggest that the SNP rs7480010 (LOC387761) can contribute to a failure in insulin secretion, thus increasing the susceptibility to T2D in Mexicans.