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/migrationrelated 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 identifed Kp-10 as a novel paracrine/endocrine regulator in fine-tuning trophoblast invasion generated by the trophoblast itself.

Smooth muscle cell (SMC) accumulation is a key event in the development of atherosclerosis, including vein bypass graft arteriosclerosis. Because members of the protein kinase C (PKC) family signal cells to undergo proliferation, differentiation, or apoptosis, we generated PKCdelta knockout mice and performed vein bypass grafts on these animals. PKCdelta(-/-) mice developed normally and were fertile. Vein segments from PKCdelta(-/-) mice isografted to carotid arteries of recipient mice of either genotype led to a more severe arteriosclerosis than was seen with PKCdelta(+/+) vein grafts. Arteriosclerotic lesions in PKCdelta(-/-) mice showed a significantly higher number of SMCs than were found in wild-type animals; this was correlated with decreased SMC death in lesions of PKCdelta(-/-) mice. SMCs derived from PKCdelta(-/-) aortae were resistant to cell death induced by any of several stimuli, but they were similar to wild-type SMCs with respect to mitogen-stimulated cell proliferation in vitro. Furthermore, pro-apoptotic treatments led to diminished caspase-3 activation, poly(ADP-ribose) polymerase cleavage, and cytochrome c release in PKCdelta(-/-) relative to wild-type SMCs, suggesting that their apoptotic resistance involves the loss of free radical generation and mitochondrial dysfunction in response to stress stimuli. Our data indicate that PKCdelta maintains SMC homeostasis and that its function in the vessel wall per se is crucial in the development of vein graft arteriosclerosis.

Smooth muscle cell (SMC) accumulation is a key event in the development of atherosclerosis, including vein bypass graft arteriosclerosis. Because members of the protein kinase C (PKC) family signal cells to undergo proliferation, differentiation, or apoptosis, we generated PKCdelta knockout mice and performed vein bypass grafts on these animals. PKCdelta(-/-) mice developed normally and were fertile. Vein segments from PKCdelta(-/-) mice isografted to carotid arteries of recipient mice of either genotype led to a more severe arteriosclerosis than was seen with PKCdelta(+/+) vein grafts. Arteriosclerotic lesions in PKCdelta(-/-) mice showed a significantly higher number of SMCs than were found in wild-type animals; this was correlated with decreased SMC death in lesions of PKCdelta(-/-) mice. SMCs derived from PKCdelta(-/-) aortae were resistant to cell death induced by any of several stimuli, but they were similar to wild-type SMCs with respect to mitogen-stimulated cell proliferation in vitro. Furthermore, pro-apoptotic treatments led to diminished caspase-3 activation, poly(ADP-ribose) polymerase cleavage, and cytochrome c release in PKCdelta(-/-) relative to wild-type SMCs, suggesting that their apoptotic resistance involves the loss of free radical generation and mitochondrial dysfunction in response to stress stimuli. Our data indicate that PKCdelta maintains SMC homeostasis and that its function in the vessel wall per se is crucial in the development of vein graft arteriosclerosis.

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Aims/hypothesis: The human placenta is a complex organ situated at the interface between mother and foetus that separates maternal from foetal blood. The placental surfaces exposed to the two bloodstreams are different, i.e. trophoblasts and endothelial cells are in contact with the maternal and foetal circulation, respectively. Both cell types produce high insulin receptor levels. The aim of the present study was to test the hypothesis that spatiotemporal changes in insulin receptor expression in trophoblasts from first trimester to the endothelium at term shift the control of insulin-dependent processes from mother to foetus. Methods: Global microarray analysis of primary trophoblasts from first trimester and term human placentas and endothelial cells from term human placentas cultured under hyperinsulinaemic and control conditions identified different sets of regulated genes in trophoblasts and endothelial cells. Results: Insulin effects on placental gene expression underwent developmental changes from trophoblasts in the first trimester to endothelial cells at term that were paralleled by changes in levels of activated insulin receptors. The changes in gene regulation were both quantitative (i.e. magnitude of effect) and qualitative (i.e. specific genes affected and direction of regulation). Conclusions/interpretation: This spatio-temporal shift in insulin sensitivity throughout pregnancy allows maternal and foetal insulin to regulate different processes within the placenta at different gestational stages, facilitated by compartmentalisation of the insulin response. Thus, by altering the levels and function of insulin receptors in space and time, control of insulin-dependent processes in the human placenta will change from mother to foetus throughout gestation. This will be of particular interest in conditions associated with altered maternal or foetal insulin levels, i.e. diabetes mellitus or intrauterine growth restriction.