Retinal ganglion cell neurodegeneration in mitochondrial inherited disorders.
Since the early days of mitochondrial medicine, it has been clear that optic atrophy is a very common and sometimes the singular pathological feature in mitochondrial disorders. The first point mutation of mitochondrial DNA (mtDNA) associated with the maternally inherited blinding disorder, Leber's hereditary optic neuropathy (LHON), was recognized in 1988. In 2000, the other blinding disorder, dominant optic atrophy (DOA) Kjer type, was found associated with mutations in the nuclear gene OPA1 that encodes a mitochondrial protein. Besides these two non-syndromic optic neuropathies, optic atrophy is a prominent feature in many other neurodegenerative diseases that are now recognized as due to primary mitochondrial dysfunction. We will consider mtDNA based syndromes such as LHON/dystonia/Mitochondrial Encephalomyopahty Lactic Acidosis Stroke-like (MELAS)/Leigh overlapping syndrome, or nuclear based diseases such as Friedreich ataxia (mutations in FXN gene), deafness-dystonia-optic atrophy (Mohr-Tranebjerg) syndrome (mutations in TIMM8A), complicated hereditary spastic paraplegia (mutations in SPG7), DOA "plus" syndromes (mutations in OPA1), Charcot-Marie-Tooth type 2A (CMT2A) with optic atrophy or hereditary motor and sensory neuropathy type VI (HMSN VI) (mutations in MFN2), and Costeff syndrome and DOA with cataract (mutations in OPA3). Thus, genetic errors in both nuclear and mitochondrial genomes often lead to retinal ganglion cell death, a specific target for mitochondrial mediated neurodegeneration. Many mechanisms have been studied and proposed as the bases for the pathogenesis of mitochondrial optic neuropathies including bioenergetic failure, oxidative stress, glutamate toxicity, abnormal mitochondrial dynamics and axonal transport, and susceptibility to apoptosis.
Carelli
Valerio
V
Department of Neurological Sciences, University of Bologna, Via Ugo Foscolo 7, 40123, Bologna, Italy. valerio.carelli@unibo.it
La Morgia
Chiara
C
Valentino
Maria Lucia
ML
Barboni
Piero
P
Ross-Cisneros
Fred N
FN
Sadun
Alfredo A
AA
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics; D018797:Cell Cycle Proteins / Q000235:genetics; D002467:Cell Nucleus / Q000235:genetics; D004247:DNA / Q000235:genetics; D004272:DNA, Mitochondrial / Q000235:genetics*; D034281:Dynamins; D005621:Friedreich Ataxia / Q000235:genetics; D020558:GTP Phosphohydrolases / Q000235:genetics; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics; D008869:Microtubule-Associated Proteins / Q000235:genetics; D028361:Mitochondrial Diseases / Q000235:genetics*; D024101:Mitochondrial Proteins / Q000235:genetics; D009410:Nerve Degeneration / Q000235:genetics*; D009687:Nuclear Proteins / Q000235:genetics; D029242:Optic Atrophy, Hereditary, Leber / Q000235:genetics* / Q000473:pathology; D009958:Orofaciodigital Syndromes / Q000235:genetics; D012165:Retinal Ganglion Cells / Q000473:pathology*
D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; D004272:DNA, Mitochondrial; C470309:MAD2L1BP protein, human; D008565:Membrane Proteins; D008869:Microtubule-Associated Proteins; D024101:Mitochondrial Proteins; D009687:Nuclear Proteins; D004247:DNA; D020558:GTP Phosphohydrolases; C470018:MFN2 protein, human; C415198:OPA1 protein, human; C110768:DNM1L protein, human; D034281:Dynamins