Editor's Choice Academic Journal Main Category: Genetics Also Included In: Neurology / Neuroscience Article Date: 22 Mar 2012 - 6:00 PDT

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During an examination of various mutant fruit flies for defects leading to progressive degeneration of photoreceptors in the flies' eye, Vafa Bayat, a recent graduate from the Program in Developmental Biology at BCM and his team discovered mutations in the fruit fly gene that encode a mitochondrial enzyme called the mitochondrial methionyl-tRNA synthetase (Aats-met) that decreases life span and causes other problems, such as lower cell proliferation.

Mitochondria are sometimes described as "cellular power plants", due to the fact that they produce most of the cell's supply of adenosine triphosphate (ATP), which is used as a source of chemical energy. However, they are also involved in processes, such as signaling, cellular differentiation, cell death and regulating cell cycles and cell growth.

Defective genes that encode mitochondrial proteins are also known to implicate human metabolic and neurological disorders.

Dr. Bayat, and his team checked medical literature for genetic neurological disorders, which scientists thought were caused by defects in the region of the genome that contains the human version of the Aats-met gene, MARS2.

Dr. Bernard Brais and team had already mapped one such disease to this region of the genome, i.e. Autosomal Recessive Spastic Ataxia with frequent Leukoencephalopathy (ARSAL). However they failed to identify the precise gene responsible. Ataxias, like ARSAL, are progressive neurodegenerative diseases, which amongst other problems cause coordination difficulties that result in modified gait and speech.

The Montreal team, led by Dr. Isabelle Thiffault, discovered that in ARSAL patients the genetic material of the MARS2 gene is comprehensively rearranged, which resulted in reduced levels of the MARS2 enzyme, reduced synthesis of proteins by the mitochondria, and impaired mitochondrial function. Similar to the fruit fly mutants, the patients' cells also displayed higher levels of reactive oxygen species that can cause damage to cells and their genetic material, as well as slow cell proliferation.

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Neurodegenerative Disorders In Humans And Fruit Flies Caused By Same Gene Mutations