Protein kinase C isoforms during the development of deciduomata in pseudopregnant rats

The activation of matrix metalloproteinase-2 induced by protein kinase C alpha in decidualization

This study investigated the protein kinase C (PKC) and matrix metalloproteinase-2 (MMP-2) in the development of deciduomata in pseudo-pregnant and pregnant rats. The results showed that the expression of MMP-2 was significantly increased from day 2 to day 5 in pseudo-pregnancy and from day 7 to day 9 in pregnancy. To further investigate the correlation between MMP-2 and protein kinase C alpha (PKC alpha), the expression of MMP-2 in the 12-O-tetradecanoylphorbol 13-acetate (TPA)-treated organotypic culture of decidual tissue was determined. The results showed that the active form of MMP-2 was significantly increased in the TPA-treated cultures. Moreover, this response was inhibited by the PKC inhibitor H7, the PKC alpha specific inhibitor Gö-6976 and the translation inhibitor cycloheximide, but not by the transcription inhibitor actinomycin D or the replication inhibitor mitomycin C. In addition, TPA also reversed the MMP-2 expression after by progesterone pretreatment in the primary decidual cells. These findings indicate that PKC alpha may play an important role in the regulation of the MMP-2 expression during decidualization.

Phospholipase C axis is the preferential pathway leading to PKC activation following PTH or PTHrP stimulation in human term placenta

Parathyroid-related peptide (PTHrP) is abundant in human syncytiotrophoblast where it was suggested to play an important role in maternal-fetal calcium homeostasis. On the other hand, parathyroid hormone (PTH), another hypercalcemic factor, would be implicated in the maintenance of the mother's calcium balance. In many cells, these hormones are associated to G-coupled receptors and activate protein kinase (PKC). Thus, the first aim of this study was to determine the cellular pathway (phospholipase; PLC and phosphatidyl-inositol-3 kinase; PI3K) leading to the activation of PKC following a PTH or PTHrP stimulation in brush border (BBM) and basal plasma membranes (BPM) of human term placenta. Both peptides were shown to be potent modulators of the PKC activity in these membranes with optimal concentrations of 10(-8)M and 10(-9)M for hPTH and hPTHrP, respectively. Furthermore, the use of bisindolylmaleimide (BIM), a non-selective PKC inhibitor, serves to demonstrate the specificity of the PKC-dependent MARCKS-psd phosphorylation. While LY-294002, a PI3K inhibitor failed to counteract the hPTH- and hPTHrP-induced PKC stimulation in BBM and BPM, U-73122, a PLC inhibitor, totally abolished the PKC stimulation by hPTH and hPTHrP. Taken together, these data suggest that the activation of PKC by hPTH or hPTHrP, in BBM and BPM, is preferentially associated to the PLC pathway rather than the PI3K's.

Protein kinase C isoforms during the development of deciduomata in pregnant rats

In this study, we determined the expression of protein kinase C (PKC) isoforms during pregnancy. At pregnant duration, PKC alpha was down-modulated in the deciduomata but not in the myometrium. Down-modulation was compatible with the increase in cell mitosis, which reached a maximum at 8-9 days. On the other hand, PKC zeta was not down-modulated. It was increased both in the cytosolic and particulate fractions of the deciduomata, and paralleled the frequency of decidual cell mitosis. The other PKC isoform of delta was also increased, but it was associated with the cell regression. Therefore, these findings confirmed that the variable expression of PKC isoforms in decidualizing tissue may be involved in the modulation of decidual cell growth.