Conformational change of RNA-helicase DHX30 by ALS/FTD-linked FUS induces mitochondrial dysfunction and cytosolic aggregates.

Genetic mutations in fused in sarcoma (FUS) cause amyotrophic lateral sclerosis (ALS). Although mitochondrial dysfunction and stress granule have been crucially implicated in FUS proteinopathy, the molecular basis remains unclear. Here, we show that DHX30, a component of mitochondrial RNA granules required for mitochondrial ribosome assembly, interacts with FUS, and plays a crucial role in ALS-FUS.

Failure of DNA double-strand break repair by tau mediates Alzheimer's disease pathology in vitro.

DNA double-strand break (DSB) is the most severe form of DNA damage and accumulates with age, in which cytoskeletal proteins are polymerized to repair DSB in dividing cells. Since tau is a microtubule-associated protein, we investigate whether DSB is involved in tau pathologies in Alzheimer's disease (AD). First, immunohistochemistry reveals the frequent coexistence of DSB and phosphorylated tau in the cortex of AD patients.

Effects of FTMT Expression by Retinal Pigment Epithelial Cells on Features of Angiogenesis.

Aberrant angiogenesis is a pathological feature of a number of diseases and arises from the uncoordinated expression of angiogenic factors as response to different cellular stresses. Age-related macular degeneration (AMD), a leading cause of vision loss, can result from pathological angiogenesis. As a mutation in the mitochondrial ferritin (FTMT) gene has been associated with AMD, its possible role in modulating angiogenic factors and angiogenesis was investigated.

Generation of Transgenic Cynomolgus Monkeys Overexpressing the Gene for Amyloid-β Precursor Protein.

Alzheimer's disease (AD) is the most common cause of dementia and understanding its pathogenesis should lead to improved therapeutic and diagnostic methods. Although several groups have developed transgenic mouse models overexpressing the human amyloid-β precursor protein (APP) gene with AD mutations, with and without presenilin mutations, as well as APP gene knock-in mouse models, these animals display amyloid pathology but do not show neurofibrillary tangles or neuronal loss. This presumably is due to differences between the etiology of the aged-related human disease and the mouse models.

Elimination of TDP-43 inclusions linked to amyotrophic lateral sclerosis by a misfolding-specific intrabody with dual proteolytic signals.

Aggregation of TAR DNA-binding protein of 43 kDa (TDP-43) is implicated in the pathogenesis of sporadic and certain familial forms of amyotrophic lateral sclerosis (ALS), suggesting elimination of TDP-43 aggregates as a possible therapeutic strategy. Here we generated and investigated a single-chain variable fragment (scFv) derived from the 3B12A monoclonal antibody (MAb) that recognises D247 of the TDP-43 nuclear export signal, an epitope masked in the physiological state. In transfected HEK293A cells, 3B12A scFv recapitulated the affinity of the full-length MAb to mislocalised TDP-43 with a defective nuclear localising signal and to a TDP-43 inclusion mimic with cysteine-to-serine substitution at RRM1.

CUL2-mediated clearance of misfolded TDP-43 is paradoxically affected by VHL in oligodendrocytes in ALS.

The molecular machinery responsible for cytosolic accumulation of misfolded TDP-43 in amyotrophic lateral sclerosis (ALS) remains elusive. Here we identified a cullin-2 (CUL2) RING complex as a novel ubiquitin ligase for fragmented forms of TDP-43. The von Hippel Lindau protein (VHL), a substrate binding component of the complex, preferentially recognized misfolded TDP-43 at Glu246 in RNA-recognition motif 2.

Attenuation of endoplasmic reticulum stress in Pelizaeus-Merzbacher disease by an anti-malaria drug, chloroquine.

Pelizaeus-Merzbacher disease (PMD) is a hypomyelinating disorder caused by the duplication and missense mutations of the proteolipid protein 1 (PLP1) gene. PLP1 missense proteins accumulate in the endoplasmic reticulum (ER) of premature oligodendrocytes and induce severe ER stress followed by apoptosis of the cells. Here, we demonstrate that an anti-malaria drug, chloroquine, decreases the amount of an ER-resident mutant PLP1 containing an alanine-243 to valine (A243V) substitution, which induces severe PMD in human.

Aberrant assembly of RNA recognition motif 1 links to pathogenic conversion of TAR DNA-binding protein of 43 kDa (TDP-43).

Aggregation of TAR DNA-binding protein of 43 kDa (TDP-43) is a pathological signature of amyotrophic lateral sclerosis (ALS). Although accumulating evidence suggests the involvement of RNA recognition motifs (RRMs) in TDP-43 proteinopathy, it remains unclear how native TDP-43 is converted to pathogenic forms. To elucidate the role of homeostasis of RRM1 structure in ALS pathogenesis, conformations of RRM1 under high pressure were monitored by NMR.

Depletion of molecular chaperones from the endoplasmic reticulum and fragmentation of the Golgi apparatus associated with pathogenesis in Pelizaeus-Merzbacher disease.

Missense mutations in the proteolipid protein 1 (PLP1) gene cause a wide spectrum of hypomyelinating disorders, from mild spastic paraplegia type 2 to severe Pelizaeus-Merzbacher disease (PMD). Mutant PLP1 accumulates in the endoplasmic reticulum (ER) and induces ER stress. However, the link between the clinical severity of PMD and the cellular response induced by mutant PLP1 remains largely unknown.

Conserved acidic amino acid residues in a second RNA recognition motif regulate assembly and function of TDP-43.

Accumulating evidence suggests that pathogenic TAR DNA-binding protein (TDP)-43 fragments contain a partial RNA-recognition motif domain 2 (RRM2) in amyotrophic lateral sclerosis (ALS)/frontotemporal lobar degeneration. However, the molecular basis for how this domain links to the conformation and function of TDP-43 is unclear. Previous crystal analyses have documented that the RRM2-DNA complex dimerizes under acidic and high salt conditions, mediated by the intermolecular hydrogen bonds of Glu246-Ile249 and Asp247-Asp247.

Effect of curcumin in a mouse model of Pelizaeus-Merzbacher disease.

PLP1 amino acid substitutions cause accumulation of misfolded protein and induce endoplasmic reticulum (ER) stress, causing Pelizaeus-Merzbacher disease (PMD), a hypomyelinating disorder of the central nerve system. Currently no effective therapy is available for PMD. Promoted by its curative effects in other genetic disease models caused by similar molecular mechanisms, we tested if curcumin, a dietary compound, can rescue the lethal phenotype of a PMD mouse model (myelin synthesis deficient, msd).

Relative importance of the tyrosine phosphorylation sites of Disabled-1 to the transmission of Reelin signaling.

Reelin regulates radial migration of the projection neurons in the developing cerebral cortex by inducing tyrosine phosphorylation of an intracellular adaptor protein, Disabled-1 (Dab1), through activation of Src family tyrosine kinases (SFKs). Five tyrosine residues of Dab1 (Y185, Y198, Y200, Y220, and Y232) are capable of being phosphorylated by SFKs. Among them, phosphorylation of Y198, Y220, and Y232 has been demonstrated after Reelin stimulation, and Y185 has been suggested to be an additional Reelin-induced phosphorylation site.

Visualizing spatiotemporal dynamics of multicellular cell-cycle progression.

The cell-cycle transition from G1 to S phase has been difficult to visualize. We have harnessed antiphase oscillating proteins that mark cell-cycle transitions in order to develop genetically encoded fluorescent probes for this purpose. These probes effectively label individual G1 phase nuclei red and those in S/G2/M phases green.

Modulation of Reelin signaling by Cyclin-dependent kinase 5.

The Reelin signaling and Cyclin-dependent kinase 5 (Cdk5) both regulate neuronal positioning in the developing brain. Using double-transgenic mice, we have previously shown that these two signaling pathways lie in parallel fashion and have a genetic interaction. Disabled-1 (Dab1), an adapter protein, mediates Reelin signaling and becomes tyrosine-phosphorylated on the binding of Reelin to its receptors.

The presence of the p53 transcripts with truncated open reading frames in Marek's disease tumor-derived cell lines.

Several kinds of the p53 transcripts in which their open reading frames (ORFs) were truncated (ranging from 101 to 765 bp) were identified in Marek's disease (MD)-derived tumor cell lines as well as avian leukosis- and reticuloendotheliosis-derived ones, detected by nested RT-PCR and subsequent nucleotide sequence analysis. In these ORFs, regions encoding the proline-rich and DNA-binding domains of the p53 protein were frequently deleted, and many of these deletions were found to cause frame shift. Western blot analysis using anti-p53 monoclonal antibodies revealed that multiple p53 isoform proteins with various molecular weights including 45-46, 35 and 28 kDa were expressed in these tumor cell lines, though the p53 protein with a molecular weight of 49 kDa was detected in chicken embryo fibroblasts transformed by the SV40 T antigen as a control.

Disabled1 regulates the intracellular trafficking of reelin receptors.

Reelin is a huge secreted protein that controls proper laminar formation in the developing brain. It is generally believed that tyrosine phosphorylation of Disabled1 (Dab1) by Src family tyrosine kinases is the most critical downstream event in Reelin signaling. The receptors for Reelin belong to the low density lipoprotein receptor family, most of whose members undergo regulated intracellular trafficking.

Regulation of actin cytoskeleton by mDab1 through N-WASP and ubiquitination of mDab1.

Migration of cells is critical to development of the central nervous system. Reelin, which was identified from the reeler mutant mice having a defect in the multilamellar structure of the brain, is thought to be a key signalling molecule that functions as a cue for determination of cell position. mDab1 (mouse Disabled homologue 1) functions downstream of Reelin.