Membrane-type matrix metalloproteinase 1 regulates trophoblast functions and is reduced in fetal growth restriction.

Fetal growth restriction (FGR) results from placental insufficiency to adequately supply the fetus. This insufficiency involves impaired cytotrophoblast functions, including reduced migration and invasion, proliferation, and syncytium formation. Membrane-type matrix metalloproteinase 1 (MT1-MMP) is a key enzyme in these cellular processes. MT1-MMP exists in various forms: a 63-kDa proenzyme is synthesized as primary translation product, which is cleaved into a 57-kDa membrane-anchored active form. We hypothesized that reduced placental MT1-MMP in FGR impairs trophoblast functions. MT1-MMP mRNA and active enzyme was quantified in placentas from FGR and age-matched control pregnancies. MT1-MMP protein was localized in first-trimester and term placentas. Putative MT1-MMP functions in trophoblasts were determined using two blocking antibodies for measuring migration and proliferation, as well as fusion of primary trophoblasts and trophoblast-derived cells. MT1-MMP was expressed predominantly in the syncytiotrophoblast and the villous and extravillous cytotrophoblasts. In FGR placentas, levels of MT1-MMP mRNA and of active MT1-MMP protein were reduced (-34.2%, P < 0.05, and -21.5%, P < 0.01, respectively), compared with age-matched controls. MT1-MMP-blocking antibodies diminished migration, proliferation, and trophoblast fusion. We conclude that reduced placental MT1-MMP in FGR may contribute to the impaired trophoblast functions associated with this pathology.

Insulin action on the human placental endothelium in normal and diabetic pregnancy.

The placental endothelium is unique among the entire human vasculature. The blood enriched in oxygen and nutrients is transported in the veins, whereas the arteries contain deoxygenated blood coming from the fetus. The placental vasculature has to develop rapidly to ensure adequate supply of the fetus. Therefore, factors present in the fetal circulation will stimulate placental angiogenesis. In the third trimester of pregnancy the placental endothelium is richly endowed with insulin receptors. In a pregnancy complicated by maternal diabetes, fetal hyperinsulinemia resulting from maternal and, hence, fetal hyperglycaemia induces changes in the placental vasculature such as increased growth and angiogenesis. This review will discuss general effects of insulin on endothelial cells and further focus on insulin effects on the placental endothelium. Isolation and culture of placental endothelial cells has allowed the identification of insulin effects in vitro. These include metabolic effects of insulin i.e. stimulation of glycogen synthesis, and modulation of angiogenesis on the placental arterial endothelium i.e. regulation of ephrin-B2 expression, an arterial specific signalling molecule implicated in sprouting. The effect of insulin on ephrin-B2 in placental arterial endothelial cells as well as their particularly high expression levels of insulin receptors and receptors for vascular endothelial growth factors indicate that placental angiogenesis is likely to emanate from the arterial compartment and is stimulated by insulin.

Lasp1 misexpression influences chondrocyte differentiation in the vertebral column.

The mouse mutant wavy tail Tg(Col1a1-lacZ)304ng was created through transgene insertion and exhibits defects of the vertebral column. Homozygous mutant animals have compressed tail vertebrae and wedge-shaped intervertebral discs, resulting in a meandering tail. Delayed closure of lumbar neural arches and lack of processus spinosi have been observed; these defects become most prominent during the transition from cartilage to bone. The spina bifida was resistant to folic acid treatment, while retinoic acid administration caused severe skeletal defects in the mutant, but none in wild type control animals. The transgene integrated at chromosome 11 band D, in an area of high gene density. The insertion site was located between the transcription start sites of the Rpl23 and Lasp1 genes. LASP1 (an actin binding protein involved in cell migration and survival) was found to be produced in resting and hypertrophic chondrocytes in the vertebrae. In mutant vertebrae, temporal and spatial misexpression of Lasp1 was observed, indicating that alterations in Lasp1 transcription are most likely responsible for the observed phenotype. These data reveal a yet unappreciated role of Lasp1 in chondrocyte differentiation during cartilage to bone transition.

Human fetal placental endothelial cells have a mature arterial and a juvenile venous phenotype with adipogenic and osteogenic differentiation potential.

Growing interest in the sources of origin of blood vessel related diseases has led to an increasing knowledge about the heterogeneity and plasticity of endothelial cells lining arteries and veins. So far, most of these studies were performed on animal models. Here, we hypothesized that the plasticity of human fetal endothelial cells depends on their vascular bed of origin i.e. vein or artery and further that the differences between arterial and venous endothelial cells would extend to phenotype and genotype. We established a method for the isolation of fetal arterial and venous endothelial cells from the human placenta and studied the characteristics of both cell types. Human placental arterial endothelial cells (HPAEC) and human placental venous endothelial cells (HPVEC) express classical endothelial markers and differ in their phenotypic, genotypic, and functional characteristics: HPAEC are polygonal cells with a smooth surface growing in loose arrangements and forming monolayers with classical endothelial cobblestone morphology. They express artery-related genes (hey-2, connexin 40, depp) and more endothelial-associated genes than HPVEC. Functional testing demonstrated that vascular endothelial growth factors (VEGFs) induce a higher proliferative response on HPAEC, whereas placental growth factors (PlGFs) are only effective on HPVEC. HPVEC are spindle-shaped cells with numerous microvilli at their surface. They grow closely apposed to each other, form fibroblastoid swirling patterns at confluence and have shorter generation and population doubling times than HPAEC. HPVEC overexpress development-associated genes (gremlin, mesenchyme homeobox 2, stem cell protein DSC54) and show an enhanced differentiation potential into adipocytes and osteoblasts in contrast to HPAEC. These data provide collective evidence for a juvenile venous and a more mature arterial phenotype of human fetal endothelial cells. The high plasticity of the fetal venous endothelial cells may reflect their role as tissue-resident endothelial progenitors during embryonic development with a possible benefit for regenerative cell therapy.

PKCdelta is involved in signal attenuation in CD3+ T cells.

PKCdelta has been implicated in the signalling events after engagement of the antigen specific receptor on B cells and the Fc-epsilon receptor on mast cells. Employing our recently established PKCdelta null mice , we here investigate the physiological function of PKCdelta in CD3+ T cells. As result, administration of anti-CD3 antibodies in vivo induced markedly increased blood plasma IL-2 levels (but not IL-4, IFN-gamma, TNF-alpha and IL-6 levels) in the PKCdelta null mice, when compared to wild-type sibling controls. Additionally, in vitro T cell proliferative responses to allogenic MHC are significantly enhanced in PKCdelta-deficient CD3+ T cells. These findings suggest that PKCdelta serves a so far unrecognized role in TCR-induced negative regulation of IL-2 cytokine production and T cell proliferation.

Kisspeptin-10, a KiSS-1/metastin-derived decapeptide, is a physiological invasion inhibitor of primary human trophoblasts.

Trophoblast invasion of the uterine extracellular matrix, a critical process of human implantation and essential for fetal development, is a striking example of controlled invasiveness. To identify molecules that regulate trophoblast invasion, mRNA signatures of trophoblast cells isolated from first trimester (high invasiveness) and term placentae (no/low invasiveness) were compared using U95A GeneChip microarrays yielding 220 invasion/migration-related genes. In this 'invasion cluster', KiSS-1 and its G-protein-coupled receptor KiSS-1R were expressed at higher levels in first trimester trophoblasts than at term of gestation. Receptor and ligand mRNA and protein were localized to the trophoblast compartment. In contrast to KiSS-1, which is only expressed in the villous trophoblast, KiSS-1R was also found in the extravillous trophoblast, suggesting endocrine/paracrine activation mechanisms. The primary translation product of KiSS-1 is a 145 amino acid polypeptide (Kp-145), but shorter kisspeptins (Kp) with 10, 13, 14 or 54 amino acid residues may be produced. We identified Kp-10, a dekapeptide derived from the primary translation product, in conditioned medium of first trimester human trophoblast. Kp-10, but not other kisspeptins, increased intracellular Ca(2+) levels in isolated first trimester trophoblasts. Kp-10 inhibited trophoblast migration in an explant as well as transwell assay without affecting proliferation. Suppressed motility was paralleled with suppressed gelatinolytic activity of isolated trophoblasts. These results identified Kp-10 as a novel paracrine/endocrine regulator in fine-tuning trophoblast invasion generated by the trophoblast itself.

Critical role of protein kinase C alpha and calcium in growth factor induced activation of the Na(+)/H(+) exchanger NHE1.

The ubiquitously expressed Na(+)/H(+) exchanger (NHE1) plays an important role in the regulation of the intracellular pH. Induction of NHE activity by phorbol esters and inhibition of growth factor-mediated stimulation of the NHE by protein kinase C (PKC) inhibitors suggest an implication of PKCs in the regulation of the NHE. Expression of PKC isotype-specific dominant negative and constitutively active mutants or downregulation of PKC by isotype-specific antisense oligonucleotides revealed that stimulation by epidermal growth factor (EGF) or phorbol ester of the NHE in NIH3T3 cells is a PKC(alpha)-specific effect. Elevation of cytoplasmic calcium by a Ca(2+) ionophore or thapsigargin causes a growth factor-independent stimulation of the NHE predominantly mediated by calcium/calmodulin kinase II. It is concluded that in NIH3T3 cells overexpressing the EGF receptor (EGFR6 cells), EGF requires cPKC(alpha) for the activation of the NHE, while calcium/calmodulin-dependent kinases are essential in thapsigargin induced stimulation of the NHE.