BBS proteins shown to run an export business that protects cilia

Dec 28, 2009
The BBSome (red) removes signaling proteins from flagella by linking them to a subset of IFT particles (green).

A protein complex mutated in human disease removes excess signaling molecules to prevent them from damaging cilia, say researchers from UMass Medical School. The study will be published in the December 28 issue of the Journal of Cell Biology.

Defective cilia cause a range of diseases including Bardet-Biedl syndrome (BBS), a rare, multi-tissue disorder linked to in 12 different proteins. Seven of these form a complex called the BBSome, but the function of this assembly in cilia and flagella is unclear.

In worms, the complex glues together the intraflagellar transport (IFT) machinery that assembles and maintains cilia by hauling cargo back and forth along the organelle's . But most mammalian cell types can still form cilia in the absence of BBS proteins, suggesting that the BBSome isn't essential for IFT.

Lechtreck et al. turned to the green alga Chlamydomonas, and found that BBS proteins were only present on a subset of IFT particles in each of the alga's two flagella. Strains lacking components of the BBSome showed normal rates of IFT and proper flagellar structure, but couldn't steer away from bright light like wild-type cells could. Mutant flagella accumulated several signaling-related proteins, which the researchers think may disrupt the alga's response to light.

The researchers speculate that a similar buildup of disruptive proteins causes cilia dysfunction in BBS patients; the BBSome may remove excess signaling proteins from flagella by linking them to a subset of IFT particles undergoing retrograde transport out of the cilia. Author Karl Lechtreck says that the next step is to fluorescently tag the signaling proteins and compare their movements to BBS and IFT proteins.

Explore further: Micro fingers for arranging single cells

More information: Lechtreck, K.-F., et al. 2009. J. Cell Biol. doi:10.1083/jcb.200909183

Related Stories

Scientists study cilia -- microscopic hair

May 05, 2006

Texas scientists studying microscopic hairs called cilia say they found an internal structure that's responsible for a cell's response to external signals.

Cilia: small organelles, big decisions

Oct 03, 2007

Johns Hopkins researchers say they have figured out how human and all animal cells tune in to a key signal, one that literally transmits the instructions that shape their final bodies. It turns out the cells assemble their ...

Some skin cancer may be mediated by primary cilia activity

Aug 23, 2009

Tiny, solitary spikes that stick out of nearly every cell in the body play a central role in a type of skin cancer, new research has found. The discovery in mice shows that the microscopic structures known as primary cilia ...

Loss of cell's 'antenna' linked to cancer's development

Jun 28, 2007

Submarines have periscopes. Insects have antennae. And increasingly, biologists are finding that most normal vertebrate cells have cilia, small hair-like structures that protrude like antennae into the surrounding ...

Recommended for you

Micro fingers for arranging single cells

Apr 24, 2015

Functional analysis of a cell, which is the fundamental unit of life, is important for gaining new insights into medical and pharmaceutical fields. For efficiently studying cell functions, it is essential ...

Detailed structure of human ribosome revealed

Apr 24, 2015

A team at the Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC - CNRS/Université de Strasbourg/Inserm) has evidenced, at the atomic scale, the three-dimensional structure of the complete ...

How to kill a protein

Apr 24, 2015

For decades scientists have been looking closely at how our cells make proteins. But the inverse is equally important: how cells kill them.

How RNA machinery navigates our genomic obstacle course

Apr 24, 2015

Once upon a time, scientists thought RNA polymerase—the molecule that kicks off protein synthesis by transcribing DNA into RNA—worked like a wind-up toy: Set it down at a start site in our DNA and it ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.