Expression and genomic imprinting of DCN, PON2 and PEG3 genes in porcine placenta

Roles of Two Small Leucine-Rich Proteoglycans Decorin and Biglycan in Pregnancy and Pregnancy-Associated Diseases

Two small leucine-rich proteoglycans (SLRP), decorin and biglycan, play important roles in structural–functional integrity of the placenta and fetal membranes, and their alterations can result in several pregnancy-associated diseases. In this review, we briefly discuss normal placental structure and functions, define and classify SLRPs, and then focus on two SLRPs, decorin (DCN) and biglycan (BGN). We discuss the consequences of deletions/mutations of DCN and BGN. We then summarize DCN and BGN expression in the pregnant uterus, myometrium, decidua, placenta, and fetal membranes. Actions of these SLRPs as ligands are then discussed in the context of multiple binding partners in the extracellular matrix and cell surface (receptors), as well as their alterations in pathological pregnancies, such as preeclampsia, fetal growth restriction, and preterm premature rupture of membranes. Lastly, we raise some unanswered questions as food for thought.

A functional outside-in signaling network of proteoglycans and matrix molecules regulating autophagy

Proteoglycans and selected extracellular matrix constituents are emerging as intrinsic and critical regulators of evolutionarily conversed, intracellular catabolic pathways. Often, these secreted molecules evoke sustained autophagy in a variety of cell types, tissues, and model systems. The unique properties of proteoglycans have ushered in a paradigmatic shift to broaden our understanding of matrix-mediated signaling cascades. The dynamic cellular pathway controlling autophagy is now linked to an equally dynamic and fluid signaling network embedded in a complex meshwork of matrix molecules. A rapidly emerging field of research encompasses multiple matrix-derived candidates, representing a menagerie of soluble matrix constituents including decorin, biglycan, endorepellin, endostatin, collagen VI and plasminogen kringle 5. These matrix constituents are pro-autophagic and simultaneously anti-angiogenic. In contrast, perlecan, laminin α2 chain, and lumican have anti-autophagic functions. Mechanistically, each matrix constituent linked to intracellular catabolic events engages a specific cell surface receptor that often converges on a common core of the autophagic machinery including AMPK, Peg3 and Beclin 1. We consider this matrix-evoked autophagy as non-canonical given that it occurs in an allosteric manner and is independent of nutrient availability or prevailing bioenergetics control. We propose that matrix-regulated autophagy is an important outside-in signaling mechanism for proper tissue homeostasis that could be therapeutically leveraged to combat a variety of diseases.

The Landscape of Genomic Imprinting at the Porcine SGCE/PEG10 Locus from Methylome and Transcriptome of Parthenogenetic Embryos

In mammals, imprinted genes often exist in the form of clusters in specific chromosome regions. However, in pigs, genomic imprinting of a relatively few genes and clusters has been identified, and genes within or adjacent to putative imprinted clusters need to be investigated including those at the SGCE/PEG10 locus. The objective of this study was to, using porcine parthenogenetic embryos, investigate imprinting status of genes within the genomic region spans between the COL1A2 and ASB4 genes in chromosome 9. Whole-genome bisulfite sequencing (WGBS) and RNA sequencing (RNA-seq) were conducted with normal and parthenogenetic embryos, and methylome and transcriptome were analyzed. As a result, differentially methylated regions (DMRs) between the embryos were identified, and parental allele-specific expressions of the SGCE and PEG10 genes were verified. The pig imprinted interval was limited between SGCE and PEG10, since both the COL1A2 and CASD1 genes at the centromere-proximal region and the genes between PPP1R9A and ASB4 toward the telomere were non-imprinted and biallelically expressed. Consequently, our combining analyses of methylome, transcriptome, and informative polymorphisms revealed the boundary of imprinting cluster at the SGCE/PEG10 locus in pig chromosome 9 and consolidated the landscape of genomic imprinting in pigs.

Decorin-inducible Peg3 Evokes Beclin 1-mediated Autophagy and Thrombospondin 1-mediated Angiostasis

We previously discovered that systemic delivery of decorin for treatment of breast carcinoma xenografts induces paternally expressed gene 3 (Peg3), an imprinted gene encoding a zinc finger transcription factor postulated to function as a tumor suppressor. Here we found that de novo expression of Peg3 increased Beclin 1 promoter activity and protein expression. This process required the full-length Peg3 as truncated mutants lacking either the N-terminal SCAN domain or the zinc fingers failed to translocate to the nucleus and promote Beclin 1 transcription. Importantly, overexpression of Peg3 in endothelial cells stimulated autophagy and concurrently inhibited endothelial cell migration and evasion from a 3D matrix. Mechanistically, we found that Peg3 induced the secretion of the powerful angiostatic glycoprotein Thrombospondin 1 independently of Beclin 1 transcriptional induction. Thus, we provide a new mechanism whereby Peg3 can simultaneously evoke autophagy in endothelial cells and attenuate angiogenesis.

Paraoxonase 2 gene polymorphisms and prenatal phthalates' exposure in Chinese newborns

BACKGROUND

Phthalates were reported to be associated with increased risk of LBW in newborns, but the mechanism and potential influencing factor was still unclear. The objectives of this study were to investigate whether paraoxonase-2 (PON2) Ala148Gly (A148G) polymorphisms have impacts on fetal growth, and evaluate potential modifying effect on the association between phthalate exposures and LBW and short birth length.

METHODS

In the current case-control study, 185 mother-newborn pairs including 74 low birth weight (LBW) cases and 111 controls were enrolled. Newborns' meconium specimens were collected and detected for mono-n-butyl phthalate (MBP) and mono-2-ethyhexyl phthalate (MEHP) by the method of high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). Umbilical vein blood samples were used to identify PON2 A148G polymorphisms by using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method.

RESULTS

Newborns prenatally exposed to higher level of phthalates had lower birth weight (β=-0.92. p=0.045 for MBP, β=-0.62, p=0.013 for MEHP) and short birth length (SBL) (β=-0.024. p=0.049 for MBP, β=-0.023, p=0.007 for MEHP). Comparing with low-phthalate-exposed subjects with PON2 148AA genotype, newborns with PON2 148AG/GG genotype exposed to high concentrations of MBP and MEHP had higher risks of LBW and short birth length (LBW: OR: 5.0, p=0.017 for MEHP; OR: 2.6, p=0.023 for MBP; SBL: OR: 6.6, p=0.005 for MEHP; OR: 6.4, p=0.017 for MBP). Effects of MBP and MEHP on LBW were significantly modified by PON2 A148G (p=0.044 and 0.034, respectively), while the modifying effect of PON2 A148G polymorphisms on the association of two phthalate metabolites with SBL was not significant.

CONCLUSION

Prenatal exposure to phthalates affected birth weight and length in newborns. PON2 A148G polymorphisms modified the effects of prenatal phthalates' exposure on fetal development. Newborns with PON2 148AG/GG genotype and exposed to high concentrations of MBP and MEHP had higher risks of LBW and SBL.