NOV 29, 2015 10:03 AM PST

Ciliopathies and Joubert Syndrome

Nearly all mammalian cells contain cilia – microscopic hair-like structures that extend from the surface of cells. They can be up to 10 micrometers in length and up to 1 micrometer wide. Motile cilia can be found in the respiratory tract as well as the middle ear. These moving cilia work to keep these areas free of mucous accumulation. They are also known to help propel sperm within the reproductive tract. Non-motile cilia play a crucial role in many organs acting as sensory receptors for the cell by receiving signals from other cells or fluids nearby.
 
Cilia are located on almost all mammalian cells and can be either motile or non-motile serving as sensors to the cells.


Ciliary defects cause a variety of symptoms including disease of the kidneys, blindness and nervous system defects. Cilia have sub compartments characterized by distinct molecular compositions. These molecular compositions encode for receptors and signaling components. There are also “gated” diffusion barriers at the base of cilia which regulate entry of proteins and other types of molecules into the cell. This ciliary gate is associated with an axon called the transition zone (TZ) which connects cell microtubules to the cell membrane. The TZ is thought to contribute to diffusion barrier properties of the cilia sub compartment.

Mutations in genes associated with the TZ are known to be the cause of ciliopathies such as Joubert Syndrome which is a rare developmental disorder affecting the brain and kidneys. In babies diagnosed with Joubert syndrome, developmental delay can cause breathing abnormalities and movement disorders. Retinal degeneration has been observed in some patients in combination with kidney disease. Newborns may also have extra fingers or toes (polydactyly) in some cases. It can be inherited in an autosomal recessive manner however; sporadic cases have also occurred.

Researchers from the University of Dublin sought to further dissect the molecular composition and mechanisms involving organization and barrier regulation of the TZ. They investigated the coexpression and coevolution of the protein TMEM107, which is mutated in persons with Joubert syndrome experiencing oral-facial-digital syndrome.



Using an animal model, they found that TMEM107 controls the composition of cilia and functions with another protein, NPHP4 to regulate the integrity of cilia as well as TZ docking. They also found that ciliopathy proteins are anchored at the TZ membrane which is crucial for proper function of the diffusion membrane. MKS2 proteins were found to be anchored in the TZ, playing an important role in barrier functions. This research provides insight into the architecture of the TZ domain as well as proteins involved in diffusion barrier formation, leading to ciliopathic diseases. Researchers suggest using similar genetic methods to characterize other ciliary models such as the IFT-A and IFT-B models.

Sources: Nature Cell Biology; National Institutes of Health; Ciliopathy Alliance
 
About the Author
  • I am a postdoctoral researcher with interests in pre-harvest microbial food safety, nonthermal food processing technologies, zoonotic pathogens, and plant-microbe interactions. My current research projects involve the optimization of novel food processing technologies to reduce the number of foodborne pathogens on fresh produce. I am a food geek!
You May Also Like
OCT 25, 2018
Health & Medicine
OCT 25, 2018
Sedentary Lifestyle More Deadly Than Smoking
A number of recent studies have found that first cardiovascular associations with regular high-intensity exercise. These studies......
NOV 05, 2018
Immunology
NOV 05, 2018
Amino Acid Helps to Promote T cells
Scientists at Vanderbilt show that the amino acid glutamine can contribute to a subset of T cell function and activation...
NOV 12, 2018
Microbiology
NOV 12, 2018
Some Bacteria Gain Resistance Even Without Exposure to Antibiotics
Most bacteria are harmless, some are even beneficial to us. But some of the dangerous ones pose a real threat to public health....
NOV 16, 2018
Health & Medicine
NOV 16, 2018
Liver gets activated by just seeing and smelling food!
liver also gets activated by sight and the smell of food in anticipation of the prerequisite metabolic changes required for food intake....
DEC 03, 2018
Genetics & Genomics
DEC 03, 2018
Reducing the Potential for Negative Side Effects in CRISPR
CRISPR-Cas9 is an amazing gene-editing tool, but there are some drawbacks. This work aims to fix that....
DEC 07, 2018
Microbiology
DEC 07, 2018
Epigenetic Inheritance is Revealed in Archaea
Researchers may have found a great new way to study tags that are added to the genome, which change how genes are expressed....
Loading Comments...