The ULK complex-LRRK1 axis regulates Parkin-mediated mitophagy via Rab7 Ser-72 phosphorylation.

Mitophagy, a type of selective autophagy, specifically targets damaged mitochondria. The ULK complex regulates Parkin-mediated mitophagy, but the mechanism through which the ULK complex initiates mitophagosome formation remains unknown. The Rab7 GTPase (herein referring to Rab7a) is a key initiator of mitophagosome formation, and Ser-72 phosphorylation of Rab7 is important for this process. We have previously identified LRRK1 as a protein kinase responsible for Rab7 Ser-72 phosphorylation. In this study, we investigated the role of LRRK1 in mitophagy. We showed that LRRK1 functions downstream of ULK1 and ULK2 in Parkin-mediated mitophagy. Furthermore, we demonstrated that ectopic targeting of active LRRK1 to mitochondria is sufficient to induce the Ser-72 phosphorylation of Rab7, circumventing the requirement for ATG13, a component of the ULK complex. Thus, the ULK complex recruits LRRK1 to mitochondria by interacting with ATG13 to initiate mitophagosome formation. This study highlights the crucial role of the ULK complex-LRRK1 axis in the regulation of Parkin-mediated mitophagy.

Identification of compounds that preferentially suppress the growth of T-cell acute lymphoblastic leukemia-derived cells.

T-cell acute lymphoblastic leukemia (T-ALL) is one of the most frequently occurring cancers in children and is associated with a poor prognosis. Here, we performed large-scale screening of natural compound libraries to identify potential drugs against T-ALL. We identified three low-molecular-weight compounds (auxarconjugatin-B, rumbrin, and lavendamycin) that inhibited the proliferation of the T-ALL cell line CCRF-CEM, but not that of the B lymphoma cell line Raji in a low concentration range. Among them, auxarconjugatin-B and rumbrin commonly contained a polyenyl 3-chloropyrrol in their chemical structure, therefore we chose auxarconjugatin-B for further analyses. Auxarconjugatin-B suppressed the in vitro growth of five human T-ALL cell lines and two T-ALL patient-derived cells, but not that of adult T-cell leukemia patient-derived cells. Cultured normal T cells were several-fold resistant to auxarconjugatin-B. Auxarconjugatin-B and its synthetic analogue Ra#37 depolarized the mitochondrial membrane potential of CCRF-CEM cells within 3 h of treatment. These compounds are promising seeds for developing novel anti-T-ALL drugs.

Synthesis and anti-tumor activities in human leukemia-derived cells of polyenylpyrroles with a methyl group at the conjugated polyene terminus.

To develop novel drugs for treating T-cell acute lymphoblastic leukemia (T-ALL) and acute myeloid leukemia (AML) which are highly malignant hematological tumors, a series of analogs having a polyenylpyrrole structure of natural compounds (rumbrin and auxarconjugatin B) were synthesized and investigated their structure-activity relationships (SAR) of in vitro anti-T-ALL and anti-AML activities. We obtained three findings: (1) introduction of a methyl group at the conjugated polyene terminus enhanced anti-T-ALL activity, (2) analogs with a 3-chloropyrrole moiety had even higher selectivity for T-ALL cells, and (3) some analogs were effective against AML-derived cells. Among the studied compounds, 3-chloro-2-(8-ethoxycarbonylnona-1,3,5,7-tetraenyl) pyrrole 4e was the most promising candidate of T-ALL- and AML-treating drug. This study provides useful structural information for designing novel drugs treating T-ALL and AML.

LRRK1 phosphorylation of Rab7 at S72 links trafficking of EGFR-containing endosomes to its effector RILP.

Ligand-induced activation of epidermal growth factor receptor (EGFR) initiates trafficking events that re-localize the receptor from the cell surface to intracellular endocytic compartments. EGFR-containing endosomes are transported to lysosomes for degradation by the dynein-dynactin motor protein complex. However, this cargo-dependent endosomal trafficking mechanism remains largely uncharacterized. Here, we show that GTP-bound Rab7 is phosphorylated on S72 by leucine-rich repeat kinase 1 (LRRK1) at the endosomal membrane. This phosphorylation promotes the interaction of Rab7 (herein referring to Rab7a) with its effector RILP, resulting in recruitment of the dynein-dynactin complex to Rab7-positive vesicles. This, in turn, facilitates the dynein-driven transport of EGFR-containing endosomes toward the perinuclear region. These findings reveal a mechanism regulating the cargo-specific trafficking of endosomes.

Synthesis of polyenylpyrrole derivatives with selective growth inhibitory activity against T-cell acute lymphoblastic leukemia cells.

T-cell acute lymphoblastic leukemia (T-ALL) is a hardly curable disease with a high relapse rate. 20 analogs were synthesized based on the structures of two kinds of fungi-derived polyenylpyrrole products (rumbrin (1) and auxarconjugatin-B (2)) to suppress the growth of T-ALL-derived cell line CCRF-CEM and tested for growth-inhibiting activity. The octatetraenylpyrrole analog gave an IC50 of 0.27 µM in CCRF-CEM cells, while it did not affect Burkitt lymphoma-derived cell line Raji and the cervical cancer cell line HeLa, or the oral cancer cell line HSC-3 (IC50 > 10 µM). This compound will be a promising compound for developing T-ALL-specific drugs.

A soluble endoplasmic reticulum factor as regenerative therapy for Wolfram syndrome.

Endoplasmic reticulum (ER) stress-mediated cell death is an emerging target for human chronic disorders, including neurodegeneration and diabetes. However, there is currently no treatment for preventing ER stress-mediated cell death. Here, we show that mesencephalic astrocyte-derived neurotrophic factor (MANF), a neurotrophic factor secreted from ER stressed cells, prevents ER stress-mediated ß cell death and enhances ß cell proliferation in cell and mouse models of Wolfram syndrome, a prototype of ER disorders. Our results indicate that molecular pathways regulated by MANF are promising therapeutic targets for regenerative therapy of ER stress-related disorders, including diabetes, retinal degeneration, neurodegeneration, and Wolfram syndrome.

Quantitative 3D Shape Analysis of CT Images of Thymoma: A Comparison With Histological Types.

OBJECTIVE. The purpose of this study is to differentiate between low- and high-risk types of thymoma using quantitative 3D shape analysis of CT images. MATERIALS AND METHODS. This retrospective study included 44 patients with a pathologic diagnosis of thymoma. Two radiologists semiautomatically contoured CT images of the tumors and evaluated 3D shape parameters-namely, quantitative indicators of surface smoothness, including sphericity, ellipsoidality, and discrete compactness. The visual CT findings that were analyzed included longest diameter, shape (round-oval, lobulated, or irregular), calcification, cystic or necrotic changes, and enhancement pattern (homogeneous or heterogeneous). The difference and discriminating performance between low-risk (types A, AB, and B1) and high-risk (types B2 and B3) thymomas were statistically assessed. Interobserver agreement was determined using the concordance correlation coefficient. RESULTS. Twenty-three low-risk and 21 high-risk thymomas were identified on the basis of pathologic findings. The median values of sphericity and ellipsoidality were significantly higher for low-risk thymomas than for high-risk thymomas (for sphericity, 0.566 vs 0.517; for ellipsoidality, 0.941 vs 0.875; p < 0.05 for both). The AUC values of sphericity and ellipsoidality were 0.704 and 0.712, respectively. The best cutoff values were 0.528 and 0.919 for sphericity and ellipsoidality, respectively. Risk assessment combining these cutoff values and the mode of tumor detection (incidental detection or detection based on the presence of symptoms) improved the AUC value to 0.856 (sensitivity, 81.0% [17 of 21 patients]; specificity, 82.6% [19 of 23 patients]). All 3D shape parameters showed almost perfect interobserver agreement (concordance correlation coefficient, > 0.90). The visual CT findings were not significantly different between low- and high-risk thymomas (p > 0.05 for all). CONCLUSION. Quantitative 3D shape analysis has excellent reproducibility, and combining this technique with information on the detection mode helps differentiate low- from high-risk thymomas.

Poly-dipeptides encoded by the C9ORF72 repeats block global protein translation.

The expansion of the GGGGCC hexanucleotide repeat in the non-coding region of the Chromosome 9 open-reading frame 72 (C9orf72) gene is the most common genetic cause of frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). This genetic alteration leads to the accumulation of five types of poly-dipeptides translated from the GGGGCC hexanucleotide repeat. Among these, poly-proline-arginine (poly-PR) and poly-glycine-arginine (poly-GR) peptides are known to be neurotoxic. However, the mechanisms of neurotoxicity associated with these poly-dipeptides are not clear. A proteomics approach identified a number of interacting proteins with poly-PR peptide, including mRNA-binding proteins, ribosomal proteins, translation initiation factors and translation elongation factors. Immunostaining of brain sections from patients with C9orf72 ALS showed that poly-GR was colocalized with a mRNA-binding protein, hnRNPA1. In vitro translation assays showed that poly-PR and poly-GR peptides made insoluble complexes with mRNA, restrained the access of translation factors to mRNA, and blocked protein translation. Our results demonstrate that impaired protein translation mediated by poly-PR and poly-GR peptides plays a role in neurotoxicity and reveal that the pathways altered by the poly-dipeptides-mRNA complexes are potential therapeutic targets for treatment of C9orf72 FTD/ALS.

Evidence of a link between ubiquilin 2 and optineurin in amyotrophic lateral sclerosis.

A mutation in the ubiquilin 2 gene (UBQLN2) was recently identified as a cause of X-linked amyotrophic lateral sclerosis (ALS)/frontotemporal dementia (FTD) and a major component of the inclusion bodies commonly found with a wide variety of ALS. ALS-linked mutations in UBQLN2 are clustered in a unique proline-X-X repeat region, reportedly leading to impairment of the ubiquitin proteasome system. However, the molecular properties of mutant UBQLN2 remain unclear. To gain insight into the pathogenesis of UBQLN2-linked ALS/FTD, we examined the biochemical and cellular characteristics of mutant UBQLN2 in vitro. UBQLN2 localized in Rab11-positive endosomal vesicles formed by the ALS-linked molecule optineurin (OPTN). These vesicles were ubiquitin- and p62-immunopositive and also co-localized with an initiator of the autophagic process, ULK1, after amino acid starvation. An ALS-linked mutation (E478G) in OPTN abolished vesicle formation. ALS-linked mutations in UBQLN2 additively enhanced UBQLN2 aggregation and formation of inclusion bodies, resulting in mislocation from OPTN vesicles. UBQLN2 was found to be a potent regulator of the levels of the FTD-linked secretory factor progranulin, possibly via the endosomal system, and ALS-linked mutations disturbed these functional consequences. This study demonstrates that ALS-linked mutations in both OPTN and UBQLN2 interfere with the constitution of specific endosomal vesicles, suggesting that the vesicles are involved in protein homeostasis and that these proteins function in common pathological processes. These data suggest a novel disease spectrum and provide new pathological insights into OPTN and UBQLN2, enhancing our understanding of the molecular basis of ALS/FTD.

Mislocated FUS is sufficient for gain-of-toxic-function amyotrophic lateral sclerosis phenotypes in mice.

Mutations in RNA-binding proteins, including fused in sarcoma (FUS) and TAR DNA-binding protein 43 (TDP-43, encoded by TARDBP), are associated with sporadic and familial amyotrophic lateral sclerosis. A major question is whether neuronal loss is caused by toxic gain-of-function cytoplasmic aggregates or loss of nuclear RNA-binding protein function. We generated a transgenic mouse overexpressing exogenous FUS without a nuclear localization signal (ΔNLS-FUS), which developed progressive spastic motor deficits and neuronal loss in the motor cortex. The ΔNLS-FUS protein was restricted to the cytoplasm and formed ubiquitin/p62-positive aggregates. Endogenous FUS expression, nuclear localization, and splicing activity were not altered, indicating that mislocated FUS is sufficient for proteinopathy. Crossing ΔNLS-FUS with wild-type human TDP-43 transgenic mice exacerbated pathological and behavioural phenotypes, suggesting that both proteins are involved in a common cascade. RNA-sequence analysis revealed specific transcriptome alterations, including genes regulating dynein-associated molecules and endoplasmic reticulum stress. ΔNLS-FUS mice are promising tools for understanding amyotrophic lateral sclerosis pathogenesis and testing new therapeutic approaches.

Enhanced aggregation of androgen receptor in induced pluripotent stem cell-derived neurons from spinal and bulbar muscular atrophy.

Spinal and bulbar muscular atrophy (SBMA) is an X-linked motor neuron disease caused by a CAG repeat expansion in the androgen receptor (AR) gene. Ligand-dependent nuclear accumulation of mutant AR protein is a critical characteristic of the pathogenesis of SBMA. SBMA has been modeled in AR-overexpressing animals, but precisely how the polyglutamine (polyQ) expansion leads to neurodegeneration is unclear. Induced pluripotent stem cells (iPSCs) are a new technology that can be used to model human diseases, study pathogenic mechanisms, and develop novel drugs. We established SBMA patient-derived iPSCs, investigated their cellular biochemical characteristics, and found that SBMA-iPSCs can differentiate into motor neurons. The CAG repeat numbers in the AR gene of SBMA-iPSCs and also in the atrophin-1 gene of iPSCs derived from another polyQ disease, dentato-rubro-pallido-luysian atrophy (DRPLA), remain unchanged during reprogramming, long term passage, and differentiation, indicating that polyQ disease-associated CAG repeats are stable during maintenance of iPSCs. The level of AR expression is up-regulated by neuronal differentiation and treatment with the AR ligand dihydrotestosterone. Filter retardation assays indicated that aggregation of ARs following dihydrotestosterone treatment in neurons derived from SBMA-iPSCs increases significantly compared with neurological control iPSCs, easily recapitulating the pathological feature of mutant ARs in SBMA-iPSCs. This phenomenon was not observed in iPSCs and fibroblasts, thereby showing the neuron-dominant phenotype of this disease. Furthermore, the HSP90 inhibitor 17-allylaminogeldanamycin sharply decreased the level of aggregated AR in neurons derived from SBMA-iPSCs, indicating a potential for discovery and validation of candidate drugs. We found that SBMA-iPSCs possess disease-specific biochemical features and could thus open new avenues of research into not only SBMA, but also other polyglutamine diseases.

Evidence of TRK-Fused Gene (TFG1) function in the ubiquitin-proteasome system.

A heterozygous mutation in the TRK-Fused Gene (TFG1) has recently been identified in hereditary motor and sensory neuropathy with proximal dominant involvement (HMSN-P). TFG1 protein is reportedly localized at endoplasmic reticulum (ER) exit sites and modulates ER export, but the mechanism of its action in neurodegeneration remains unclear. To clarify the molecular pathogenesis of HMSN-P, we examined the biochemical and cellular characteristics of wild-type and mutant (P285L) TFG1 in vitro. A coexpression study of human TFG1 and ER substrates, which are degraded by the ubiquitin-proteasome system (UPS), showed that TFG1 is an inhibitory regulator of the UPS. Deletion mutant constructs revealed that the proline/glutamine-rich domain in TFG1 was critical for regulation of the UPS and proper localization at ER exit sites. Furthermore, overexpression of wild-type TFG1 increased ubiquitination of ER-resident proteins and led to ER stress. Mutant (P285L) TFG1, which is in the proline/glutamine-rich domain, enhanced the inhibitory effect on the UPS and the level of ER stress. These data provide new pathological insights into HMSN-P, and we suspect that the pathogenesis is tightly associated with disruption of intracellular protein homeostasis and ER stress.

Characterization of inclusion bodies with cytoprotective properties formed by seipinopathy-linked mutant seipin.

Gain-of-toxic mutations in the N-glycosylation motif of the seipin/BSCL2 gene (namely, the N88S and S90L mutations) cause autosomal dominant motor neuron diseases, termed 'seipinopathy'. Expressed mutant seipin is improperly folded and accumulates in the endoplasmic reticulum (ER), leading to an unfolded protein response (UPR). Furthermore, cells expressing mutant seipin contain unique cytoplasmic inclusion bodies (IB) that form via a different mechanism from that of ubiquitinated inclusions, or aggresomes. Whether the formation of these IB is pathogenic or protective in neurodegenerative diseases remains unclear. Here, we determined that mutant seipin IB are negative for two well-established ER markers, immunoglobulin-heavy-chain-binding protein and calnexin, indicating a distinct compartmentalization from the main ER, and that mutant seipin IB are formed via a mechanism that is independent of major UPR transducers and ER chaperons. Electron microscopy and coexpression study with variant α1-antitrypsin cDNA showed that seipin IB are compatible with unique cytoplasmic vesicles known as ER-derived protective organelles (ERPO). We also obtained evidence that seipin IB exhibit a cytoprotective property via the attenuation of ER stress. These findings suggest that ERPO, such as seipin IB, are a novel adaptation machinery against the accumulation of unfolded proteins in the ER.

Fatal intracranial hemorrhage after intravenous thrombolytic therapy for acute ischemic stroke associated with cancer-related nonbacterial thrombotic endocarditis.

Nonbacterial thrombotic endocarditis (NBTE) is associated with hypercoagulability in patients with inflammatory states such as cancer and autoimmune diseases. Cardiac vegetations caused by NBTE often lead to life-threatening systemic thromboembolism that most frequently affects the brain, spleen, and kidneys. A 54-year-old woman diagnosed with ovarian cancer suddenly developed back pain and left hemiparesis. Although intravenous alteplase (rt-PA) therapy was administered to treat hyperacute ischemic infarction detected by magnetic resonance imaging, intracranial hemorrhage occurred in the left hemisphere several hours later as the patient started to lose consciousness. Transthoracic echocardiography then detected aseptic vegetations on the mitral and aortic valves, indicating NBTE associated with ovarian cancer. Because therapies for NBTE are limited to heparinization and control of underlying diseases, thrombolytic therapy for acute embolic stroke in NBTE has not yet been validated. We postulated that thrombolytic therapy for cancer-related NBTE might easily cause hemorrhagic complications because cancer-related NBTE is often similar to the state of disseminated intravascular coagulation.

Pulmonary hypertension in an adult patient with congenital central hypoventilation syndrome: a case report.

Background: Congenital central hypoventilation syndrome (CCHS) is a life-threatening disorder of autonomic respiratory control. Mutations in the paired-like homeobox 2B (PHOX2B) gene impair respiratory drive, causing hypercarbia and hypoxaemia. Most patients with CCHS are diagnosed in the neonatal period; however, a few are diagnosed in adulthood. Case summary: We report a 32-year-old man with a history of unexplained cyanosis 14 days after birth. He presented to our hospital with breathlessness and abnormal electrocardiogram findings discovered in a health check-up. Pulmonary hypertension (PH) was suspected based on electrocardiographic and echocardiographic evidence of right ventricular (RV) overload. Results of pulmonary function tests and chest computed tomography were normal. Arterial blood gas analysis revealed type 2 respiratory failure without a significant alveolar-arterial oxygen gradient, indicating alveolar hypoventilation. Right heart catheterization (RHC) showed pre-capillary PH [pulmonary artery pressure 47/24 (35) mmHg], and a hyperventilation challenge test and a non-invasive positive pressure ventilation (NPPV) treatment during RHC provided drastic improvement in PH [pulmonary artery pressure 28/12 (18) mmHg]. Congenital central hypoventilation syndrome was diagnosed based on genetic testing (20/25 polyalanine repeat expansion mutations in PHOX2B). After NPPV therapy initiation, the RV overload was slightly improved. Discussion: Some patients with CCHS develop mild hypoventilation without overt clinical signs, and PH can be the first clinical manifestation. In our case, the hyperventilation challenge test improved PH. Although CCHS causes chronic alveolar hypoxia and hypoxic pulmonary vasoconstriction with subsequent PH, optimal ventilation therapy can improve pulmonary circulation even in affected adults.

A new therapeutic target for systemic lupus erythematosus: the current landscape for drug development of a toll-like receptor 7/8 antagonist through academia-industry-government collaboration.

Systemic Lupus Erythematosus (SLE) is an autoimmune disease characterized by inflammation in multiple organs. A few treatments for SLE currently exist, including antimalarials, glucocorticoids, immunosuppressants, and two recently approved antibody agents; however, an unmet medical need remains for SLE. In addition, developing new drugs targeting SLE is a challenge since no specific biomarkers exist for the prediction of disease progression or drug response. A new drug candidate, E6742, is a specific antagonist of the toll-like receptors 7/8. To address the challenges for drug development in SLE, the process of developing E6742 utilizes a unique system of the Japan Agency for Medical Research and Development (AMED), the Cyclic Innovation for Clinical Empowerment (CiCLE) program. In the CiCLE program, a Phase 1 study in healthy adults was completed (NCT04683185) and a Phase 1/2 study in patients with SLE is on-going (NCT05278663). One of the potential benefits of this program is to conduct academia-led clinical research to identify specific biomarkers for E6742 in parallel with clinical studies (UMIN000042037). The aim of this review is to present current progress within the strategic collaboration of the AMED CiCLE program that optimize clinical development for patients with SLE.

Association between pre-treatment computed tomography findings and post-treatment persistent decrease in lung perfusion blood volume.

The purpose of this study was to evaluate pre-treatment CT findings in patients with acute pulmonary embolism (PE) and determine the imaging findings associated with residual hypoperfused segments in post-treatment lung perfused blood volume (LPBV). We evaluated 91 patients with acute PE who underwent dual-energy CT before and after treatment. The location of thrombi (proximal or distal) and patency of the pulmonary artery (occlusive or non-occlusive) were recorded using pre-treatment computed tomography pulmonary angiography (CTPA). Residual hypoperfusion was defined as a perfusion-decreased area seen in both the pre- and post-treatment LPBVs. The association of the location of the thrombus and vascular patency of pre-treatment CTPA with residual hypoperfusion on a segmental and patient basis was examined. In the segment-based analysis, the proportion of residual hypoperfusion in the proximal group was significantly higher than that in the peripheral group (33/125 [26.4%] vs. 9/87 [10.3%], P = 0.004). Patient-based analysis also showed that the proportion of residual hypoperfusion in patients with pre-treatment proximal thrombus was significantly higher than those without (16/42 [38.1%] vs. 3/25 (12.0%); P = 0.022). Pre-treatment vascular patency was not significantly associated with residual hypoperfusion (P > 0.05). Therefore, careful follow-up is necessary, especially in patients with proximal thrombi.

Prognostic Value and Pathological Correlation of Peritumoral Radiomics in Surgically Resected Non-Small Cell Lung Cancer.

RATIONALE AND OBJECTIVES: To determine the additional value of peritumoral radiomics in predicting overall survival (OS) in surgically resected non-small cell lung cancer (NSCLC) and its correlation with pathological findings. METHODS: A total of 526 patients with surgically resected NSCLC were included (191 training, 160 internal validation, and 175 external validation cohorts). CT images were used to segment the gross tumor volume (GTV) and peritumoral volume (PTV) within distances of 3, 6, 9 mm from the tumor boundary (PTV3, PTV6, and PTV9), and radiomic features were extracted. Four prognostic models for OS (GTV, GTV + PTV3, GTV + PTV6, and GTV + PTV9) were constructed using the training cohort. The prognostic ability and feature importance were evaluated using the validation cohorts. Pathological findings were compared between the two patient groups (n = 30 for each) having the top 30 and bottom 30 values of the most important peritumoral feature. RESULTS: The GTV+ PTV3 models exhibited the highest predictive ability, which was higher than that of the GTV model in the internal validation cohort (C-index: 0.666 vs. 0.616, P = 0.027) and external validation cohort (C-index: 0.705 vs. 0.656, P = 0.048). The most important feature was GLDM_Dependence_Entropy, extracted from PTV3. High peritumoral GLDM_Dependence_Entropy was associated with a high proportion of invasive histological types, tumor spread through air spaces, and tumor-infiltrating lymphocytes (all P < 0.05). CONCLUSION: The GTV and PTV3 combination demonstrated a higher prognostic ability, compared to GTV alone. Peritumoral radiomic features may be associated with various pathological prognostic factors.

N88S seipin mutant transgenic mice develop features of seipinopathy/BSCL2-related motor neuron disease via endoplasmic reticulum stress.

Heterozygosity for mutations (N88S and P90L) in the N-glycosylation site of seipin/BSCL2 is associated with the autosomal dominant motor neuron diseases, spastic paraplegia 17 and distal hereditary motor neuropathy type V, referred to as 'seipinopathies'. Previous in vitro studies have shown that seipinopathy-linked mutations result in accumulation of unfolded proteins in the endoplasmic reticulum (ER), leading to the unfolded protein response and cell death, suggesting that seipinopathies is closely associated with ER stress. To further understand the molecular pathogenesis of seipinopathies, we generated a transgenic (tg) mouse line expressing the human N88S seipin mutant with the murine Thy-1 promoter to permit analyses of in vivo phenotypic changes. The N88S seipin tg mice develop a progressive spastic motor deficit, reactive gliosis in the spinal cord and neurogenic muscular atrophy, recapitulating the symptomatic and pathological phenotype in patients of seipinopathy. We also found that expression of mutant seipin in mice upregulated the ER stress marker, immunoglobulin-heavy-chain-binding protein, protein disulfide isomerase and X-box binding protein 1, but was not linked to significant neuronal loss in affected tissue, thereby indicating that ER stress is sufficient, while neuronal death is not necessary, for the development of motor phenotypes of seipinopathies. Our findings in the mutant seipin tg mouse provide clues to understand the relationship with ER stress and neurodegeneration, and the seipin tg mouse is a valid tool for the development of novel therapeutic strategies against ER stress-related diseases.

Modeling familial Alzheimer's disease with induced pluripotent stem cells.

Alzheimer's disease (AD) is the most common form of age-related dementia, characterized by progressive memory loss and cognitive disturbance. Mutations of presenilin 1 (PS1) and presenilin 2 (PS2) are causative factors for autosomal-dominant early-onset familial AD (FAD). Induced pluripotent stem cell (iPSC) technology can be used to model human disorders and provide novel opportunities to study cellular mechanisms and establish therapeutic strategies against various diseases, including neurodegenerative diseases. Here we generate iPSCs from fibroblasts of FAD patients with mutations in PS1 (A246E) and PS2 (N141I), and characterize the differentiation of these cells into neurons. We find that FAD-iPSC-derived differentiated neurons have increased amyloid ß42 secretion, recapitulating the molecular pathogenesis of mutant presenilins. Furthermore, secretion of amyloid ß42 from these neurons sharply responds to γ-secretase inhibitors and modulators, indicating the potential for identification and validation of candidate drugs. Our findings demonstrate that the FAD-iPSC-derived neuron is a valid model of AD and provides an innovative strategy for the study of age-related neurodegenerative diseases.