background:
Twinkle, also known as PEO1 (Progressive external ophthalmoplegia 1 protein), PEOA3, SANDO or TWINL, is a mitochondrial protein that functions as a 5’-3’ nucleotide-dependent DNA helicase. Colocalized with mtDNA (mitochondrial DNA) in mitochondrial nucleoids, Twinkle is important in the metabolism and maintenance of mtDNA, playing a crucial role in the regulation of mtDNA copy numbers. Twinkle is expressed at high levels in testis, pancreas and skeletal muscle and exists as three isoforms due to alternative splicing events. Defects in the gene encoding Twinkle are the cause of two conditions: progressive external ophthalmoplegia with mitochondrial DNA deletions autosomal dominant 3 (PEOA3) and sensory ataxic neuropathy dysarthria and ophthalmoparesis (SANDO). PEOA3 is characterized by ptosis and weak muscles, while SANDO is characterized by ophthalmoparesis, dysarthria and sensory ataxic neuropathies.
Function:
Twinkle, also known as PEO1, is involved in mitochondrial DNA (mtDNA) metabolism, possibly by functioning as an adenine nucleotide-dependent DNA helicase at the mitochondrial DNA replication fork. It may be a key regulator of mitochondrial DNA copy number in mammals. Mutations in Twinkle lead to infantile-onset spinocerebellar ataxia, a severe neurodegenerative disorder. Mutations in Twinkle are also associated with a number of diseases that manifest with symptoms such as sensory ataxia, neuropathy, ophthalmoplegia, and hearing loss.
Subunit:
Forms multimers in vitro, including hexamers. Interacts with POLG in vitro.
Subcellular Location:
Mitochondrion matrix, mitochondrion nucleoid. Note=Colocalizes with mtDNA in mitochondrial nucleoids, a nucleoproteins complex consisting of a number of copies of proteins associated with mtDNA, probably involved in mtDNA maintenance and expression.
Tissue Specificity:
High relative levels in skeletal muscle, testis and pancreas. Lower levels of expression in the heart, brain, placenta, lung, liver, kidney, spleen, thymus, prostate, ovary, small intestine, colon and leukocytes. Expression is coregulated with MRPL43.
DISEASE:
Progressive external ophthalmoplegia with mitochondrial DNA deletions autosomal dominant 3 (PEOA3) [MIM:609286]: A disorder characterized by progressive weakness of ocular muscles and levator muscle of the upper eyelid. In a minority of cases, it is associated with skeletal myopathy, which predominantly involves axial or proximal muscles and which causes abnormal fatigability and even permanent muscle weakness. Ragged-red fibers and atrophy are found on muscle biopsy. A large proportion of chronic ophthalmoplegias are associated with other symptoms, leading to a multisystemic pattern of this disease. Additional symptoms are variable, and may include cataracts, hearing loss, sensory axonal neuropathy, ataxia, depression, hypogonadism, and parkinsonism. Note=The disease is caused by mutations affecting the gene represented in this entry.
[DISEASE] Sensory ataxic neuropathy dysarthria and ophthalmoparesis (SANDO) [MIM:607459]: A systemic disorder resulting from mitochondrial dysfunction associated with mitochondrial depletion in skeletal muscle and peripheral nerve tissue. The clinical triad of symptoms consists of sensory ataxic neuropathy, dysarthria, and ophthalmoparesis. However, the phenotype varies widely, even within the same family, and can also include myopathy, seizures, and hearing loss. An atypical form of the disease is characterized by headaches and/or seizures manifesting in childhood or adolescence, followed by development of cerebellar and sensory ataxia, dysarthria, progressive external ophthalmoplegia, and myoclonus in early adulthood. Note=The disease is caused by mutations affecting the gene represented in this entry.
Mitochondrial DNA depletion syndrome 7 (MTDPS7) [MIM:271245]: A severe disease associated with mitochondrial dysfunction. Some patients are affected by progressive atrophy of the cerebellum, brain stem, the spinal cord, and sensory axonal neuropathy. Clinical features include hypotonia, athetosis, ataxia, ophthalmoplegia, sensorineural hearing deficit, sensory axonal neuropathy, epileptic encephalopathy and female hypogonadism. In some individuals liver dysfunction and multi-organ failure is present. Note=The disease is caused by mutations affecting the gene represented in this entry.
Similarity:
Contains 1 SF4 helicase domain.
Database links:
Entrez Gene: 56652 Human
Entrez Gene: 226153 Mouse
Entrez Gene: 309441 Rat
Omim: 606075 Human
SwissProt: Q96RR1 Human
SwissProt: Q8CIW5 Mouse
Unigene: 22678 Human
Unigene: 105585 Mouse
Important Note:
This product as supplied is intended for research use only, not for use in human, therapeutic or diagnostic applications.
|
|
