Jim Lessard Group (GUDMAP1)
Smooth muscle is critical for the function of many organs that make up the lower urinary tract and reproductive systems. For example, controlled contraction of bladder smooth muscle is needed to empty the bladder at will and rhythmic contractions of uterine smooth muscle are crucial to the delivery of babies. We will follow the development and organization of these and other smooth muscle rich organs in the genitourinary tract using mice that produce fluorescent proteins exclusively in smooth muscle or other cellular compartments of these genitourinary tissues (Figure 1). Our studies will determine what genes are expressed in the cells that make up these organs as they form in the mouse at different times during development. This information will help identify and understand the genes and signals involved in the development and function of these organs.
Our basic strategy is to isolate samples of cells from distinct parts of developing genitourinary organs in the mouse and determine what genes are active at key times for smooth muscle formation by measuring the level of mRNA produced from each gene in the mouse. For example, by determining what genes are active in regions that give rise to smooth muscle, we hope to provide the world-wide research community with clues that will help find genes that will mark (identify) cells that are precursors to smooth muscle. Likewise, by determining what genes are active in cells around the smooth muscle-forming regions in these tissues, identify factors produced by these nearby cells that may stimulate (or inhibit) the formation and regulate the size of the smooth muscles in these organs. We will do this by harvesting an organ of interest (bladder, ureter, vas deferens, vagina, etc.) at key stages of their development. These tissues will be cut into thin sections and samples of various cellular compartments will be isolated using laser capture microdissection (LCM) (Figure 2). For example, we plan to isolate samples from the developing the region of the bladder that gives rise to (or has already formed) smooth muscle as well as capture other regions such as stroma, serosa, and epithelium (Figure 3). The RNA from these compartments will be isolated, amplified, and analyzed (see the protocols for details) to determine what genes are expressed at each developmental stage in the forming bladder (and the many other organs to be studied) using commercially available microarray chips to measure the expression level of essentially all known mouse genes.
Relationship to the Overall Goals of GUDMAP
Congenital birth defects involving the genitourinary tract are all too frequent and the incidence of some of these birth defects appears to be increasing. Currently, research in the area of genitourinary development is limited by (1) a lack of cell specific markers for key lineages within the developing GU tract, (2) an incomplete understanding of the normal three-dimensional cellular structure of the major genitourinary organs and (3) an incomplete understanding of the morphogenetic and molecular events that occur during organogenesis. The goal of this project is to look for evidence of distinct stages of differentiation in smooth muscle cells and other cellular compartments within genitourinary tissues of the mouse and identify candidate mechanisms for signaling among these compartments. Thus, the information being generated by this project relates to all three of these issues and should facilitate future studies designed to further our understanding of genitourinary tract development. The hope is that a better understanding of genetic and molecular mechanisms involved will ultimately lead to strategies to prevent and/or correct congenital disorders of the genitourinary tract.