Premature polyadenylation-mediated loss of stathmin-2 is a hallmark of TDP-43-dependent neurodegeneration.

Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are associated with loss of nuclear transactive response DNA-binding protein 43 (TDP-43). Here we identify that TDP-43 regulates expression of the neuronal growth-associated factor stathmin-2. Lowered TDP-43 levels, which reduce its binding to sites within the first intron of stathmin-2 pre-messenger RNA, uncover a cryptic polyadenylation site whose utilization produces a truncated, non-functional mRNA. Reduced stathmin-2 expression is found in neurons trans-differentiated from patient fibroblasts expressing an ALS-causing TDP-43 mutation, in motor cortex and spinal motor neurons from patients with sporadic ALS and familial ALS with GGGGCC repeat expansion in the C9orf72 gene, and in induced pluripotent stem cell (iPSC)-derived motor neurons depleted of TDP-43. Remarkably, while reduction in TDP-43 is shown to inhibit axonal regeneration of iPSC-derived motor neurons, rescue of stathmin-2 expression restores axonal regenerative capacity. Thus, premature polyadenylation-mediated reduction in stathmin-2 is a hallmark of ALS-FTD that functionally links reduced nuclear TDP-43 function to enhanced neuronal vulnerability

Cerebellar c9RAN proteins associate with clinical and neuropathological characteristics of C9ORF72 repeat expansion carriers.

Clinical and neuropathological characteristics associated with G4C2 repeat expansions in chromosome 9 open reading frame 72 (C9ORF72), the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia, are highly variable. To gain insight on the molecular basis for the heterogeneity among C9ORF72 mutation carriers, we evaluated associations between features of disease and levels of two abundantly expressed "c9RAN proteins" produced by repeat-associated non-ATG (RAN) translation of the expanded repeat. For these studies, we took a departure from traditional immunohistochemical approaches and instead employed immunoassays to quantitatively measure poly(GP) and poly(GA) levels in cerebellum, frontal cortex, motor cortex, and/or hippocampus from 55 C9ORF72 mutation carriers [12 patients with ALS, 24 with frontotemporal lobar degeneration (FTLD) and 19 with FTLD with motor neuron disease (FTLD-MND)]. We additionally investigated associations between levels of poly(GP) or poly(GA) and cognitive impairment in 15 C9ORF72 ALS patients for whom neuropsychological data were available. Among the neuroanatomical regions investigated, poly(GP) levels were highest in the cerebellum. In this same region, associations between poly(GP) and both neuropathological and clinical features were detected. Specifically, cerebellar poly(GP) levels were significantly lower in patients with ALS compared to patients with FTLD or FTLD-MND. Furthermore, cerebellar poly(GP) associated with cognitive score in our cohort of 15 patients. In the cerebellum, poly(GA) levels similarly trended lower in the ALS subgroup compared to FTLD or FTLD-MND subgroups, but no association between cerebellar poly(GA) and cognitive score was detected. Both cerebellar poly(GP) and poly(GA) associated with C9ORF72 variant 3 mRNA expression, but not variant 1 expression, repeat size, disease onset, or survival after onset. Overall, these data indicate that cerebellar abnormalities, as evidenced by poly(GP) accumulation, associate with neuropathological and clinical phenotypes, in particular cognitive impairment, of C9ORF72 mutation carriers

CUG initiation and frameshifting enable production of dipeptide repeat proteins from ALS/FTD C9ORF72 transcripts

Expansion of G4C2 repeats in the C9ORF72 gene is the most prevalent inherited form of amyotrophic lateral sclerosis and frontotemporal dementia. Expanded transcripts undergo repeat-associated non-AUG (RAN) translation producing dipeptide repeat proteins from all reading frames. We determined cis-factors and trans-factors influencing translation of the human C9ORF72 transcripts. G4C2 translation operates through a 5′–3′ cap-dependent scanning mechanism, requiring a CUG codon located upstream of the repeats and an initiator Met-tRNAMeti. Production of poly-GA, poly-GP, and poly-GR proteins from the three frames is influenced by mutation of the same CUG start codon supporting a frameshifting mechanism. RAN translation is also regulated by an upstream open reading frame (uORF) present in mis-spliced C9ORF72 transcripts. Inhibitors of the pre-initiation ribosomal complex and RNA antisense oligonucleotides selectively targeting the 5′-flanking G4C2 sequence block ribosomal scanning and prevent translation. Finally, we identified an unexpected affinity of expanded transcripts for the ribosomal subunits independently from translation

ALS-causative mutations in FUS/TLS confer gain- and loss-of-function by altered association with SMN and U1-snRNP

The RNA-binding protein FUS/TLS, mutation in which is causative of the fatal motor neuron disease ALS, is demonstrated to directly bind to the U1-snRNP and SMN complexes. ALS-causative mutations in FUS/TLS are shown to abnormally enhance their interaction with SMN and dysregulate its function, including loss of Gems and altered levels of small nuclear RNAs (snRNAs). The same mutants are found to have reduced association with U1-snRNP. Correspondingly, global RNA analysis reveals a mutant-dependent loss of splicing activity, with ALS-linked mutants failing to reverse changes caused by loss of wild-type FUS/TLS. Furthermore, a common FUS/TLS mutant-associated RNA splicing signature is identified in ALS patient fibroblasts. Taken together, these studies establish potentially converging disease mechanisms in ALS and spinal muscular atrophy, with ALS-causative mutants acquiring properties representing both gain (dysregulation of SMN) and loss (reduced RNA processing mediated by U1-snRNP) of function

Identification of the genes responsible for Marinesco-Sjögren syndrome and a new form of ataxia associated with coenzyme Q10 deficit.

Par une stratégie de cartographie par homozygotie, nous avons identifié les gènes responsables de deux ataxies autosomiques récessives : le syndrome de Marinesco-Sjögren (MS) et une nouvelle forme d’ataxie associée à un déficit en coenzyme Q10 (CoQ). Le syndrome MS est une affection congénitale multisystémique avec notamment la présence d’une ataxie, d’une myopathie et d’une cataracte bilatérale. Nous avons localisé le gène en 5q31, et identifié en collaboration avec le Pr Lehesjoki des mutations dans le gène SIL1 codant pour un facteur d’échange nucléotidique d’une protéine chaperones HSP70. Puis, nous avons identifié des mutations d’ADCK3 dans une nouvelle forme d’ataxie. Les homologues d’ADCK3 chez E. coli et S. cerevisiae (respectivement ubiB et abc1/coq8) sont impliqués dans la biosynthèse du CoQ. Nous avons montré que les patients présentent un déficit en CoQ et qu’ADCK3 appartient à la super-famille des « kinases atypiques ».By homozygosity mapping, we have identified the genes responsible for two autosomal recessive ataxia : Marinesco-Sjögren syndrome (MS) and a new form of recessive ataxia associated with coenzyme Q10 (CoQ) deficit. MS syndrome is a multisystemic disease with the association of an ataxia, a myopathy and bilateral cataracts. We have localized the gene on chromosome 5q31, and in collaboration with Pr Lehesjoki, we have identified mutations in the gene SIL1 encoding for a nucleotide exchange factor for an HSP70 molecular chaperonne. We have also identified mutations in the gene ADCK3 in a new form of ataxia. ADCK3 bacteria and yeast homologs (ubiB and abc1/coq8 respectively) are involved in CoQ biosynthesis. We have shown that the patients dysplay CoQ deficit and that ADCK3 belongs to the protein kinases-like superfamily

Identification of the genes responsible for Marinesco-Sjögren syndrome and a new from of ataxia associated with coenzyme Q10 deficit

Par une stratégie de cartographie par homozygotie, nous avons identifié les gènes responsables de deux ataxies autosomiques récessives : le syndrome de Marinesco-Sjögren (MS) et une nouvelle forme d'ataxie associée à un déficit en coenzyme Q10 (CoQ). Le sBy homozygosity mapping, we have identified the genes responsible for two autosomal recessive ataxia : Marinesco-Sjögren syndrome (MS) and a new form of recessive ataxia associated with coenzyme Q10 (CoQ) deficit. MS syndrome is a multisystemic disease w

Identification of the genes responsible for Marinesco-Sjögren syndrome and a new from of ataxia associated with coenzyme Q10 deficit

Par une stratégie de cartographie par homozygotie, nous avons identifié les gènes responsables de deux ataxies autosomiques récessives : le syndrome de Marinesco-Sjögren (MS) et une nouvelle forme d'ataxie associée à un déficit en coenzyme Q10 (CoQ). Le syndrome MS est une affection congénitale multisystémique avec notamment la présence d'une ataxie, d'une myopathie et d'une cataracte bilatérale. Nous avons localisé le gène en 5q31, et identifié en collaboration avec le Pr Lehesjoki des mutations dans le gène SIL1 codant pour un facteur d'échange nucléotidique d'une protéine chaperones HSP70. Puis, nous avons identifié des mutations d'ADCK3 dans une nouvelle forme d'ataxie. Les homologues d'ADCK3 chez E. coli et S. cerevisiae (respectivement ubiB et abc1/coq8) sont impliqués dans la biosynthèse du CoQ. Nous avons montré que les patients présentent un déficit en CoQ et qu ADCK3 appartient à la super-famille des kinases atypiques .By homozygosity mapping, we have identified the genes responsible for two autosomal recessive ataxia : Marinesco-Sjögren syndrome (MS) and a new form of recessive ataxia associated with coenzyme Q10 (CoQ) deficit. MS syndrome is a multisystemic disease with the association of an ataxia, a myopathy and bilateral cataracts. We have localized the gene on chromosome 5q31, and in collaboration with Pr Lehesjoki, we have identified mutations in the gene SIL1 encoding for a nucleotide exchange factor for an HSP70 molecular chaperonne. We have also identified mutations in the gene ADCK3 in a new form of ataxia. ADCK3 bacteria and yeast homologs (ubiB and abc1/coq8 respectively) are involved in CoQ biosynthesis. We have shown that the patients dysplay CoQ deficit and that ADCK3 belongs to the protein kinases-like superfamily