A case series of Fabry diseases with CKD in Japan

BACKGROUND

It is well known that kidney injury is vital organ damage in Fabry disease (FD). Renin-angiotensin system (RAS) inhibitors are known to reduce proteinuria in patients with chronic kidney disease (CKD) by dilating the glomerular export arteries and reducing intraglomerular pressure. This improvement in intraglomerular pressure, although lowering the glomerular filtration rate, is thought to prevent renal damage and be renoprotective in the long term. RAS inhibitors may be effective in FD patients with proteinuria to prevent the progression of kidney disease, however, the degree to which they are used in clinical practice is unknown.

METHODS

The J-CKD-DB-Ex is a comprehensive multicenter database that automatically extracts medical data on CKD patients. J-CKD-DB-Ex contains data on 187,398 patients in five medical centers. FD patients were identified by ICD-10. Clinical data and prescriptions of FD patients between January 1 of 2014, and December 31 of 2020 were used for the analysis.

RESULTS

We identified 39 patients with FD from the J-CKD-DB-Ex including those with suspected FD. We confirmed 22 patients as FD. Half of the patients received RAS inhibitors. RAS inhibitors tended to be used in CKD patients with more severe renal impairment.

CONCLUSIONS

This case series revealed the actual clinical practice of FD patients with CKD. In particular, we found cases in which patients had proteinuria, but were not treated with RAS inhibitors. The database was shown to be useful in assessing the clinical patterns of patients with rare diseases.

Impaired lysosomal acidity maintenance in acid lipase-deficient cells leads to defective autophagy

The lysosome is an acid organelle that contains a variety of hydrolytic enzymes and plays a significant role in intracellular degradation to maintain cellular homeostasis. Genetic variants in lysosome-related genes can lead to severe congenital diseases, such as lysosomal storage diseases. In the present study, we investigated the impact of depleting lysosomal acid lipase A (LIPA), a lysosomal esterase that metabolizes esterified cholesterol or triglyceride, on lysosomal function. Under nutrient-rich conditions, LIPA gene KO (LIPAKO) cells exhibited impaired autophagy, whereas, under starved conditions, they showed normal autophagy. The cause underlying the differential autophagic activity was increased sensitivity of LIPAKO cells to ammonia, which was produced from l-glutamine in the medium. Further investigation revealed that ammonia did not affect upstream signals involved in autophagy induction, autophagosome-lysosome fusion, and hydrolytic enzyme activities in LIPAKO cells. On the other hand, LIPAKO cells showed defective lysosomal acidity upon ammonia loading. Microscopic analyses revealed that lysosomes of LIPAKO cells enlarged, whereas the amount of lysosomal proton pump V-ATPase did not proportionally increase. Since the enlargement of lysosomes in LIPAKO cells was not normalized under starved conditions, this is the primary change that occurred in the LIPAKO cells, and autophagy was affected by impaired lysosomal function under the specific conditions. These findings expand our comprehension of the pathogenesis of Wolman's disease, which is caused by a defect in the LIPA gene, and suggest that conditions, such as hyperlipidemia, may easily disrupt lysosomal functions.

HOPS, CORVET and newly-identified Hybrid tethering complexes contribute differentially towards multiple modes of endocytosis

Vesicular transport driven by membrane trafficking systems conserved in eukaryotes is critical to cellular functionality and homeostasis. It is known that homotypic fusion and vacuole protein sorting (HOPS) and class C core endosomal vacuole tethering (CORVET) interact with Rab-GTPases and SNARE proteins to regulate vesicle transport, fusion, and maturation in autophagy and endocytosis pathways. In this study, we identified two novel "Hybrid" tethering complexes in mammalian cells in which one of the subunits of HOPS or CORVET is replaced with the subunit from the other. Substrates taken up by receptor-mediated endocytosis or pinocytosis were transported by distinctive pathways, and the newly identified hybrid complexes contributed to pinocytosis in the presence of HOPS, whereas receptor-mediated endocytosis was exclusively dependent on HOPS. Our study provides new insights into the molecular mechanisms of the endocytic pathway and the function of the vacuolar protein sorting-associated (VPS) protein family.

A case of Marfanoid-progeroid-lipodystrophy syndrome: experimental proof of skipping exons and escaping nonsense-mediated decay

We report a Japanese patient with tall stature, dolichocephaly, prominent forehead, narrow nasal ridge, mild retrognathia, subcutaneous fat reduction, bilateral entropion of both eyelids, high arched palate, long fingers, and mild hyperextensible finger joints as a case of Marfanoid-progeroid-lipodystrophy syndrome. Genetic investigation revealed a heterozygous variant NC_000015.10(NM_000138.5):c.8226+5G>A in the FBN1 gene. Skipping of exon 65 and escaping nonsense-mediated decay followed by frameshift were experimentally confirmed in the proband's mRNA.

Prenatal Diagnosis of Mucopolysaccharidosis-Plus Syndrome (MPSPS)

Mucopolysaccharidosis-plus syndrome (MPSPS) is an autosomal-recessive disorder caused by c.1492C>T (p.R498W) in the VPS33A gene. MPSPS is a severe disorder that causes a short lifespan in patients. Currently, there is no specific treatment for patients. The Yakut population is more prone to this disease than others. Diagnosing MPSPS relies on clinical manifestations, and genetic testing (GT) is used to confirm the diagnosis. In this research, we examined two pregnancy cases, one of which involved a prenatal diagnosis for MPSPS. Notably, neither pregnant woman had a known family history of the disorder. During their pregnancies, both women underwent prenatal ultrasonography, which revealed increased prenasal thickness during the second trimester. In the first case, ultrasonography indicated increased prenasal thickness in the second trimester, but a definitive diagnosis was not made at that time. The patient was eventually diagnosed with MPSPS at 11 months of age. On the contrary, in the second case, GT uncovered that the parents were carriers of MPSPS. Consequently, a placental biopsy was performed, leading to an early diagnosis of MPSPS. This study emphasizes the importance of ultrasonography findings in prenatal MPSPS diagnosis. Combining ultrasonography with GT can be a valuable approach to confirming MPSPS at an early stage, allowing for the appropriate planning of delivery methods and medical care. Ultimately, this comprehensive approach can significantly enhance the quality of life of both affected patients and their parents.

A Case of Mucopolysaccharidosis II Caused by a Novel Variant with Skin Linear Hyperpigmented Streaks along Blaschko′s Lines

We report a case of an eight-year-old boy with mucopolysaccharidosis (MPS) II with atypical skin lesions of hyperpigmented streaks along Blaschko′s lines. This case presented with mild symptoms of MPS such as hepatosplenomegaly, joint stiffness, and quite mild bone deformity, which was the reason for the delay in diagnosis until the age of seven years. However, he showed an intellectual disability that did not meet the diagnostic criteria for an attenuated form of MPS II. Iduronate 2-sulfatase activity was reduced. Clinical exome sequencing of DNA from peripheral blood revealed a novel pathogenic missense variant (NM_000202.8(IDS_v001):c.703C>A, p.(Pro235Thr)) in the IDS gene, which was confirmed in the mother with a heterozygous state. His brownish skin lesions differed from the Mongolian blue spots or “pebbling” of the skin that are observed in MPS II.

Identification of CUL4A-DDB1-WDFY1 as an E3 ubiquitin ligase complex involved in initiation of lysophagy

Macroautophagy is a bulk degradation system in which double membrane-bound structures called autophagosomes to deliver cytosolic materials to lysosomes. Autophagy promotes cellular homeostasis by selectively recognizing and sequestering specific targets, such as damaged organelles, protein aggregates, and invading bacteria, termed selective autophagy. We previously reported a type of selective autophagy, lysophagy, which helps clear damaged lysosomes. Damaged lysosomes become ubiquitinated and recruit autophagic machinery. Proteomic studies using transfection reagent-coated beads and further evaluations reveal that a CUL4A-DDB1-WDFY1 E3 ubiquitin ligase complex is essential to initiate lysophagy and clear damaged lysosomes. Moreover, we show that LAMP2 is ubiquitinated by the CUL4A E3 ligase complex as a substrate on damaged lysosomes. These results reveal how cells selectively tag damaged lysosomes to initiate autophagy for the clearance of lysosomes.

A novel nonsense variant in ARID1B causing simultaneous RNA decay and exon skipping is associated with Coffin-Siris syndrome

Coffin-Siris syndrome (CSS) is a congenital disorder that is characterized by an absent/hypoplastic fifth distal phalanx, psychomotor developmental delay, and coarse facial features. One of the causative genes, ARID1B (AT-rich interactive domain-containing protein 1B), encodes components of the BAF chromatin remodeling complexes. Here, we report a case of a 3-year 8-month-old male with a novel nonsense variant (NM_001374820.1:c.4282C > T, p.(Gln1428*)) in the ARID1B gene, which was identified with whole-exome sequencing. He showed clinical symptoms of cleft soft palate, distinctive facial features (flat nasal bridge, thick eyebrows, and long eyelashes), right cryptorchidism, and hypertrichosis that partially overlapped with CSS. One of the most characteristic features of CSS is absent/hypoplastic fifth distal phalanx. He showed no obvious clinical finding in the lengths of his fingers or in the formation of his fingernails. However, radiographic analyses of the metacarpophalangeal bones revealed shortening of all the distal phalanges and fifth middle phalanges, suggesting brachydactyly. We performed mRNA analyses and revealed that both nonsense-mediated decay and nonsense-associated altered splicing were simultaneously caused by the c.4282C > T nonsense variant. The proband's clinical manifestations fit the previously reported criteria of disease for CSS or intellectual disability with ARID1B variant. Altogether, we suggest that c.4282C > T is a pathogenic variant that causes this clinical phenotype.

Hematopoietic Disorders, Renal Impairment and Growth in Mucopolysaccharidosis-Plus Syndrome

Mucopolysaccharidoses (MPS) are rare lysosomal storage disorders (LSD) characterized by the excessive accumulation of glycosaminoglycans (GAG). Conventional MPS, caused by inborn deficiencies of lysosomal enzymes involved in GAG degradation, display various multisystemic symptoms—including progressive neurological complications, ophthalmological disorders, hearing loss, gastrointestinal and hepatobiliary issues, cardiorespiratory problems, bone and joint abnormalities, dwarfism, and coarse facial features. Mucopolysaccharidosis-Plus Syndrome (MPSPS), an autosomal recessive disease caused by a mutation in the endo-lysosomal tethering protein VPS33A, shows additional renal and hematopoietic abnormalities (“Plus symptoms”) uncommon in conventional MPS. Here, we analyze data from biochemical, histological, and physical examinations—particularly of blood counts and kidney function—to further characterize the clinical phenotype of MPSPS. A series of blood tests indicate hematopoietic symptoms including progressive anemia and thrombocytopenia, which correlate with histological observations of hypoplastic bone marrow. High urinary excretion of protein (caused by impairments in renal filtration), hypoalbuminemia, and elevated levels of creatinine, cholesterol, and uric acid indicate renal dysfunction. Histological analyses of MPSPS kidneys similarly suggest the extensive destruction of glomerular structures by foamy podocytes. Height and weight did not significantly deviate from the average, but in some cases, growth began to decline at around six months or one year of age.

Mucolipidosis Ⅱ and III with neurological symptoms due to spinal cord compression

In mucopolysaccharidoses (MPS), spinal cord compression (SCC) resulting from glycosaminoglycan (GAG) accumulation is a critical complication that can cause significant neurological and respiratory morbidities. However, clinically similar disorders such as mucolipidosis types II and III (ML) with SCC have been scarcely reported. Herein, we report four patients with ML who had SCC. Brain MRI revealed progressive spinal canal stenosis and SCC. In addition, T2-weighted high signal changes in the cervical cord were detected in two cases. Severe cases of SCC were detected as early as 1 year of age. All cases had respiratory problems. One case showed severe hypoxia and another, severe sleep apnea. In two cases, respiratory insufficiency and tetraplegia rapidly progressed as SCC progressed. Then, the patients became bedridden and needed artificial ventilation. In addition, two of the four patients died of respiratory failure. The autopsy of one patient revealed a compressed cervical cord and marked dura mater thickening due to GAG accumulation. These findings suggest that the accumulation of substrates in the dura mater caused SCC in the patients with ML. Our cases indicate that SCC is expected to be a common and critical complication of ML and MPS. MRI evaluation of cervical involvements and careful clinical observation are required in patients with ML.

Atomic-level characterization of free volume in the structure of Cu67Zr33amorphous alloy

The structure of Cu₆₇Zr₃₃amorphous alloy was investigated in terms of packing density and free volume by using neutron, x-ray diffraction and reverse Monte Carlo (RMC) modelling. The RMC model was analysed by a method of decomposing the three-dimensional atomic configuration into fundamental polyhedral units (termed as 'holes' referencing the Bernal's works) of which faces are all triangles consisting of chemical bonds. Not only tetrahedral and octahedral holes but also other larger holes were identified. Moreover, the atomic packing fractions and free volumes in the respective polyhedral holes were evaluated with reference to those for the corresponding crystal structures. The results show that the distribution of free volumes for the larger holes can be described by the exponential function assuming that there are no energetic interactions between each other. On the other hand, the local structural fluctuations due to densely and loosely packed tetrahedral holes were observed, leading to the negative free volume spaces.

[A case of spastic paraplegia 48 with a novel mutation in the AP5Z1 gene]

We describe an additional patient with spastic paraplegia 48 (SPG48). A 52-year-old woman with gradually increasing gait disturbance was admitted to our hospital. When she was 47 years old, acquaintances noted a shuffling gait. Gait worsening was evident at 48 years. Spastic gait was apparent at 50, and she required a walking stick at 54. Her elder brother had similar gait disturbance. No consanguinity was known. Neurologic examination at 52 disclosed spasticity and moderate weakness in the lower limbs. Spasticity and brisk reflexes in all limbs. Laboratory studies including HTLV-1 titer detected no abnormalities. MRI demonstrated mild corpus callosum narrowing and prominent anterior periventricular hyperintensities in fluid attenuation inversion recovery images. In limb muscles, electromyography (EMG) showed a chronic neurogenic pattern including reduced interference. Gene analysis identified compound homozygosity in exon 7 of adaptor-related protein complex 5 subunit zeta 1 (AP5Z1), including a novel frameshift mutation, c.1662_1672del;p.Glu554Hfs*15 in the patient, and a heterozygous missense mutation in asymptomatic family members, including her mother, two siblings, and a daughter. The frameshift mutation is considered a pathogenic variant according to American College of Medical Genetics and Genomics standards and guidelines. Based on clinical features, imaging findings and genetic abnormalities, we diagnosed this patient with SPG48. Mutations in AP5Z1, which encodes the ζ subunit of AP-5, underlie SPG48. The AP-5 adaptor protein complex, which is mutated in SPG48, binds to both spastizin and spatacsin. While hereditary spastic paraplegias generally are clinically and genetically heterogenous, SPG48, SPG11, and SPG15 are clinically similar.

Observation of High-Frequency Transverse Phonons in Metallic Glasses

Using inelastic neutron scattering and molecular dynamics simulations on a model Zr-Cu-Al metallic glass, we show that transverse phonons persist well into the high-frequency regime, and can be detected at large momentum transfer. Furthermore, the apparent peak width of the transverse phonons was found to follow the static structure factor. The one-to-one correspondence, which was demonstrated for both Zr-Cu-Al metallic glass and a three-dimensional Lennard-Jones model glass, suggests a universal correlation between the phonon dynamics and the underlying disordered structure. This remarkable correlation, not found for longitudinal phonons, underscores the key role that transverse phonons hold for understanding the structure-dynamics relationship in disordered materials.

Starvation-induced autophagy via calcium-dependent TFEB dephosphorylation is suppressed by Shigyakusan

Kampo, a system of traditional Japanese therapy utilizing mixtures of herbal medicine, is widely accepted in the Japanese medical system. Kampo originated from traditional Chinese medicine, and was gradually adopted into a Japanese style. Although its effects on a variety of diseases are appreciated, the underlying mechanisms remain mostly unclear. Using a quantitative tf-LC3 system, we conducted a high-throughput screen of 128 kinds of Kampo to evaluate the effects on autophagy. The results revealed a suppressive effect of Shigyakusan/TJ-35 on autophagic activity. TJ-35 specifically suppressed dephosphorylation of ULK1 and TFEB, among several TORC1 substrates, in response to nutrient deprivation. TFEB was dephosphorylated by calcineurin in a Ca²⁺ dependent manner. Cytosolic Ca²⁺ concentration was increased in response to nutrient starvation, and TJ-35 suppressed this increase. Thus, TJ-35 prevents the starvation-induced Ca²⁺ increase, thereby suppressing induction of autophagy.

Mucopolysaccharidosis-Plus Syndrome

Previously, we reported a novel disease of impaired glycosaminoglycans (GAGs) metabolism without deficiency of known lysosomal enzymes—mucopolysaccharidosis-plus syndrome (MPSPS). MPSPS, whose pathophysiology is not elucidated, is an autosomal recessive multisystem disorder caused by a specific mutation p.R498W in the VPS33A gene. VPS33A functions in endocytic and autophagic pathways, but p.R498W mutation did not affect both of these pathways in the patient’s skin fibroblast. Nineteen patients with MPSPS have been identified: seventeen patients were found among the Yakut population (Russia) and two patients from Turkey. Clinical features of MPSPS patients are similar to conventional mucopolysaccharidoses (MPS). In addition to typical symptoms for conventional MPS, MPSPS patients developed other features such as congenital heart defects, renal and hematopoietic disorders. Diagnosis generally requires evidence of clinical picture similar to MPS and molecular genetic testing. Disease is very severe, prognosis is unfavorable and most of patients died at age of 10–20 months. Currently there is no specific therapy for this disease and clinical management is limited to supportive and symptomatic treatment.

Biallelic VPS35L pathogenic variants cause 3C/Ritscher-Schinzel-like syndrome through dysfunction of retriever complex

BACKGROUND

3C/Ritscher-Schinzel syndrome is characterised by congenital cranio-cerebello-cardiac dysplasia, where CCDC22 and WASHC5 are accepted as the causative genes. In combination with the retromer or retriever complex, these genes play a role in endosomal membrane protein recycling. We aimed to identify the gene abnormality responsible for the pathogenicity in siblings with a 3C/Ritscher-Schinzel-like syndrome, displaying cranio-cerebello-cardiac dysplasia, coloboma, microphthalmia, chondrodysplasia punctata and complicated skeletal malformation.

METHODS

Exome sequencing was performed to identify pathogenic variants. Cellular biological analyses and generation of knockout mice were carried out to elucidate the gene function and pathophysiological significance of the identified variants.

RESULTS

We identified compound heterozygous pathogenic variants (c.1097dup; p.Cys366Trpfs*28 and c.2755G>A; p.Ala919Thr) in the VPS35L gene, which encodes a core protein of the retriever complex. The identified missense variant lacked the ability to form the retriever complex, and the frameshift variant induced non-sense-mediated mRNA decay, thereby confirming biallelic loss of function of VPS35L. In addition, VPS35L knockout cells showed decreased autophagic function in nutrient-rich and starvation conditions, as well as following treatment with Torin 1. We also generated Vps35l^-/- mice and demonstrated that they were embryonic lethal at an early stage, between E7.5 and E10.5.

CONCLUSIONS

Our results suggest that biallelic loss-of-function variants in VPS35L underlies 3C/Ritscher-Schinzel-like syndrome. Furthermore, VPS35L is necessary for autophagic function and essential for early embryonic development. The data presented here provide a new insight into the critical role of the retriever complex in fetal development.

A brain-enriched Drp1 isoform associates with lysosomes, late endosomes, and the plasma membrane

Dynamin-related protein 1 (Drp1) constricts mitochondria as a mechanochemical GTPase during mitochondrial division. The Drp1 gene contains several alternative exons and produces multiple isoforms through RNA splicing. Here we performed a systematic analysis of Drp1 transcripts in different mouse tissues and identified a previously uncharacterized isoform that is highly enriched in the brain. This Drp1 isoform is termed Drp1_ABCD because it contains four alterative exons: A, B, C, and D. Remarkably, Drp1_ABCD is located at lysosomes, late endosomes, and the plasma membrane in addition to mitochondria. Furthermore, Drp1_ABCD is concentrated at the interorganelle interface between mitochondria and lysosomes/late endosomes. The localizations of Drp1_ABCD at lysosomes, late endosomes, and the plasma membrane require two exons, A and B, that are present in the GTPase domain. Drp1_ABCD assembles onto these membranes in a manner that is regulated by its oligomerization and GTP hydrolysis. Experiments using lysosomal inhibitors show that the association of Drp1_ABCD with lysosomes/late endosomes depends on lysosomal pH but not their protease activities. Thus, Drp1 may connect mitochondria to endosomal-lysosomal pathways in addition to mitochondrial division.

Unfolded protein response is activated in Krabbe disease in a manner dependent on the mutation type

Krabbe disease, one of the autosomal-recessive lysosomal storage disorders (LSDs), is caused by a deficiency of galactocerebrosidase (GALC) activity, resulting in the intracellular accumulation of psychosine, which is cytotoxic for neuronal cells. Genetically pathogenic mutations result in conformational changes in GALC and disrupt the lysosmal trafficking of cargos, which subsequently accumulate in the endoplasmic reticulum (ER). Recently, ER stress together with the activation of the unfolded protein response (UPR) has been suggested to play a key role in the pathogenesis of LSDs. In this study, we hence investigated whether the UPR is activated in Krabbe disease using COS-7 cells expressing pathogenic GALC mutants and skin fibroblasts (SFs) from Krabbe disease patients with various phenotypes, using a combination of semiquantitative and quantitative real-time polymerase chain reactions. We found that UPR activation in Krabbe disease depends on the mutations and cell types, and there is the possibility that multiple pathways, involving ER chaperones, inositol-requiring kinase 1, and protein kinase regulated by RNA-like ER kinase are activated by mutations associated with the infantile form. These results indicate that in Krabbe disease, each misfolded/unfolded protein evokes different UPR activation depending on the mutation, and that the activated pathways affect the phenotypes.

Challenge of phenotype estimation for optimal treatment of Krabbe disease

Krabbe disease is an autosomal recessive, inherited demyelinating disease caused by deficiency of the lysosomal enzyme galactocerebrosidase. It is recognized as one of the predominant genetic diseases showing leukodystrophy from infancy to adulthood. The clinical phenotype and genotype for this disease show considerable variation worldwide, which makes accurate diagnosis difficult. Effective therapy is limited, although hematopoietic stem cell transplantation at an early stage has been established to some extent. We report here the long-term clinical effect on juvenile Krabbe disease for two brothers who underwent hematopoietic stem cell transplantation at an early stage of their disease. We review research into genotype-phenotype correlation for the possibility of early diagnosis at a presymptomatic stage. Medical care for this intractable disease will improve in the near future as a result of the increasing awareness of its molecular pathology and improvements in medical treatment. © 2016 Wiley Periodicals, Inc.

Mutation in VPS33A affects metabolism of glycosaminoglycans: a new type of mucopolysaccharidosis with severe systemic symptoms

Mucopolysaccharidoses (MPS) are a group of genetic deficiencies of lysosomal enzymes that catabolize glycosaminoglycans (GAG). Here we describe a novel MPS-like disease caused by a specific mutation in the VPS33A gene. We identified several Yakut patients showing typical manifestations of MPS: coarse facial features, skeletal abnormalities, hepatosplenomegaly, respiratory problems, mental retardation, and excess secretion of urinary GAG. However, these patients could not be diagnosed enzymatically as MPS. They showed extremely high levels of plasma heparan sulphate (HS, one of GAG); 60 times the normal reference range and 6 times that of MPS patients. Additionally, most patients developed heart, kidney, and hematopoietic disorders, which are not typical symptoms for conventional MPS, leading to a fatal outcome between 1 and 2-years old. Using whole exome and Sanger sequencing, we identified homozygous c.1492C > T (p.Arg498Trp) mutations in the VPS33A gene of 13 patients. VPS33A is involved in endocytic and autophagic pathways, but the identified mutation did not affect either of these pathways. Lysosomal over-acidification and HS accumulation were detected in patient-derived and VPS33A-depleted cells, suggesting a novel role of this gene in lysosomal functions. We hence propose a new type of MPS that is not caused by an enzymatic deficiency.

Defects in autophagosome-lysosome fusion underlie Vici syndrome, a neurodevelopmental disorder with multisystem involvement

Vici syndrome (VICIS) is a rare, autosomal recessive neurodevelopmental disorder with multisystem involvement characterized by agenesis of the corpus callosum, cataracts, cardiomyopathy, combined immunodeficiency, developmental delay, and hypopigmentation. Mutations in EPG5, a gene that encodes a key autophagy regulator, have been shown to cause VICIS, however, the precise pathomechanism underlying VICIS is yet to be clarified. Here, we describe detailed clinical (including brain MRI and muscle biopsy) and genetic features of nine Japanese patients with VICIS. Genetic dissection of these nine patients from seven families identified 14 causative mutations in EPG5. These included five nonsense, two frameshift, three splicing, one missense, and one multi-exon deletion mutations, and two initiation codon variants. Furthermore, cultured skin fibroblasts (SFs) from two affected patients demonstrated partial autophagic dysfunction. To investigate the function of EPG5, siRNA based EPG5 knock-down, and CRISPR/Cas9 mediated EPG5 knock-out HeLa cells were generated. EPG5-depleted cells exhibited a complete block of autophagic flux caused by defective autophagosome-lysosome fusion. Unexpectedly, endocytic degradation was normal in both VICIS SFs and EPG5 depleted cells, suggesting that EPG5 function is limited to the regulation of autophagosome-lysosome fusion.

Lysophagy: A Method for Monitoring Lysosomal Rupture Followed by Autophagy-Dependent Recovery

Selective autophagy recognizes specific targets, including damaged mitochondria (mitophagy), aggregated proteins (aggrephagy), and invading bacteria (xenophagy) to engulf by isolation membrane, and degrades toxic materials within lysosomes. We recently revealed that a membrane-damaged lysosome itself also becomes a target of autophagy and named this process lysophagy. In this chapter, we describe methods for monitoring lysophagy; detecting lysosomal damage by staining of galectin and study the subsequent autophagic process in cultured mammalian cells.

Autophagosome-lysosome fusion in neurons requires INPP5E, a protein associated with Joubert syndrome

Autophagy is a multistep membrane traffic pathway. In contrast to autophagosome formation, the mechanisms underlying autophagosome-lysosome fusion remain largely unknown. Here, we describe a novel autophagy regulator, inositol polyphosphate-5-phosphatase E (INPP5E), involved in autophagosome-lysosome fusion process. In neuronal cells, INPP5E knockdown strongly inhibited autophagy by impairing the fusion step. A fraction of INPP5E is localized to lysosomes, and its membrane anchoring and enzymatic activity are necessary for autophagy. INPP5E decreases lysosomal phosphatidylinositol 3,5-bisphosphate (PI(3,5)P2), one of the substrates of the phosphatase, that counteracts cortactin-mediated actin filament stabilization on lysosomes. Lysosomes require actin filaments on their surface for fusing with autophagosomes. INPP5E is one of the genes responsible for Joubert syndrome, a rare brain abnormality, and mutations found in patients with this disease caused defects in autophagy. Taken together, our data reveal a novel role of phosphoinositide on lysosomes and an association between autophagy and neuronal disease.

Mannose 6 phosphorylation of lysosomal enzymes controls B cell functions

Antigen processing and presentation and cytotoxic targeting depend on the activities of several lysosomal enzymes that require mannose 6-phosphate (M6P) sorting signals for efficient intracellular transport and localization. In this paper, we show that mice deficient in the formation of M6P residues exhibit significant loss of cathepsin proteases in B cells, leading to lysosomal dysfunction with accumulation of storage material, impaired antigen processing and presentation, and subsequent defects in B cell maturation and antibody production. The targeting of lysosomal and granular enzymes lacking M6P residues is less affected in dendritic cells and T cells and sufficient for maintenance of degradative and lytic functions. M6P deficiency also impairs serum immunoglobulin levels and antibody responses to vaccination in patients. Our data demonstrate the critical role of M6P-dependent transport routes for B cell functions in vivo and humoral immunity in mice and human.

Decreased bone formation and increased osteoclastogenesis cause bone loss in mucolipidosis II

Mucolipidosis type II (MLII) is a severe multi-systemic genetic disorder caused by missorting of lysosomal proteins and the subsequent lysosomal storage of undegraded macromolecules. Although affected children develop disabling skeletal abnormalities, their pathogenesis is not understood. Here we report that MLII knock-in mice, recapitulating the human storage disease, are runted with accompanying growth plate widening, low trabecular bone mass and cortical porosity. Intralysosomal deficiency of numerous acid hydrolases results in accumulation of storage material in chondrocytes and osteoblasts, and impaired bone formation. In osteoclasts, no morphological or functional abnormalities are detected whereas osteoclastogenesis is dramatically increased in MLII mice. The high number of osteoclasts in MLII is associated with enhanced osteoblastic expression of the pro-osteoclastogenic cytokine interleukin-6, and pharmacological inhibition of bone resorption prevented the osteoporotic phenotype of MLII mice. Our findings show that progressive bone loss in MLII is due to the presence of dysfunctional osteoblasts combined with excessive osteoclastogenesis. They further underscore the importance of a deep skeletal phenotyping approach for other lysosomal diseases in which bone loss is a prominent feature.

An adult patient with mucolipidosis III alpha/beta presenting with parkinsonism

A 36-year-old man with mucolipidosis type III alpha/beta presented with hypoactivity, mutism, muscle rigidity, and involuntary movement. The involuntary movement was interpreted to be tremor at rest on physical examination and surface electromyography, which revealed mostly asynchronous contractions at 3-4 Hz of the biceps and triceps brachii muscles. All these symptoms were consistent with abnormalities of parkinsonism, which is caused by an insult to the basal ganglia that permeates the entire basal ganglia-thalamocortical circuitry. This report is the first to present a case of mucolipidosis type III alpha/beta in association with parkinsonism.

14-3-3ε gene variants in a Japanese patient with left ventricular noncompaction and hypoplasia of the corpus callosum

BACKGROUND

Left ventricular noncompaction (LVNC) is a cardiomyopathy characterized by a prominent trabecular meshwork and deep intertrabecular recesses, and is thought to be due to an arrest of normal endomyocardial morphogenesis. However, the genes contributing to this process remain poorly understood. 14-3-3ε, encoded by YWHAE, is an adapter protein belonging to the 14-3-3 protein family which plays important roles in neuronal development and is involved in Miller-Dieker syndrome. We recently showed that mice lacking this gene develop LVNC. Therefore, we hypothesized that variants in YWHAE may contribute to the pathophysiology of LVNC in humans.

METHODS AND RESULTS

In 77 Japanese patients with LVNC, including the probands of 29 families, mutation analysis of YWHAE by direct DNA sequencing identified 7 novel variants. One of them, c.-458G>T, in the YWHAE promoter, was identified in a familial patient with LVNC and hypoplasia of the corpus callosum. The -458G>T variant is located within a regulatory CCAAT/enhancer binding protein (C/EBP) response element of the YWHAE promoter, and it reduced promoter activity by approximately 50%. Increased binding of an inhibitory C/EBPβ isoform was implicated in decreasing YWHAE promoter activity. Interestingly, we had previously shown that C/EBPβ is a key regulator of YWHAE.

CONCLUSIONS

These data suggest that the -458G>T YWHAE variant contributes to the abnormal myocardial morphogenesis characteristic of LVNC as well as abnormal brain development, and implicate YWHAE as a novel candidate gene in pediatric cardiomyopathies.

Long-term efficacy of hematopoietic stem cell transplantation on brain involvement in patients with mucopolysaccharidosis type II: a nationwide survey in Japan

Hematopoietic stem cell transplantation (HSCT) has not been indicated for patients with mucopolysaccharidosis II (MPS II, Hunter syndrome), while it is indicated for mucopolysaccharidosis I (MPS I) patients <2 years of age and an intelligence quotient (IQ) of ≥ 70. Even after the approval of enzyme replacement therapy for both of MPS I and II, HSCT is still indicated for patients with MPS I severe form (Hurler syndrome). To evaluate the efficacy and benefit of HSCT in MPS II patients, we carried out a nationwide retrospective study in Japan. Activities of daily living (ADL), IQ, brain magnetic resonance image (MRI) lesions, cardiac valvular regurgitation, and urinary glycosaminoglycan (GAG) were analyzed at baseline and at the most recent visit. We also performed a questionnaire analysis about ADL for an HSCT-treated cohort and an untreated cohort (natural history). Records of 21 patients were collected from eight hospitals. The follow-up period in the retrospective study was 9.6 ± 3.5 years. ADL was maintained around baseline levels. Cribriform changes and ventricular dilatation on brain MRI were improved in 9/17 and 4/17 patients, respectively. Stabilization of brain atrophy was shown in 11/17 patients. Cardiac valvular regurgitation was diminished in 20/63 valves. Urinary GAG concentration was remarkably lower in HSCT-treated patients than age-matched untreated patients. In the questionnaire analysis, speech deterioration was observed in 12/19 patients in the untreated cohort and 1/7 patient in HSCT-treated cohort. HSCT showed effectiveness towards brain or heart involvement, when performed before signs of brain atrophy or valvular regurgitation appear. We consider HSCT is worthwhile in early stages of the disease for patients with MPS II.

Formation of NaCl-type monodeuteride LaD by the disproportionation reaction of LaD2

Previous x-ray diffraction measurements revealed the pressure-induced decomposition of an fcc LaH2.3 into H-rich and H-poor fcc phases around 11 GPa. The present neutron diffraction measurements on LaD2 confirm the formation of NaCl-type LaD as a counterpart of the D-rich LaD2+δ by disproportionation. First-principles enthalpy and lattice dynamic calculations demonstrate that the NaCl-type LaH is stabilized at high pressures and can be recovered at ambient conditions. Finding the NaCl-type LaH will pave the way for investigations on the site-dependent nature of hydrogen-metal interactions.

Genistein reduces heparan sulfate accumulation in human mucolipidosis II skin fibroblasts

Genistein, a soy isoflavone, reduces glycosaminoglycan synthesis and its effect on mucopolysaccharidoses has been tested. In this report, we examined the effect of genistein in human mucolipidosis II skin fibroblasts in vitro. Heparan sulfate was accumulated within both cells and in extracellular spaces in mucolipidosis II. Genistein reduced the amount of heparan sulfate in cultured cells dose dependently and also inhibited cell growth dose dependently.

Lysosomal storage causes cellular dysfunction in mucolipidosis II skin fibroblasts

Mucolipidosis II (ML-II) is a fatal inherited metabolic disease caused by deficiency of GlcNAc-phosphotransferase, which plays a role in generating the mannose 6-phosphate recognition marker on lysosomal enzymes. In ML-II, many lysosomal acid hydrolases are mistargeted out of cells, and lysosomes become filled with undigested substrates, which explains inclusion cell disease as an alternative name for this disease. In this study, we revealed various cellular phenotypes in ML-II skin fibroblasts. We quantitated phospholipid and cholesterol within cells and showed ~2-fold accumulation in ML-II as compared with normal cells. Lysosomal pH of ML-II cells was higher than that of normal cells (5.29 ± 0.08 versus 4.79 ± 0.10, p < 0.001). The proliferated lysosomes in ML-II cells were accumulated ~3-fold in amount as compared with normal cells. Intracellular logistics including endocytosis and mannose 6-phosphate receptor recycling were impaired in ML-II cells. To confirm whether these ML-II cellular phenotypes derive from deficient lysosomal acid hydrolases within lysosomes, we performed supplementation of lysosomal enzymes using a partially purified total enzyme mixture, which was derived from the conditioned culture medium of normal skin fibroblasts after NH(4)Cl treatment. This supplementation corrected all of the previously described ML-II phenotypes. In addition, the autophagic and mitochondrial impairment that we have previously reported improved, and inclusion bodies disappeared on electron micrography following total lysosomal enzyme supplementation. Our results indicate that various cellular phenotypes in ML-II are caused by the deficiency of many lysosomal enzymes and massive accumulation of undigested substrates.

Examination of gas desorption by B4C resin for use in neutron scattering experiment

Gas desorption rates for several types of B(4)C resins were investigated using a throughput method. The investigation was particularly focused on determining the out gas composition, effects of dry air, grain size (density) effects on the gas desorption rates. It is found that water is the main component of out gas and that dry air can effectively reduce gas desorption.

Elevated Bone Turnover in an Infantile Patient with Mucolipidosis II; No Association with Hyperparathyroidism

This present report concerns an infantile patient with mucolipidosis II, who showed transient cortical bone hyperostosis followed by severe osteopenia. The diagnosis of mucolipidosis II was made based on the leakage of lysosomal enzymes in serum and conditioned media of the patient's skin fibroblasts, low activity of lysosomal enzymes of the fibroblasts and mutation of c.2086_2089insC (p.L697fs) and c.3565C>T (p.R1189X) in the GNPTAB gene. Bone X-ray analysis demonstrated a periosteal reaction and elevated bone resorption at the age of 2 mo. Bone markers, including alkaline phosphatase, osteocalcin and urine deoxypyridinoline, also indicated a high turnover of bone metabolism; however, no apparent rickets-like changes and no increased levels of PTH were observed. Elevated bone resorption is possibly associated with the leakage of lysosomal enzyme from osteoclasts into bone matrices. Bone formation gradually reduced, and increased bone resorption persisted. This led to severe osteopenia at the age of 6 mo. Characteristic bone findings may contribute to early diagnosis of mucolipidosis II, but their pathogenesis remains to be clarified.

Pathology of the first autopsy case diagnosed as mucolipidosis type III α/β suggesting autophagic dysfunction

Mucolipidosis type III (MLIII) is a mild form of Mucolipidosis type II (MLII, I-cell disease) of late onset, of which almost no pathological study has been reported, as it is a very rare disease. We encountered the case of a 23-year-old man of Japanese and Caucasian mixed parentage diagnosed with MLIII by enzyme assay and genotyping. He died suddenly due to severe dilated cardiomyopathy. On the day after his death, autopsy was performed, and accumulation of Luxol Fast Blue (LFB) positive material was found to be most severe in the neuronal cells of dorsal root ganglions (DRG). Electromicroscopic DRG revealed the neuronal cytoplasm was filled with a zebra-body-like membranous matrix. We tried immunohistochemistry to investigate the mechanism of such accumulation in the DRG that resulted in double positive anti-ubiquitin antibody (FK-2) and anti-LC3 antibody (as specific marker for autophagy) staining, and speculated activating of autophagosome pathway, and 'zebra-body' should be suspected as dysfunctional autophagosome. We also detected foamy cell proliferation in the dura mater, Auerbach's plexus (peripheral nervous system), podocytes of almost all glomeruli, cartilage tissue in lumbar discs, and in cardiac muscle. We tried FK-2 and anti-LC3 antibody staining also for the podocytes, the area with the most marked proliferation of foamy cells, but the result was negative. This led us to speculate that these pathological findings, namely, accumulation of LFB-positive material and foamy fibroblast proliferation, might be the forms of dysfunctional autophagosome at various stages of development. This pathological study of MLIII supports the theory that MLIII is a mild type of MLII because of the close similarity of their pathological findings.

Inhibition of autophagosome formation restores mitochondrial function in mucolipidosis II and III skin fibroblasts

Mucolipidosis II and III are progressive lysosomal storage disorders caused by a deficiency of N-acetylglucosamine-1-phosphotransferase, leading to massive accumulation of undigested substrates in lysosomes (inclusion bodies) in skin fibroblast. In this study, we demonstrated accumulation of autolysosomes and increased levels of p62 and ubiquitin proteins in cultured fibroblasts. These autophagic elevations were milder in mucolipidosis III compared with mucolipidosis II. Mitochondrial structure was fragmented and activity was impaired in the affected cells, and 3-methyladenine, an inhibitor of autophagosome formation, restored these. These results show for the first time autophagic and mitochondrial dysfunctions in this disorder.

A prospective, double-blind, randomized trial of caudal block using ropivacaine 0.2% with or without fentanyl 1 microg kg-1 in children

BACKGROUND

It has been reported that ropivacaine produces vasoconstriction in contrast to vasodilation produced by bupivacaine. It is possible that additives to ropivacaine can provide further analgesic advantages compared with bupivacaine. We thus evaluated whether the addition of fentanyl to ropivacaine prolonged the duration of analgesia after a single shot caudal block.

METHODS

A total of 36 children undergoing surgical procedures below the umbilicus were randomly allocated to one of two groups: Group F received ropivacaine 0.2%, 1 ml kg(-1) with fentanyl 1 microg kg(-1) and Group S received ropivacaine 0.2%, 1 ml kg(-1) with saline. The analgesic effect of the caudal block was evaluated using the Children's Hospital of Eastern Ontario Pain Scale (CHEOPS) and sedation was assessed using the Steward score at 30 min after extubation and at 1, 2, 4, 6, 12 and 24 h. The first analgesic requirement time and side-effects in a 24 h period were also recorded.

RESULTS

There were no differences in characteristics between the groups. The end-tidal concentration of sevoflurane at extubation in Group F was significantly lower than in Group S. However, there was no significant difference in time from discontinuation of the volatile anaesthetics to tracheal extubation. No statistical differences were found in the CHEOPS and Steward score, and the time to first analgesia. The incidence of postoperative vomiting was not significantly different.

CONCLUSION

We found that the addition of fentanyl 1 mug kg(-1) to ropivacaine 0.2% for caudal analgesia provides no further analgesic advantages over ropivacaine 0.2% alone.