Ciliopathy Features in Mouse Models of Down Syndrome
openNIA - National Institute on Aging
SUMMARY
Down syndrome (DS), also known as Trisomy 21 (T21), is a common genetic disorder caused by an extra
copy of chromosome 21. This additional genetic material disrupts multiple molecular pathways and leads to a
range of health problems, including cognitive impairment.
The circulation of cerebrospinal fluid (CSF) through the brain's ventricular system is crucial for
maintaining brain homeostasis. This involves distributing nutrients, eliminating waste, managing fluid pressure,
and regulating ventricular neurogenesis. The flow of CSF is supported by the coordinated beating of multiple
cilia of the ciliated cells of the ependymal lining of the ventricles. Recent studies using mouse models with trisomy
of genes orthologous to those on human chromosome 21 have revealed various defects characteristic of
ciliopathies, suggesting a potential link between DS and impaired ciliary function. In the brain, this link may
manifest as alterations in ependymal architecture, morphology and arrangement of ciliated cells, ciliary motion,
fluid flow, and adult neurogenesis.
Our collaborative team has developed novel techniques for live imaging and analysis of ciliated cell
arrangement, ciliary motion, ciliary beat frequency (CBF), and CSF flow in brain ventricles. These include
innovative algorithms for analyzing ependymal architecture in the lateral ventricles, arrangement and planar
polarity of multiciliated ependymal cells, automatically quantifying CBF, and analyzing cilia motion, flow velocity,
and flow directionality in live imaging experiments. These methods have enabled us to uncover previously
unrecognized features in the arrangement and function of ciliated cells in the ventricular walls and to characterize
ciliopathies in mutant mouse lines. Specifically, we discovered that in addition to the primary posterior-to-anterior
flow along the ventricular wall, there are multiple local microflows with diverse trajectories exist there, including
both direct and curved paths, which deviate from the main flow direction. We also found that across extensive
areas of the ventricular walls, multiciliated cells align only locally with immediate neighbors, forming defined cell
domains with diverging polarity; this arrangement likely facilitates the complex mosaic of the microflows,
enhancing CSF distribution across the ependyma.
We now propose to apply these advanced novel methods to analyze ependyma architecture, ciliary
motion, and flow in DS mouse models. In our first specific aim we will determine the changes in the overall
architecture of the ependyma (ciliated cell domain arrangement, translational polarity, neurogenesis) in an
overlapping set of DS model lines, as compared to the mice of the background strain. In our second specific aim
we will use live imaging to compare flow velocity and composition, ciliary motion, and CBF between DS models
and control mice. Together, these experiments will help determine whether ciliary dysfunction may contribute to
DS neurological phenotypes.
Up to $429K
health research