Fritz is one of the downstream players in the Planar Cell Polarity (PCP) pathway.
PCP signaling was first identified in Drosophila, and many vertebrate homologues of
PCP genes have been shown to be central to neural tube development and closure in
vertebrate animals, including humans. Recently, it has also been shown that some PCP
genes are involved in the formation of cilia. A critical function for cilia during embryonic
development involves transducing Hedgehog signaling, which is essential for neural tube
closure. However, the role of Fritz in vertebrate neural tube formation has not yet been
studied.
The expression patterns of Fritz during the early development of Xenopus laevis
embryos have been determined. Also, phenotypic changes in Xenopus laevis embryos
have been observed when the Fritz protein is knocked down by antisense morpholino
oligonucleotide injection— embryos failed to close their neural tube properly, indicating
that Fritz is involved in neural tube closure as well as convergent extension. GFP fusion
to Fritz and immunostaining reveal that Fritz protein is localized at the base of cilia.
Morpholino injection resulted in defective cilia inside the neural tube and in the
epidermis of these morphant embryos. These results indicated that Fritz is an essential
gene for cilia formation. Furthermore, the expression level of Hedgehog target genes was
greatly reduced within Fritz morphants. Fritz morphants also exhibit characteristic
craniofacial defects associated with defective Hedgehog signaling. Though much work is
left to determine the exact role of Fritz, these experiments illustrate that the Fritz gene is
involved in cilia formation, and consequently Hedgehog signaling, which is critical for
neural tube closure and development in vertebrate animals.
Neural tube closure and Hedgehog signaling are two processes that are essential
for proper vertebrate development. The neural tube later gives rise to the brain and spinal
cord, while Hedgehog signaling is necessary for brain development, limb development,
and establishment of the midline. Considering that Fritz plays a role in both of these
processes, a better understanding of Fritz can provide vital information about early
vertebrate development. More importantly, because a lack of Fritz disrupts these
processes, one can gain insight into why certain developmental defects occur. These
include Holoprosencephaly, which results in severe defects in brain formation, and Spina
Bifida, a spinal cord formation defect that is one of the most common birth defects
worldwide. It is my hope that my work on Fritz has contributed to the body of
knowledge regarding these types of defects, and that my work may be someday used to
help prevent or treat these defects, and save the lives of children worldwide.Biological Sciences, School o