Myofibroblast-like Cells and Junctional Complex Development Play a Role in Mouse Pubic Symphysis Remodeling During Pregnancy and Postpartum

TL;DR

During mouse pregnancy, pubic symphysis cells become myofibroblast-like and form junctions that may help with delivery and postpartum recovery.

Contribution

The study reveals junctional complex development in myofibroblast-like cells during mouse pubic symphysis remodeling.

Findings

Intercellular contacts in IpL myofibroblast-like cells include adherens and GAP junctions during late pregnancy.

Junctional complexes connect IpL cells to each other and the ECM, possibly aiding mechanical force changes during pregnancy.

These junctions may help pelvic bone closure after delivery and suggest roles in preterm labor research.

Abstract

During mouse pregnancy, the pubic symphysis (PS) undergoes a gradual transitioning into an interpubic ligament (IpL) for a successful delivery. After birth, this IpL is rapidly remodeled, returning to the non-pregnant morphology. The PS fibrocartilaginous cells acquire a myofibroblast-like phenotype, characterized by extracellular matrix (ECM) secretion, expression of α-smooth muscle actin (α-SMA), and vimentin. While the presence of myofibroblast-like cells during the IpL remodeling is well described, cell–cell interactions and how this might contribute to the delivery remains poorly understood. This study uses ultrastructure and molecular approaches to investigate cell–cell and cell–ECM junctions during mouse pregnancy and postpartum. Our findings reveal that the intercellular contacts between adjacent IpL myofibroblast-like cells, particularly at late pregnancy stages, are characterized as adherens and GAP junctions. The acquisition of contractile elements by IpL cells, coupled with neighboring cells and the surrounding ECM via junctional complexes, suggests an important role in supporting changes in the mechanical forces generated by pubic bone movements during mouse pregnancy and also in tying the pelvic bones together, which may help the birth canal closure after delivery. Further studies in PS biology may investigate fibroblast to myofibroblast differentiation signaling cascades, which regulate the expression of pro-fibrotic proteins and may provide new insights for preterm labor.

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