Publications by authors named "Yasuhisa Ohata"

43 Publications

Genotype-phenotype analysis, and assessment of the importance of the zinc-binding site in PHEX in Japanese patients with X-linked hypophosphatemic rickets using 3D structure modeling.

Bone 2021 Jul 29:116135. Epub 2021 Jul 29.

Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Japan. Electronic address:

X-linked hypophosphatemic rickets (XLH) is an inheritable type of rickets caused by inactivating variants in the phosphate regulating endopeptidase homolog X-linked (PHEX) gene, which results in the overproduction of fibroblast growth factor 23 (FGF23). The mechanism by which PHEX impairment leads to FGF23 overproduction is unknown. Because little is known regarding the genotype-phenotype correlation in Japanese XLH, we summarized the available clinical and genetic data and analyzed the genotype-phenotype relationships using 3-dimensional (3D) structure modeling to clarify the XLH pathophysiology. We retrospectively reviewed the clinical features and performed genetic analysis of 39 Japanese patients with XLH from 28 unrelated pedigrees carrying any known or novel PHEX variant. To predict changes in the 3D structure of mutant PHEX, we constructed a putative 3D model of each mutant and evaluated the effect of structural alteration by genotype-phenotype correlation analysis. Genetic analysis revealed 23 PHEX variants, including eight novel variants. They were associated with high i-FGF23 levels, hypophosphatemia, phosphaturia, high alkaline phosphatase levels, and short stature. No gene dosage effect or genotype-phenotype correlation was observed when truncating and non-truncating variants were compared. However, the conservation of the zinc-binding site and cavity in PHEX had an impact on the elevation of i-FGF23 levels. Via genotype-phenotype relationship analysis using 3D modeling, we showed that the zinc-binding site and cavity in PHEX can play a critical role in its function. These findings provide new genetic clues for investigating the function of PHEX and the pathogenesis of XLH.
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http://dx.doi.org/10.1016/j.bone.2021.116135DOI Listing
July 2021

Alkaline phosphatase in pediatric patients with genu varum caused by vitamin D-deficient rickets.

Endocr J 2021 Jul 24;68(7):807-815. Epub 2021 Mar 24.

Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan.

An elevated serum alkaline phosphatase (ALP) level is one of the markers for the presence of rickets in children, but it is also associated with bone formation. However, its role in diagnosing genu varum in pediatric patients with vitamin D-deficient rickets is still unknown. To clarify the role of the serum ALP level in assessing the severity of genu varum, we retrospectively investigated this issue statistically using data on rickets such as serum intact parathyroid hormone (iPTH), 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, ALP, the level of creatinine as the percentage of the median according to age (%Cr), and the metaphyseal diaphyseal angle (MDA) in the lower extremities as an index of the severity of genu varum. A multiple regression analysis revealed that log ALP and %Cr values were negatively associated with MDA values. The former association was also confirmed by a linear mixed model, while iPTH was positively associated with MDA by path model analysis. To elucidate the association of ALP with MDA in the presence of iPTH, we investigated three-dimensional figures by neural network analysis. This indicated the presence of a biphasic association of ALP with MDA: the first phase increases while the second decreases MDA. The latter phenomenon is considered to be associated with the increase in bone formation due to the mechanical stress loaded on the lower extremities. These findings are important and informative for pediatricians to understand the significance of the serum ALP level in pediatric patients with genu varum caused by vitamin D deficiency.
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http://dx.doi.org/10.1507/endocrj.EJ20-0622DOI Listing
July 2021

Neonatal cholestasis can be the first symptom of McCune-Albright syndrome: A case report.

World J Clin Pediatr 2021 Mar 9;10(2):7-14. Epub 2021 Mar 9.

Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan.

Background: McCune-Albright syndrome (MAS) is caused by postzygotic somatic mutations of the gene. It is characterized by the clinical triad of fibrous dysplasia, café-au-lait skin spots, and endocrinological dysfunction. Myriad complications in MAS, including hepatobiliary manifestations, are also reported.

Case Summary: This is a case of a 4-year-old boy who presented with MAS with neonatal cholestasis. He was suspected to have Alagille syndrome due to neonatal cholestasis with intrahepatic bile duct paucity in liver biopsy, peripheral pulmonary artery stenosis, and renal tubular dysfunction. By the age of 2 years, his cholestatic liver injury gradually improved, but he had repeated left femoral fractures. He did not exhibit endocrinological abnormality or café-au-lait skin spots. However, MAS was suspected due to fibrous dysplasia at the age of 4 years. No mutation was identified in the gene in the DNA isolated from the peripheral blood, but an activating point mutation (c.601C>T, p.Arg201Cys) was observed in the DNA extracted from the affected bone tissue and that extracted from the formalin-fixed paraffin-embedded liver tissue, which was obtained at the age of 1 mo.

Conclusion: MAS should be considered as a differential diagnosis for transient cholestasis in infancy.
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http://dx.doi.org/10.5409/wjcp.v10.i2.7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7958557PMC
March 2021

A case of HDR syndrome coexisting with tetralogy of Fallot, with a novel GATA3 mutation, which manifested as a renal abscess.

CEN Case Rep 2021 05 7;10(2):241-243. Epub 2020 Nov 7.

Department of Pediatrics, Oita University Faculty of Medicine, 1-1 Idaigaoka, Hasama, Yufu, Oita, 879-5593, Japan.

HDR syndrome is characterized by the triad of primary hypoparathyroidism, sensorineural hearing loss and renal malformation with widely variable manifestations. It is an autosomal dominant inherited disease caused by a mutation of the GATA3 (NM_001002295.2), which is located on chromosome 10p14. Congenital heart disease, such as tetralogy of Fallot, a typical complication of DiGeorge syndrome, is a rare complication of HDR syndrome. We herein report a case of HDR syndrome coexisting tetralogy of Fallot with a novel mutation, c.964C > T (p.Gln322*). This case suggested that the screening of renal involvement should be carefully performed in patients with a phenotypic combination of hypoparathyroidism and sensorineural hearing loss, to facilitate the early diagnosis of HDR syndrome. In addition, when the deletion of chromosome 22q11.2 is not detected by a fluorescence in situ hybridization analysis in patients exhibiting the partial phenotype of DiGeorge syndrome, the possibility of HDR syndrome should be considered and the renal function should be repeatedly evaluated.
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http://dx.doi.org/10.1007/s13730-020-00551-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8019435PMC
May 2021

4-Phenylbutyric acid enhances the mineralization of osteogenesis imperfecta iPSC-derived osteoblasts.

J Biol Chem 2021 Jan-Jun;296:100027. Epub 2020 Nov 23.

Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.

Osteogenesis imperfecta (OI) is a heritable brittle bone disease mainly caused by mutations in the two type I collagen genes. Collagen synthesis is a complex process including trimer formation, glycosylation, secretion, extracellular matrix (ECM) formation, and mineralization. Using OI patient-derived fibroblasts and induced pluripotent stem cells (iPSCs), we investigated the effect of 4-phenylbutyric acid (4-PBA) on collagen synthesis to test its potential as a new treatment for OI. Endoplasmic reticulum (ER) retention of type I collagen was observed by immunofluorescence staining in OI patient-derived fibroblasts with glycine substitution and exon skipping mutations. Liquid chromatography-mass spectrometry analysis revealed excessive glycosylation of secreted type I collagen at the specific sites in OI cells. The misfolding of the type I collagen triple helix in the ECM was demonstrated by the incorporation of heat-dissociated collagen hybridizing peptide in OI cells. Type I collagen was produced excessively by OI fibroblasts with a glycine mutation, but this excessive production was normalized when OI fibroblasts were cultured on control fibroblast-derived ECM. We also found that mineralization was impaired in osteoblasts differentiated from OI iPSCs. In summary, treatment with 4-PBA normalizes the excessive production of type I collagen, reduces ER retention, partially improves misfolding of the type I collagen helix in ECM, and improves osteoblast mineralization. Thus, 4-PBA may improve not only ER retention, but also type I collagen synthesis and mineralization in human cells from OI patients.
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http://dx.doi.org/10.1074/jbc.RA120.014709DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7948972PMC
November 2020

Increased S1P expression in osteoclasts enhances bone formation in an animal model of Paget's disease.

J Cell Biochem 2021 04 27;122(3-4):335-348. Epub 2020 Oct 27.

Department of Medicine/Hematology-Oncology, Indiana University, Indianapolis, Indiana, USA.

Paget's disease (PD) is characterized by increased numbers of abnormal osteoclasts (OCLs) that drive exuberant bone formation, but the mechanisms responsible for the increased bone formation remain unclear. We previously reported that OCLs from 70% of PD patients express measles virus nucleocapsid protein (MVNP), and that transgenic mice with targeted expression of MVNP in OCLs (MVNP mice) develop bone lesions and abnormal OCLs characteristic of PD. In this report, we examined if OCL-derived sphingosine-1-phosphate (S1P) contributed to the abnormal bone formation in PD, since OCL-derived S1P can act as a coupling factor to increase normal bone formation via binding S1P-receptor-3 (S1PR3) on osteoblasts (OBs). We report that OCLs from MVNP mice and PD patients expressed high levels of sphingosine kinase-1 (SphK-1) compared with wild-type (WT) mouse and normal donor OCLs. SphK-1 production by MVNP-OCLs was interleukin-6 (IL-6)-dependent since OCLs from MVNP/IL-6 mice expressed lower levels of SphK-1. Immunohistochemistry of bone biopsies from a normal donor, a PD patient, WT and MVNP mice confirmed increased expression levels of SphK-1 in OCLs and S1PR3 in OBs of the PD patient and MVNP mice compared with normal donor and WT mice. Further, MVNP-OCLs cocultured with OBs from MVNP or WT mice increased OB-S1PR3 expression and enhanced expression of OB differentiation markers in MVNP-OBs precursors compared with WT-OBs, which was mediated by IL-6 and insulin-like growth factor 1 secreted by MVNP-OCLs. Finally, the addition of an S1PR3 antagonist (VPC23019) to WT or MVNP-OBs treated with WT and MVNP-OCL-conditioned media (CM) blocked enhanced OB differentiation of MVNP-OBs treated with MVNP-OCL-CM. In contrast, the addition of the SIPR3 agonist, VPC24191, to the cultures enhanced osterix and Col-1A expression in MVNP-OBs treated with MVNP-OCL-CM compared with WT-OBs treated with WT-OCL-CM. These results suggest that IL-6 produced by PD-OCLs increases S1P in OCLs and S1PR3 on OBs, to increase bone formation in PD.
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http://dx.doi.org/10.1002/jcb.29861DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7887003PMC
April 2021

Potential pathological role of single nucleotide polymorphism (c.787T>C) in alkaline phosphatase (ALPL) for the phenotypes of hypophosphatasia.

Endocr J 2020 Dec 8;67(12):1227-1232. Epub 2020 Aug 8.

Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan.

Hypophosphatasia (HPP; OMIM 241510, 241500, and 146300) is an inherited metabolic disease characterized by defects of bone and tooth mineralization, which is caused by loss-of-function mutations in the ALPL gene encoding tissue non-specific alkaline phosphatase (TNSALP). In the last three decades, several studies have focused on the genotype-phenotype correlation in hypophosphatasia (HPP). In particular, functional tests based on in vitro analysis for the residual enzymatic activities of mutations have revealed a clear but imperfect genotype-phenotype correlation, suggesting that multiple potential factors modulate the phenotype. One of the missense variants identified in the tissue non-specific alkaline phosphatase (ALPL) gene, c.787T>C, has been considered as a benign polymorphism in HPP; however, its pathogenicity and role in disease manifestation remain controversial. We here report our recent experience of three unrelated families harboring the c.787T>C variant, suggesting clinical implications regarding the controversial pathogenicity of c.787T>C. First, despite the lack of obvious clinical phenotypes, homozygous c.787T>C would decrease the serum level of ALP activity. Second, c.787T>C might deteriorate phenotypes of a patient harboring another ALPL variant, especially one that has thus far presumed to be benign, e.g., the c.1144G>A variant. These cases contribute to the recent advances in understanding HPP to facilitate clinical recognition of more subtle phenotypes, further providing insights into the pathogenesis of HPP.
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http://dx.doi.org/10.1507/endocrj.EJ20-0203DOI Listing
December 2020

Phenotypes of a family with XLH with a novel mutation.

Hum Genome Var 2020 31;7. Epub 2020 Mar 31.

2Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan.

X-linked hypophosphatemia (XLH) is the most common form of heritable hypophosphatemic rickets. We encountered a 4-year-old boy with a novel variant in the phosphate-regulating neutral endopeptidase homolog X-linked () gene who presented with a short stature, genu valgum, and scaphocephaly. The same mutation was identified in his mother and sister; however, the patient presented with a more severe case.
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http://dx.doi.org/10.1038/s41439-020-0095-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7109063PMC
March 2020

Osteoclast-derived IGF1 is required for pagetic lesion formation in vivo.

JCI Insight 2020 03 26;5(6). Epub 2020 Mar 26.

Division of Hematology and Oncology, Department of Medicine, Indiana University (IU), Indianapolis, Indiana, USA.

We report that transgenic mice expressing measles virus nucleocapsid protein (MVNP) in osteoclasts (OCLs) (MVNP mice) are Paget's disease (PD) models and that OCLs from patients with PD and MVNP mice express high levels of OCL-derived IGF1 (OCL-IGF1). To determine OCL-IGF1's role in PD and normal bone remodeling, we generated WT and MVNP mice with targeted deletion of Igf1 in OCLs (Igf1-cKO) and MVNP/Igf1-cKO mice, and we assessed OCL-IGF1's effects on bone mass, bone formation rate, EphB2/EphB4 expression on OCLs and osteoblasts (OBs), and pagetic bone lesions (PDLs). A total of 40% of MVNP mice, but no MVNP/Igf1-cKO mice, had PDLs. Bone volume/tissue volume (BV/TV) was decreased by 60% in lumbar vertebrae and femurs of MVNP/Igf1-cKO versus MVNP mice with PDLs and by 45% versus all MVNP mice tested. Bone formation rates were decreased 50% in Igf1-cKO and MVNP/Igf1-cKO mice versus WT and MVNP mice. MVNP mice had increased EphB2 and EphB4 levels in OCLs/OBs versus WT and MVNP/Igf1-cKO, with none detectable in OCLs/OBs of Igf1-cKO mice. Mechanistically, IL-6 induced the increased OCL-IGF1 in MVNP mice. These results suggest that high OCL-IGF1 levels increase bone formation and PDLs in PD by enhancing EphB2/EphB4 expression in vivo and suggest OCL-IGF1 may contribute to normal bone remodeling.
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http://dx.doi.org/10.1172/jci.insight.133113DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7213785PMC
March 2020

Clinical Practice Guidelines for Achondroplasia.

Clin Pediatr Endocrinol 2020 9;29(1):25-42. Epub 2020 Jan 9.

Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan.

Achondroplasia (ACH) is a skeletal dysplasia that presents with limb shortening, short stature, and characteristic facial configuration. ACH is caused by mutations of the gene, leading to constantly activated FGFR3 and activation of its downstream intracellular signaling pathway. This results in the suppression of chondrocyte differentiation and proliferation, which in turn impairs endochondral ossification and causes short-limb short stature. ACH also causes characteristic clinical symptoms, including foramen magnum narrowing, ventricular enlargement, sleep apnea, upper airway stenosis, otitis media, a narrow thorax, spinal canal stenosis, spinal kyphosis, and deformities of the lower extremities. Although outside Japan, papers on health supervision are available, they are based on reports and questionnaire survey results. Considering the scarcity of high levels of evidence and clinical guidelines for patients with ACH, clinical practical guidelines have been developed to assist both healthcare professionals and patients in making appropriate decisions in specific clinical situations. Eleven clinical questions were established and a systematic literature search was conducted using PubMed/MEDLINE. Evidence-based recommendations were developed, and the guidelines describe the recommendations related to the clinical management of ACH. We anticipate that these clinical practice guidelines for ACH will be useful for healthcare professionals and patients alike.
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http://dx.doi.org/10.1297/cpe.29.25DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6958518PMC
January 2020

Clinical Practice Guidelines for Hypophosphatasia.

Clin Pediatr Endocrinol 2020 9;29(1):9-24. Epub 2020 Jan 9.

Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan.

Hypophosphatasia (HPP) is a rare bone disease caused by inactivating mutations in the gene, which encodes tissue-nonspecific alkaline phosphatase (TNSALP). Patients with HPP have varied clinical manifestations and are classified based on the age of onset and severity. Recently, enzyme replacement therapy using bone-targeted recombinant alkaline phosphatase (ALP) has been developed, leading to improvement in the prognosis of patients with life-threatening HPP. Considering these recent advances, clinical practice guidelines have been generated to provide physicians with guides for standard medical care for HPP and to support their clinical decisions. A task force was convened for this purpose, and twenty-one clinical questions (CQs) were formulated, addressing the issues of clinical manifestations and diagnosis (7 CQs) and those of management and treatment (14 CQs). A systematic literature search was conducted using PubMed/MEDLINE, and evidence-based recommendations were developed. The guidelines have been modified according to the evaluations and suggestions from the Clinical Guideline Committee of The Japanese Society for Pediatric Endocrinology (JSPE) and public comments obtained from the members of the JSPE and a Japanese HPP patient group, and then approved by the Board of Councils of the JSPE. We anticipate that the guidelines will be revised regularly and updated.
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http://dx.doi.org/10.1297/cpe.29.9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6958520PMC
January 2020

Parental somatogonadal COL2A1 mosaicism contributes to intrafamilial recurrence in a family with type 2 collagenopathy.

Am J Med Genet A 2020 03 19;182(3):454-460. Epub 2019 Dec 19.

Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan.

The COL2A1 gene encodes the alpha-1 chain of procollagen type 2. Pathogenic variants in the COL2A1 gene are associated with several different types of skeletal dysplasia collectively known as type 2 collagenopathies. Type 2 collagenopathies have an autosomal dominant inheritance. Some germline or somatogonadal mosaicism cases have been reported. We investigated whether somatogonadal mosaicism occurred in a family with two children suspected of type 2 collagenopathies or related diseases. First, we detected a pathogenic variant in the COL2A1 gene in the two affected children by whole exome sequencing (WES). Next, we performed targeted deep sequencing to their parents without the variant by WES. A low level of COL2A1 mosaicism was revealed in the mother's tissues. We concluded that the mother had somatogonadal mosaicism with the COL2A1 mutation arose in the epiblast, and that the intrafamilial recurrence rate of the disease by the somatogonadal mosaicism was higher than by the germline mosaicism. This report suggests that parental low-level mosaicism should be evaluated in those parents with children carrying de novo germline mutations and the targeted deep sequencing is useful to detect them.
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http://dx.doi.org/10.1002/ajmg.a.61422DOI Listing
March 2020

Effect of Asfotase Alfa on Muscle Weakness in a Japanese Adult Patient of Hypophosphatasia with Low ALP Levels.

Intern Med 2020 Mar 29;59(6):811-815. Epub 2019 Nov 29.

Department of Gastroenterology and Metabolism, Nagoya City University Graduate School of Medical Science, Japan.

A 40-year-old Japanese woman presented to our hospital with general fatigue and muscle weakness. She had a history of premature loss of deciduous teeth at 4 years old, her serum alkaline phosphatase (ALP) activity was as low as 91 U/L, and radiologic studies revealed thoracic deformity and sacroiliac calcification. Genetic sequencing revealed a heterozygous c.1559delT mutation in the tissue non-specific alkaline phosphatase gene (ALPL). Based on these findings, she was diagnosed with hypophosphatasia (HPP), and treatment with asfotase alfa, a recombinant human tissue-nonspecific alkaline phosphatase (TNSALP), was initiated. After six months of treatment with asfotase alfa, improvements were observed in the SF-36 score, six-minute walk distance, and grasping power. Although the overdiagnosis needs to be avoided, HPP should be considered in patients with undiagnosed musculoskeletal symptoms and a low serum ALP activity.
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http://dx.doi.org/10.2169/internalmedicine.3298-19DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7118397PMC
March 2020

Complete oculocerebrorenal phenotype of Lowe syndrome in a female patient with half reduction of inositol polyphosphate 5-phosphatase.

CEN Case Rep 2020 05 9;9(2):95-100. Epub 2019 Nov 9.

Department of Pediatrics, Minoh City Hospital, 5-7-1 Kayano, Minoh City, Osaka, 562-8562, Japan.

The oculocerebrorenal disorder of Lowe syndrome is an X-linked mutation in the gene oculocerebrorenal syndrome of Lowe 1 (OCRL), characterized by the triad of congenital cataracts, severe intellectual impairment, and renal tubular dysfunction. Manifestations of phenotype in female carriers and patients are extremely rare. We present a female case with congenital cataracts, severe intellectual impairment, sensorineural hearing loss, and renal tubular dysfunction as Lowe syndrome. A 9-year-old Japanese girl visited our hospital due to prolonged proteinuria. Her renal biopsy revealed diffuse mesangium proliferation, sclerosis and dilatation of renal tubules, and mild IgA deposition in the mesangial region. Furthermore, she had congenital cataracts, severe intellectual impairment, and sensorineural hearing loss. Genetic screening did not identify mutations of the ORCL gene encoding inositol polyphosphate 5-phosphatase (IPP-5P) (46 XX, female). However, we found the reduction of enzyme activity of IPP-5P to 50% of the normal value. Furthermore, her renal function had deteriorated to renal failure within a decade. Finally, she received peritoneal dialysis and renal transplantation. We present the oculocerebrorenal phenotype of Lowe syndrome in a female patient with reduced activity of IPP-5P without OCRL gene mutation.
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http://dx.doi.org/10.1007/s13730-019-00434-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7148414PMC
May 2020

IGF2 Mutations.

J Clin Endocrinol Metab 2020 01;105(1)

Department of Pediatrics, Hamamatsu University School of Medicine, Hamamatsu, Japan.

Objective: IGF2 is a paternally expressed growth-promoting gene. Here, we report five cases with IGF2 mutations and review IGF2 mutation-positive patients described in the literature. We also compare clinical features between patients with IGF2 mutations and those with H19/IGF2:IG-DMR epimutations.

Results: We recruited five cases with IGF2 mutations: case 1 with a splice site mutation (c.-6-1G>C) leading to skipping of exon 2 and cases 2-5 with different missense mutations (p.(Cys70Tyr), p.(Cys71Arg), p.(Cys33Ser), and p.(Cys45Ser)) affecting cysteine residues involved in the S-S bindings. All the mutations resided on the paternally inherited allele, and the mutation of case 5 was present in a mosaic condition. Clinical assessment revealed Silver-Russell syndrome (SRS) phenotype with Netchine-Harbison scores of ≥5/6 in all the apparently nonmosaic 14 patients with IGF2 mutations (cases 1-4 described in this study and 10 patients reported in the literature). Furthermore, compared with H19/IGF2:IG-DMR epimutations, IGF2 mutations were associated with low frequency of hemihypoplasia, high frequency of feeding difficulty and/or reduced body mass index, and mild degree of relative macrocephaly, together with occasional development of severe limb malformations, high frequency of cardiovascular anomalies and developmental delay, and low serum IGF-II values.

Conclusions: This study indicates that IGF2 mutations constitute a rare but important cause of SRS. Furthermore, while both IGF2 mutations and H19/IGF2:IG-DMR epimutations lead to SRS, a certain degree of phenotypic difference is observed between the two groups, probably due to the different IGF2 expression pattern in target tissues.
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http://dx.doi.org/10.1210/clinem/dgz034DOI Listing
January 2020

Genetic correction of induced pluripotent stem cells mediated by transcription activator-like effector nucleases targeting ALPL recovers enzyme activity and calcification in vitro.

Mol Genet Metab 2019 06 28;127(2):158-165. Epub 2019 May 28.

Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan. Electronic address:

Hypophosphatasia (HPP) is an inheritable disease affecting both skeletal systems and extra-skeletal organs due to mutations of the gene ALPL, which encodes tissue-nonspecific alkaline phosphatase. Recently, an enzyme replacement therapy using asfotase alfa was developed to ameliorate the complications of HPP. However, it requires frequent injections and is expensive to maintain. As an alternative, cell and gene therapy using human induced pluripotent stem cells (iPSCs) after precise correction of the mutation is feasible due to advances in genome-editing technology. In the study, we examined the alkaline phosphatase (ALP) activity and calcification in vitro of two childhood HPP patient-derived iPSCs after the correction of the c.1559delT mutation, which is the most frequent mutation in Japanese patients with HPP, using transcription activator-like effector nucleases (TALENs). The gene correction targeting vector was designed for site-directed mutagenesis using TALEN. After selection with antibiotics, some clones with the selection cassette were obtained. Gene correction was confirmed by Sanger sequencing. The mutation was corrected in one allele of ALPL in homozygous patients and compound heterozygous patients. The correction of ALPL did not result in an increase in ALP when the selection cassette remained. Conversely, iPSCs exhibited ALP activity after the elimination of the cassette using Cre/LoxP. The quantitative analysis showed the half ALP activity in corrected iPSCs of that of control iPSCs, corresponding to heterozygous correction of the mutation. In addition, osteoblasts differentiated from the corrected iPSCs exhibited high ALP activity and some calcification in vitro. Moreover, the osteoblast-like phenotype was confirmed by increased expression of osteoblast-specific genes such as COL1A1 and osteocalcin. These results suggest that gene correction in iPSCs may be a candidate treatment for HPP patients.
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http://dx.doi.org/10.1016/j.ymgme.2019.05.014DOI Listing
June 2019

A novel mutation in basal cell nevus syndrome with rare craniofacial features.

Hum Genome Var 2019 2;6:16. Epub 2019 Apr 2.

1Department of Orthodontics and Dentofacial Orthopedics, Osaka University Graduate School of Dentistry, Suita, Japan.

Basal cell nevus syndrome (BCNS) is a rare, multisystem, autosomal dominant disorder that is characterized by various phenotypes, including multiple basal cell carcinomas of the skin, odontogenic keratocysts of the jaws, and occasionally cleft lip and/or palate. In this report, we describe a 6-year-old Japanese girl with a novel heterozygous nonsense mutation in who exhibited rare craniofacial phenotypes, such as oligodontia and a short-tooth root.
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http://dx.doi.org/10.1038/s41439-019-0047-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6445144PMC
April 2019

Metreleptin treatment for congenital generalized lipodystrophy type 4 (CGL4): a case report.

Clin Pediatr Endocrinol 2019 31;28(1):1-7. Epub 2019 Jan 31.

Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan.

Congenital generalized lipodystrophy type 4 (CGL4) is a rare disease caused by mutations in the gene polymerase I and transcript release factor (), the main symptoms of which are systemic reductions in adipose tissue and muscular dystrophy. The strategy of treating CGL4 is to improve the insulin resistance and hypertriglyceridemia that result from systemic reductions in adipose tissue. Metreleptin, a synthetic analog of human leptin, is effective against generalized lipodystrophies; however, there are no reports of the use of metreleptin in the treatment of CGL4. Herein, we discuss the treatment of a six-year-old boy diagnosed with CGL4 due to a homozygous mutation in with metreleptin. His serum triglyceride level and homeostasis model assessment of insulin resistance (HOMA-IR) value decreased after two months of metreleptin treatment. However, the efficacy of metreleptin gradually decreased, and the treatment was suspended because anaphylaxis occurred after the dosage administered was increased. Subsequently, his serum triglyceride level and HOMA-IR value significantly increased. Anti-metreleptin-neutralizing antibodies were detected in his serum, which suggested that these antibodies reduced the efficacy of metreleptin and caused increased hypersensitivity. Thus, metreleptin appeared to be efficacious in the treatment of CGL4 in the short term, although an adverse immune response resulted in treatment suspension. Further studies are needed to evaluate metreleptin treatments for CGL4.
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http://dx.doi.org/10.1297/cpe.28.1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6356095PMC
January 2019

Japanese patient with Cole-carpenter syndrome with compound heterozygous variants of SEC24D.

Am J Med Genet A 2018 12 21;176(12):2882-2886. Epub 2018 Nov 21.

Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan.

Cole-Carpenter syndrome is a rare skeletal dysplasia associated with low-bone mass or an osteogenesis imperfecta (OI)-like syndrome. Only 3 and 6 variants in SEC24D have been reported in patients with Cole-Carpenter syndrome type 2 and autosomal recessive OI, respectively. We describe a 15-year-old Japanese boy with short stature of the short-trunk type and craniofacial abnormalities including ocular proptosis, marked frontal bossing, midface hypoplasia, and micrognathia. These features were consistent with a diagnosis of Cole-Carpenter syndrome. He had low-bone mineral density and basilar impression. Whole exome sequencing analysis identified biallelic variants in SEC24D (p.Arg484* and p.Arg313His) in the patient. We will report a patient with compound heterozygous variants of SEC24D causing Cole-Carpenter syndrome type 2.
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http://dx.doi.org/10.1002/ajmg.a.40643DOI Listing
December 2018

Functional analysis of monocarboxylate transporter 8 mutations in Japanese Allan-Herndon-Dudley syndrome patients.

Endocr J 2019 Jan 25;66(1):19-29. Epub 2018 Oct 25.

Department of Pediatrics, Graduate School of Medicine, Osaka University, Suita, Japan.

Monocarboxylate transporter 8 (MCT8) facilitates T3 uptake into cells. Mutations in MCT8 lead to Allan-Herndon-Dudley syndrome (AHDS), which is characterized by severe psychomotor retardation and abnormal thyroid hormone profile. Nine uncharacterized MCT8 mutations in Japanese patients with severe neurocognitive impairment and elevated serum T3 levels were studied regarding the transport of T3. Human MCT8 (hMCT8) function was studied in wild-type (WT) or mutant hMCT8-transfected human placental choriocarcinoma cells (JEG3) by visualizing the locations of the proteins in the cells, detecting specific proteins, and measuring T3 uptake. We identified 6 missense (p.Arg445Ser, p.Asp498Asn, p.Gly276Arg, p.Gly196Glu, p.Gly401Arg, and p.Gly312Arg), 2 frameshift (p.Arg355Profs*64 and p.Tyr550Serfs*17), and 1 deletion (p.Pro561del) mutation(s) in the hMCT8 gene. All patients exhibited clinical characteristics of AHDS with high free T3, low-normal free T4, and normal-elevated TSH levels. All tested mutants were expressed at the protein level, except p.Arg355Profs*64 and p.Tyr550Serfs*17, which were truncated, and were inactive in T3 uptake, excluding p.Arg445Ser and p.Pro561del mutants, compared with WT-hMCT8. Immunocytochemistry revealed plasma membrane localization of p.Arg445Ser and p.Pro561del mutants similar with WT-hMCT8. The other mutants failed to localize in significant amount(s) in the plasma membrane and instead localized in the cytoplasm. These data indicate that p.Arg445Ser and p.Pro561del mutants preserve residual function, whereas p.Asp498Asn, p.Gly276Arg, p.Gly196Glu, p.Gly401Arg, p.Gly312Arg, p.Arg355Profs*64, and p.Tyr550Serfs*17 mutants lack function. These findings suggest that the mutations in MCT8 cause loss of function by reducing protein expression, impairing trafficking of protein to plasma membrane, and disrupting substrate channel.
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http://dx.doi.org/10.1507/endocrj.EJ18-0251DOI Listing
January 2019

Endocrinological and phenotype evaluation in a patient with acrodysostosis.

Clin Pediatr Endocrinol 2017 27;26(3):177-182. Epub 2017 Jul 27.

Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan.

Acrodysostosis is characterized by distinctive facial features and severe brachydactyly. Mutations in or are known to be responsible for this disease. Cases of hormonal resistance have been reported, particularly in patients with mutations. The physical characteristics and endocrine function of pseudohypoparathyroidism type Ia is known to resemble acrodysostosis. We report the case of a 4-yr-old patient with a mutation. He had characteristic facies with an upturned nose and cone-shaped epiphyses of most phalanges. These findings have not been reported as extensive for cases of pseudohypoparathyroidism type Ia. He also had TSH resistance from birth. We performed endocrinological stimulation tests to further evaluate his endocrine status. These examinations revealed resistance to TSH and PTH, but there was normal secretion of ACTH, GH, and cortisol. An Ellsworth-Howard test resulted in normal urinary cAMP excretion. This response differs from that of pseudohypoparathyroidism type Ia. In summary, the constellation of an upturned nose, cone-shaped epiphyses of most if not all phalanges, and PTH resistance with a normal urinary cAMP response may satisfactorily enable clinical diagnosis of acrodysostosis.
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http://dx.doi.org/10.1297/cpe.26.177DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5537214PMC
July 2017

Measles virus nucleocapsid protein increases osteoblast differentiation in Paget's disease.

J Clin Invest 2016 Mar 15;126(3):1012-22. Epub 2016 Feb 15.

Paget's disease (PD) is characterized by focal and dramatic bone resorption and formation. Treatments that target osteoclasts (OCLs) block both pagetic bone resorption and formation; therefore, PD offers key insights into mechanisms that couple bone resorption and formation. Here, we evaluated OCLs from 3 patients with PD and determined that measles virus nucleocapsid protein (MVNP) was expressed in 70% of these OCLs. Moreover, transgenic mice with OCL-specific expression of MVNP (MVNP mice) developed PD-like bone lesions that required MVNP-dependent induction of high IL-6 expression levels in OCLs. In contrast, mice harboring a knockin of p62P394L (p62-KI mice), which is the most frequent PD-associated mutation, exhibited increased bone resorption, but not formation. Evaluation of OCLs from MVNP, p62-KI, and WT mice revealed increased IGF1 expression in MVNP-expressing OCLs that resulted from the high IL-6 expression levels in these cells. IL-6, in turn, increased the expression of coupling factors, specifically ephrinB2 on OCLs and EphB4 on osteoblasts (OBs). IGF1 enhanced ephrinB2 expression on OCLs and OB differentiation. Importantly, ephrinB2 and IGF1 levels were increased in MVNP-expressing OCLs from patients with PD and MVNP-transduced human OCLs compared with levels detected in controls. Further, anti-IGF1 or anti-IGF1R blocked Runx2 and osteocalcin upregulation in OBs cocultured with MVNP-expressing OCLs. These results suggest that in PD, MVNP upregulates IL-6 and IGF1 in OCLs to increase ephrinB2-EphB4 coupling and bone formation.
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http://dx.doi.org/10.1172/JCI82012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4767344PMC
March 2016

Current concepts in perinatal mineral metabolism.

Clin Pediatr Endocrinol 2016 Jan 30;25(1):9-17. Epub 2016 Jan 30.

Department of Bone and Mineral Research, Osaka Medical Center and Research Institute for Maternal and Child Health, Izumi, Japan.

The serum levels of calcium (Ca) and phosphate are maintained higher in the fetus than in the pregnant mother, especially in late gestation, to meet the demands of fetal bone development. In order to maintain this fetal stage-specific mineral homeostasis, the placenta plays a critical role through active transcellular mineral transport. Although the molecular mechanism of transplacental Ca transport has been well studied, little is known about the transport mechanism of phosphate and magnesium. Maternal mineral homeostasis is also altered during pregnancy to supply minerals to the fetus. In the lactating mother, osteocytic osteolysis is suggested to be involved in the supply of minerals to the baby. The levels of some calcitropic and phosphotropic (Ca- and phosphate-regulating, respectively) hormones in the fetus are also different from those in the adult. The PTH level in the fetus is lower than that in the mother and nonpregnant adult. It is suggested, however, that low fetal PTH plays an important role in fetal mineral metabolism. The concentration of PTHrP in the fetus is much higher than that of PTH and plays a critical role in perinatal Ca homeostasis. Uncovering the molecular mechanisms for fetal stage-specific mineral metabolism will lead to better management of perinatal patients with mineral abnormalities.
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http://dx.doi.org/10.1297/cpe.25.9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4738188PMC
January 2016

Successful induction of sclerostin in human-derived fibroblasts by 4 transcription factors and its regulation by parathyroid hormone, hypoxia, and prostaglandin E2.

Bone 2016 Apr 2;85:91-8. Epub 2016 Feb 2.

Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan. Electronic address:

Sclerostin, coded by SOST, is a secretory protein that is specifically expressed in osteocytes and suppresses osteogenesis by inhibiting WNT signaling. The regulatory mechanism underlying SOST expression remains unclear mainly due to the absence of an adequate human cell model. Thus, we herein attempted to establish a cell model of human dermal fibroblasts in order to investigate the functions of sclerostin. We selected 20 candidate transcription factors (TFs) that induce SOST expression by analyzing gene expression patterns in the human sarcoma cell line, SaOS-2, between differentiation and maintenance cultures using microarrays. An effective set of TFs to induce SOST expression was sought by their viral transduction into fibroblasts, and a combination of four TFs: ATF3, KLF4, PAX4, and SP7, was identified as the most effective inducer of SOST expression. Quantitative PCR demonstrated that the expression levels of SOST in fibroblasts treated with the 4 TFs were 199- and 1439-fold higher than those of the control after 1-week and 4-week cultures, respectively. The level of sclerostin in the conditioned medium, as determined by ELISA, was 21.2pmol/l 4weeks after the transduction of the 4 TFs. Interestingly, the production of Dickkopf1 (DKK1), another secreted inhibitor of WNT signaling, was also increased by transduction of these 4 TFs. Parathyroid hormone (PTH) significantly suppressed the induced SOST by 38% and sclerostin by 82% that of the vehicle. Hypoxia increased the induced SOST by 62% that of normoxia. Furthermore, prostaglandin E2 (PGE2) increased SOST expression levels to 16-fold those of the vehicle. In conclusion, the efficient induction of SOST expression and sclerostin production was achieved in human dermal fibroblasts by the transduction of ATF3, KLF4, PAX4, and SP7, and the induced SOST and sclerostin were regulated by PTH, hypoxia, and PGE2. This model may contribute to elucidating the regulatory mechanisms underlying SOST expression and advancing drug development for metabolic bone diseases.
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http://dx.doi.org/10.1016/j.bone.2016.01.024DOI Listing
April 2016

Serum NT-proCNP levels increased after initiation of GH treatment in patients with achondroplasia/hypochondroplasia.

Clin Endocrinol (Oxf) 2016 06 25;84(6):845-50. Epub 2016 Feb 25.

Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan.

Objective: Serum amino-terminal propeptide of C-type natriuretic peptide (NT-proCNP) levels have been proposed as a biomarker of linear growth in healthy children. The usefulness of NT-proCNP in patients with achondroplasia (ACH)/hypochondroplasia (HCH) remains to be elucidated. The objective was to study whether serum NT-proCNP level is a good biomarker for growth in ACH/HCH and other patients of short stature.

Design: This was a longitudinal cohort study.

Patients: Sixteen children with ACH (aged 0·4-4·3 years), six children with HCH (2·7-6·3 years), 23 children with idiopathic short stature (ISS) (2·2-9·0 years), eight short children with GH deficiency (GHD) (2·9-6·8 years) and five short children born small for gestational age (SGA) (2·0-6·6 years). Patients with ACH/HCH received GH treatment for 1 year.

Measurements: Serum NT-proCNP levels and height were measured.

Results: NT-proCNP levels positively correlated with height velocity in these short children (P < 0·05, r = 0·27). NT-proCNP levels inversely correlated with age in children with ISS alone (P < 0·01, r = -0·55). Serum NT-proCNP levels in patients with ACH/HCH were increased 3 months following the initiation of GH treatment (P < 0·05). Height SDS gain during GH treatment for 1 year was positively correlated with the changes in NT-proCNP levels after the initiation of GH (P < 0·01, r = 0·72).

Conclusion: Serum NT-proCNP levels may be a good biomarker to indicate the effect of GH treatment on growth in patients with ACH/HCH at least in the first year and height velocity in short stature patients.
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http://dx.doi.org/10.1111/cen.13025DOI Listing
June 2016

Acromesomelic dysplasia, type maroteaux caused by novel loss-of-function mutations of the NPR2 gene: Three case reports.

Am J Med Genet A 2016 Feb 14;170A(2):426-434. Epub 2015 Nov 14.

Division of Pediatric Orthopaedics, Seoul National University Children's Hospital, Seoul, Republic of Korea.

The C-type natriuretic peptide (CNP)-natriuretic peptide receptor 2 (NPR2) signaling pathway plays an important role in chondrocyte development. Homozygous loss-of-function mutations of the NPR2 gene cause acromesomelic dysplasia, type Maroteaux (AMDM). The aim of this study was to identify and characterize NPR2 loss-of-function mutations in patients with AMDM. The NPR2 gene was sequenced in three Korean patients with AMDM and functional analysis of the mutated proteins was performed in vitro. Five novel NPR2 mutations were found in the three patients: two compound heterozygous mutations [c.1231T>C (Tyr411His) and c.2761C>T (Arg921X) in Patient 1 and c.1663A>T (Lys555X) and c.1711-1G>C (M571VfsX12) in Patient 3] and a homozygous mutation [c.2762G>A (Arg921Gln) in Patient 2]. Serum NT-proCNP concentration was significantly increased in each patient compared to control subjects. Cells transfected with the expression vector of each mutant except those found in Patient 3 showed a negligible or a markedly low cGMP response after treatment with CNP. HA-tagged wild-type (wt) and HA-mutant NPR2 were expressed at comparable levels: there were two bands of ∼130 and ∼120 kDa in wt and Arg921Gln, a single ∼120 kDa band in Tyr411His, and a single ∼110 kDa in the nonsense mutant. With respect to subcellular localization, Arg921Gln as well as wt-NPR2 reached the cell surface, whereas Tyr411His and Arg921X mutants did not. The Tyr411His and Arg921X NPR2 proteins were co-localized with an endoplasmic reticulum (ER) marker and failed to traffic from the ER to the Golgi apparatus. These results are consistent with deglycosylation experiments. Tyr411His and Arg921X NPR2 are complete loss-of-function mutations, whereas Arg921Gln behaves as a receptor for CNP with limited function.
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http://dx.doi.org/10.1002/ajmg.a.37463DOI Listing
February 2016

Interleukin-1-induced acute bone resorption facilitates the secretion of fibroblast growth factor 23 into the circulation.

J Bone Miner Metab 2015 May 5;33(3):342-54. Epub 2014 Jul 5.

Department of Bone and Mineral Research, Osaka Medical Center and Research Institute for Maternal and Child Health, Izumi, Osaka, 594-1101, Japan.

Fibroblast growth factor 23 (FGF23), a central regulator of phosphate and vitamin D metabolism, is mainly produced by osteocytes in bone and exerts its effects on distant organs. Despite its endocrine function, the mechanism controlling serum FGF23 levels is not fully understood. Here we tested the hypothesis that osteoclastic bone resorption may play a role in regulating circulating levels of FGF23, using a mouse model where injections of interleukin (IL)-1β into the subcutaneous tissue over the calvaria induced rapid bone resorption. A significant amount of FGF23 was detected in the extracts from mouse bones, which supports the idea that FGF23 stays in bone for a while after its production. IL-1β-induced bone resorption was associated with elevated serum FGF23 levels, an effect abolished by pre-treatment with pamidronate. Fgf23 expression was not increased in either the calvariae or tibiae of IL-1β-injected mice, which suggests that IL-1β facilitated the entry of FGF23 protein into circulation by accelerating bone resorption rather than increasing its gene expression. The direct effect of IL-1β on bone was confirmed when it increased FGF23 levels in the conditioned media of mouse calvariae in organ culture. Repeated treatment of the cultured calvariae with IL-1β led to a refractory phase, where FGF23 was not mobilized by IL-1β anymore. Consistent with the in vivo results, treatment with IL-1β failed to increase Fgf23 mRNA in isolated primary osteocytes and osteoblasts. These results suggest that FGF23 produced by osteocytes remains in bone, and that rapid bone resorption facilitates its entry into the bloodstream.
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http://dx.doi.org/10.1007/s00774-014-0598-2DOI Listing
May 2015

Dysregulated gene expression in the primary osteoblasts and osteocytes isolated from hypophosphatemic Hyp mice.

PLoS One 2014 7;9(4):e93840. Epub 2014 Apr 7.

Department of Bone and Mineral Research, Osaka Medical Center and Research Institute for Maternal and Child Health, Izumi, Osaka, Japan.

Osteocytes express multiple genes involved in mineral metabolism including PHEX, FGF23, DMP1 and FAM20C. In Hyp mice, a murine model for X-linked hypophosphatemia (XLH), Phex deficiency results in the overproduction of FGF23 in osteocytes, which leads to hypophosphatemia and impaired vitamin D metabolism. In this study, to further clarify the abnormality in osteocytes of Hyp mice, we obtained detailed gene expression profiles in osteoblasts and osteocytes isolated from the long bones of 20-week-old Hyp mice and wild-type (WT) control mice. The expression of Fgf23, Dmp1, and Fam20c was higher in osteocytic cells than in osteoblastic cells in both genotypes, and was up-regulated in Hyp cells. Interestingly, the up-regulation of these genes in Hyp bones began before birth. On the other hand, the expression of Slc20a1 encoding the sodium/phosphate (Na+/Pi) co-transporter Pit1 was increased in osteoblasts and osteocytes from adult Hyp mice, but not in Hyp fetal bones. The direct effects of extracellular Pi and 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] on isolated osteoblastic and osteocytic cells were also investigated. Twenty-four-hour treatment with 10-8 M 1,25(OH)2D3 increased the expression of Fgf23 in WT osteoblastic cells but not in osteocytic cells. Dmp1 expression in osteocytic cells was increased due to the 24-hour treatment with 10 mM Pi and was suppressed by 10-8 M 1,25(OH)2D3 in WT osteocytic cells. We also found the up-regulation of the genes for FGF1, FGF2, their receptors, and Egr-1 which is a target of FGF signaling, in Hyp osteocytic cells, suggesting the activation of FGF/FGFR signaling. These results implicate the complex gene dysregulation in osteoblasts and osteocytes of Hyp mice, which might contribute to the pathogenesis.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0093840PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3977859PMC
January 2015

[Bone and Stem Cells. The mechanism of osteogenic differentiation from mesenchymal stem cell].

Clin Calcium 2014 Apr;24(4):501-8

Department of Pediatrics, Osaka University Graduate School of Medicine, Japan.

Osteoblasts and osteocytes originate from pluripotent mesenchymal stem cells. Mesenchymal stem cells commit to osteogenic lineage and differentiate into mature osteoblasts and osteocytes through osteoprogenitor cells and preosteoblasts in response to multiple stimuli. The osteoblast commitment, differentiation, and functions are governed by several transcription factors. Among these transcription factors, runt-related transcription factor 2 (Runx2) is a crucial factor in osteoblast differentiation and controls bone formation. Differentiation toward these osteogenic lineage is controlled by a multitude of cytokines including WNTs, bone morphogenetic protein (BMP) , transforming growth factor-β (TGF-β) , hedgehog, parathyroid hormone (PTH) /parathyroid hormone related protein (PTHrP) , insulin-like growth factor-1 (IGF-1) , fibroblast growth factor (FGF) , and Notch. Although regulation of Runx2 activity is a point of convergence of many of the signal transduction routes, there is also a high degree of cross-talk between these pathways. Thus, the combined action of the signal transduction pathways induced by some cytokines determines the commitment and differentiation of mesenchymal stem cells toward the osteogenic lineage.
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http://dx.doi.org/CliCa1404501508DOI Listing
April 2014

Serum fibroblast growth factor 23 is a useful marker to distinguish vitamin D-deficient rickets from hypophosphatemic rickets.

Horm Res Paediatr 2014 26;81(4):251-7. Epub 2014 Feb 26.

Department of Pediatrics, Graduate School of Medicine, Osaka, Japan.

Background/aims: Vitamin D-deficient rickets (DR) has recently re-emerged among developed countries. Vitamin D deficiency can influence biochemical results of patients with fibroblast growth factor 23 (FGF23)-related hereditary hypophosphatemic rickets (HR), making differential diagnosis difficult. In the present study we evaluated the utility of serum FGF23 levels in the diagnosis of DR and during its treatment.

Methods: The study group comprised 24 children with DR and 8 children with HR. Serum FGF23 levels and bone metabolism-related measurements were assessed.

Results: Serum FGF23 levels in patients with DR were less than 19 pg/ml, while those in patients with HR were more than 57 pg/ml. There were significant differences in serum levels of calcium, phosphate, parathyroid hormone, and 1,25-dihydroxyvitamin D, as well as tubular maximum phosphate reabsorption per glomerular filtration rate between patients with DR and HR, but these values were not fully mutually exclusive. In addition, serum FGF23 and phosphate levels were increased following treatment.

Conclusion: Serum FGF23 level is the most critical biochemical marker for distinguishing DR from HR and might be a good indicator of biochemical response to the intervention. Serum FGF23 levels show utility for the diagnosis of DR and in the assessment of its response to treatment.
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http://dx.doi.org/10.1159/000357142DOI Listing
January 2015
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