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. In vitro studies using primary mouse cortical neurons show that non-p-tau accumulates perinuclearly together with the tubulin after DSB induction with etoposide, followed by the accumulation of phosphorylated tau. Moreover, the knockdown of endogenous tau exacerbates DSB in neurons, suggesting the protective role of tau on DNA repair. Interestingly, synergistic exposure of neurons to microtubule disassembly and the DSB strikingly augments aberrant p-tau aggregation and apoptosis. These data suggest that DSB plays a pivotal role in AD-tau pathology and that the failure of DSB repair leads to tauopathy

Optineurin regulates osteoblastogenesis through STAT1

A sophisticated and delicate balance between bone resorption by osteoclasts and bone formation by osteoblasts regulates bone metabolism. Optineurin (OPTN) is a gene involved in primary open-angle glaucoma and amyotrophic lateral sclerosis. Although its function has been widely studied in ophthalmology and neurology, recent reports have shown its possible involvement in bone metabolism through negative regulation of osteoclast differentiation. However, little is known about the role of OPTN in osteoblast function. Here, we demonstrated that OPTN controls not only osteoclast but also osteoblast differentiation. Different parameters involved in osteoblastogenesis and osteoclastogenesis were assessed in Optn−/- mice. The results showed that osteoblasts from Optn−/- mice had impaired alkaline phosphatase activity, defective mineralized nodules, and inability to support osteoclast differentiation. Moreover, OPTN could bind to signal transducer and activator of transcription 1 (STAT1) and regulate runt-related transcription factor 2 (RUNX2) nuclear localization by modulating STAT1 levels in osteoblasts. These data suggest that OPTN is involved in bone metabolism not only by regulating osteoclast function but also by regulating osteoblast function by mediating RUNX2 nuclear translocation via STAT1

P301S Mutant Human Tau Transgenic Mice Manifest Early Symptoms of Human Tauopathies with Dementia and Altered Sensorimotor Gating

Tauopathies are neurodegenerative disorders characterized by the accumulation of abnormal tau protein leading to cognitive and/or motor dysfunction. To understand the relationship between tau pathology and behavioral impairments, we comprehensively assessed behavioral abnormalities in a mouse tauopathy model expressing the human P301S mutant tau protein in the early stage of disease to detect its initial neurological manifestations. Behavioral abnormalities, shown by open field test, elevated plus-maze test, hot plate test, Y-maze test, Barnes maze test, Morris water maze test, and/or contextual fear conditioning test, recapitulated the neurological deficits of human tauopathies with dementia. Furthermore, we discovered that prepulse inhibition (PPI), a marker of sensorimotor gating, was enhanced in these animals concomitantly with initial neuropathological changes in associated brain regions. This finding provides evidence that our tauopathy mouse model displays neurofunctional abnormalities in prodromal stages of disease, since enhancement of PPI is characteristic of amnestic mild cognitive impairment, a transitional stage between normal aging and dementia such as Alzheimer's disease (AD), in contrast with attenuated PPI in AD patients. Therefore, assessment of sensorimotor gating could be used to detect the earliest manifestations of tauopathies exemplified by prodromal AD, in which abnormal tau protein may play critical roles in the onset of neuronal dysfunctions

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. WT FUS did not affect mitochondrial localization of DHX30, but the mutant FUS lowered the signal of mitochondrial DHX30 and promoted the colocalization of cytosolic FUS aggregates and stress granule markers. The immunohistochemistry of the spinal cord from an ALS-FUS patient also confirmed the colocalization, and the immunoelectron microscope demonstrated decreased mitochondrial DHX30 signal in the spinal motor neurons. Subcellular fractionation by the detergent-solubility and density-gradient ultracentrifugation revealed that mutant FUS also promoted cytosolic mislocalization of DHX30 and aggregate formation. Interestingly, the mutant FUS disrupted the DHX30 conformation with aberrant disulfide formation, leading to impaired mitochondrial translation. Moreover, blue-native gel electrophoresis revealed an OXPHOS assembly defect caused by the FUS mutant, which was similar to that caused by DHX30 knockdown. Collectively, our study proposes DHX30 as a pivotal molecule in which disulfide-mediated conformational change mediates mitochondrial dysfunction and cytosolic aggregate formation in ALS-FUS

DNA-Based Synthetic Growth Factor Surrogates with Fine-Tuned Agonism

Designing synthetic surrogates of functional proteins is an important, albeit challenging, task in the field of chemistry. A strategy toward the design of synthetic agonists for growth factors or cytokine receptors that elicit a desired signal activity has been in high demand, as such ligands hold great promise as safer and more effective therapeutics. In the present study, we used a DNA aptamer as a building block and described the strategy-guided design of a synthetic receptor agonist with fine-tuned agonism

生体酵素および受容体の精密活性制御に向けた機能性分子の設計

主1工学_物質創造工

インターフェロンαが著効した腎癌骨格筋・小腸転移の1例

Skeletal muscle and small intestine are rare sites of metastasis in renal cell carcinoma. Therefore very few reports of interferon-alpha (IFN-alpha) therapy exist for these types of metastasis. Here, a case of metastatic renal cell carcinoma to muscle and jejunum is reported. After IFN-alpha therapy for 9 weeks, muscle metastasis completely disappeared and intestinal lesions were markedly reduced. However, subsequent patient compliance for this therapy was poor, resulting in death after relapse of the RCC.腎癌では骨格筋転移や小腸転移は稀であり, これらの転移に対するインターフェロンαによる療法の報告は非常に少ない。われわれは腎癌骨格筋・空腸転移の1例を経験した。9週間のインターフェロンα療法により筋肉転移は完全に消失し, 空腸転移も著明に縮小した。しかしながら治療の自己中断により病変の再燃を認め, 癌死の転帰をとった。(著者抄録

生体酵素および受容体の精密活性制御に向けた機能性分子の設計

主1工学_物質創造工

A DNA Aptamer That Inhibits the Formation of Unliganded Receptor Dimer and Ligand-Independent Signaling in Cancer Cells

Growth factor receptors are activated through dimerization by the binding of their ligands and play pivotal roles in normal cell function. However, in cancer cells, the overexpression of receptors often causes the formation of unliganded receptor dimers, which can be activated in a ligand-independent manner. Thus, the unliganded receptor dimer is a promising target to inhibit aberrant signaling in cancer. Here, we report an aptamer that inhibits ligand-independent receptor activation via preventing the formation of unliganded receptor dimer. By biasing the receptor monomer–dimer equilibrium to the monomer, this aptamer inhibited aberrant cell signaling caused by the unliganded receptor dimer. This work presents a new possibility of oligonucleotide-based therapeutics for cancer.</p