OBJECTIVE: To investigate cyclophilin A in early second trimester of pregnancy before the onset of preeclampsia.
METHODS: In this prospective case-control study, 51 pregnant women whose serum were collected and stored and who developed preeclampsia in later follow-up and 41 pregnant women as control group were included.
RESULTS: Maternal serum cyclophilin A levels in the study group who developed preeclampsia in later follow-up were significantly higher than those of normal healthy pregnant women.
CONCLUSIONS: Cyclophilin A may be a valuable predictor for pregnant women who subsequently develop preeclampsia in their pregnancies.

Protein-mediated interactions and enzymatic function provide the foundation upon which cellular signaling cascades control all of the activities of a cell. Post-translational modifications such as phosphorylation or ubiquitiation are well known means for modulating protein activity within the cell. These chemical modifications create new recognition motifs on proteins or shift conformational preferences such that protein catalytic and binding functions are altered in response to external stimuli. Moreover, detection of such modifications is often straightforward by conventional biochemical methods leading investigators toward mechanistic models of cell signaling involving post-translational modifications such as phosphorylation/dephosphorylation. While there is little doubt that such modifications play a significant role in transmission of information throughout the cell, there are certainly other mechanisms at work that are not as well understood at this time. Of particular interest in the context of this review is the intrinsic conformational switch afforded to a polypeptide by peptidyl prolyl cis/trans isomerization. Proline isomerization is emerging as a critical component of certain cell signaling cascades. In addition to serving as a conformational switch that enables a protein to adopt functionally distinct states, proline isomerization may serve as a recognition element for the ubiquitous peptidyl prolyl isomerases. This overview takes a close look at one particular signaling protein, the T cell specific tyrosine kinase Itk, and examines the role of proline isomerization and the peptidyl prolyl isomerase cyclophilin A in mediating Itk function following T cell receptor engagement.