Features | Partner Sites | Information | LinkXpress
Sign In
GLOBETECH PUBLISHING LLC
PZ HTL SA
GLOBETECH PUBLISHING LLC

Certain Optic Cells Export Their Damaged Mitochondria for Destruction Elsewhere

By BiotechDaily International staff writers
Posted on 25 Jun 2014
Image: Pictured is mouse optic nerve and retina, responsible for relaying information from the eye to the brain. The tissue has been fluorescently stained to reveal the distribution of astrocytes (yellow), retinal ganglion cell axons (purple), myelin (green) and nuclei (cyan). Retinal ganglion cell axons transfer mitochondria to adjacent astrocytes in the optic nerve head behind the retina. Astrocytes degrade the mitochondria in a process called transmitophagy (Photo courtesy of the University of California, San Diego).
Image: Pictured is mouse optic nerve and retina, responsible for relaying information from the eye to the brain. The tissue has been fluorescently stained to reveal the distribution of astrocytes (yellow), retinal ganglion cell axons (purple), myelin (green) and nuclei (cyan). Retinal ganglion cell axons transfer mitochondria to adjacent astrocytes in the optic nerve head behind the retina. Astrocytes degrade the mitochondria in a process called transmitophagy (Photo courtesy of the University of California, San Diego).
A recent paper revealed that certain cells in the eye transfer damaged mitochondria to neighboring cells for destruction (mitophagy) and recycling.

Mitophagy is considered a subset of the process known as autophagy, by which damaged organelles are enwrapped and delivered to lysosomes for degradation. As such, it was always assumed that a cell degraded its own mitochondria. However, results presented in the June 16, 2014, online edition of the journal Proceedings of the National Academy of Sciences of the United States of America (PNAS) by investigators at the University of California, San Diego (USA) and Johns Hopkins University (Baltimore, MD, USA) suggest that this assumption may be incorrect.

The investigators used advanced electron microscopy and molecular staining techniques to show that in the optic nerve head, large numbers of mitochondria were shed from neurons to be degraded by the lysosomes of adjoining glial cells. This investigation had been prompted by findings from a glaucoma mouse model that protein products from the retina were accumulating in the optic nerve head just behind the eye.

In the study, a virally introduced tandem fluorophore protein reporter of acidified mitochondria was introduced into mice retinal ganglion cells. The reporter revealed that acidified axonal mitochondria originating from the retinal ganglion cells became associated with lysosomes within columns of astrocytes in the optic nerve head. According to this reporter, a greater proportion of retinal ganglion cell mitochondria were degraded at the optic nerve head than in the ganglions. The investigators coined the term "transmitophagy" to describe this phenomenon.

“It does call into question the conventional assumption that cells necessarily degrade their own organelles. We do not yet know how generalized this process is throughout the brain, but our work suggests it is probably widespread,” said co-senior author Dr. Mark H. Ellisman, professor of neurosciences at the University of California, San Diego. “Mitochondria play prominent roles in the health of axons, which are fundamental to connecting neurons and transmitting information. It should be a priority to further explore what happens in transmitophagy and whether defects in this phenomenon contribute to neuronal dysfunction or disease.”

“The discovery of a standard process for transfer of trash from neuron to glia will most likely be very important to understanding age-related declines in function of the brain and neurodegenerative or metabolic disorders,” said co-senior author Dr. Nicholas Marsh-Armstrong, assistant professor of ophthalmology and neuroscience at Johns Hopkins University. “We expect the impact to be significant in other areas of biomedicine as well.”

Related Links:

University of California, San Diego
Johns Hopkins University



RANDOX LABORATORIES
SLAS - Society for Laboratory Automation and Screening
BIOSIGMA S.R.L.
comments powered by Disqus

Channels

Drug Discovery

view channel

Omega 3 Found to Improve Behavior in Children with ADHD

Supplements of the fatty acids omega 3 and 6 can help children and adolescents who have a specific kind of have attention deficit hyperactivity disorder (ADHD). Moreover, these findings indicate that a customized cognitive training program can improve problem behavior in children with ADHD. Statistics show that 3%–6%... Read more

Biochemistry

view channel

Blocking Enzyme Switch Turns Off Tumor Growth in T-Cell Acute Lymphoblastic Leukemia

Researchers recently reported that blocking the action of an enzyme “switch” needed to activate tumor growth is emerging as a practical strategy for treating T-cell acute lymphoblastic leukemia. An estimated 25% of the 500 US adolescents and young adults diagnosed yearly with this aggressive disease fail to respond to... Read more

Lab Technologies

view channel
Image: Mouse kidneys, liver, and pancreas imaged after treatment with a variety of protocols: a saline solution, Scale, SeeDB (see deep brain), CUBIC, and carotid body (CB) perfusion (which was used in this study) (Photo courtesy of RIKEN Quantitative Biology Center).

Nearly Transparent Mice Offers Potential of Whole-Organism Imaging

Japanese researchers have developed a method that combines tissue decolorization and light-sheet fluorescent microscopy to take extremely detailed images of the interior of individual organs and even entire... Read more

Business

view channel

Two Industry Partnerships Initiated to Fuel Neuroscience Research

Faster, more complex neural research is now attainable by combining technology from two research companies. Blackrock Microsystems, LLC (Salt Lake City, UT, USA), a developer of neuroscience research equipment, announced partnerships with two neuroscience research firms—PhenoSys, GmbH (Berlin, Germany) and NAN Instruments, Ltd.... Read more
 
Copyright © 2000-2014 Globetech Media. All rights reserved.