Effect of the volume of resected discoid lateral meniscus on the contact stress of the tibiofemoral joint: A finite element analysis.

BACKGROUND: Partial meniscectomy is commonly performed for symptomatic patients with discoid lateral meniscus (DLM) if conservative treatment fails. However, the development of knee osteoarthritis and osteochondral lesion are detrimental postoperative complications. This study aimed to evaluate the effect of the volume of resected DLM on the contact stress of the tibiofemoral joint using a finite element analysis. METHODS: Subject-specific finite-element models of the knee joint of a patient with DLM were developed from computed tomographic and magnetic resonance images. To evaluate the effect of partial meniscectomy on the contact stress in the lateral tibiofemoral joint, six knee models were created in the study (the native DLM, and five partially meniscectomized DLMs (according to the preserved width of the meniscus: 12 mm, 10 mm, 8 mm, 6 mm, and 4 mm)). RESULTS: As the volume of resected DLM increased, higher contact stress was applied to the lateral tibiofemoral joint. Greater contact stress was applied to the preserved lateral meniscus than to the native DLM. CONCLUSIONS: From a biomechanical viewpoint, the native DLM was the most protective against lateral tibiofemoral contact stress in comparison to partially meniscectomized DLMs.

Casein kinase 1δ/ε phosphorylates fused in sarcoma (FUS) and ameliorates FUS-mediated neurodegeneration.

Aberrant cytoplasmic accumulation of an RNA-binding protein, fused in sarcoma (FUS), characterizes the neuropathology of subtypes of ALS and frontotemporal lobar degeneration, although the effects of post-translational modifications of FUS, especially phosphorylation, on its neurotoxicity have not been fully characterized. Here, we show that casein kinase 1δ (CK1δ) phosphorylates FUS at 10 serine/threonine residues in vitro using mass spectrometric analyses. We also show that phosphorylation by CK1δ or CK1ε significantly increased the solubility of FUS in human embryonic kidney 293 cells. In transgenic Drosophila that overexpress wt or P525L ALS-mutant human FUS in the retina or in neurons, we found coexpression of human CK1δ or its Drosophila isologue Dco in the photoreceptor neurons significantly ameliorated the observed retinal degeneration, and neuronal coexpression of human CK1δ extended fly life span. Taken together, our data suggest a novel regulatory mechanism of the assembly and toxicity of FUS through CK1δ/CK1ε-mediated phosphorylation, which could represent a potential therapeutic target in FUS proteinopathies.

Prediction of the haemostatic effects of bypassing therapy using comprehensive coagulation assays in emicizumab prophylaxis-treated haemophilia A patients with inhibitors.

In emicizumab prophylaxis, the concomitant therapy using bypassing agents (BPAs) is required for breakthrough bleeding and invasive procedures with attention to thrombotic complications. To predict coagulant effects of BPAs in emicizumab-treated patients with haemophilia A (PwHA) with inhibitor (PwHAwI), blood samples from emicizumab-treated PwHAwI (n = 8) and PwHA without inhibitor (n = 2) in phase 1/2 and HAVEN 1 study, spiked with activated prothrombin complex concentrates (aPCC) or recombinant factor VIIa (rFVIIa) ex vivo, and blood samples from emicizumab-treated PwHAwI-receiving BPAs were analysed by Ca2+ -triggered rotational thromboelastometry (ROTEM) and ellagic acid/tissue factor-triggered clot waveform analysis (CWA). Spiked aPCC, corresponded to 10-100 U/kg, markedly shortened ROTEM parameters beyond the normal range, while spiked rFVIIa, corresponded to 90-270 µg/kg, shortened them within near-normal range. Each of the spiked BPA-improved adjusted maximum coagulation velocity of CWA to within or near the normal range. In blood samples at post-infusion of aPCC (44-73 U/kg) or rFVIIa (79-93 µg/kg), the parameters of both assays improved to approximately the normal range. Taken together, ex vivo results of spiking tests in ROTEM and CWA, except aPCC spiking test in ROTEM, were relatively consistent with in vivo ones, and could usefully predict the coagulant effects of concomitant bypassing therapy for emicizumab-treated PwHAwI.

Self-assembly of FUS through its low-complexity domain contributes to neurodegeneration.

Aggregation of fused in sarcoma (FUS) protein, and mutations in FUS gene, are causative to a range of neurodegenerative disorders including amyotrophic lateral sclerosis (ALS) and frontotemporal dementia. To gain insights into the molecular mechanism whereby FUS causes neurodegeneration, we generated transgenic Drosophila melanogaster overexpressing human FUS in the photoreceptor neurons, which exhibited mild retinal degeneration. Expression of familial ALS-mutant FUS aggravated the degeneration, which was associated with an increase in cytoplasmic localization of FUS. A carboxy-terminally truncated R495X mutant FUS also was localized in cytoplasm, whereas the degenerative phenotype was diminished. Double expression of R495X and wild-type FUS dramatically exacerbated degeneration, sequestrating wild-type FUS into cytoplasmic aggregates. Notably, replacement of all tyrosine residues within the low-complexity domain, which abolished self-assembly of FUS, completely eliminated the degenerative phenotypes. Taken together, we propose that self-assembly of FUS through its low-complexity domain contributes to FUS-induced neurodegeneration.

Familial Amyotrophic Lateral Sclerosis-linked Mutations in Profilin 1 Exacerbate TDP-43-induced Degeneration in the Retina of Drosophila melanogaster through an Increase in the Cytoplasmic Localization of TDP-43.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by progressive and selective loss of motor neurons. Causative genes for familial ALS (fALS), e.g. TARDBP or FUS/TLS, have been found, among which mutations within the profilin 1 (PFN1) gene have recently been identified in ALS18. To elucidate the mechanism whereby PFN1 mutations lead to neuronal death, we generated transgenic Drosophila melanogaster overexpressing human PFN1 in the retinal photoreceptor neurons. Overexpression of wild-type or fALS mutant PFN1 caused no degenerative phenotypes in the retina. Double overexpression of fALS mutant PFN1 and human TDP-43 markedly exacerbated the TDP-43-induced retinal degeneration, i.e. vacuolation and thinning of the retina, whereas co-expression of wild-type PFN1 did not aggravate the degenerative phenotype. Notably, co-expression of TDP-43 with fALS mutant PFN1 increased the cytoplasmic localization of TDP-43, the latter remaining in nuclei upon co-expression with wild-type PFN1, whereas co-expression of TDP-43 lacking the nuclear localization signal with the fALS mutant PFN1 did not aggravate the retinal degeneration. Knockdown of endogenous Drosophila PFN1 did not alter the degenerative phenotypes of the retina in flies overexpressing wild-type TDP-43 These data suggest that ALS-linked PFN1 mutations exacerbate TDP-43-induced neurodegeneration in a gain-of-function manner, possibly by shifting the localization of TDP-43 from nuclei to cytoplasm.

Calcium-responsive transactivator (CREST) protein shares a set of structural and functional traits with other proteins associated with amyotrophic lateral sclerosis.

BACKGROUND: Mutations in calcium-responsive transactivator (CREST) encoding gene have been recently linked to ALS. Similar to several proteins implicated in ALS, CREST contains a prion-like domain and was reported to be a component of paraspeckles. RESULTS: We demonstrate that CREST is prone to aggregation and co-aggregates with FUS but not with other two ALS-linked proteins, TDP-43 and TAF15, in cultured cells. Aggregation of CREST affects paraspeckle integrity, probably by trapping other paraspeckle proteins within aggregates. Like several other ALS-associated proteins, CREST is recruited to induced stress granules. Neither of the CREST mutations described in ALS alters its subcellular localization, stress granule recruitment or detergent solubility; however Q388stop mutation results in elevated steady-state levels and more frequent nuclear aggregation of the protein. Both wild-type protein and its mutants negatively affect neurite network complexity of unstimulated cultured neurons when overexpressed, with Q388stop mutation being the most deleterious. When overexpressed in the fly eye, wild-type CREST or its mutants lead to severe retinal degeneration without obvious differences between the variants. CONCLUSIONS: Our data indicate that CREST and certain other ALS-linked proteins share several features implicated in ALS pathogenesis, namely the ability to aggregate, be recruited to stress granules and alter paraspeckle integrity. A change in CREST levels in neurons which might occur under pathological conditions would have a profound negative effect on neuronal homeostasis.