Domain Analysis and Motif Matcher (DAMM): A Program to Predict Selectivity Determinants in Monosiga brevicollis PDZ Domains Using Human PDZ Data.

Choanoflagellates are single-celled eukaryotes with complex signaling pathways. They are considered the closest non-metazoan ancestors to mammals and other metazoans and form multicellular-like states called rosettes. The choanoflagellate Monosiga brevicollis contains over 150 PDZ domains, an important peptide-binding domain in all three domains of life (Archaea, Bacteria, and Eukarya). Therefore, an understanding of PDZ domain signaling pathways in choanoflagellates may provide insight into the origins of multicellularity. PDZ domains recognize the C-terminus of target proteins and regulate signaling and trafficking pathways, as well as cellular adhesion. Here, we developed a computational software suite, Domain Analysis and Motif Matcher (DAMM), that analyzes peptide-binding cleft sequence identity as compared with human PDZ domains and that can be used in combination with literature searches of known human PDZ-interacting sequences to predict target specificity in choanoflagellate PDZ domains. We used this program, protein biochemistry, fluorescence polarization, and structural analyses to characterize the specificity of A9UPE9_MONBE, a M. brevicollis PDZ domain-containing protein with no homology to any metazoan protein, finding that its PDZ domain is most similar to those of the DLG family. We then identified two endogenous sequences that bind A9UPE9 PDZ with <100 µM affinity, a value commonly considered the threshold for cellular PDZ-peptide interactions. Taken together, this approach can be used to predict cellular targets of previously uncharacterized PDZ domains in choanoflagellates and other organisms. Our data contribute to investigations into choanoflagellate signaling and how it informs metazoan evolution.

The role of prostaglandins E1 and E2, dinoprostone, and misoprostol in cervical ripening and the induction of labor: a mechanistic approach.

PURPOSE: Prostaglandins play a critical role in cervical ripening by increasing inflammatory mediators in the cervix and inducing cervical remodeling. Prostaglandin E1 (PGE1) and prostaglandin E2 (PGE2) exert different effects on these processes and on myometrial contractility. These mechanistic differences may affect outcomes in women treated with dinoprostone, a formulation identical to endogenous PGE2, compared with misoprostol, a PGE1 analog. The objective of this review is to evaluate existing evidence regarding mechanistic differences between PGE1 and PGE2, and consider the clinical implications of these differences in patients requiring cervical ripening for labor induction. METHODS: We conducted a critical narrative review of peer-reviewed articles identified using PubMed and other online databases. RESULTS: While both dinoprostone and misoprostol are effective in cervical ripening and labor induction, they differ in their clinical and pharmacological profiles. PGE2 has been shown to stimulate interleukin-8, an inflammatory cytokine that promotes the influx of neutrophils and induces remodeling of the cervical extracellular matrix, and to induce functional progesterone withdrawal. Misoprostol has been shown to elicit a dose-dependent effect on myometrial contractility, which may affect rates of uterine tachysystole in clinical practice. CONCLUSIONS: Differences in the mechanism of action between misoprostol and PGE2 may contribute to their variable effects in the cervix and myometrium, and should be considered to optimize outcomes.