Establishment and visual analysis of CBA/J-Pde6bY347Y/Y347X and C3H/HeJ-Pde6bY347Y/Y347X mice.

In CBA/J and C3H/HeJ mice, retinitis pigmentosa is inherited as an autosomal-recessive trait due to a mutation in Pde6b, which encodes cGMP phosphodiesterase subunit b. In these strains, the Y347X mutation in Pde6b leads to the upregulation of cGMP levels, increased Ca2+ influx induces rod death, and the outer segment and rod cells entirely disappeared by 35 days after birth. In the present study, we utilized the clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated (Cas) 9-mediated gene editing to repair the Y347X mutation in CBA/J and C3H/HeJ mice. Evaluation of the established CBA/J-Pde6bY347Y/Y347X and C3H/HeJ-Pde6bY347Y/Y347X mice, which were confirmed to have normal retinal layers by live fundoscopic imaging and histopathological analysis, revealed improved visual acuity based on the visual cliff and light/dark latency tests. Furthermore, our analyses revealed that the visible platform test was a more effective tool for testing visual behavior in these mice. The results suggest that the established strains can serve as control groups for CBA/J and C3H/HeJ in ophthalmology studies involving retinitis pigmentosa.

Relationships of rapid eating with visceral and subcutaneous fat mass and plasma adiponectin concentration.

Rapid eating has been demonstrated to be associated with obesity and overweight. However, few studies have characterized the separate relationships of eating speed with visceral and subcutaneous fat mass or circulating adiponectin concentration. We hypothesized that rapid eating is associated with the larger visceral fat tissue (VFT) area and lower adiponectin concentration, but not with the subcutaneous fat tissue (SFT) area in men and women. We performed a cross-sectional study of 712 adults aged 20-86 years (528 men and 184 women; mean ± SD age 59.36 ± 13.61 years). The participants completed a self-reported questionnaire, and underwent anthropometric and laboratory measurements and computed tomographic imaging of the abdomen as a part of annual medical check-ups. Multivariate linear regression analyses revealed that rapid eating was associated with larger visceral (B = 24.74; 95% CI 8.87-40.61, p = 0.002) and subcutaneous fat areas (B = 31.31; 95% CI 12.23-50.38, p = 0.001), lower adiponectin concentration (B = - 2.92; 95% CI - 4.39- - 1.46, p < 0.001), higher body mass index (BMI) (B = 2.13; 95% CI 1.02-3.25, p < 0.001), and larger waist circumference (B = 5.23; 95% CI 2.16-8.30, p < 0.001) in men, which is partially consistent with the hypothesis. In contrast, rapid eating was found to be associated only with BMI, and not with abdominal adipose area or adiponectin concentration in women, which is a result that is not consistent with the hypothesis. These results suggest that there is no difference in the association of rapid eating with VFT and SFT areas.

At-risk internet addiction and related factors among senior high school teachers in Japan based on a Nationwide survey.

BACKGROUND: Internet addiction (IA) has been drawing attention to mental health. However, few reports have been found on the related factors of at-risk IA among regular workers by a nationwide survey. The study aimed to evaluate the characteristics of at-risk IA and identify related factors among senior high school teachers in Japan. METHODS: This survey was a cross-sectional survey of high schools across Japan in 2017. There were 3189 teachers (2088 males and 1098 female) who participated in this survey. The questionnaire asked about their devices, both the time and the activities of using their internet, and sociodemographic factors. IA was measured by the internet addiction test (IAT) by which 40-79 points were classified as at-risk IA, and more as IA. We compared the related factors of at-risk IA and non-IA using descriptive analysis and multivariable regression analysis. RESULTS: The rates of IA and at-risk IA were 0.09% (n = 3) and 6.91% (n = 220), respectively. At-risk IA was positively associated with activities on the internet for gaming, entertainment, net-surfing, and younger ages. In addition, the at-risk IA group had a longer time spent on the internet than the non-IA group. CONCLUSIONS: Around 7% of high school teachers are at-risk IA in this survey, though they have regular work. Our results suggest that at-risk IA may be reinforced not only by the active internet use such as gaming, but also by purposeless behaviors, such as net-surfing. Managing time on the internet may support preventing at-risk IA among senior high school teachers.

Blunted cortisol and normal sympathetic nervous system responses to an acute psychosocial stressor in internet addiction.

Studies have demonstrated that addiction leads to blunted responses of cortisol and sympathetic nervous system (SNS) to acute stressors; however, limited studies have examined the neuroendocrine and SNS stress responses in Internet addiction (IA). To examine acute stress responses in IA, the current study recruited a total of 76 Japanese university students and staff members (51 females and 25 males, mean age = 22.4 years, SD = 4.7), and measured the salivary cortisol, salivary alpha-amylase (sAA), and blood pressure (BP) responses to an acute stressor under stress or a nonstress placebo conditions in IA and non-IA groups. The results revealed that patients with IA showed a blunted cortisol response to a stressor. In contrast, no differences were found in the sAA and BP responses between the IA and non-IA groups. These results suggest that IA may be characterized by blunted cortisol responses in acute stress settings.

Modification of cardiac disease by transgenically altered histone deacetylase 6.

Histone deacetylase 6 (HDAC6) is known to deacetylate amino acid lysine in alpha-tubulin. However, the functional role of HDAC6 in the progression of cardiac disease remains uncertain. The functional role of HDAC6 in the hearts was examined using transgenic (TG) mice expressing either human wild-type HDAC6, deacetylase inactive HDAC6 (HDAC6H216A, H611A), and human HDAC6 replaced all serine or threonine residues with aspartic acid at N-terminal 1- 43 amino acids (HDAC6NT-allD) specifically in the hearts. Overexpression of wild-type HDAC6 significantly reduced acetylated tubulin levels, and overexpression of HDAC6H216A, H611A significantly increased it in the mouse hearts. Detectable acetylated tubulin disappeared in HDAC6NT-allD TG mouse hearts. Neither histological alteration nor alteration of cardiac function was observed in the HDAC6 TG mouse hearts. To analyze the role of HDAC6 and acetylated tubulin in disease conditions, we examined HDAC6 in isoprenaline-induced hypertrophy or pressure-overload hypertrophy (TAC). No obvious alteration in the heart weight/body weight ratio or gene expressions of hypertrophic markers between NTG and HDAC6NT-allD mice was observed following treatment with isoprenaline. In contrast, a marked reduction in the shortening fraction and dilated chamber dilatation was detected in the HDAC6NT-allD TG mouse hearts 2 weeks after TAC. A sustained low level of acetylated tubulin and acetylated cortactin was observed in the TAC HDAC6NT-allD TG mouse hearts. Cardiac HDAC6 activity that can regulate acetylated levels of tubulin and cortactin may be critical factors involved in cardiac disease such as pressure-overload hypertrophy.

The association between problematic internet use and neck pain among Japanese schoolteachers.

OBJECTIVES: Problematic internet use (PIU) has been suggested in relation to psychological symptoms among schoolteachers, but the relationship with physical symptoms remains unclear. We examined whether PIU or longer Internet usage time is associated with neck pain in schoolteachers. METHODS: We conducted a cross-sectional study among 2582 teachers aged 20 years or older (35.6% women) in Shimane and Tottori, Japan in 2018. Neck pain was defined as ≥5 points on the Neck Disability Index. The Compulsive Internet Use Scale (CIUS) was used to assess PIU. Internet usage time on weekdays and weekends was divided into five groups: 0, 1-29, 30-59, 60-119, and ≥120 min/day. Logistic regression analysis was conducted to examine the association of the CIUS score and Internet usage time on weekdays or weekends with neck pain, adjusting for sex, age, position at school, insomnia, and psychological distress. RESULTS: We observed 800 (31.0%) teachers with neck pain. The median (interquartile range) of their CIUS scores was 7 (2, 14). A higher CIUS score was independently associated with a higher prevalence of neck pain (odds ratio of 4th vs. 1st quartiles, 1.41; 95% confidence interval, 1.06-1.87; trend P = .006). Compared with non-Internet users, Internet users on weekdays had almost double the odds of neck pain although the difference did not reach the customary level for designating statistical significance. CONCLUSIONS: In conclusion, teachers with higher scores in CIUS were associated with a higher prevalence of neck pain in Japan, suggesting adults with PIU being at risk of physical disorders.

Relationships between Slc1a5 and Osteoclastogenesis.

Slc1a5 (ASCT2) encodes a small neutral amino-acid exchanger and is the most well-studied glutamine transporter in cancer cells. To investigate the role of Slc1a5 in osteoclastogenesis, we developed Slc1a5-deficient mice by using a conventional gene-targeting approach. The Slc1a5-/- mice showed no obvious abnormalities in growth. Glutamine uptake was assessed in Slc1a5+/+ and Slc1a5-/- bone marrow cells stimulated with RANKL. The rate of glutamine uptake in Slc1a5-/- bone marrow cells was reduced to 70% of that of cells from Slc1a5+/+ bone marrow. To confirm the involvement of Slc1a5 in osteoclast formation, bone marrow cells derived from Slc1a5+/+ or Slc1a5-/- mice were stimulated with RANKL and macrophage colony-stimulating factor and stained with tartrate-resistant acid phosphatase. The bone resorption activity and actin ring formation of stimulated cells were measured. The formation of multinucleated osteoclasts in bone marrow cells isolated from Slc1a5-/- mice was severely impaired compared with those from Slc1a5+/+ mice. RANKL-induced expression of ERK, NFκB, p70S6K, and NFATc1 was suppressed in Slc1a5-/- osteoclasts. These results show that Slc1a5 plays an important role in osteoclast formation.

Relationship between insomnia with alcohol drinking before sleep (Ne-Zake) or in the morning (Mukae-Zake) among Japanese farmers.

BACKGROUND: Ne-Zake is the drinking of alcohol before sleeping for helping to fall asleep and sleep well, and Mukae-Zake is the drinking of alcohol in the morning for "calming down" or "curing hangovers". OBJECTIVE: We sought to examine the relationship of insomnia with Ne-Zake and Mukae-Zake among healthy middle-aged Japanese farmers. METHODS: In a cross-sectional study of 746 participants (mean age, 59.5 years; women, 25.9%), Ne-Zake and Mukae-Zake were defined based on a self-administered questionnaire. Insomnia was defined as the Athens Insomnia Scale Japanese version ≥6 or usage of sleeping pills in the previous year. Logistic regression was used to calculate odds ratio (OR) of insomnia related to Ne-Zake and Mukae-Zake adjusting for sex, age, presence of sleep-related disorders, frequency of alcohol consumption, and quantity of alcohol consumed per one occasion. RESULTS: We observed insomnia, Ne-Zake, and Mukae-Zake in 174 (23.3%), 140 (18.8%), and 37 (5.0%) participants, respectively. After adjustment for demographic and confounding factors, participants with Ne-Zake had a significantly higher prevalence of insomnia (OR 2.00 [95% confidence interval, 1.27-3.16]), compared to those without Ne-Zake. Mukae-Zake was also independently associated with a higher prevalence of insomnia among men (OR 3.26 [1.55-6.87]). Participants with both Ne-Zake and Mukae-Zake had a highly significant association with insomnia (OR 4.77 [2.01-11.3]) than those with neither Ne-Zake nor Mukae-Zake. Additionally, for insomnia, the association of Mukae-Zake was more pronounced than that of Ne-Zake (OR 4.09, 95% CI 1.14-14.7, p = 0.031; and OR 1.81, 95% CI 1.08-3.06, p = 0.026, respectively). CONCLUSION: Ne-Zake and Mukae-Zake were associated with insomnia independent of the quantity and frequency of alcohol consumption among Japanese farmers. This finding can be used for stratifying individuals with insomnia not only to improve sleep hygiene but also to prevent alcohol dependence by informing the general population that alcohol has a negative effect on sleep, contrary to popular beliefs.

Similar responsiveness between C57BL/6N and C57BL/6J mouse substrains to superovulation.

Superovulation is a method for the drug-induced release of multiple eggs and useful for in vitro fertilization. Thus, its high efficiency largely reduces the number of mice used per experiment. We compared the responsivity to superovulation between C57BL/6N (B6N) and C57BL/6J (B6J) substrains. The average number of ovulated eggs was strikingly higher in both substrains treated with anti-inhibin serum (AIS) plus equine chorionic gonadotropin (eCG) than those treated with eCG alone. Our data indicate that hypothalamus-pituitary-ovarian axis similarly responds to eCG treatment in B6N and B6J mice, and that this responsiveness is enhanced by the presence of AIS.

Loss of the branched-chain amino acid transporter CD98hc alters the development of colonic macrophages in mice.

Comprehensive development is critical for gut macrophages being essential for the intestinal immune system. However, the underlying mechanisms of macrophage development in the colon remain elusive. To investigate the function of branched-chain amino acids in the development of gut macrophages, an inducible knock-out mouse model for the branched-chain amino acid transporter CD98hc in CX3CR1+ macrophages was generated. The relatively selective deletion of CD98hc in macrophage populations leads to attenuated severity of chemically-induced colitis that we assessed by clinical, endoscopic, and histological scoring. Single-cell RNA sequencing of colonic lamina propria macrophages revealed that conditional deletion of CD98hc alters the "monocyte waterfall"-development to MHC II+ macrophages. The change in the macrophage development after deletion of CD98hc is associated with increased apoptotic gene expression. Our results show that CD98hc deletion changes the development of colonic macrophages.

Zscan5b Deficiency Impairs DNA Damage Response and Causes Chromosomal Aberrations during Mitosis.

Zygotic genome activation (ZGA) begins after fertilization and is essential for establishing pluripotency and genome stability. However, it is unclear how ZGA genes prevent mitotic errors. Here we show that knockout of the ZGA gene Zscan5b, which encodes a SCAN domain with C2H2 zinc fingers, causes a high incidence of chromosomal abnormalities in embryonic stem cells (ESCs), and leads to the development of early-stage cancers. After irradiation, Zscan5b-deficient ESCs displayed significantly increased levels of γ-H2AX despite increased expression of the DNA repair genes Rad51l3 and Bard. Re-expression of Zscan5b reduced γ-H2AX content, implying a role for Zscan5b in DNA damage repair processes. A co-immunoprecipitation analysis showed that Zscan5b bound to the linker histone H1, suggesting that Zscan5b may protect chromosomal architecture. Our report demonstrates that the ZGA gene Zscan5b is involved in genomic integrity and acts to promote DNA damage repair and regulate chromatin dynamics during mitosis.

At-risk Internet addiction and related factors among junior high school teachers-based on a nationwide cross-sectional study in Japan.

BACKGROUND: School teachers have a possibility toward at-risk Internet addiction (IA) due to increased opportunities to use the Internet, along with the spread of the Internet in recent years. Burnout syndrome (BOS) is found to be one of the symptoms related to unhealthy mental health, especially among teachers. This study aims to research the relationship between at-risk IA and the Internet usage or BOS by conducting a nationwide cross-sectional survey and examining the factors associated with IA. METHOD: This study was a cross-sectional survey by anonymous questionnaire. This survey was a random sampling survey of junior high schools across Japan in 2016. The participants were 1696 teachers at 73 schools (response rate in teachers 51.0%). We asked participants for details of their backgrounds, Internet usage, the Internet Addiction Test (IAT) by Young, and the Japanese Burnout Scale (JBS). We divided the participants into either the at-risk IA group (IAT score ≧ 40, n = 96) or the non-IA group (IAT score < 40, n = 1600). To compare the difference between at-risk IA and non-IA, we used nonparametric tests and t test according to variables. To analyze the relationship between the IAT score and the scores of three factors of the JBS (emotional exhaustion, depersonalization, and personal accomplishment), we used both ANOVA and ANCOVA, adjusted by relevant confounding factors. To clarify the contribution of each independent variable to IAT scores, we used multiple logistic regression analysis. RESULTS: In our study, at-risk IA was associated with using the internet many hours privately, being on the Internet both on weekdays and weekends, playing games, and surfing the Internet. In the relationship between IAT score and BOS factor score, a higher score for "depersonalization" had a positive relationship with at-risk IA, and the highest quartile for "decline of personal accomplishment" had a lower odds ratio with at-risk IA by multiple logistic regression analysis. CONCLUSION: We clarified there is a significant relationship between at-risk IA and BOS among junior high school teachers in a nationwide survey. Our results suggest that finding depersonalization at the early stage may lead to the prevention of at-risk IA among teachers. Those who are at-risk of IA may feel personal accomplishment through use of the Internet.

Mouse polycomb group gene Cbx2 promotes osteoblastic but suppresses adipogenic differentiation in postnatal long bones.

A set of key developmental genes is essential for skeletal growth from multipotent progenitor cells at weaning. Polycomb group proteins, which regulate such genes contributes to the cell lineage commitment and subsequent differentiation via epigenetic chromatin modification and remodeling. However, it is unclear which cell lineage and gene sets are targeted by polycomb proteins during skeletal growth. We now report that mice deficient in a polycomb group gene Cbx2cterm/cterm exhibited skeletal hypoplasia in the tibia, femur, and cranium. Long bone cavities in these mice contained fewer multipotent mesenchymal stromal cells. RNA-sequencing of bone marrow cells showed downregulation and upregulation of osteoblastic and adipogenic genes, respectively. Furthermore, the expression levels of genes specifically expressed in B-cell precursors were decreased. Forced expression of Cbx2 in Cbx2cterm/cterm bone marrow stromal cell recovered fibroblastic colony formation and suppressed adipogenic differentiation. Collectively, our results suggest that Cbx2 controls the maintenance and adipogenic differentiation of mesenchymal stromal cells in the bone marrow.

Bcl-2-associated athanogene 3 (BAG3) is an enhancer of small heat shock protein turnover via activation of autophagy in the heart.

Bcl-2-associated athanogene 3 (BAG3) is strongly expressed in both cardiac and skeletal muscle. A recent study showed that BAG3 may play a protective role in muscles. Little is known, however, regarding the detailed role of BAG3 in cardiac muscle. To better understand the functional role of cardiac BAG3 in the heart, we generated transgenic (TG) mice that overexpress BAG3. A decrease in fractional shortening, and the induction of cardiac atrial natriuretic peptide, were observed in BAG3 TG mice. Moreover, a marked reduction in the protein level of small HSPs was detected in BAG3 TG mouse hearts. We analyzed the cardiac small HSP levels when either the ubiquitin-proteasome system (UPS) or the autophagy system (AS) was inhibited in BAG3 TG mice. The protein turnovers of small HSPs by the AS were activated in BAG3 TG mouse hearts. Thus, BAG3 is critical for the protein turnover of small HSPs via activation of autophagy in the heart.

Prevalence and Risk Factors of Internet Addiction Among Employed Adults in Japan.

BACKGROUND: The prevalence of Internet addiction (IA) among employed adults has not been reported using a large sample. To clarify the actual status of addictive Internet use among employed adults, this study aimed to evaluate the prevalence and the risk factors of IA and at-risk IA among employed adults in Japan. METHODS: This cross-sectional study surveyed all junior and senior high school personnel in Shimane Prefecture, a rural area in Japan. Eligible participants included 3,211 junior and senior high school personnel (1,259 men and 1,952 women). Participants completed a questionnaire on their activities and factors related to Internet use. RESULTS: The prevalence of IA and at-risk IA was 0.03% and 4.82%, respectively. Furthermore, game playing was shown to be the Internet activity most closely associated with at-risk IA. CONCLUSIONS: This study showed that around 5% of school personnel in a rural area in Japan are at risk for developing addiction to the Internet and that using the Internet for game playing is related to at-risk IA. Our results suggest that employed adults should be instructed to use the Internet properly.

Post-event Processing Predicts Impaired Cortisol Recovery Following Social Stressor: The Moderating Role of Social Anxiety.

There is growing evidence that individuals with social anxiety show impaired cortisol recovery after experiencing social evaluative stressors. Yet, little is known regarding the cognitive processes underlying such impaired cortisol recovery. The present study examined the effect of post-event processing (PEP), referred to as repetitive thinking about social situations, on cortisol recovery following a social stressor. Forty-two non-clinical university students (23 women, 19 men, mean age = 22.0 ± 2.0 years) completed the Trier Social Stress Test (TSST), followed by a thought sampling procedure which assessed the frequency of PEP reflecting the TSST. A growth curve model showed PEP and social anxiety interactively predicted cortisol recovery. In particular, PEP predicted impaired cortisol recovery in those with low levels of social anxiety but not in those with high levels of social anxiety, which contradicted the initial hypothesis. These findings suggest that PEP is differentially associated with cortisol recovery depending on levels of social anxiety. The possible mechanisms underlying these findings were discussed in terms of protective inhibition framework.

Slc3a2 Mediates Branched-Chain Amino-Acid-Dependent Maintenance of Regulatory T Cells.

Foxp3+ regulatory T (Treg) cells, which suppress immune responses, are highly proliferative in vivo. However, it remains unclear how the active replication of Treg cells is maintained in vivo. Here, we show that branched-chain amino acids (BCAAs), including isoleucine, are required for maintenance of the proliferative state of Treg cells via the amino acid transporter Slc3a2-dependent metabolic reprogramming. Mice fed BCAA-reduced diets showed decreased numbers of Foxp3+ Treg cells with defective in vivo proliferative capacity. Mice lacking Slc3a2 specifically in Foxp3+ Treg cells showed impaired in vivo replication and decreased numbers of Treg cells. Slc3a2-deficient Treg cells showed impaired isoleucine-induced activation of the mTORC1 pathway and an altered metabolic state. Slc3a2 mutant mice did not show an isoleucine-induced increase of Treg cells in vivo and exhibited multi-organ inflammation. Taken together, these findings demonstrate that BCAA controls Treg cell maintenance via Slc3a2-dependent metabolic regulation.

Neuregulin-1 type III knockout mice exhibit delayed migration of Schwann cell precursors.

In an embryonic developmental stage of the peripheral nervous system (PNS), Schwann cell precursors migrate along neuronal axons to their final destinations. After birth, they eventually wrap around individual axons to form myelin sheaths, which insulate axons to increase the nerve conduction velocity. Some growth factors and adhesion molecules are known to control these developmental stages from in the fish to in the mammal. Neuregulin-1 (NRG1), which is composed of many alternative splicing variants, is such a growth factor. Among these variants, the type III isoform of NRG1, interacting with ErbB2 and ErbB3 receptors on Schwann cells, plays an essential role in myelination in the fish and the mammal. NRG1 type III is also known to promote migration of fish Schwann cell precursors; however, it still remains to be clarified whether mammalian type III isoform does it. We have therefore generated type III isoform-specific knockout mice in inbred strain. The mice result in delayed migration of the precursors from the dorsal to ventral root via a peripheral ganglion, comparing littermate controls. Similar results are observed in an in vitro migration assay using reaggregated Schwann cell precursors. Furthermore, the knockout mice exhibit reduced myelin thickness, consistent with the established role of NRG1 type III in myelination. These results indicate that in mice, NRG1 type III plays a key role not only in myelination but also in migration.

Impaired CD98 signaling protects against graft-versus-host disease by increasing regulatory T cells.

Graft-versus-host disease (GvHD) is a major barrier to the broader use of allogenic hematopoietic stem cell transplantation for non-malignant clinical applications. A murine model of C57BL/6 to B6D2F1 acute GvHD was employed with T lymphocytes harboring a deletion of the CD98 heavy chain (CD98hc(-/-)) as donor cells. The CD98hc(-/-) resulted in lower responses to alloantigen stimulation in a mixed leukocyte reaction assay, and prevented the mortality associated with disease progression. The percentage of donor CD8 T lymphocytes was significantly decreased, while the percentage of Foxp3-positive regulatory T cells (Tregs) in recipients was increased by CD98hc(-/-). Decreased expression of FAS, FASL, ICOS, ICOSL, PD-1 and PD-L1 by donor CD8 T cells, and mRNA expression of cytotoxic T cell-related cytokines in the recipients were shown in those with CD98hc(-/-). Fewer infiltrated cells are found in the lungs, liver, tongue and skin of recipients with CD98hc(-/-) compared with the wild type recipients. Taken together, our data indicate that T cell-specific deletion of CD98hc can contribute to the prevention of GvHD development due to the attenuation of lymphocyte migration and by increasing the generation of Treg cells. These findings are expected to make it possible to develop novel approaches for the prevention of GvHD.

Conditional deletion of CD98hc inhibits osteoclast development.

The CD98 heavy chain (CD98hc) regulates virus-induced cell fusion and monocyte fusion, and is involved in amino acid transportation. Here, we examined the role that CD98hc plays in the formation of osteoclasts using CD98hcflox/floxLysM-cre peritoneal macrophages (CD98hc-defect macrophages). Peritoneal macrophages were stimulated with co-cultured with osteoblasts in the presence of 1,25(OH)2 vitamin D3, and thereafter stained with tartrate-resistant acid phosphatase staining solution. The multinucleated osteoclast formation was severely impaired in the peritoneal macrophages isolated from the CD98hc-defect mice compared with those from wild-type mice. CD98hc mediates integrin signaling and amino acid transport through the CD98 light chain (CD98lc). In integrin signaling, suppression of the M-CSF-RANKL-induced phosphorylation of ERK, Akt, JNK and p130Cas were observed at the triggering phase in the CD98h-defect peritoneal macrophages. Moreover, we showed that the general control non-derepressible (GCN) pathway, which was activated by amino acid starvation, was induced by the CD98hc-defect peritoneal macrophages stimulated with RANKL. These results indicate that CD98 plays two important roles in osteoclast formation through integrin signaling and amino acid transport.