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Archive - Sep 25, 2012

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Cilia-Based Gene Therapy Restores Sense of Smell in Mice

A team of scientists from Johns Hopkins and other institutions report that restoring tiny, hair-like structures to defective cells in the olfactory system of mice is enough to restore a lost sense of smell. The results of the experiments were published online on September 2, 2012 in Nature Medicine, and are believed to represent the first successful application of gene therapy to restore this function in live mammals. An expert in olfaction, Randall Reed, Ph.D., professor of molecular biology and genetics and co-director of the Center for Sensory Biology at the Johns Hopkins Institute for Basic Biomedical Sciences, cautions that researchers are still years away from applying the same therapy in people, and that if and when it comes, it will likely be most effective for those who suffer from anosmia (lack of smell) due to inherited genetic disorders. “But our work has already contributed to a better understanding of the cellular factors involved in anosmia, and that will give us insights into other neurological disorders, as well,” he says. The mice used in the current study carried a genetic mutation that destroyed the production of a protein critical for the functioning of cilia in the cells responsible for smell, called olfactory sensory neurons. These specialized cells each display several of the protruding, hair-like structures that contain receptors for odorants. Without functional cilia, the cells become a broken link in the chain of events necessary for proper odor detection in the environment, the researchers explained. Beginning with a common cold virus, which readily infects the cells of the nasal cavity, researchers replaced some of the viral genes with a corrected version of the defective cilia gene.

Mechanism That Leads to Non-Familial Parkinson's Disease Identified

Researchers in the Taub Institute at Columbia University Medical Center (CUMC) have identified a mechanism that appears to underlie the common sporadic (non-familial) form of Parkinson's disease, the progressive movement disorder. The discovery highlights potential new therapeutic targets for Parkinson's and could lead to a blood test for the disease. The study, based mainly on analysis of human brain tissue, was published online on September 25, 2012 in Nature Communications. Studies of rare, familial (heritable) forms of Parkinson's show that a protein called alpha-synuclein plays a role in the development of the disease. People who have extra copies of the alpha-synuclein gene produce excess alpha-synuclein protein, which can damage neurons. The effect is most pronounced in dopamine neurons, a population of brain cells in the substantia nigra that plays a key role in controlling normal movement and is lost in Parkinson's. Another key feature of Parkinson's is the presence of excess alpha-synuclein aggregates in the brain. As the vast majority of patients with Parkinson's do not carry rare familial mutations, a key question has been why these individuals with common sporadic Parkinson's nonetheless acquire excess alpha-synuclein protein and lose critical dopamine neurons, leading to the disease. Using a variety of techniques, including gene-expression analysis and gene-network mapping, the CUMC researchers discovered how common forms of alpha-synuclein contribute to sporadic Parkinson's. "It turns out multiple different alpha-synuclein transcript forms are generated during the initial step in making the disease protein; our study implicates the longer transcript forms as the major culprits," said study leader Asa Abeliovich, M.D., Ph.D., associate professor of pathology and neurology at CUMC.

Researchers ID Protein That Suppresses Breast Cancer Metastases

A receptor protein suppresses local invasion and metastasis of breast cancer cells, the most lethal aspect of the disease, according to a research team headed by scientists from The University of Texas MD Anderson Cancer Center. Reporting online on September 23, 2012 in Nature Medicine, the team described using high-throughput RNA sequencing to identify the leukemia inhibitory factor receptor (LIFR) as a novel suppressor of breast cancer metastasis, the spread of the disease to other organs. "Based on our findings, we propose that restoring the expression or the function of key metastasis suppressors like LIFR could be used to block breast cancer metastasis," said lead investigator Li Ma, Ph.D., assistant professor in MD Anderson's Department of Experimental Radiation Oncology. "Lack of clinically proven prognostic markers and therapeutic agents for metastasis are major barriers for eradicating breast cancer deaths," Dr. Ma said. "Although many metastasis-promoting genes have been identified, they have not been translated into clinical practice. The exceptions are the HER2- and VEGF-targeting agents, which have shown measurable, but moderate, benefit in the clinic." Only a few genes have been established as metastasis suppressors, Dr. Ma said, and many researchers believe that such genes play only a minor role in metastasis. The investigators in this study, however, found that LIFR is "highly relevant in human tumors." While 94 percent of normal human breast tissues show high LIFR expression, LIFR is downregulated or lost in a significant fraction of patients with ductal carcinoma in situ (DCIS) or invasive breast cancer, and loss of LIFR closely correlates with poor clinical outcomes. Dr.