Dr. Julie Siegenthaler's initial interest in neuroscience started at Mount Holyoke College where she majored in the newly formed Neuroscience and Behavior program and was first introduced to experimental design and research while studying behavior in fish for her senior thesis project. After graduating cum laude with high honors in 2000, Dr. Siegenthaler pursued her interests in cellular and molecular neuroscience as a graduate student with Dr. Michael Miller at SUNY Upstate Medical University. While a graduate student, Dr. Siegenthaler described a role for TGF2 in neocortical development and as a potential target of alcohol in the brain defects seen in fetal alcohol syndrome. She continued in Dr. Miller's lab for a brief but productive postdoctoral training where she found that the transcription factor Foxg1 was an important regulator of TGF2 signaling in forebrain development. In total, Dr. Siegenthaler published five 1st author publications while at SUNY Upstate in such journals as Cerebral Cortex and Journal of Neuroscience. In May 2006, Dr. Siegenthaler joined Dr. Sam Pleasure's lab at UCSF where she began work on a project looking at the role of the secreted factors from the meninges in the development of the neocortex. Using Foxc1 mutant mice that fail to make complete meninges and have severe defects in forebrain development, she showed that meningeal-derived retinoic acid is key element driving neuron generation during corticogenesis. This research resulted in a first-author publication in the journal Cell. Dr. Siegenthaler has also generated substantial data regarded the brain vascular defects in the Foxc1 mutants and she is dedicated to developing an independent research plan focused on understanding how different structures and cell types contribute to the formation of the cerebral vasculature. Dr. Siegenthaler has developed a comprehensive career development plan to meet her career goals. While in the mentored K99 phase, Dr. Siegenthaler will continue to benefit from the mentorship and guidance of her sponsor, Dr. Sam Pleasure, and acquire new skills as she completes the specific aims outlined the Research Plan. The experimental data and techniques acquired during the K99 phase will be valuable in the research planned for the R00 phase. Dr. Siegenthaler's long-term goal is to develop a comprehensive, multi-faceted research program that investigates the development and function of the meninges in the embryo and adult, the functional role of Foxc1 in perivascular cells, and the interaction between the neural tissues and the vasculature during brain development. Environment. Dr. Siegenthaler has her own work space and desk on the 5th floor of Rock Hall on the Mission Bay Campus of UCSF. She has full access to the equipment and space of her mentor, Dr. Pleasure, including general lab equipment, centrifuges, freezers, a dissection room and adjacent tissue culture hood and incubators, microscopes, and space in the animal facility. She also has access to UCSF core facilities including those for cell sorting and real time PCR equipment. Dr. Siegenthaler has the equipment and facilities needed to complete the experiments outlined for the K99 phase. Her research will be conducted at UCSF, an extremely well-regarded research institution dedicated to improving the health of individuals through biomedical research, patient care and education. The research facilities at the Mission Bay Campus are part of a substantial effort by UCSF to improve and expand its research capabilities. Along with the neighboring Gladstone Institute, the Mission Bay Campus provides ample opportunities for Dr. Siegenthaler to attend seminars, presentations, journal clubs, and have informal meetings with faculty members that will contribute greatly to her training and preparation for an independent research career. Research. This proposal uses the Foxc1 mutant mice, which have defects in vascular and brain development, to gain further insight into how the brain vasculature forms. Experiments in the K99 phase are designed to understand how the absence of the meninges and defects in forebrain development in the Foxc1 mutants differentially contributes to the blood vessel malformations. Experiments in the R00 phase will investigate potential targets of meningeal-derived signals on endothelial cells, the cell autonomous role for Foxc1 in the differentiation and function of mural cells associated with the vasculature in and around the brain, and further explore the role of the neural-derived signals in the vascularization of the developing cortex. Foxc1 is expressed by neural crest-derived meningeal cells and mural cells (collective term for pericytes and smooth muscle cells) in the developing embryo and in the adult. Yet Foxc1 mutant mice have severe defects in both cortical development and formation of the forebrain vasculature. I have previously shown that the defects in dorsal forebrain development are due to loss of meningeal-derived retinoic acid. My preliminary evidence suggests that retinoic acid from the meninges also regulates endothelial cell proliferation and vessel formation around the forebrain (referred to as the perineural vascular plexus (PNVP). Experiments in specific aim 1 will specifically address the role of retinoic acid in the formation of the PNVP.
In specific aim 2, I will address the role of Foxc1 in the differentiation and function of CNS mural cells using mural cell-specific ablation of Foxc1. In addition to defects in the PNVP, the intracortical vasculature fails to form properly in the Foxc1 mutants. In the third aim, I will test the hypothesis that the intracortical vascular phenotype in the Foxc1 mutants is due to loss of important angiogenic cues from the dorsal forebrain.
Stroke is a significant cause of long-term disability and death and can result from congenital vascular defects that occur during fetal development. The research in this proposal seeks to significantly expand our understanding of what controls the formation of the vasculature in and around the cerebral cortex. Understanding how the cerebral vasculature forms will not only shed light on the etiology of congenital vascular malformations but also provide additional insight into the developmental angiogenic pathways that are likely reactivated during stroke recovery.
