Kathleen Molyneaux Assistant Professor Ph.D. Training Faculty

Department of Genetics School of Medicine Case Western Reserve University Biomedical Research Building 726 2109 Adelbert Road Cleveland, Ohio 44106-4955 Tel: (216) 368-1823 Fax: (216) 368-3432 E-mail: kathleen.molyneaux@case.edu

About Kathleen Molyneaux

Kathy Molyneaux received her undergraduate degree in Biology at Carnegie Mellon University. In 1999, she received her Ph.D. from the Department of Cell Biology at the Weill Graduate School of Medical Sciences. Her thesis work was performed in Barry Gumbiner’s laboratory at the Memorial Sloan Kettering Cancer Center. As a graduate student, she studied the role of beta-catenin in axis formation using Xenopus laevis as a model system. She spent five years as a post-doctoral fellow in Chris Wylie and Janet Heasman’s laboratory with in the Division of Developmental Biology at the Cincinnati Children’s Hospital Medical Center. There she developed an organ culture system for studying germ cell migration using a line of mice that express GFP under the control of a germ cell specific promoter. Dr. Molyneaux joined the Department of Genetics in 2004.

Research

The Molyneaux lab studies development of the mammalian gonad. The somatic and germ cell components of the gonad arise independently and PGCs must migrate and assemble with the somatic cells in order to form a functioning organ. Very little is known about the cell-cell interactions required for this process. We are currently attempting to:

[a] Identify novel genes that are expressed in the early gonad using gene chip technology, in situs and RT-PCR.

[b] Establish transgenic mice that express fluorescent marker genes within epithelial and mesenchymal cell populations of the genital ridge.

[c] Generate cell lines that resemble the early, sexually naive ridge.

[d] Analyze the role of BMP-signaling in gonadogenesis.

* Cells within the mesenchyme of the genital ridge exhibit elevated levels of phospho-smad1 indicating the presence of a BMP-signaling center within the ridge (Figure 1).


Figure 1. p-smad staining is elevated in the mesonephric mesenchyme. Tissue was dissected from an E10.5 Oct4PE:GFP embryo and stained for p-smad1/5/8 (red channel). PGCs express GFP (green channel). p-smad staining is elevated in the condensing mesonephric mesenchyme (mm). PGCs accumulate in the ventral portion of the genital ridge (gr), a region of low p-smad staining.

* Inhibiting BMP-signaling in an organ culture system affects PGCs numbers and motility (Figure 2 and Figure 3).


Figure 2. Blocking BMP-signaling perturbs PGC migration. Transverse slices were dissected from Oct4-delta-PE:GFP embryos and cultured in the presence or absence of noggin for 18 hrs. In control slices, the majority of PGCs move away from the midline and accumulate at the genital ridges. In the presence of noggin (a BMP-antagonist) many PGCs remain on the midline (boxed regions). "g" indicates the position of the gut.


Figure 3. Noggin treatment randomizes PGC movements. Transverse slices were dissected from Oct4-delta-PE:GFP embryos and cultured in the presence or absence of noggin, and filmed for 8 hrs. using a Zeiss LSM510 confocal. Still images show selected cell trajectories (red) overlaid on the first frame of the movie. Noggin treatment affects PGCs starting near the midline. These cells exhibit shortened and twisted trajectories. "g" indicates the position of the gut.

* Evidence suggests that BMPs may do this by controlling expression of two chemokines (steel and SDF) with in the ridge. We are currently investigating how BMP-signaling controls assembly of the gonad using in vitro (cell motility assays) and in vivo (Cre-LoxP system) approaches.

Selected Publications