RESUMO
We postulate that protein kinase C α (PKCα) may contribute to the maintenance of pregnancy myometrial quiescence in humans. We studied the changes in myometrial PKCα gene products (messenger RNA [mRNA] and protein) in 4 groups of women: preterm not in labor (PT-NL), preterm in labor (PT-L), term not in labor (T-NL), and term in labor (T-L). The degree of PKCα activation was studied by comparing the levels of particulate (active) PKCα with the total PKCα protein levels and by measuring PKCα activity in the cytosolic and particulate fractions. Protein kinase Cα abundance (mRNA and protein) did not increase during myometrial quiescence (PT-NL), whereas the level of PKCα activity significantly increased during quiescence. The activity of PKCα significantly decreased in the T-NL, T-L, and PT-L groups. These findings suggest that PKCα plays a significant role in the maintenance of myometrial quiescence and that PKCα activity must decrease at the end of pregnancy allowing myometrial activation. Additionally, our data demonstrate an association between reduced PKCα activity and preterm labor, which merits further investigation.
Assuntos
Trabalho de Parto/metabolismo , Miométrio/enzimologia , Trabalho de Parto Prematuro/enzimologia , Proteína Quinase C-alfa/biossíntese , Biomarcadores/metabolismo , Ativação Enzimática/fisiologia , Feminino , Humanos , Isoenzimas/biossíntese , Isoenzimas/genética , Trabalho de Parto/genética , Trabalho de Parto Prematuro/genética , Gravidez , Proteína Quinase C-alfa/genética , RNA Mensageiro/biossíntese , RNA Mensageiro/genéticaRESUMO
1. Kallikrein enzyme activity has been previously reported in the uterus of several species and implicated in implantation and parturition. In order to provide further evidence for a local kallikrein-kinin system in this tissue, we wished to determine if the gene encoding kallikrein (KLK1) was expressed in the human uterus and determine the pattern of its expression across the menstrual cycle. 2. Reverse-transcriptase polymerase chain reaction (RT-PCR) of endometrial and myometrial total RNA coupled with Southern blot analysis showed that KLK1 was expressed in the human endometrium and myometrium. Endometrial expression of KLK1 was confirmed by DNA sequence analysis of the PCR products. Kallikrein was also localized by immunocytochemistry, primarily in the glandular epithelium of the endometrium. 3. Quantitative RT-PCR of 37 endometrial samples ranging from day 1 to 29 from across the menstrual cycle showed significantly higher KLK1 (kallikrein) expression from the mid proliferative to the early secretory phase compared with the late secretory and menstrual phases. 4. We have demonstrated for the first time that KLK1, the gene encoding glandular kallikrein, is expressed in the human uterus. The increase in endometrial KLK1 gene expression during the proliferative phase of the menstrual cycle suggests a role for kallikrein in the preparation of the endometrial lining for implantation.