Clinical effects of wasabi extract containing 6-MSITC on myalgic encephalomyelitis/chronic fatigue syndrome: an open-label trial

BACKGROUND

Wasabi (Eutrema japonicum) is a common pungent spice used in Japan. 6-Methylsulfinylhexyl isothiocyanate (6-MSITC) found in the rhizome of wasabi has been shown to have anti-inflammatory and antioxidant effects, as well as improve neuroinflammation and memory. Therefore, we hypothesized that these effects would be beneficial for treating myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). The present study was conducted to investigate the effectiveness of wasabi extract containing 6-MSITC on ME/CFS in an open-label trial.

METHODS

Fifteen patients (3 males, 12 females, 20-58 years old) were orally administered wasabi extract (9.6 mg of 6-MSITC/day) for 12 weeks. The following parameters and test results were compared pre- and post-treatment: performance status (PS), self-rating questionnaires, pressure pain threshold (PPT) on the occiput, Trail Making test-A (TMT-A), and hemodynamic patterns determined by an active standing test.

RESULTS

After treatment with 6-MSITC, PS improved significantly (p = 0.001). Although the scores on the 11-item Chalder Fatigue scale (CFS-11) and numerical rating scale (NRS) of fatigue did not show significant changes, subjective symptoms improved significantly, including headache frequency (4.1 to 3.0 times/week, p = 0.001) and myalgia (4.1 to 2.4 times/week, p = 0.019), NRS brain fog scores (5.7 to 4.5, p = 0.011), difficulty finding appropriate words (4.8 to 3.7, p = 0.015), photophobia (4.8 to 3.5, p = 0.008), and the Profile of Mood Status vigor score (46.9 to 50.0, p = 0.045). The PPT of the right occiput (17.3 to 21.3 kPa, p = 0.01) and TMT-A scores (53.0 to 38.1 s, p = 0.007) also changed, suggesting reduced pain sensitivity, and improved cognitive function, respectively. Orthostatic patterns determined by a standing test did not show remarkable changes. There were no serious adverse reactions.

CONCLUSION

This study suggests that 6-MSITC improves PS as well as subjective symptoms such as pain and cognitive dysfunction, and psychological vitality of patients with ME/CFS. It also improved cognitive performance and increased pain thresholds in these patients. 6-MSITC may be a promising therapeutic option especially for improving cognitive dysfunction associated with ME/CFS.

NRF2 Pathway Activation Attenuates Aging-Related Renal Phenotypes due to α-Klotho Deficiency

Oxidative stress is one of the major causes of the age-related functional decline in cells and tissues. The KEAP1-NRF2 system plays a central role in the regulation of redox balance, and NRF2 activation exerts antiaging effects by controlling oxidative stress in aged tissues. α-Klotho was identified as an aging suppressor protein based on the premature aging phenotypes of its mutant mice, and its expression is known to gradually decrease during aging. Because α-Klotho has been shown to possess antioxidant function, aging-related phenotypes of α-Klotho mutant mice seem to be attributable to increased oxidative stress at least in part. To examine whether NRF2 activation antagonizes aging-related phenotypes caused by α-Klotho deficiency, we crossed α-Klotho-deficient (Kl–/–) mice with a Keap1-knockdown background, in which the NRF2 pathway is constitutively activated in the whole body. NRF2 pathway activation in Kl–/– mice extended the lifespan and dramatically improved aging-related renal phenotypes. With elevated expression of antioxidant genes accompanied by an oxidative stress decrease, the antioxidant effects of NRF2 seem to make a major contribution to the attenuation of aging-related renal phenotypes of Kl–/– mice. Thus, NRF2 is expected to exert an antiaging function by partly compensating for the functional decline of α-Klotho during physiological aging.

Down syndrome cell adhesion molecule like-1 (DSCAML1) links the GABA system and seizure susceptibility

The Ihara epileptic rat (IER) is a mutant model with limbic-like seizures whose pathology and causative gene remain elusive. In this report, via linkage analysis, we identified Down syndrome cell adhesion molecule-like 1(Dscaml1) as the responsible gene for IER. A single base mutation in Dscaml1 causes abnormal splicing, leading to lack of DSCAML1. IERs have enhanced seizure susceptibility and accelerated kindling establishment. Furthermore, GABAergic neurons are severely reduced in the entorhinal cortex (ECx) of these animals. Voltage-sensitive dye imaging that directly presents the excitation status of brain slices revealed abnormally persistent excitability in IER ECx. This suggests that reduced GABAergic neurons may cause weak sustained entorhinal cortex activations, leading to natural kindling via the perforant path that could cause dentate gyrus hypertrophy and epileptogenesis. Furthermore, we identified a single nucleotide substitution in a human epilepsy that would result in one amino acid change in DSCAML1 (A2105T mutation). The mutant DSCAML1^A2105T protein is not presented on the cell surface, losing its homophilic cell adhesion ability. We generated knock-in mice (Dscaml1^A2105T) carrying the corresponding mutation and observed reduced GABAergic neurons in the ECx as well as spike-and-wave electrocorticogram. We conclude that DSCAML1 is required for GABAergic neuron placement in the ECx and suppression of seizure susceptibility in rodents. Our findings suggest that mutations in DSCAML1 may affect seizure susceptibility in humans.

Structural Insight into an Alzheimer's Brain-Derived Spherical Assembly of Amyloid β by Solid-State NMR

Accumulating evidence suggests that various neurodegenerative diseases, including Alzheimer's disease (AD), are linked to cytotoxic diffusible aggregates of amyloid proteins, which are metastable intermediate species in protein misfolding. This study presents the first site-specific structural study on an intermediate called amylospheroid (ASPD), an AD-derived neurotoxin composed of oligomeric amyloid-β (Aβ). Electron microscopy and immunological analyses using ASPD-specific "conformational" antibodies established synthetic ASPD for the 42-residue Aβ(1-42) as an excellent structural/morphological analogue of native ASPD extracted from AD patients, the level of which correlates with the severity of AD. (13)C solid-state NMR analyses of approximately 20 residues and interstrand distances demonstrated that the synthetic ASPD is made of a homogeneous single conformer containing parallel β-sheets. These results provide profound insight into the native ASPD, indicating that Aβ is likely to self-assemble into the toxic intermediate with β-sheet structures in AD brains. This approach can be applied to various intermediates relevant to amyloid diseases.

Cdk5 and its substrates, Dcx and p27kip1, regulate cytoplasmic dilation formation and nuclear elongation in migrating neurons

Neuronal migration is crucial for development of the mammalian-specific six-layered cerebral cortex. Migrating neurons are known to exhibit distinct features; they form a cytoplasmic dilation, a structure specific to migrating neurons, at the proximal region of the leading process, followed by nuclear elongation and forward movement. However, the molecular mechanisms of dilation formation and nuclear elongation remain unclear. Using ex vivo chemical inhibitor experiments, we show here that rottlerin, which is widely used as a specific inhibitor for PKCδ, suppresses the formation of a cytoplasmic dilation and nuclear elongation in cortical migrating neurons. Although our previous study showed that cortical neuronal migration depends on Jnk, another downstream target of rottlerin, Jnk inhibition disturbs only the nuclear elongation and forward movement, but not the dilation formation. We found that an unconventional cyclin-dependent kinase, Cdk5, is a novel downstream target of rottlerin, and that pharmacological or knockdown-mediated inhibition of Cdk5 suppresses both the dilation formation and nuclear elongation. We also show that Cdk5 inhibition perturbs endocytic trafficking as well as microtubule organization, both of which have been shown to be required for dilation formation. Furthermore, knockdown of Dcx, a Cdk5 substrate involved in microtubule organization and membrane trafficking, or p27(kip1), another Cdk5 substrate involved in actin and microtubule organization, disturbs the dilation formation and nuclear elongation. These data suggest that Cdk5 and its substrates, Dcx and p27(kip1), characterize migrating neuron-specific features, cytoplasmic dilation formation and nuclear elongation in the mouse cerebral cortex, possibly through the regulation of microtubule organization and an endocytic pathway.

Enhanced stability of hippocampal place representation caused by reduced magnesium block of NMDA receptors in the dentate gyrus

Background

Voltage-dependent block of the NMDA receptor by Mg²⁺ is thought to be central to the unique involvement of this receptor in higher brain functions. However, the in vivo role of the Mg²⁺ block in the mammalian brain has not yet been investigated, because brain-wide loss of the Mg²⁺ block causes perinatal lethality. In this study, we used a brain-region specific knock-in mouse expressing an NMDA receptor that is defective for the Mg²⁺ block in order to test its role in neural information processing.

Results

We devised a method to induce a single amino acid substitution (N595Q) in the GluN2A subunit of the NMDA receptor, specifically in the hippocampal dentate gyrus in mice. This mutation reduced the Mg²⁺ block at the medial perforant path–granule cell synapse and facilitated synaptic potentiation induced by high-frequency stimulation. The mutants had more stable hippocampal place fields in the CA1 than the controls did, and place representation showed lower sensitivity to visual differences. In addition, behavioral tests revealed that the mutants had a spatial working memory deficit.

Conclusions

These results suggest that the Mg²⁺ block in the dentate gyrus regulates hippocampal spatial information processing by attenuating activity-dependent synaptic potentiation in the dentate gyrus.

In vivo function and evolution of the eutherian-specific pluripotency marker UTF1

Embryogenesis in placental mammals is sustained by exquisite interplay between the embryo proper and placenta. UTF1 is a developmentally regulated gene expressed in both cell lineages. Here, we analyzed the consequence of loss of the UTF1 gene during mouse development. We found that homozygous UTF1 mutant newborn mice were significantly smaller than wild-type or heterozygous mutant mice, suggesting that placental insufficiency caused by the loss of UTF1 expression in extra-embryonic ectodermal cells at least in part contributed to this phenotype. We also found that the effects of loss of UTF1 expression in embryonic stem cells on their pluripotency were very subtle. Genome structure and sequence comparisons revealed that the UTF1 gene exists only in placental mammals. Our analyses of a family of genes with homology to UTF1 revealed a possible mechanism by which placental mammals have evolved the UTF1 genes.

Inactivation of JAK2/STAT3 signaling axis and downregulation of M1 mAChR cause cognitive impairment in klotho mutant mice, a genetic model of aging

We previously reported cognitive dysfunction in klotho mutant mice. In the present study, we further examined novel mechanisms involved in cognitive impairment in these mice. Significantly decreased janus kinase 2 (JAK2) and signal transducer and activator of transcription3 (STAT3) phosphorylation were observed in the hippocampus of klotho mutant mice. A selective decrease in protein expression and binding density of the M1 muscarinic cholinergic receptor (M1 mAChR) was observed in these mice. Cholinergic parameters (ie, acetylcholine (ACh), choline acetyltransferase (ChAT), and acetylcholinesterase (AChE)) and NMDAR-dependent long-term potentiation (LTP) were significantly impaired in klotho mutant mice. McN-A-343 (McN), an M1 mAChR agonist, significantly attenuated these impairments. AG490 (AG), a JAK2 inhibitor, counteracted the attenuating effects of McN, although AG did not significantly alter the McN-induced effect on AChE. Furthermore, AG significantly inhibited the attenuating effects of McN on decreased NMDAR-dependent LTP, protein kinase C βII, p-ERK, p-CREB, BDNF, and p-JAK2/p-STAT3-expression in klotho mutant mice. In addition, k252a, a BDNF receptor tyrosine kinase B (TrkB) inhibitor, significantly counteracted McN effects on decreased ChAT, ACh, and M1 mAChR and p-JAK2/p-STAT3 expression. McN-induced effects on cognitive impairment in klotho mutant mice were consistently counteracted by either AG or k252a. Our results suggest that inactivation of the JAK2/STAT3 signaling axis and M1 mAChR downregulation play a critical role in cognitive impairment observed in klotho mutant mice.

Plasma soluble α-klotho protein levels in premature and term neonates: correlations with growth and metabolic parameters

OBJECTIVE

α-Klotho (α-KL), a protein with antiaging properties, regulates phosphate, calcium, and bone metabolism, induces resistance to oxidative stress, and may participate in insulin signaling. The role of α-KL in neonates, known to be prone to metabolic disturbances and oxidative stress, is not known. The aim of this study was to evaluate circulating soluble α-KL concentrations in preterm and full-term neonates and unravel possible correlations with growth, metabolism, and indices of oxidative stress.

DESIGN

Prospective study.

METHODS

Plasma-soluble α-KL levels were determined by specific ELISA in 50 healthy neonates (25 preterm, mean (s.d.) gestational age (GA) 33.7 (1.1) weeks, and 25 full-term infants) at days 14 and 28 of life. Associations of α-KL with anthropometric, metabolic parameters, and indices of oxidative stress were examined.

RESULTS

α-KL levels were significantly higher in full-term than in preterm infants at both days 14 (1099 (480) pg/ml vs 884 (239) pg/ml respectively; P<0.05) and 28 (1277 (444) pg/ml vs 983 (264) pg/ml respectively; P<0.01). In both preterm and full-term infants, α-KL levels increased significantly from day 14 to 28 of life (P<0.001). Circulating α-KL concentrations correlated with GA (β=0.32, P=0.001), body weight (β=0.34, P=0.001), body length (β=0.33, P=0.001), 1,25-dihydroxy-vitamin D level (β=0.24, P<0.05), and malondialdehyde level (β=0.20, P<0.05) but not with glucose, insulin, or homeostasis model assessment index of insulin resistance values.

CONCLUSIONS

Soluble α-KL levels rise as GA and postnatal age advance in neonates and may have an impact on vitamin D metabolism and oxidative stress. Whether α-KL may have a role in the regulation of infants' growth should be further studied.

Decreased renal α-Klotho expression in early diabetic nephropathy in humans and mice and its possible role in urinary calcium excretion

Hypercalciuria is one of the early manifestations of diabetic nephropathy. We explored here the role of α-Klotho, a protein expressed predominantly in distal convoluted tubules that has a role in calcium reabsorption. We studied 31 patients with early diabetic nephropathy and compared them with 31 patients with IgA nephropathy and 7 with minimal change disease. Renal α-Klotho expression was significantly lower and urinary calcium excretion (UCa/UCr) significantly higher in diabetic nephropathy than in IgA nephropathy or minimal change disease. Multiple regression analyses indicated that α-Klotho mRNA was inversely correlated with calcium excretion. We next measured these parameters in a mouse model of streptozotocin (STZ)-induced diabetic nephropathy, characterized by glomerular hyperfiltration, as seen in early diabetic nephropathy. We also confirmed a reduction of renal α-Klotho mRNA down to almost 50% and enhanced calcium excretion in mice with STZ-induced diabetic nephropathy in comparison with nondiabetic mice. Hypercalciuria was exacerbated in heterozygous α-Klotho knockout mice in comparison with wild-type mice, each with STZ-induced diabetic nephropathy. Thus, α-Klotho expression was decreased in distal convoluted tubules in diabetic nephropathy in humans and mice. Renal loss of α-Klotho may affect urinary calcium excretion in early diabetic nephropathy.

Retinoic acid metabolism links the periodical differentiation of germ cells with the cycle of Sertoli cells in mouse seminiferous epithelium

Homeostasis of tissues relies on the regulated differentiation of stem cells. In the epithelium of mouse seminiferous tubules, the differentiation process from undifferentiated spermatogonia (A(undiff)), which harbor the stem cell functions, to sperm occurs in a periodical manner, known as the "seminiferous epithelial cycle". To identify the mechanism underlying this periodic differentiation, we investigated the roles of Sertoli cells (the somatic supporting cells) and retinoic acid (RA) in the seminiferous epithelial cycle. Sertoli cells cyclically change their functions in a coordinated manner with germ cell differentiation and support the entire process of spermatogenesis. RA is known to play essential roles in this periodic differentiation, but its precise mode of action and its regulation remains largely obscure. We showed that an experimental increase in RA signaling was capable of both inducing A(undiff) differentiation and resetting the Sertoli cell cycle to the appropriate stage. However, these actions of exogenous RA signaling on A(undiff) and Sertoli cells were strongly interfered by the differentiating germ cells of intimate location. Based on the expression of RA metabolism-related genes among multiple cell types - including germ and Sertoli cells - and their regulation by RA signaling, we propose here that differentiating germ cells play a primary role in modulating the local RA metabolism, which results in the timed differentiation of A(undiff) and the appropriate cycling of Sertoli cells. Similar regulation by differentiating progeny through the modulation of local environment could also be involved in other stem cell systems.

A simplified recipe for assigning amide NMR signals using combinatorial 14N amino acid inverse-labeling

Assignment of backbone amide proton resonances is one of the most time-consuming stages of any protein NMR study when the protein samples behave non-ideally. A robust and convenient NMR procedure for analyzing spectra of marginal-to-low quality is helpful for high-throughput structure determination. The 14N selective- and inverse-labeling method is a candidate solution. Here, we present a simplified protocol for assigning protein backbone amide NMR signals. When 14N inversely labeled residues are present in a protein, their backbone NH cross peaks vanish from the protein's 1H-(15)N HSQC spectrum, and thus, their chemical shifts can be readily identified by a process of elimination. Some metabolically related amino acids, for example, Ile, Leu, and Val, cannot be individually incorporated but can be inversely labeled together. We optimized and simplified the protocol and M9-based medium formula for the 14N selective- and inverse-labeling method without any additives. Our approach should be cost-effective, because the method could be additively applied stepwise, even when the proteins of interest were found to be non-ideal.

Circulating levels of soluble alpha-Klotho are markedly elevated in human umbilical cord blood

CONTEXT

Fetal serum levels of calcium and phosphate are higher than those in the maternal levels. Although α-Klotho is known to participate in calcium and phosphate metabolism in adults, its role in the perinatal period remains unknown.

OBJECTIVE

This study aimed to determine the baseline levels of soluble α-Klotho in fetuses and compare them with those in neonates, mothers, and adults to clarify whether α-Klotho is involved in the fetal-specific regulation of calcium and phosphate metabolism.

DESIGN AND SETTING

We conducted a cross-sectional evaluation of healthy babies (at birth and/or at 4 d after birth), their mothers, and adult volunteers at one hospital.

PARTICIPANTS

Twenty-one healthy mothers, their babies (23 in total, including two pairs of twins), and 25 adult volunteers participated in the study.

MAIN OUTCOME MEASURES

We measured the serum levels of soluble α-Klotho and fibroblast growth factor 23 (FGF23).

RESULTS

In cord blood, the level of α-Klotho was markedly higher (3243 ± 1899 pg/ml) than levels in neonates at d 4 (582 ± 90 pg/ml), mothers (768 ± 261 pg/ml), and adult volunteers (681 ± 140 pg/ml) (P < 0.001), whereas the fetal level of FGF23 was lower than levels in the other subjects. The levels of soluble α-Klotho were negatively correlated with those of FGF23 in cord blood. Immunohistochemistry demonstrated that α-Klotho was predominantly expressed in syncytiotrophoblasts in normal term placenta.

CONCLUSION

Levels of soluble α-Klotho are markedly elevated in cord blood and might be useful as a biomarker for mineral metabolism in the fetus.

Two distinct amyloid beta-protein (Abeta) assembly pathways leading to oligomers and fibrils identified by combined fluorescence correlation spectroscopy, morphology, and toxicity analyses

Nonfibrillar assemblies of amyloid β-protein (Aβ) are considered to play primary roles in Alzheimer disease (AD). Elucidating the assembly pathways of these specific aggregates is essential for understanding disease pathogenesis and developing knowledge-based therapies. However, these assemblies cannot be monitored in vivo, and there has been no reliable in vitro monitoring method at low protein concentration. We have developed a highly sensitive in vitro monitoring method using fluorescence correlation spectroscopy (FCS) combined with transmission electron microscopy (TEM) and toxicity assays. Using Aβ labeled at the N terminus or Lys(16), we uncovered two distinct assembly pathways. One leads to highly toxic 10-15-nm spherical Aβ assemblies, termed amylospheroids (ASPDs). The other leads to fibrils. The first step in ASPD formation is trimerization. ASPDs of ∼330 kDa in mass form from these trimers after 5 h of slow rotation. Up to at least 24 h, ASPDs remain the dominant structures in assembly reactions. Neurotoxicity studies reveal that the most toxic ASPDs are ∼128 kDa (∼32-mers). In contrast, fibrillogenesis begins with dimer formation and then proceeds to formation of 15-40-nm spherical intermediates, from which fibrils originate after 15 h. Unlike ASPD formation, the Lys(16)-labeled peptide disturbed fibril formation because the Aβ(16-20) region is critical for this final step. These differences in the assembly pathways clearly indicated that ASPDs are not fibril precursors. The method we have developed should facilitate identifying Aβ assembly steps at which inhibition may be beneficial.

[Regulation of calcium homeostasis by α-Klotho and FGF23]

α-klotho was first identified as an aging gene and was later shown to be a regulator of phosphate and vitamin D metabolism, and a regulator of calcium homeostasis. α-kl is expressed in the parathyroid glands, choroid plexus and kidney, where α-Kl binds to Na(+), K(+)-ATPase. Low extracellular calcium concentrations trigger rapid translocation of α-Kl/Na(+), K(+)-ATPase complex from endosomal organella to the plasma membrane. This may lead to the PTH secretion in parathyroid glands and transepithelial transport of calcium in kidney and choroid plexus. FGF members are divided into 7 subfamilies. Among them, metabolic FGF subfamily, consisted of FGF19, FGF21 and FGF23, is characterized as their hormonal effects. Indeed,FGF23 is secreted from bone and is circulated to kidney where FGF23 tranceduces signals that suppress vitamin D synthesis and phosphate reabsorption fgf23 deficient phenotypes were reminiscent of those of mice lacking the α-kl gene, which led us the discovery of molecular interaction and functional crosstalk of α-Kl and FGF23. FGF23 binds to α-Kl and converts the canonical FGF receptor 1c to specific for FGF23 and we proposed a comprehensive regulatory scheme of mineral homeostasis involving the mutually regulated positive/negative feedback actions of α-Kl, FGF23, PTH and 1,25 (OH) (2)D. α-Kl and FGF23 are novel regulators that integrate the fields of mineral homeostasis, life-style related diseases and aging. This newly established field is widely and remarkably progressing and expected to be fruitful.

Potential of bone marrow stromal cells in applications for neuro-degenerative, neuro-traumatic and muscle degenerative diseases

Cell transplantation is a promising strategy for the treatment of neurodegenerative and muscle degenerative diseases. Many kinds of cells, including embryonic stem cells and tissue stem cells, have been considered as candidates for transplantation therapy. Bone marrow stromal cells (MSCs) have great potential as therapeutic agents since they are easy to isolate and can be expanded from patients without serious ethical or technical problems. We discovered a new method for the highly efficient and specific induction of functional Schwann cells, neurons and skeletal muscle lineage cells from both rat and human MSCs. These induced cells were transplanted into animal models of neurotraumatic injuries, Parkinson's disease, stroke and muscle dystrophies, resulting in the successful integration of transplanted cells and an improvement in behavior of the transplanted animals. Here we focus on the respective potentials of MSC-derived cells and discuss the possibility of clinical application in degenerative diseases.

Unique multipotent cells in adult human mesenchymal cell populations

We found adult human stem cells that can generate, from a single cell, cells with the characteristics of the three germ layers. The cells are stress-tolerant and can be isolated from cultured skin fibroblasts or bone marrow stromal cells, or directly from bone marrow aspirates. These cells can self-renew; form characteristic cell clusters in suspension culture that express a set of genes associated with pluripotency; and can differentiate into endodermal, ectodermal, and mesodermal cells both in vitro and in vivo. When transplanted into immunodeficient mice by local or i.v. injection, the cells integrated into damaged skin, muscle, or liver and differentiated into cytokeratin 14-, dystrophin-, or albumin-positive cells in the respective tissues. Furthermore, they can be efficiently isolated as SSEA-3(+) cells. Unlike authentic ES cells, their proliferation activity is not very high and they do not form teratomas in immunodeficient mouse testes. Thus, nontumorigenic stem cells with the ability to generate the multiple cell types of the three germ layers can be obtained through easily accessible adult human mesenchymal cells without introducing exogenous genes. These unique cells will be beneficial for cell-based therapy and biomedical research.

Functional hierarchy and reversibility within the murine spermatogenic stem cell compartment

Stem cells support tissue maintenance by balancing self-renewal and differentiation. In mice, it is believed that a homogeneous stem cell population of single spermatogonia supports spermatogenesis, and that differentiation, which is accompanied by the formation of connected cells (cysts) of increasing length, is linear and nonreversible. We evaluated this model with the use of lineage analysis and live imaging, and found that this putative stem cell population is not homogeneous. Instead, the stem cell pool that supports steady-state spermatogenesis is contained within a subpopulation of single spermatogonia. We also found that cysts are not committed to differentiation and appear to recover stem cell potential by fragmentation, and that the fate of individual spermatogonial populations was markedly altered during regeneration after damage. Thus, there are multiple and reversible paths from stem cells to differentiation, and these may also occur in other systems.

Dissecting the factors involved in the locomotion mode of neuronal migration in the developing cerebral cortex

Neuronal migration is essential for proper cortical layer formation and brain function, because migration defects result in neurological disorders such as mental retardation and epilepsy. Neuronal migration is divided into several contiguous steps: early phase (multipolar mode), locomotion mode, and terminal translocation mode. The locomotion mode covers most of the migration route and thereby is the main contributor to cortical layer formation. However, analysis of the molecular mechanisms regulating this mode is difficult due to the secondary effects of defects at the early phase of migration. In this study, we established an ex vivo chemical inhibitor screening, allowing us to directly analyze the locomotion mode of migration. Roscovitine and PP2, inhibitors for Cdk5 and Src family kinases, respectively, suppressed the locomotion mode of migration. In line with this, a small percentage of Cdk5- or Src family kinase (Fyn)-knockdown cells exhibited locomoting morphology but retarded migration, although the majority of cells were stalled at the early phase of migration. We also showed that rottlerin, widely used as a specific inhibitor for protein kinase Cdelta (PKCdelta), suppressed the locomotion mode. Unexpectedly, however, the dominant-negative form as well as RNA interference for PKCdelta hardly affected the locomotion, whereas they may disturb terminal translocation. In addition, we found JNK to be a potential downstream target of rottlerin. Taken together, our novel chemical inhibitor screening provides evidence that Cdk5 and Src family kinases regulate the locomotion mode of neuronal migration. It also uncovered roles for Fyn and PKCdelta in the early and final phases of migration, respectively.

Thioredoxin binding protein 2 modulates natural killer T cell-dependent innate immunity in the liver: possible link to lipid metabolism

Thioredoxin binding protein 2 (TBP2) plays a regulatory role in lipid metabolism and immune regulation. We previously reported the effect of TBP2 loss-of-function on lipid metabolism using TBP2 knockout (TBP2KO) mice. In this study, we employed TBP2 transgenic (TBP2TG) mice to analyze the in vivo effect of TBP2 gain-of-function. We revealed a decrease in the percentage of hepatic natural killer T (NKT) cells in TBP2KO mice and an increase in the percentage of hepatic NKT cells in TBP2TG mice. The TBP2KO mice were resistant to concanavalin A (ConA)-induced hepatitis, but they were highly susceptible to other types of hepatitis. TBP2 modulates lipid metabolism as well as NKT cell activity. Moreover, TBP2 expression was increased significantly in klotho-deficient mice, which exhibit a syndrome resembling aging human phenotypes. TBP2 may play multiple roles in lipid metabolism, innate immunity, and aging.

Isolation and characterization of patient-derived, toxic, high mass amyloid beta-protein (Abeta) assembly from Alzheimer disease brains

Amyloid beta-protein (Abeta) assemblies are thought to play primary roles in Alzheimer disease (AD). They are considered to acquire surface tertiary structures, not present in physiologic monomers, that are responsible for exerting toxicity, probably through abnormal interactions with their target(s). Therefore, Abeta assemblies having distinct surface tertiary structures should cause neurotoxicity through distinct mechanisms. Aiming to clarify the molecular basis of neuronal loss, which is a central phenotype in neurodegenerative diseases such as AD, we report here the selective immunoisolation of neurotoxic 10-15-nm spherical Abeta assemblies termed native amylospheroids (native ASPDs) from AD and dementia with Lewy bodies brains, using ASPD tertiary structure-dependent antibodies. In AD patients, the amount of native ASPDs was correlated with the pathologic severity of disease. Native ASPDs are anti-pan oligomer A11 antibody-negative, high mass (>100 kDa) assemblies that induce degeneration particularly of mature neurons, including those of human origin, in vitro. Importantly, their immunospecificity strongly suggests that native ASPDs have a distinct surface tertiary structure from other reported assemblies such as dimers, Abeta-derived diffusible ligands, and A11-positive assemblies. Only ASPD tertiary structure-dependent antibodies could block ASPD-induced neurodegeneration. ASPDs bind presynaptic target(s) on mature neurons and have a mode of toxicity different from those of other assemblies, which have been reported to exert their toxicity through binding postsynaptic targets and probably perturbing glutamatergic synaptic transmission. Thus, our findings indicate that native ASPDs with a distinct toxic surface induce neuronal loss through a different mechanism from other Abeta assemblies.

[Aspects of mammalian aging from alphaklotho study]

Since the discovery of alphaklotho-mutant mice, it has been questioned whether the responsible gene, alphaklotho, makes any effect on 'intrinsic aging' process. So far we found that alphaKlotho regulates transcellular calcium transport by mediating Na,K-ATPase activity and dominates mineral-regulating hormones such as PTH, vitamin D and FGF23. A new concept is now emerged that alphaklotho integrates mineral homeostasis. Findings of human cases with mineral disorders revealed impairment of alphaklotho expression as a pathological cause. Mineral metabolic system contributes to health and thus its disruption should result in acceleration of aging and disease.

Morphological organization of the mouse preimplantation embryo

During the 4 days after fertilization, the mouse embryo proceeds in its development within the zona pellucida and reaches the blastocyst stage, when a newly formed embryonic-abembryonic (E-Ab) axis is settled before implantation. The previous findings suggested that the shape of the zona pellucida, which may function as an environmental cue for the embryo proper, is a major factor affecting the specification of the blastocyst axis orientation. The characteristics of the cells were not dependent on the shape of the zona pellucida. It is suggested that the division order of cells is under certain rules, and the differentiation of cells is dependent on the relative position of blastomeres in later stages.

Loss of yata, a novel gene regulating the subcellular localization of APPL, induces deterioration of neural tissues and lifespan shortening

Background

The subcellular localization of membrane and secreted proteins is finely and dynamically regulated through intracellular vesicular trafficking for permitting various biological processes. Drosophila Amyloid precursor protein like (APPL) and Hikaru genki (HIG) are examples of proteins that show differential subcellular localization among several developmental stages.

Methodology/Principal Findings

During the study of the localization mechanisms of APPL and HIG, we isolated a novel mutant of the gene, CG1973, which we named yata. This molecule interacted genetically with Appl and is structurally similar to mouse NTKL/SCYL1, whose mutation was reported to cause neurodegeneration. yata null mutants showed phenotypes that included developmental abnormalities, progressive eye vacuolization, brain volume reduction, and lifespan shortening. Exogenous expression of Appl or hig in neurons partially rescued the mutant phenotypes of yata. Conversely, the phenotypes were exacerbated in double null mutants for yata and Appl. We also examined the subcellular localization of endogenous APPL and exogenously pulse-induced APPL tagged with FLAG by immunostaining the pupal brain and larval motor neurons in yata mutants. Our data revealed that yata mutants showed impaired subcellular localization of APPL. Finally, yata mutant pupal brains occasionally showed aberrant accumulation of Sec23p, a component of the COPII coat of secretory vesicles traveling from the endoplasmic reticulum (ER) to the Golgi.

Conclusion/Significance

We identified a novel gene, yata, which is essential for the normal development and survival of tissues. Loss of yata resulted in the progressive deterioration of the nervous system and premature lethality. Our genetic data showed a functional relationship between yata and Appl. As a candidate mechanism of the abnormalities, we found that yata regulates the subcellular localization of APPL and possibly other proteins.

Discovery of alpha-Klotho unveiled new insights into calcium and phosphate homeostasis

alpha-Klotho was first identified as the responsible gene in a mutant mouse line whose disruption results in a variety of premature aging-related phenotypes. alpha-Klotho has been shown to participate in the regulation of parathyroid hormone secretion and trans-epithelial transport of Ca(2+) in the choroid plexus and kidney. alpha-Klotho, acting as a cofactor for FGF23, is also a major regulator of vitamin D biosynthesis and phosphate reabsorption in the kidney. These suggest that alpha-Klotho is a key player that integrates a multi-step regulatory system of calcium and phosphate homeostasis. Collectively, the molecular function of alpha-Klotho reveals a new paradigm that may change current concepts in mineral homeostasis and give rise to new insights in this field.

[Discovery of alpha-Klotho and FGF23 unveiled new insight into calcium and phosphate homeostasis]

Recent advances that have given rise to marked progress in clarifying actions of alpha-Klotho (alpha-Kl) and FGf23 can be summarized as follows ; (i) alpha-Kl binds to Na(+), K(+)-ATPase, and Na(+), K(+)-ATPase is recruited to the plasma membrane by a novelalpha-Kl dependent pathway in correlation with cleavage and secretion ofalpha-Kl in response to extracellular Ca(2+) fluctuation. (ii) The increased Na(+) gradient created by Na(+), K(+)-ATPase activity drives the transepithelial transport of Ca(2+) in the choroid plexus and the kidney, this is defective in alpha-kl(-/-) mice. (iii) The regulated PTH secretion in the parathyroid glands is triggered via recruitment of Na(+), K(+)-ATPase to the cell surface in response to extracellular Ca(2+) concentrations. (iv) alpha-Kl, in combination with FGF23, regulates the production of 1,25 (OH) (2)D in the kidney. In this pathway, alpha-Kl binds to FGF23, andalpha-Kl converts the canonical FGF receptor 1c to a specific receptor for FGF23, enabling the high affinity binding of FGF23 to the cell surface of the distal convoluted tubule where alpha-Kl is expressed. (v) FGF23 signal down-regulates serum phosphate levels, due to decreased NaPi-IIa abundance in the apical membrane of the kidney proximal tubule cells. (vi) alpha-Kl in urine increases TRPV5 channel abundance at the luminal cell surface by hydrolyzing the N-linked extracellular sugar residues of TRPV5, resulting in increased Ca(2+) influx from the lumen. These findings revealed a comprehensive regulatory scheme of mineral homeostasis that is illustrated by the mutually regulated positive/negative feedback actions of alpha-Kl, FGF23, PTH and 1,25 (OH) (2)D. In this regard, alpha-Kl and FGF23 might play pivotal roles in mineral metabolism as regulators that integrate calcium and phosphate homeostasis, although this concept requires further verification in the light of related findings. Here, the unveiling of the molecular functions of alpha-Klotho and FGF23 has recently given new insight into the field of calcium and phosphate homeostasis. Unveiled molecular functions of alpha-Kl and FGF23 provided answers for several important questions regarding the mechanisms of calcium and phosphate homeostasis that remained to be solved, such as : (i) what is the non-hormonal regulatory system that directly responds to the fluctuation of extracellular Ca(2+), (ii) how is Na(+), K(+)-ATPase activity enhanced in response to low calcium stimuli in the parathyroid glands, (iii) what is the exact role of FGF23 in calcium and phosphorus metabolism, (iv) how is Ca(2+) influx through TRPV5 controlled in the DCT nephron, and finally (v) how is calcium homeostasis regulated in cerebrospinal fluid. However, several critical questions still remain to be solved. So far reported,alpha-Kl binds to Na(+), K(+)-ATPase, FGF receptors and FGF23, and alpha-Kl hydrolyzes the sugar moieties of TRPV5. Does alpha-Kl recognize these proteins directly or indirectly?Is there any common mechanism?How can we reconcile such diverse functions of alpha-Kl?What is the Ca(2+) sensor machinery and how can we isolate it?How do hypervitaminosis D and the subsequently altered mineral-ion balance lead to the multiple phenotypes?What is the phosphate sensor machinery and how can we isolate it? How does the Fgf23/alpha-Kl system regulate phosphorus homeostasis?How are serum concentrations of Ca(2 + ) and phosphate mutually regulated?

Deficiency of zonula occludens-1 causes embryonic lethal phenotype associated with defected yolk sac angiogenesis and apoptosis of embryonic cells

Zonula occludens (ZO)-1/2/3 are the members of the TJ-MAGUK family of membrane-associated guanylate kinases associated with tight junctions. To investigate the role of ZO-1 (encoded by Tjp1) in vivo, ZO-1 knockout (Tjp1(-/-)) mice were generated by gene targeting. Although heterozygous mice showed normal development and fertility, delayed growth and development were evident from E8.5 onward in Tjp1(-/-) embryos, and no viable Tjp1(-/-) embryos were observed beyond E11.5. Tjp1(-/-) embryos exhibited massive apoptosis in the notochord, neural tube area, and allantois at embryonic day (E)9.5. In the yolk sac, the ZO-1 deficiency induced defects in vascular development, with impaired formation of vascular trees, along with defective chorioallantoic fusion. Immunostaining of wild-type embryos at E8.5 for ZO-1/2/3 revealed that ZO-1/2 were expressed in almost all embryonic cells, showing tight junction-localizing patterns, with or without ZO-3, which was confined to the epithelial cells. ZO-1 deficiency depleted ZO-1-expression without influence on ZO-2/3 expression. In Tjp1(+/+) yolk sac extraembryonic mesoderm, ZO-1 was dominant without ZO-2/3 expression. Thus, ZO-1 deficiency resulted in mesoderms with no ZO-1/2/3, associated with mislocalization of endothelial junctional adhesion molecules. As a result, angiogenesis was defected in Tjp1(-/-) yolk sac, although differentiation of endothelial cells seemed to be normal. In conclusion, ZO-1 may be functionally important for cell remodeling and tissue organization in both the embryonic and extraembryonic regions, thus playing an essential role in embryonic development.

alpha-Klotho: a regulator that integrates calcium homeostasis

Intensive study on calcium homeostasis regulation over the past several decades has established a systematized construal of its role in living phenomena, leaving us with the impression that this field is fairly defined and understood. However, the unveiling of the molecular function of alpha-Klotho has recently given new insight into this field. alpha-Klotho is a unique molecule that plays pivotal roles in: (i) the rapid tuning of extracellular Ca(2+) concentration through transepithelial Ca(2+) transport; (ii) parathyroid hormone secretion and subsequent Ca(2+) increase in the serum, and (iii) the signal transduction of FGF23 that adjusts the calcium concentration by downregulating the production of 1,25(OH)(2)D(3). Through these pathways, alpha-Klotho participates in the regulation of calcium homeostasis of the CSF and blood/body fluids by its actions in the choroid plexus, parathyroid glands and DCT nephrons. In this regard, alpha-Klotho is a key player that integrates 'a multi-step regulatory system of calcium homeostasis' that rapidly adjusts the extracellular calcium concentration and continuously maintains its concentration within a narrow physiological range.

Opposing roles in neurite growth control by two seven-pass transmembrane cadherins

The growth of neurites (axon and dendrite) should be appropriately regulated by their interactions in the development of nervous systems where a myriad of neurons and their neurites are tightly packed. We show here that mammalian seven-pass transmembrane cadherins Celsr2 and Celsr3 are activated by their homophilic interactions and regulate neurite growth in an opposing manner. Both gene-silencing and coculture assay with rat neuron cultures showed that Celsr2 enhanced neurite growth, whereas Celsr3 suppressed it, and that their opposite functions were most likely the result of a difference of a single amino acid residue in the transmembrane domain. Together with calcium imaging and pharmacological analyses, our results suggest that Celsr2 and Celsr3 fulfill their functions through second messengers, and that differences in the activities of the homologs results in opposite effects in neurite growth regulation.

alpha-Klotho as a regulator of calcium homeostasis

alpha-klotho was identified as a gene associated with premature aging-like phenotypes characterized by short lifespan. In mice, we found the molecular association of alpha-Klotho (alpha-Kl) and Na+,K+-adenosine triphosphatase (Na+,K+-ATPase) and provide evidence for an increase of abundance of Na+,K+-ATPase at the plasma membrane. Low concentrations of extracellular free calcium ([Ca2+]e) rapidly induce regulated parathyroid hormone (PTH) secretion in an alpha-Kl- and Na+,K+-ATPase-dependent manner. The increased Na+ gradient created by Na+,K+-ATPase activity might drive the transepithelial transport of Ca2+ in cooperation with ion channels and transporters in the choroid plexus and the kidney. Our findings reveal fundamental roles of alpha-Kl in the regulation of calcium metabolism.

Platelet-derived growth factor (PDGF)-BB inhibits AMPA receptor-mediated synaptic transmission via PDGF receptor-beta in murine nucleus tractus solitarius

Although platelet-derived growth factor (PDGF)-BB activates PDGF receptor-beta (PDGFR-beta) and, in turn, inhibits the glutamate N-methyl-D-aspartate (NMDA) receptor function, whether PDGF-BB modulates the CNS function mediated by another glutamate receptors, alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptors, remains poorly understood. Here we now report the inhibitory effect of PDGF-BB on the AMPA receptor function in the nucleus tractus solitarius (NTS) by using slice patch-clamp techniques. Excitatory postsynaptic currents (EPSCs) were evoked by electrical stimulation of the tractus solitarius in mouse NTS second-order neurons. EPSCs were nearly completely eliminated by CNQX but not by MK-801, implying mediation through non-NMDA receptors. PDGF-BB significantly decreased the amplitude of EPSCs without affecting the mean decay time constant. This inhibitory effect was transient and reversible after removing PDGF-BB. Furthermore, PDGF-BB significantly reduced the amplitude of AMPA-induced currents in NTS neurons, which showed that PDGF-BB could suppress the AMPA receptor-mediated excitatory input via the postsynaptic mechanism. The inhibitory effect of PDGF-BB on EPSCs was not observed in mutant mice with conditional deletion of the PDGFR-beta gene in neurons. Together, these studies suggest that the PDGF-B/PDGFR-beta axis inhibits the AMPA receptor-mediated synaptic transmission that comprises the major part of the primary afferent to the NTS second-order neuron. The detected inhibitory action may be involved in the CNS regulation of the respiratory response.

Morphological mechanism of the development of pulmonary emphysema in klotho mice

The concept of fractal geometry is useful for the analysis of irregular and complex structures often seen in nature. Here we apply this concept to investigate the structural mechanism of the development of pulmonary emphysema in the klotho mouse, which, after milk feeding, exhibits characteristics resembling aging and develops emphysema. We calculated the relationships between perimeter and size characterizing shape and between cumulative frequency and size of the terminal air spaces identified from histologic slides and found that both relations followed a power law with fractal properties. However, the fractal dimensions related to the shape and size (Dsn) in the klotho mice were significantly lower than in controls. Additionally, in the klotho mice, Dsn decreased with age without significant change in mean linear intercept. These abnormal morphological changes were restored when the klotho mice were fed with a vitamin D-deficient diet. Previously undescribed morphological model simulations showed that a random destruction, in which the destruction process occurs homogeneously in the lungs, was more consistent with the data than a correlated destruction that is usually seen in smoking-related human emphysema. These results suggest that the pathological changes in the lungs of the klotho mice are derived not from localized causes, but from systemic causes that are related to abnormal activation of vitamin D. The morphogenesis of emphysema in the klotho mice and morphological analyses using fractal geometry may contribute to the understanding of the progressive nature and cause of parenchymal destruction in human emphysema.

Correlation between hyperphosphatemia and type II Na-Pi cotransporter activity in klotho mice

Recent studies have demonstrated that klotho protein plays a role in calcium/phosphate homeostasis. The goal of the present study was to investigate the regulation of Na-Pi cotransporters in klotho mutant (kl/kl) mice. The kl/kl mice displayed hyperphosphatemia, high plasma 1,25(OH)2D3 levels, increased activity of the renal and intestinal sodium-dependent Pi cotransporters, and increased levels of the type IIa, type IIb, and type IIc transporter proteins compared with wild-type mice. Interestingly, transcript levels of the type IIa/type IIc transporter mRNA abundance, but not transcripts levels of type IIb transporter mRNA, were markedly decreased in kl/kl mice compared with wild-type mice. Furthermore, plasma fibroblast growth factor 23 (FGF23) levels were 150-fold higher in kl/kl mice than in wild-type mice. Feeding of a low-Pi diet induced the expression of klotho protein and decreased plasma FGF23 levels in kl/kl mice, whereas colchicine treatment experiments revealed evidence of abnormal membrane trafficking of the type IIa transporter in kl/kl mice. Finally, feeding of a low-Pi diet resulted in increased type IIa Na-Pi cotransporter protein in the apical membrane in the wild-type mice, but not in kl/kl mice. These results indicate that hyperphosphatemia in klotho mice is due to dysregulation of expression and trafficking of the renal type IIa/IIc transporters rather than to intestinal Pi uptake.

TBP-interacting protein 120B (TIP120B)/cullin-associated and neddylation-dissociated 2 (CAND2) inhibits SCF-dependent ubiquitination of myogenin and accelerates myogenic differentiation

Despite fast protein degradation in muscles, protein concentrations remain constant during differentiation and maintenance of muscle tissues. Myogenin, a basic helix-loop-helix-type myogenic transcription factor, plays a critical role through transcriptional activation in myogenesis as well as muscle maintenance. TBP-interacting protein 120/cullin-associated neddylation-dissociated (TIP120/CAND) is known to bind to cullin and negatively regulate SCF (Skp1-Cullin1-F-box protein) ubiquitin ligase, although its physiological role has not been elucidated. We have identified a muscle-specific isoform of TIP120, named TIP120B/CAND2. In this study, we found that TIP120B is not only induced in association with myogenic differentiation but also actively accelerates the myogenic differentiation of C2C12 cells. Although myogenin is a short lived protein and is degraded by a ubiquitin-proteasome system, TIP120B suppressed its ubiquitination and subsequent degradation of myogenin. TIP120B bound to cullin family proteins, especially Cullin 1 (CUL1), and was associated with SCF complex in cells. It was demonstrated that myogenin was also associated with SCF and that CUL1 small interference RNA treatment inhibited ubiquitination of myogenin and stabilized it. TIP120B was found to break down the SCF-myogenin complex. Consequently suppression of SCF-dependent ubiquitination of myogenin by TIP120B, which leads to stabilization of myogenin, can account for the TIP120B-directed accelerated differentiation of C2C12 cells. TIP120B is proposed to be a novel regulator for myogenesis.

Mouse brains deficient in neuronal PDGF receptor-beta develop normally but are vulnerable to injury

Platelet-derived growth factors (PDGFs) and PDGF receptors (PDGFRs) are widely expressed in the mammalian CNS, though their functional significance remains unclear. The corresponding null-knockout mutations are lethal. Here, we developed novel mutant mice in which the gene encoding the beta subunit of PDGFR (PDGFR-beta) was genetically deleted in CNS neurons to elucidate the role of PDGFR-beta, particularly in the post-natal stage. Our mutant mice reached adulthood without apparent anatomical defects. In the mutant brain, immunohistochemical analyses showed that PDGFR-beta detected in neurons and in the cells in the subventricular zone of the lateral ventricle in wild-type mice was depleted, but PDGFR-beta detected in blood vessels remained unaffected. The cerebral damage after cryogenic injury was severely exacerbated in the mutants compared with controls. Furthermore, TdT-mediated dUTP-biotin nick end labeling (TUNEL)-positive neuronal cell death and lesion formation in the cerebral hemisphere were extensively exacerbated in our mutant mice after direct injection of NMDA without altered NMDA receptor expression. Our results clearly demonstrate that PDGFR-beta expressed in neurons protects them from cryogenic injury and NMDA-induced excitotoxicity.

Toward a better understanding of Klotho

klotho mutant mice were originally described as a short-lived mouse model with premature aging-like disorders. The klotho gene responsible for these phenotypes encodes a type I membrane protein with a considerable similarity to beta-glycosidase. klotho is predominantly expressed in tissues functioning in the regulation of calcium homeostasis. Suggested functions of Klotho are (i) a fundamental regulator of calcium homeostasis, namely, a cofactor for the fibroblast growth factor (FGF) receptor 1c in FGF23 signaling and a regulator of parathyroid hormone secretion; (ii) a hormone that interferes with the intracellular signaling of insulin and insulin-like growth factor-1; and (iii) a beta-glucuronidase that activates the transient receptor potential ion channel TRPV5 by trimming its sugar moiety. How can we reconcile these pleiotropic functions of Klotho? Is there any common mechanism? Further in vivo studies, and biochemical as well as physiological analyses, are required for a better understanding of the molecular aspects of Klotho.

Olig2-positive progenitors in the embryonic spinal cord give rise not only to motoneurons and oligodendrocytes, but also to a subset of astrocytes and ependymal cells

Motoneurons and oligodendrocytes in the embryonic spinal cord are produced from a restricted domain of the ventral ventricular zone, termed the pMN domain. The pMN domain is the site of expression of two basic helix-loop-helix transcription factors, Olig1 and Olig2, which are essential for motoneuron and oligodendrocyte development. Previous lineage-tracing experiments using Olig1-Cre and Olig2-GFP mice suggested that motoneurons and oligodendrocytes, but not astrocytes, are produced from the pMN domain. However, important questions remain, including the fate of neuroepithelial cells in the pMN domain, and specifically whether motoneurons and oligodendrocytes are the only types of cells produced in the pMN domain. We performed lineage-tracing experiments using a tamoxifen-inducible Cre-recombinase inserted into the Olig2 locus. We demonstrated that motoneurons and oligodendrocyte progenitors are derived from the Olig2+ progenitors in the pMN domain, and also found that a subset of astrocytes at the ventral surface of the spinal cord and ependymal cells at the ventricular surface are also produced from the pMN domain. These findings demonstrate that motoneurons and oligodendrocytes are not the only cell types originating from this domain.

The first round of mouse spermatogenesis is a distinctive program that lacks the self-renewing spermatogonia stage

Mammalian spermatogenesis is maintained by a continuous supply of differentiating cells from self-renewing stem cells. The stem cell activity resides in a small subset of primitive germ cells, the undifferentiated spermatogonia. However, the relationship between the establishment of this population and the initiation of differentiation in the developing testes remains unclear. In this study, we have investigated this issue by using the unique expression of Ngn3, which is expressed specifically in the undifferentiated spermatogonia, but not in the differentiating spermatogonia or their progenitors, the gonocytes. Our lineage analyses demonstrate that the first round of mouse spermatogenesis initiates directly from gonocytes,without passing through the Ngn3-expressing stage (Ngn3- lineage). By contrast, the subsequent rounds of spermatogenesis are derived from Ngn3-positive undifferentiated spermatogonia, which are also immediate descendents of the gonocytes and represent the stem cell function(Ngn3+ lineage). Thus, in mouse spermatogenesis, the state of the undifferentiated spermatogonia is not an inevitable step but is a developmental option that ensures continuous sperm production. In addition,the segregation of gonocytes into undifferentiated spermatogonia(Ngn3+ lineage) or differentiating spermatogonia (Ngn3-lineage) is topographically related to the establishment of the seminiferous epithelial cycle, thus suggesting a role of somatic components in the establishment of stem cells.

Involvement of a Rac activator,P-Rex1, in neurotrophin-derived signaling and neuronal migration

Rho-family GTPases play key roles in regulating cytoskeletal reorganization, contributing to many aspects of nervous system development. Their activities are known to be regulated by guanine nucleotide exchange factors (GEFs), in response to various extracellular cues. P-Rex1, a GEF for Rac, has been mainly investigated in neutrophils, in which this molecule contributes to reactive oxygen species formation. However, its role in the nervous system is essentially unknown. Here we describe the expression profile and a physiological function of P-Rex1 in nervous system development. In situ hybridization revealed that P-Rex1 is dynamically expressed in a variety of cells in the developing mouse brain, including some cortical and DRG neurons. In migrating neurons in the intermediate zone, P-Rex1 protein was found to localize in the leading process and adjacent cytoplasmic region. When transfected in pheochromocytoma PC12 cells, P-Rex1 can be activated by NGF, causing an increase in GTP-bound Rac1 and cell motility. Deletion analyses suggested roles for distinct domains of this molecule. Experiments using a P-Rex1 mutant lacking the Dbl-homology domain, a dominant-negative-like form, and small interfering RNA showed that endogenous P-Rex1 was involved in cell migration of PC12 cells and primary cultured neurons from the embryonic day 14 cerebral cortices, induced by extracellular stimuli (NGF, BDNF, and epidermal growth factor). Furthermore, in utero electroporation of the mutant protein into the embryonic cerebral cortex perturbed radial neuronal migration. These findings suggest that P-Rex1, which is expressed in a variety of cell types, is activated by extracellular cues such as neurotrophins and contributes to neuronal migration in the developing nervous system.

Marrow stromal cells: implications in health and disease in the nervous system

Chronic degenerative diseases and traumatic injuries are responsible for a decline in neuronal function, which often limit life span. While solid organ transplantation such as liver and kidney has been already applied for thousands of patients, great limitation exists in case of nervous system. Cell transplantation is one of the strategies with potential for treatment of such neural disorders, and many kinds of cells including embryonic stem cells and neural stem cells have been considered as candidates for transplantation therapy. Bone marrow stromal cells (MSCs) have great potential as therapeutic agents, since they are easy to isolate and can be expanded from patients without serious ethical and technical problems. We found a method for the highly efficient and specific induction of functional neurons and Schwann cells from both rat and human MSCs. Induced neurons and Schwann cells were transplanted in animal models of Parkinson's disease, stroke, peripheral nerve injury, and spinal cord injury resulting in the successful integration of transplanted cells and improvement in behavior of transplanted animals. Here we focus on the respective potentials of MSC-derived cells and discuss the possibility of clinical application in neurodegenerative and neurotraumatic diseases.

Cdk5 phosphorylates and stabilizes p27kip1 contributing to actin organization and cortical neuronal migration

p27(kip1), a cyclin-dependent kinase (CDK) inhibitor (CKI), generally suppresses CDK activity in proliferating cells. Although another role of p27 in cell migration has been recently suggested in vitro, the physiological importance of p27 in cell migration remains elusive, as p27-deficient mice have not shown any obvious migration-defect-related phenotypes. Here, we show that Cdk5, an unconventional neuronal CDK, phosphorylates and stabilizes p27 as an upstream regulator, maintaining the amount of p27 in post-mitotic neurons. In vivo RNA interference (RNAi) experiments showed that reduced amounts of p27 caused inhibition of cortical neuronal migration and decreased the amount of F-actin in the processes of migrating neurons. The Cdk5-p27 pathway activates an actin-binding protein, cofilin, which is also shown to be involved in cortical neuronal migration in vivo. Our findings shed light on a previously unknown new relationship between CDK and CKI in G0-arrested cells that regulates cytoskeletal reorganization and neuronal migration during corticogenesis.

Bone marrow stromal cells generate muscle cells and repair muscle degeneration

Bone marrow stromal cells (MSCs) have great potential as therapeutic agents. We report a method for inducing skeletal muscle lineage cells from human and rat general adherent MSCs with an efficiency of 89%. Induced cells differentiated into muscle fibers upon transplantation into degenerated muscles of rats and mdx-nude mice. The induced population contained Pax7-positive cells that contributed to subsequent regeneration of muscle upon repetitive damage without additional transplantation of cells. These MSCs represent a more ready supply of myogenic cells than do the rare myogenic stem cells normally found in muscle and bone marrow.

MAP1B phosphorylation is differentially regulated by Cdk5/p35, Cdk5/p25, and JNK

Mode I phosphorylated MAP1B is observed in developing and pathogenic brains. Although Cdk5 has been believed to phosphorylate MAP1B in the developing cerebral cortex, we show that a Cdk5 inhibitor does not suppress mode I phosphorylation of MAP1B in primary and slice cultures, while a JNK inhibitor does. Coincidently, an increase in phosphorylated MAP1B was not observed in COS7 cells when Cdk5 was cotransfected with p35, but this did occur with p25 which is specifically produced in pathogenic brains. Our primary culture studies showed an involvement of Cdk5 in regulating microtubule dynamics without affecting MAP1B phosphorylation status. The importance of regulating microtubule dynamics in neuronal migration was also demonstrated by in utero electroporation experiments. These findings suggest that mode I phosphorylation of MAP1B is facilitated by JNK but not Cdk5/p35 in the developing cerebral cortex and by Cdk5/p25 in pathogenic brains, contributing to various biological events.

Klotho insufficiency causes decrease of ribosomal RNA gene transcription activity, cytoplasmic RNA and rough ER in the spinal anterior horn cells

The klotho gene was identified in 1997 as the gene whose severe insufficiency (kl/kl) causes a syndrome resembling human aging, such as osteoporosis, arteriosclerosis, gonadal atrophy, emphysema, and short life span in a mouse strain. Regarding the gait disturbance reported in kl/kl mice, the present study examined the spinal cord of kl/kl mice, and revealed decreases in the number of large anterior horn cells (AHCs), the amount of cytoplasmic RNA, the number of ribosomes and rough endoplasmic reticulum (rER), and the activity of ribosomal (r) RNA gene transcription without significant loss of the total number of neurons in the ventral gray matter. Increased immunostaining of phosphorylated neurofilament in the AHCs and of glial fibrillary acidic protein in reactive astrocytes in the anterior horn of kl/kl mice were also observed. On the other hand, the posterior horn was quite well preserved. The results suggest that the kl/kl insufficiency causes atrophy and dysfunction of the spinal AHCs through decreased activity of rRNA gene transcription, which may reduce the amount of cytoplasmic RNA and the number of ribosomes and rER. These findings resemble those found in the spinal cord of patients with classic amyotrophic lateral sclerosis (ALS). The results show that klotho gene insufficiency causes dysfunction of the protein synthesizing system in the AHCs, and might indicate the klotho gene is involved in the pathological mechanism of classic ALS. The kl/kl is a new animal model of AHC degeneration, and may provide clues to understanding the etiology of classic ALS.

PAR-6–PAR-3 mediates Cdc42-induced Rac activation through the Rac GEFs STEF/Tiam1

A polarity complex of PAR-3, PAR-6 and atypical protein kinase C (aPKC) functions in various cell-polarization events, including neuron specification. The small GTPase Cdc42 binds to PAR-6 and regulates cell polarity. However, little is known about the downstream signals of the Cdc42-PAR protein complex. Here, we found that PAR-3 directly interacted with STEF/Tiam1, which are Rac-specific guanine nucleotide-exchange factors, and that STEF formed a complex with PAR-3-aPKC-PAR-6-Cdc42-GTP. Cdc42 induces lamellipodia in a Rac-dependent manner in N1E-115 neuroblastoma cells. Disruption of Cdc42-PAR-6 or PAR-3-STEF binding inhibited Cdc42-induced lamellipodia but not filopodia. The isolated STEF-binding PAR-3 fragment was sufficient to induce lamellipodia independently of Cdc42 and PAR-6. PAR-3 is required for Cdc42-induced Rac activation, but is not essential for lamellipodia formation itself. In cultured hippocampal neurons, STEF accumulated at the tip of the growing axon and colocalized with PAR-3. The spatio-temporal activation and signalling of Cdc42-PAR-6-PAR-3-STEF/Tiam1-Rac seem to be involved in neurite growth and axon specification. We propose that the PAR-6-PAR-3 complex mediates Cdc42-induced Rac activation by means of STEF/Tiam1, and that this process seems to be required for the establishment of neuronal polarity.