由美国国立卫生研究院资助的研究者发现了一个对于神经细胞来说非常关键的主调控基因：该基因的损伤，将会打破其他相关基因相互作用制造髓鞘（包围在神经细胞外的脂层，可以加快神经细胞电信号传播的速度和保真性）的过程。
此项发现将有助于对髓鞘合成紊乱的理解，这些紊乱会影响到外周神经系统（在脑和脊柱之外的神经）的功能，我们将之称为外周神经病（peripheral neuropathy）。外周神经病会导致麻木、无力、疼痛和运动损伤，还包括一种最为常见的遗传性紊乱——腓骨肌萎缩症（Charcot-Marie-Tooth disease），该病症会引起渐行性肌肉萎缩症。
研究者揭示出的这个基因是早期生长反应基因2（early growth response gene 2；EGR2）。在研究中，研究者发现该基因的单拷贝发生损伤后，不仅影响自身基因的正常拷贝，而且还影响到了其他基因的正常功能，最终导致了外周神经病的发生。
“研究者已经解析出了对于髓鞘组装来说非常重要的一段序列，” NICHD（NIH的研究所）的负责人Duane Alexander介绍说，“他们的发现将让我们更为深入地探究髓鞘合成紊乱的病症所在。”
相关英文原文：
Public release date: 16-Apr-2007
[
Print Article | E-mail Article
| Close Window ]
Contact: Robert Bock
bockr@mail.nih.gov
301-496-5133
NIH/National Institute of Child Health and Human Development
Researchers discover gene crucial for nerve cell insulation
Researchers funded by the National Institutes of Health have discovered how a defect in a single master gene disrupts the process by which several genes interact to create myelin, a fatty coating that covers nerve cells and increases the speed and reliability of their electrical signals.
The discovery has implications for understanding disorders of myelin production. These disorders can affect the peripheral nervous system梩he nerves outside the brain and spine. These disorders are known collectively as peripheral neuropathies. Peripheral neuropathies can result in numbness, weakness, pain, and impaired movement. They include one of the most common genetically inherited disorders, Charcot-Marie-Tooth disease, which causes progressive muscle weakening.
The myelin sheath that surrounds a nerve cell is analogous to the insulating material that coats an electrical cord or wire, keeping nerve impulses from dissipating, allowing them to travel farther and faster along the length of the nerve cell.
The researchers discovered how a defect in just one copy of the gene, known as early growth response gene 2 (EGR2) affects the normal copy of the gene as well as the functioning of other genes, resulting in peripheral neuropathy.
"The researchers have deciphered a key sequence essential to the assembly of myelin," said Duane Alexander, M.D., Director of the NICHD, the NIH institute that funded the study. "Their discovery will provide important insight into the origins of disorders affecting myelin production."
The study appears in the online version of Molecular and Cellular Biology.
John Svaren, Ph.D., an associate professor in the Department of Comparative Bioscience at the University of Wisconsin朚adison's School of Veterinary Medicine, worked with colleagues Scott E. LeBlanc, and Rebecca M. Ward, to conduct the study. Dr. Svaren is an affiliate of NICHD-funded mental retardation and developmental disabilities research center at the Waisman Center at the University of Wisconsin.
Until this discovery, researchers did not fully understand the complex genetic process that enables Schwann cells, found in the peripheral nervous system, to coat nerves with myelin.
The Newly Discovered Role of EGR2
During this study, the scientists found that EGR2 produces a protein that activates several other genes necessary for myelin production. Some of these genes contain the information needed to make peripheral myelin protein 22 (PMP-22) and myelin protein zero (MPZ). MPZ is the most abundant protein in myelin in the peripheral nervous system.
The overproduction or underproduction of the proteins PMP22 and MPZ account for the majority of inherited peripheral neuropathies, Dr. Svaren said.
Ultimately, the sequence of activating genes "switches on" the Schwann cell, which wraps the nerve axon, the arm-like projection that conveys nerve impulses, in a myelin sheath.
The scientists' research also resolved a long-standing mystery surrounding why a single mutant copy of the EGR2 gene disrupts the functioning of the normal EGR2 gene, leading to a disorder of the nervous system.
In many genetic conditions, the unaffected copy of an affected gene continues to produce its protein. However, the researchers found that the mutant EGR2 copy interferes with the interaction between the normal EGR2 gene and another myelin gene, SOX10, as the two try to work together to produce the myelin protein MPZ.
Therapeutic Potential
By understanding the process which creates myelin, researchers may now be able to investigate new therapies for disorders affecting myelin.
"Our research has uncovered a whole new mechanism for regulating myelin genes," said Dr. Svaren. "Our hope is to exploit this knowledge so that we can adjust the levels of myelin genes such as PMP22 and MPZ, and thereby create an effective treatment for myelin diseases."
Understanding the process by which nerve cells are myelinated also could be applied to other disorders as well, Dr. Svaren said. Diabetic neuropathy, which results in a loss of feeling in the extremities, also is thought to involve myelin production.
Dr. Svaren added that it is possible that the current study's findings about myelin production in the peripheral nervous system could lead to greater understanding of how myelination takes place in the central nervous system (the brain and spinal cord). Myelination in the central nervous system is not well understood. Multiple sclerosis, a degenerative muscular disorder that can be fatal, results from the destruction of myelin in the central nervous system.
Information about Charcot-Marie-Tooth syndrome and multiple sclerosis is available from The National Institute of Neurological Disorders and Stroke at: http://www.ninds.nih.gov/disorders/charcot_marie_tooth/charcot_marie_tooth.htm and http://www.ninds.nih.gov/disorders/multiple_sclerosis/multiple_sclerosis.htm.
The NICHD sponsors research on development, before and after birth; maternal, child, and family health; reproductive biology and population issues; and medical rehabilitation. For more information, visit the Institute's website at http://www.nichd.nih.gov.
The National Institutes of Health (NIH)梩he nation's medical research agency梚ncludes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. It is the primary federal agency for conducting and supporting basic, clinical, and translational medical research; and it investigates the causes, treatments, and cures for both common and rare diseases. For more information about the NIH and its programs, visit http://www.nih.gov.
上一篇：X染色体易裂症的病理机制：以稳定对付迟钝 下一篇：J.Neurosci：大脑快速控制行为的机制
|
