Limits...
Drosha inclusions are new components of dipeptide-repeat protein aggregates in FTLD-TDP and ALS C9orf72 expansion cases.

Porta S, Kwong LK, Trojanowski JQ, Lee VM - J. Neuropathol. Exp. Neurol. (2015)

Bottom Line: Moreover, through a repeat-associated non-ATG translation mechanism, G4C2 repeats translation leads to dipeptide-repeat protein aggregation in the cytoplasm of neurons.Further characterization of Drosha-positive neuronal cytoplasmic inclusions in the hippocampus, frontal cortex, and cerebellum revealed colocalization with p62 and ubiquilin-2, 2 pathognomonic signatures of c9FTLD-TDP and c9ALS cases; however, Drosha inclusions rarely colocalized with TDP-43 pathology.We conclude that Drosha may play a unique pathogenic role in the onset or progression of FTLD-TDP/ALS in patients with the C9orf72 mutation.

View Article: PubMed Central - PubMed

Affiliation: From the Center for Neurodegenerative Disease Research, Department of Pathology and Laboratory Medicine, University of Pennsylvania, Perelman School of Medicine, Philadelphia, Pennsylvania.

ABSTRACT
Frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS) are 2 neurodegenerative disorders that share clinical, genetic, and neuropathologic features. The presence of abnormal expansions of GGGGCC repeats (G4C2 repeats) in a noncoding region of the Chromosome 9 open reading frame 72 (C9orf72) gene is the major genetic cause of both FTLD and ALS. Transcribed G4C2 repeats can form nuclear RNA foci and recruit RNA-binding proteins, thereby inhibiting their normal function. Moreover, through a repeat-associated non-ATG translation mechanism, G4C2 repeats translation leads to dipeptide-repeat protein aggregation in the cytoplasm of neurons. Here, we identify Drosha protein as a new component of these dipeptide-repeat aggregates. In C9orf72 mutation cases of FTLD-TDP (c9FTLD-TDP) and ALS (c9ALS), but not in FTLD or ALS cases without C9orf72 mutation, Drosha is mislocalized to form neuronal cytoplasmic inclusions in the hippocampus, frontal cortex, and cerebellum. Further characterization of Drosha-positive neuronal cytoplasmic inclusions in the hippocampus, frontal cortex, and cerebellum revealed colocalization with p62 and ubiquilin-2, 2 pathognomonic signatures of c9FTLD-TDP and c9ALS cases; however, Drosha inclusions rarely colocalized with TDP-43 pathology. We conclude that Drosha may play a unique pathogenic role in the onset or progression of FTLD-TDP/ALS in patients with the C9orf72 mutation.

Show MeSH

Related in: MedlinePlus

Drosha is a component of dipeptide-repeat (DPR) aggregates. (A–F) Immunohistochemistry (IHC) results for Drosha (A, D), polyGly-Ala (GA) (B, E), and polyGly-Pro (GP) (C, F) proteins in the hippocampus and cerebellum of patients with C9orf72 expansion mutations. Comparative analyses of Drosha, GA, and GP IHC in consecutive brain sections show fewer Drosha-positive inclusions compared with the numbers of GA- and GP-positive aggregates (see examples identified by arrows). (G–L) Double immunofluorescence staining with anti-Drosha (red, G, J, insets) and anti-GA (green, H, K, insets) antibodies in dentate granule neurons shows that Drosha-positive neuronal cytoplasmic inclusions (NCIs) colocalize with GA-immunoreactive aggregates albeit with Drosha in the center of these inclusions that are surrounded by GA positivity (I, arrowhead and inset). Asterisks indicate cell wherein there are GA-positive aggregates that do not contain mislocalized Drosha (G–I). Cell nuclei stained with Dapi (blue). xyz cut of a Drosha-positive NCI (red, J and L) surrounded by GA-immunoreactive material (green, K and L). Scale bars = (G–I) 10 μm; (J–L) 2 μm.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC4362478&req=5

Figure 3: Drosha is a component of dipeptide-repeat (DPR) aggregates. (A–F) Immunohistochemistry (IHC) results for Drosha (A, D), polyGly-Ala (GA) (B, E), and polyGly-Pro (GP) (C, F) proteins in the hippocampus and cerebellum of patients with C9orf72 expansion mutations. Comparative analyses of Drosha, GA, and GP IHC in consecutive brain sections show fewer Drosha-positive inclusions compared with the numbers of GA- and GP-positive aggregates (see examples identified by arrows). (G–L) Double immunofluorescence staining with anti-Drosha (red, G, J, insets) and anti-GA (green, H, K, insets) antibodies in dentate granule neurons shows that Drosha-positive neuronal cytoplasmic inclusions (NCIs) colocalize with GA-immunoreactive aggregates albeit with Drosha in the center of these inclusions that are surrounded by GA positivity (I, arrowhead and inset). Asterisks indicate cell wherein there are GA-positive aggregates that do not contain mislocalized Drosha (G–I). Cell nuclei stained with Dapi (blue). xyz cut of a Drosha-positive NCI (red, J and L) surrounded by GA-immunoreactive material (green, K and L). Scale bars = (G–I) 10 μm; (J–L) 2 μm.

Mentions: Next, we compared the distribution of Drosha inclusions and GA and GP DPRs in hippocampus and cerebellum of our autopsy cohort. As reported by others (18), GA- and GP-immunoreactive protein aggregates were only found in c9FTLD-TDP and c9ALS cases (data not shown). Furthermore, side-by-side comparison of Drosha-positive NCI and GA or GP DPRs in consecutive brain sections showed fewer Drosha-positive inclusions compared with GA- and GP-positive DPR aggregates (Fig. 3A–F), suggesting that Drosha mislocalization does not occur in all cells with DPR aggregates.


Drosha inclusions are new components of dipeptide-repeat protein aggregates in FTLD-TDP and ALS C9orf72 expansion cases.

Porta S, Kwong LK, Trojanowski JQ, Lee VM - J. Neuropathol. Exp. Neurol. (2015)

Drosha is a component of dipeptide-repeat (DPR) aggregates. (A–F) Immunohistochemistry (IHC) results for Drosha (A, D), polyGly-Ala (GA) (B, E), and polyGly-Pro (GP) (C, F) proteins in the hippocampus and cerebellum of patients with C9orf72 expansion mutations. Comparative analyses of Drosha, GA, and GP IHC in consecutive brain sections show fewer Drosha-positive inclusions compared with the numbers of GA- and GP-positive aggregates (see examples identified by arrows). (G–L) Double immunofluorescence staining with anti-Drosha (red, G, J, insets) and anti-GA (green, H, K, insets) antibodies in dentate granule neurons shows that Drosha-positive neuronal cytoplasmic inclusions (NCIs) colocalize with GA-immunoreactive aggregates albeit with Drosha in the center of these inclusions that are surrounded by GA positivity (I, arrowhead and inset). Asterisks indicate cell wherein there are GA-positive aggregates that do not contain mislocalized Drosha (G–I). Cell nuclei stained with Dapi (blue). xyz cut of a Drosha-positive NCI (red, J and L) surrounded by GA-immunoreactive material (green, K and L). Scale bars = (G–I) 10 μm; (J–L) 2 μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4362478&req=5

Figure 3: Drosha is a component of dipeptide-repeat (DPR) aggregates. (A–F) Immunohistochemistry (IHC) results for Drosha (A, D), polyGly-Ala (GA) (B, E), and polyGly-Pro (GP) (C, F) proteins in the hippocampus and cerebellum of patients with C9orf72 expansion mutations. Comparative analyses of Drosha, GA, and GP IHC in consecutive brain sections show fewer Drosha-positive inclusions compared with the numbers of GA- and GP-positive aggregates (see examples identified by arrows). (G–L) Double immunofluorescence staining with anti-Drosha (red, G, J, insets) and anti-GA (green, H, K, insets) antibodies in dentate granule neurons shows that Drosha-positive neuronal cytoplasmic inclusions (NCIs) colocalize with GA-immunoreactive aggregates albeit with Drosha in the center of these inclusions that are surrounded by GA positivity (I, arrowhead and inset). Asterisks indicate cell wherein there are GA-positive aggregates that do not contain mislocalized Drosha (G–I). Cell nuclei stained with Dapi (blue). xyz cut of a Drosha-positive NCI (red, J and L) surrounded by GA-immunoreactive material (green, K and L). Scale bars = (G–I) 10 μm; (J–L) 2 μm.
Mentions: Next, we compared the distribution of Drosha inclusions and GA and GP DPRs in hippocampus and cerebellum of our autopsy cohort. As reported by others (18), GA- and GP-immunoreactive protein aggregates were only found in c9FTLD-TDP and c9ALS cases (data not shown). Furthermore, side-by-side comparison of Drosha-positive NCI and GA or GP DPRs in consecutive brain sections showed fewer Drosha-positive inclusions compared with GA- and GP-positive DPR aggregates (Fig. 3A–F), suggesting that Drosha mislocalization does not occur in all cells with DPR aggregates.

Bottom Line: Moreover, through a repeat-associated non-ATG translation mechanism, G4C2 repeats translation leads to dipeptide-repeat protein aggregation in the cytoplasm of neurons.Further characterization of Drosha-positive neuronal cytoplasmic inclusions in the hippocampus, frontal cortex, and cerebellum revealed colocalization with p62 and ubiquilin-2, 2 pathognomonic signatures of c9FTLD-TDP and c9ALS cases; however, Drosha inclusions rarely colocalized with TDP-43 pathology.We conclude that Drosha may play a unique pathogenic role in the onset or progression of FTLD-TDP/ALS in patients with the C9orf72 mutation.

View Article: PubMed Central - PubMed

Affiliation: From the Center for Neurodegenerative Disease Research, Department of Pathology and Laboratory Medicine, University of Pennsylvania, Perelman School of Medicine, Philadelphia, Pennsylvania.

ABSTRACT
Frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS) are 2 neurodegenerative disorders that share clinical, genetic, and neuropathologic features. The presence of abnormal expansions of GGGGCC repeats (G4C2 repeats) in a noncoding region of the Chromosome 9 open reading frame 72 (C9orf72) gene is the major genetic cause of both FTLD and ALS. Transcribed G4C2 repeats can form nuclear RNA foci and recruit RNA-binding proteins, thereby inhibiting their normal function. Moreover, through a repeat-associated non-ATG translation mechanism, G4C2 repeats translation leads to dipeptide-repeat protein aggregation in the cytoplasm of neurons. Here, we identify Drosha protein as a new component of these dipeptide-repeat aggregates. In C9orf72 mutation cases of FTLD-TDP (c9FTLD-TDP) and ALS (c9ALS), but not in FTLD or ALS cases without C9orf72 mutation, Drosha is mislocalized to form neuronal cytoplasmic inclusions in the hippocampus, frontal cortex, and cerebellum. Further characterization of Drosha-positive neuronal cytoplasmic inclusions in the hippocampus, frontal cortex, and cerebellum revealed colocalization with p62 and ubiquilin-2, 2 pathognomonic signatures of c9FTLD-TDP and c9ALS cases; however, Drosha inclusions rarely colocalized with TDP-43 pathology. We conclude that Drosha may play a unique pathogenic role in the onset or progression of FTLD-TDP/ALS in patients with the C9orf72 mutation.

Show MeSH
Related in: MedlinePlus