Characterization of intercellular junctions in fibroblasts of mouse pubic symphysis during pregnancy

• Grant number: 11/23748-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: July 01, 2012
• End date: December 31, 2012
• Field of knowledge: Biological Sciences - Morphology - Histology
• Principal Investigator: Paulo Pinto Joazeiro
• Grantee: Viviane de Souza Rosa
• Host Institution: Instituto de Biologia (IB). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

Appropriate remodeling of organs that form the birth canal are essential for normal pregnancy and so that childbirth to occur without dystocia. Bearing in mind that during childbirth the uterus contracts while to the birth canal needs to be relaxed, this remodeling needs to be appropriately coordinated. Some rodents show an accentuated remodeling pubic symphysis (PS) for the accommodate the birth canal. In mice, after the 12 th day of pregnancy this fibrocartilagineous joint rigid which measure 0,3 mm is rapidly remodeled, resulting in interpubic ligament (IpL) flexible that on delivery day (Day 19) measures approximately 6.0 mm. Soon after birth, this IpL is quickly restored and the space between the pubic bones closes around the fifth day postpartum. It is known that the hormone relaxin facilitates the growth and remodeling of the organs of the female reproductive tract, altering the regulation of biochemical processes involved in the connective tissue remodeling of pregnant uterus, cervix and vagina. No other set of organs or system in adults passes through so fast growing and involution due to cellular changes that lead to hyperplasia, hypertrophy and cell death, as well as synthesis and degradation of extracellular matrix. But little emphasis is given to changes in cell phenotypes of SP or IpL during pregnancy. During the remodeling of the symphysis of the mouse, fibrocartilaginous cells acquire characteristics similar to those of myofibroblasts in IpL. These fibroblasts express alpha-smooth muscle actin and actively incorporate this actin isoform in the cytoskeleton. In addition, the fibroblasts of IpL showed as characteristics phenotypic nucleus with irregular contours, specialized junctions similar to 'fibronexus' as well as cell-cell, which potentially are able to transmit cellular contractility to the ECM. Such contacts ensure coordination of mechanical forces present during the remodeling of tissues intepubic. Despite showing such features, to date no studies which report evidence of intercellular contacts in fibroblasts of the IpL. Thus the present work aims to study morphological features of intercellular junctions between similar to myofibroblasts in order to verify the existence of junctions or adhesions that may occur from 12 th days gestation. We will analyze and compared the morphological characteristics of the interactions of cells in tissues of 12 th, 15 th, 18 th days of pregnancy, using light and transmission electron microscopy, immunofluorescence and also western blotting to identify the major proteins of the intercellular junctions.