Mitoscriptome In Biomedicine- Mitochondrial Genomics In Health and Disease

in medicine, biology, omics

Mitochondria are the fuel power plants of animal cells.  The number of mitochondria in a cell varies from tissue to tissue. Some cells have only few mitochondria while the cells that need lots of energy to function may have thousands of mitochondria. 

Mitochondria are cellular organelles that make the potent energy molecule called ATP, acronym for adenosine triphosphate. 

Mitochondria are responsible for creating more than 90% of the energy needed by the body. Mitochondria are special among organelles, because they have their own DNA and they replicate.  The only other DNA in the cell is the nuclear one. The DNA inside a mitochondrion is  more than ceremonial, because though they code for only few genes they are critical for the function of the mitochondria. Mitochondrial DNA codes for 37 transcripts: 13 protein coding transcripts, 22 transfer RNAs and two ribosomal RNAs.

mitochondria picture

Mitochondria need thousands of proteins for their structure and function. Only 13 of these proteins come from their own DNA, the rest of proteins are made from genes on the nuclear DNA. Individuals with mitochondrial disorders resulting from mtDNA mutations may harbor a mixture of mutant and wild-type mtDNA within each cell.  Changes in the expression of these genes (mitochondrial as well as nuclear) can cause mitochondrial functional defects and diseases.  Defects in mitochondria-related genes are associated with a large number of clinical disease phenotypes.  Some diseases that are known to be associated with mitochondrial defects are: mitochondrial myopathy, diabetes mellitus and deafness (DAD), Leigh syndrome, subacute sclerosing encephalopathy, Leber's hereditary optic neuropathy (LHON) and myoclonic epilepsy with ragged red fibers (MERRF). Mitochondrial defect is being increasingly speculated in the cause of several diseases such as Type 2 diabetes, Parkinson's disease, atherosclerotic heart disease, stroke, Alzheimer's disease and cancer.  Changes in mitochondria occur with age and aging itself can diminish mitochondrial function.

Mitochondrial genomics is the study of gene sequences, expression and regulation relating to mitochondrial structure and function. The study of gene expression profile is also called transcriptomics.  One recent paper suggests the name ‘mitoscriptome’ for the transcriptome of nuclear and mitochondrial DNA that are involved in the structure and function of mitochondria.  Technologies such as gene chip microarrays and polymerase chain reaction allow the specific study of mitoscriptome in diseases.  Mitochondria is getting a renewed focus and it is likely that this new direction may identify more links between mitochondrial function and human diseases.  

 References used for this article

  1. R. Raju et al. The mitoscriptome in aging and disease. Aging Dis. 2(2);2011:174-180.
  2. P.F.Chinnery. Mitochondrial Disorders Overview. Gene Reviews. Bookshelf ID: NBK1224 PMID: 20301403

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