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Ricci S, Abu-Rumeileh S, Campagna N, Barbati F, Stagi S, Canessa C, Lodi L, Palterer B, Maggi L, Matucci A, Vultaggio A, Annunziato F, Azzari C. Case Report: A child with NFKB1 haploinsufficiency explaining the linkage between immunodeficiency and short stature. Front Immunol 2023; 14:1224603. [PMID: 37600787 PMCID: PMC10434558 DOI: 10.3389/fimmu.2023.1224603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 07/17/2023] [Indexed: 08/22/2023] Open
Abstract
We report the case of a patient with common variable immunodeficiency (CVID) presenting with short stature and treated with recombinant human growth hormone (rhGH). Whole exome sequencing revealed a novel single-nucleotide duplication in the NFKB1 gene (c.904dup, p.Ser302fs), leading to a frameshift and thus causing NFKB1 haploinsufficiency. The variant was considered pathogenic and was later found in the patient's mother, also affected by CVID. This is the first reported case of a patient with CVID due to NFKB1 mutation presenting with short stature. We analyzed the interconnection between NFKB1 and GH - IGF-1 pathways and we hypothesized a common ground for both CVID and short stature in our patient.
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Affiliation(s)
- S. Ricci
- Department of Health Sciences, University of Florence, Florence, Italy
- Immunology Division, Section of Pediatrics, Meyer Children’s Hospital Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Florence, Italy
| | - S. Abu-Rumeileh
- Department of Health Sciences, University of Florence, Florence, Italy
| | - N. Campagna
- Department of Health Sciences, University of Florence, Florence, Italy
| | - F. Barbati
- Department of Health Sciences, University of Florence, Florence, Italy
| | - S. Stagi
- Department of Health Sciences, University of Florence, Florence, Italy
- Endocrinology Division, Section of Pediatrics, Meyer Children’s Hospital Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Florence, Italy
| | - C. Canessa
- Department of Health Sciences, University of Florence, Florence, Italy
- Immunology Division, Section of Pediatrics, Meyer Children’s Hospital Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Florence, Italy
| | - L. Lodi
- Department of Health Sciences, University of Florence, Florence, Italy
- Immunology Division, Section of Pediatrics, Meyer Children’s Hospital Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Florence, Italy
| | - B. Palterer
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - L. Maggi
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - A. Matucci
- Immunoallergology Unit, Careggi University Hospital, Florence, Italy
| | - A. Vultaggio
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
- Immunoallergology Unit, Careggi University Hospital, Florence, Italy
| | - F. Annunziato
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
- Flow Cytometry Diagnostic Center and Immunotherapy, Careggi University Hospital, Florence, Italy
| | - C. Azzari
- Department of Health Sciences, University of Florence, Florence, Italy
- Immunology Division, Section of Pediatrics, Meyer Children’s Hospital Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Florence, Italy
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2
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R Mangone F, Av Valoyes M, G do Nascimento R, Pf Conceição M, R Bastos D, C Pavanelli A, C Soares I, S de Mello E, Nonogaki S, Ab de T Osório C, A Nagai M. Prognostic and predictive value of Pleckstrin homology-like domain, family A family members in breast cancer. Biomark Med 2020; 14:1537-1552. [PMID: 33179538 DOI: 10.2217/bmm-2020-0417] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Aim: The PHLDA (pleckstrin homology like domain, family A) gene family encodes proteins capable of inhibiting AKT (serine/threonine kinase) signaling through phosphoinositol binding competition. Results & methodology: Using in silico analysis, we found that Luminal A and B patients' short relapse-free survival was associated with low PHLDA1 or PHLDA3 and high PHLDA2 expression. In a cohort of 393 patients with luminal breast cancer evaluated by immunohistochemistry on tissue microarrays, we found a direct association of PHLDA3 expression with hormonal therapy response (p = 0.013). Conclusion: Our findings provide new information on the role played by the PHLDA family members as prognostic markers in breast cancer, and more importantly, we provide evidence that they might also predict a response to endocrine therapy.
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Affiliation(s)
- Flavia R Mangone
- Discipline of Oncology, Department of Radiology & Oncology, Faculty of Medicine, University of Sao Paulo, 01246-903, Sao Paulo, Brazil.,Laboratory of Molecular Genetics, Center for Translational Research in Oncology, Cancer Institute of Sao Paulo, 01246-000, Sao Paulo, Brazil
| | - Maira Av Valoyes
- Discipline of Oncology, Department of Radiology & Oncology, Faculty of Medicine, University of Sao Paulo, 01246-903, Sao Paulo, Brazil.,Laboratory of Molecular Genetics, Center for Translational Research in Oncology, Cancer Institute of Sao Paulo, 01246-000, Sao Paulo, Brazil
| | - Renan G do Nascimento
- Discipline of Oncology, Department of Radiology & Oncology, Faculty of Medicine, University of Sao Paulo, 01246-903, Sao Paulo, Brazil.,Laboratory of Molecular Genetics, Center for Translational Research in Oncology, Cancer Institute of Sao Paulo, 01246-000, Sao Paulo, Brazil
| | - Mércia Pf Conceição
- Discipline of Oncology, Department of Radiology & Oncology, Faculty of Medicine, University of Sao Paulo, 01246-903, Sao Paulo, Brazil.,Laboratory of Molecular Genetics, Center for Translational Research in Oncology, Cancer Institute of Sao Paulo, 01246-000, Sao Paulo, Brazil
| | - Daniel R Bastos
- Discipline of Oncology, Department of Radiology & Oncology, Faculty of Medicine, University of Sao Paulo, 01246-903, Sao Paulo, Brazil.,Laboratory of Molecular Genetics, Center for Translational Research in Oncology, Cancer Institute of Sao Paulo, 01246-000, Sao Paulo, Brazil
| | - Ana C Pavanelli
- Discipline of Oncology, Department of Radiology & Oncology, Faculty of Medicine, University of Sao Paulo, 01246-903, Sao Paulo, Brazil.,Laboratory of Molecular Genetics, Center for Translational Research in Oncology, Cancer Institute of Sao Paulo, 01246-000, Sao Paulo, Brazil
| | - Iberê C Soares
- Department of Pathology, Instituto do Cancer, Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, 01246-903, São Paulo, Brazil
| | - Evandro S de Mello
- Department of Pathology, Instituto do Cancer, Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, 01246-903, São Paulo, Brazil
| | - Suely Nonogaki
- Department of Pathological Anatomy, A. C. Camargo Cancer Center, 01509-020, Sao Paulo, Brazil
| | - Cynthia Ab de T Osório
- Department of Pathological Anatomy, A. C. Camargo Cancer Center, 01509-020, Sao Paulo, Brazil
| | - Maria A Nagai
- Discipline of Oncology, Department of Radiology & Oncology, Faculty of Medicine, University of Sao Paulo, 01246-903, Sao Paulo, Brazil.,Laboratory of Molecular Genetics, Center for Translational Research in Oncology, Cancer Institute of Sao Paulo, 01246-000, Sao Paulo, Brazil
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3
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De Luca F. Regulatory role of NF-κB in growth plate chondrogenesis and its functional interaction with Growth Hormone. Mol Cell Endocrinol 2020; 514:110916. [PMID: 32569858 DOI: 10.1016/j.mce.2020.110916] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 06/08/2020] [Accepted: 06/09/2020] [Indexed: 11/26/2022]
Abstract
Nuclear Factor kappa B (NF-kB) is a family of transcription factors that participates in the regulation of cell proliferation, migration, and apoptosis. Impaired NF-kB activity appears to be involved in the pathophysiology of inflammatory states, autoimmune diseases, and cancer. Genetic manipulation in mice leading to impaired NF-kB function is associated with abnormal limb development and delayed bone growth. We have previously shown in rodent cultured chondrocytes and cultured metatarsal bones that NF-kB promotes longitudinal bone growth and growth plate chondrocyte function. These NF-kB growth-promoting effects appear to be facilitated by Growth Hormone (GH) and Insulin-like Growth factor-1 (IGF-1). These stimulatory effects of GH and IGF-1 on NF-kB activity are supported by observational evidence in humans; a number of individuals carrying mutations that alter NF-kB function exhibit growth failure and GH insensitivity.
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Affiliation(s)
- Francesco De Luca
- Division of Endocrinology and Diabetes, Children's Mercy Kansas City, University of Missouri Kansas City-School of Medicine, Kansas City, MO, 64111, USA.
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4
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Storr HL, Chatterjee S, Metherell LA, Foley C, Rosenfeld RG, Backeljauw PF, Dauber A, Savage MO, Hwa V. Nonclassical GH Insensitivity: Characterization of Mild Abnormalities of GH Action. Endocr Rev 2019; 40:476-505. [PMID: 30265312 PMCID: PMC6607971 DOI: 10.1210/er.2018-00146] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 07/31/2018] [Indexed: 12/12/2022]
Abstract
GH insensitivity (GHI) presents in childhood with growth failure and in its severe form is associated with extreme short stature and dysmorphic and metabolic abnormalities. In recent years, the clinical, biochemical, and genetic characteristics of GHI and other overlapping short stature syndromes have rapidly expanded. This can be attributed to advancing genetic techniques and a greater awareness of this group of disorders. We review this important spectrum of defects, which present with phenotypes at the milder end of the GHI continuum. We discuss their clinical, biochemical, and genetic characteristics. The objective of this review is to clarify the definition, identification, and investigation of this clinically relevant group of growth defects. We also review the therapeutic challenges of mild GHI.
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Affiliation(s)
- Helen L Storr
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London EC1M 6BQ, United Kingdom
| | - Sumana Chatterjee
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London EC1M 6BQ, United Kingdom
| | - Louise A Metherell
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London EC1M 6BQ, United Kingdom
| | - Corinne Foley
- Division of Endocrinology, Cincinnati Center for Growth Disorders, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - Ron G Rosenfeld
- Department of Pediatrics, Oregon Health and Science University, Portland, Oregon
| | - Philippe F Backeljauw
- Division of Endocrinology, Cincinnati Center for Growth Disorders, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - Andrew Dauber
- Division of Endocrinology, Cincinnati Center for Growth Disorders, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - Martin O Savage
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London EC1M 6BQ, United Kingdom
| | - Vivian Hwa
- Division of Endocrinology, Cincinnati Center for Growth Disorders, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, Ohio
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5
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Finken MJJ, van der Steen M, Smeets CCJ, Walenkamp MJE, de Bruin C, Hokken-Koelega ACS, Wit JM. Children Born Small for Gestational Age: Differential Diagnosis, Molecular Genetic Evaluation, and Implications. Endocr Rev 2018; 39:851-894. [PMID: 29982551 DOI: 10.1210/er.2018-00083] [Citation(s) in RCA: 106] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2018] [Accepted: 06/21/2018] [Indexed: 12/25/2022]
Abstract
Children born small for gestational age (SGA), defined as a birth weight and/or length below -2 SD score (SDS), comprise a heterogeneous group. The causes of SGA are multifactorial and include maternal lifestyle and obstetric factors, placental dysfunction, and numerous fetal (epi)genetic abnormalities. Short-term consequences of SGA include increased risks of hypothermia, polycythemia, and hypoglycemia. Although most SGA infants show catch-up growth by 2 years of age, ∼10% remain short. Short children born SGA are amenable to GH treatment, which increases their adult height by on average 1.25 SD. Add-on treatment with a gonadotropin-releasing hormone agonist may be considered in early pubertal children with an expected adult height below -2.5 SDS. A small birth size increases the risk of later neurodevelopmental problems and cardiometabolic diseases. GH treatment does not pose an additional risk.
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Affiliation(s)
- Martijn J J Finken
- Department of Pediatrics, VU University Medical Center, MB Amsterdam, Netherlands
| | - Manouk van der Steen
- Department of Pediatrics, Erasmus University Medical Center/Sophia Children's Hospital, CN Rotterdam, Netherlands
| | - Carolina C J Smeets
- Department of Pediatrics, Erasmus University Medical Center/Sophia Children's Hospital, CN Rotterdam, Netherlands
| | - Marie J E Walenkamp
- Department of Pediatrics, VU University Medical Center, MB Amsterdam, Netherlands
| | - Christiaan de Bruin
- Department of Pediatrics, Leiden University Medical Center, RC Leiden, Netherlands
| | - Anita C S Hokken-Koelega
- Department of Pediatrics, Erasmus University Medical Center/Sophia Children's Hospital, CN Rotterdam, Netherlands
| | - Jan M Wit
- Department of Pediatrics, Leiden University Medical Center, RC Leiden, Netherlands
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6
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Domené HM, Fierro-Carrión G. Genetic disorders of GH action pathway. Growth Horm IGF Res 2018; 38:19-23. [PMID: 29249625 DOI: 10.1016/j.ghir.2017.12.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Revised: 12/05/2017] [Accepted: 12/09/2017] [Indexed: 11/24/2022]
Abstract
While insensitivity to GH (GHI) is characterized by low IGF-I levels, normal or elevated GH levels, and lack of IGF-I response to GH treatment, IGF-I resistance is characterized by elevated IGF-I levels with normal/high GH levels. Several genetic defects are responsible for impairment of GH and IGF-I actions resulting in short stature that could affect intrauterine growth or be present in the postnatal period. The genetic defects affecting GH and/or IGF-I action can be divided into five different groups: GH insensitivity by defects affecting the GH receptor (GHR), the intracellular GH signaling pathway (STAT5B, STAT3, IKBKB, IL2RG, PIK3R1), the synthesis of insulin-like growth factors (IGF1, IGF2), the transport/bioavailability of IGFs (IGFALS, PAPPA2), and defects affecting IGF-I sensitivity (IGF1R). Complete GH insensitivity (GHI) was first reported by Zvi Laron and his colleagues in patients with classical appearance of GH deficiency, but presenting elevated levels of GH. The association of GH insensitivity with several clinical sings of immune-dysfunction and autoimmune dysregulation are characteristic of molecular defects in the intracellular GH signaling pathway (STAT5B, STAT3, IKBKB, IL2RG, PIK3R1). Gene mutations in the IGF1 and IGF2 genes have been described in patients presenting intrauterine growth retardation and postnatal short stature. Molecular defects have also been reported in the IGFALS gene, that encodes the acid-labile subunit (ALS), responsible to stabilize circulating IGF-I in ternary complexes, and more recently in the PAPPA2 gen that encodes the pregnancy-associated plasma protein-A2, a protease that specifically cleaves IGFBP-3 and IGFBP-5 regulating the accessibility of IGFs to their target tissues. Mutations in the IGF1R gene resulted in IGF-I insensitivity in patients with impaired intrauterine and postnatal growth. These studies have revealed novel molecular mechanisms of GH insensitivity/primary IGF-I deficiency beyond the GH receptor gene. In addition, they have also underlined the importance of several players of the GH-IGF axis in the complex system that promotes human growth.
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Affiliation(s)
- Horacio M Domené
- Centro de Investigaciones Endocrinológicas (CEDIE-CONICET), "Dr. César Bergadá", División de Endocrinología, Hospital de Niños R. Gutiérrez, Buenos Aires, Argentina.
| | - Gustavo Fierro-Carrión
- Escuela de Medicina, Colegio de Ciencias de la Salud, Universidad San Francisco de Quito, Quito, Ecuador
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7
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Lyu JH, Huang B, Park DW, Baek SH. Regulation of PHLDA1 Expression by JAK2-ERK1/2-STAT3 Signaling Pathway. J Cell Biochem 2016; 117:483-90. [PMID: 26239656 DOI: 10.1002/jcb.25296] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 07/30/2015] [Indexed: 02/05/2023]
Abstract
Toll-like receptor 2 (TLR2)-mediated signaling cascades and gene regulation are mainly involved in diseases, such as immunity and inflammation. In this study, microarray analysis was performed using bone marrow-derived macrophages (BMDM) and Raw 264.7 cells to identify novel proteins involved in the TLR2-mediated cellular response. We found that pleckstrin homology-like domain family, member 1 (PHLDA1) is a novel gene up-regulated by TLR2 stimulation and determined the unique signaling pathway for its expression. Treatment with TLR2 agonist Pam3 CSK4 increased mRNA, protein, and fluorescence staining of PHLDA1. Induction of PHLDA1 by TLR2 stimulation disappeared from TLR2 KO mice-derived BMDM. Among janus kinase (JAK) family members, JAK2 was involved in TLR2-stimulated PHLDA1 expression. Signal transducer and activator of transcription 3 (STAT3) also participated in PHLDA1 expression downstream of the JAK2. Interestingly, ERK1/2 was an intermediate between JAK2 and STAT3. In silico analysis revealed the presence of highly conserved γ-activated sites within mouse PHLDA1 promoter and confirmed the JAK2-STAT3 pathway is important to Pam3 CSK4 -induced PHLDA1 transcription. These findings suggest that the JAK2-ERK1/2-STAT3 pathway is an important signaling pathway for PHLDA1 expression and that these proteins may play a critical role in eliciting TLR2-mediated immune and inflammatory response.
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Affiliation(s)
- Ji Hyo Lyu
- Department of Biochemistry and Molecular Biology, College of Medicine, Yeungnam University, 170 Hyeonchung-ro, Nam-gu, Daegu, 705-703, South Korea
| | - Bin Huang
- Department of Biochemistry and Molecular Biology, College of Medicine, Yeungnam University, 170 Hyeonchung-ro, Nam-gu, Daegu, 705-703, South Korea
| | - Dae-Weon Park
- Department of Biochemistry and Molecular Biology, College of Medicine, Yeungnam University, 170 Hyeonchung-ro, Nam-gu, Daegu, 705-703, South Korea
| | - Suk-Hwan Baek
- Department of Biochemistry and Molecular Biology, College of Medicine, Yeungnam University, 170 Hyeonchung-ro, Nam-gu, Daegu, 705-703, South Korea
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8
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Wit JM, de Luca F. Atypical defects resulting in growth hormone insensitivity. Growth Horm IGF Res 2016; 28:57-61. [PMID: 26670721 DOI: 10.1016/j.ghir.2015.11.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Revised: 10/27/2015] [Accepted: 11/28/2015] [Indexed: 12/13/2022]
Abstract
Besides four well-documented genetic causes of GH insensitivity (GHI) (GHR, STAT5B, IGF1, IGFALS defects), several other congenital and acquired conditions are associated with GHI. With respect to its anabolic actions, GH induces transcription of IGF1, IGFBP3 and IGFALS through a complex regulatory cascade including GH binding to its receptor (GHR), activation of JAK2 and phosphorylation of STAT5b, which then trafficks to the nucleus. GH also activates the MAPK and PI3K pathways. The synthesis of GHR can be reduced by estrogen deficiency or corticosteroid excess, and is possibly decreased in African pygmies. An increased degradation of GHRs because of overexpression of cytokine-inducible SH2-containing protein (CIS) was suggested for some children with idiopathic short stature. Effects on several downstream components of GH signaling were observed for FGF21, cytokines, sepsis, fever and chronic renal failure. In Noonan syndrome and other "rasopathies" the activation of the RAS-RAF-MAPK-ERK pathway leads to inhibition of the JAK/STAT pathway. In contrast, fibroblasts from tall patients with Sotos syndrome showed a downregulation of this axis. Experimental and clinical evidence suggests that the NF-κB pathway plays a role in GH signaling. In a patient with an IκBα mutation presenting with short stature, GHI, severe immune deficiency and other features, NF-κB nuclear transportation and STAT5 and PI3K expression and activity were reduced. A patient with a mosaic de novo duplication of 17q21-25 presented with several congenital anomalies, GHI and mild immunodeficiency. Studies in blood lymphocytes showed disturbed signaling of the CD28 pathway, involving NF-κB and related proteins. Functional studies on skin fibroblasts revealed that NF-κB activation, PI3K activity and STAT5 phosphorylation in response to GH were suppressed, while the sensitivity to GH in terms of MAPK phosphorylation was increased. The expression of one of the duplicated genes, PRKCA, was significantly higher than in control cells, which might be the cause of this clinical syndrome.
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Affiliation(s)
- Jan M Wit
- Department of Pediatrics, Leiden University Medical Center, Leiden, The Netherlands.
| | - Francesco de Luca
- Section of Endocrinology and Diabetes, St. Christopher's Hospital for Children, Drexel University, College of Medicine, Philadelphia, PA, USA
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9
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Wit JM, Oostdijk W, Losekoot M, van Duyvenvoorde HA, Ruivenkamp CAL, Kant SG. MECHANISMS IN ENDOCRINOLOGY: Novel genetic causes of short stature. Eur J Endocrinol 2016; 174:R145-73. [PMID: 26578640 DOI: 10.1530/eje-15-0937] [Citation(s) in RCA: 111] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 11/16/2015] [Indexed: 12/17/2022]
Abstract
The fast technological development, particularly single nucleotide polymorphism array, array-comparative genomic hybridization, and whole exome sequencing, has led to the discovery of many novel genetic causes of growth failure. In this review we discuss a selection of these, according to a diagnostic classification centred on the epiphyseal growth plate. We successively discuss disorders in hormone signalling, paracrine factors, matrix molecules, intracellular pathways, and fundamental cellular processes, followed by chromosomal aberrations including copy number variants (CNVs) and imprinting disorders associated with short stature. Many novel causes of GH deficiency (GHD) as part of combined pituitary hormone deficiency have been uncovered. The most frequent genetic causes of isolated GHD are GH1 and GHRHR defects, but several novel causes have recently been found, such as GHSR, RNPC3, and IFT172 mutations. Besides well-defined causes of GH insensitivity (GHR, STAT5B, IGFALS, IGF1 defects), disorders of NFκB signalling, STAT3 and IGF2 have recently been discovered. Heterozygous IGF1R defects are a relatively frequent cause of prenatal and postnatal growth retardation. TRHA mutations cause a syndromic form of short stature with elevated T3/T4 ratio. Disorders of signalling of various paracrine factors (FGFs, BMPs, WNTs, PTHrP/IHH, and CNP/NPR2) or genetic defects affecting cartilage extracellular matrix usually cause disproportionate short stature. Heterozygous NPR2 or SHOX defects may be found in ∼3% of short children, and also rasopathies (e.g., Noonan syndrome) can be found in children without clear syndromic appearance. Numerous other syndromes associated with short stature are caused by genetic defects in fundamental cellular processes, chromosomal abnormalities, CNVs, and imprinting disorders.
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Affiliation(s)
- Jan M Wit
- Departments of PaediatricsClinical GeneticsLeiden University Medical Center, PO Box 9600, 2300 RC Leiden, The Netherlands
| | - Wilma Oostdijk
- Departments of PaediatricsClinical GeneticsLeiden University Medical Center, PO Box 9600, 2300 RC Leiden, The Netherlands
| | - Monique Losekoot
- Departments of PaediatricsClinical GeneticsLeiden University Medical Center, PO Box 9600, 2300 RC Leiden, The Netherlands
| | - Hermine A van Duyvenvoorde
- Departments of PaediatricsClinical GeneticsLeiden University Medical Center, PO Box 9600, 2300 RC Leiden, The Netherlands
| | - Claudia A L Ruivenkamp
- Departments of PaediatricsClinical GeneticsLeiden University Medical Center, PO Box 9600, 2300 RC Leiden, The Netherlands
| | - Sarina G Kant
- Departments of PaediatricsClinical GeneticsLeiden University Medical Center, PO Box 9600, 2300 RC Leiden, The Netherlands
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10
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Nagai MA. Pleckstrin homology-like domain, family A, member 1 ( PHLDA1) and cancer. Biomed Rep 2016; 4:275-281. [PMID: 26998263 DOI: 10.3892/br.2016.580] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 01/19/2016] [Indexed: 12/12/2022] Open
Abstract
Pleckstrin homology-like domain, family A, member 1 (PHLDA1) encodes a member of an evolutionarily conserved pleckstrin homology-related domain protein family. It was first identified as a potential transcription factor required for Fas expression and activation-induced apoptosis in mouse T cell hybridomas. The exact molecular and biological functions of PHLDA1 remain to be elucidated. However, its expression is induced by a variety of external stimuli and there is evidence that it may function as a transcriptional activator that acts as a mediator of apoptosis, proliferation, differentiation and cell migration dependent on the cellular type and context. Recently, PHLDA1 has received attention due to its association with cancer. In the present review, the current knowledge of PHLDA1 protein structure, expression regulation and function is summarized. In addition, the current data in the literature is reviewed with regards to the role of PHLDA1 in cancer pathogenesis.
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Affiliation(s)
- Maria Aparecida Nagai
- Discipline of Oncology, Department of Radiology, Faculty of Medicine, University of São Paulo, Laboratory of Molecular Genetics, Center for Translational Research in Oncology, Cancer Institute of São Paulo, São Paulo, SP 01246-000, Brazil
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11
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Baron J, Sävendahl L, De Luca F, Dauber A, Phillip M, Wit JM, Nilsson O. Short and tall stature: a new paradigm emerges. Nat Rev Endocrinol 2015; 11:735-46. [PMID: 26437621 PMCID: PMC5002943 DOI: 10.1038/nrendo.2015.165] [Citation(s) in RCA: 189] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
In the past, the growth hormone (GH)-insulin-like growth factor 1 (IGF-1) axis was often considered to be the main system that regulated childhood growth and, therefore, determined short stature and tall stature. However, findings have now revealed that the GH-IGF-1 axis is just one of many regulatory systems that control chondrogenesis in the growth plate, which is the biological process that drives height gain. Consequently, normal growth in children depends not only on GH and IGF-1 but also on multiple hormones, paracrine factors, extracellular matrix molecules and intracellular proteins that regulate the activity of growth plate chondrocytes. Mutations in the genes that encode many of these local proteins cause short stature or tall stature. Similarly, genome-wide association studies have revealed that the normal variation in height seems to be largely due to genes outside the GH-IGF-1 axis that affect growth at the growth plate through a wide variety of mechanisms. These findings point to a new conceptual framework for understanding short and tall stature that is centred not on two particular hormones but rather on the growth plate, which is the structure responsible for height gain.
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Affiliation(s)
- Jeffrey Baron
- Section on Growth and Development, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Lars Sävendahl
- Division of Pediatric Endocrinology, Department of Women’s and Children’s Health, Karolinska Institutet, SE-171 76 Stockholm, Sweden
| | - Francesco De Luca
- St. Christopher’s Hospital for Children, Section of Endocrinology and Diabetes; Drexel University College of Medicine, Department of Pediatrics, Philadelphia, PA, U.S.A
| | - Andrew Dauber
- Cincinnati Center for Growth Disorders, Cincinnati Children’s Hospital Medical Center, Division of Endocrinology, Cincinnati, Ohio, USA
| | - Moshe Phillip
- The Jesse Z and Sara Lea Shafer Institute for Endocrinology and Diabetes, National Center for Children’s Diabetes, Schneider Children’s Medical Center of Israel, Petah Tikva, Israel
| | - Jan M. Wit
- Department of Pediatrics, Leiden University Medical Center, Leiden, The Netherlands
| | - Ola Nilsson
- Division of Pediatric Endocrinology, Department of Women’s and Children’s Health, Karolinska Institutet, SE-171 76 Stockholm, Sweden
- Center for Molecular Medicine, Department of Women’s and Children’s Health, Karolinska Institutet, SE-171 76 Stockholm, Sweden
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12
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Iliev DI, Kannenberg K, Weber K, Binder G. IGF-I sensitivity in Silver-Russell syndrome with IGF2/H19 hypomethylation. Growth Horm IGF Res 2014; 24:187-191. [PMID: 25066218 DOI: 10.1016/j.ghir.2014.06.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Revised: 06/23/2014] [Accepted: 06/26/2014] [Indexed: 10/25/2022]
Abstract
BACKGROUND Silver-Russell syndrome (SRS) is characterized by intrauterine and postnatal growth retardation, typical facial appearance and body asymmetry. The mechanism of growth retardation is unclear. 50% of the patients have a paternal chromosome 11 epimutation-DNA hypomethylation of the imprinting center region 1 (ICR1) of the insulin-like growth factor 2 (IGF2)/H19 locus. SRS children who carry such an epimutation have increased levels of IGF-I and IGFBP-3 in relation to their stature and body weight, suggesting IGF-I resistance. No IGF-I receptor (IGF-1R) defect has been discovered. Therefore, another mechanism, probably an IGF-I post-receptor signaling defect, might be present. OBJECTIVE The aim of this in-vitro study was to examine: 1) if IGF-I- and IGF-II-induced fibroblast growth is different in SRS children with IGF2/H19 hypomethylation compared to controls; and 2) whether there is IGF-I insensitivity in this subgroup of SRS children due to IGF-I post-receptor signaling defects. DESIGN Four SRS patients (two males, two females; 9.2 to 16.6 years of age) with an IGF2/H19 hypomethylation defect and three age-matched healthy controls were included in the in-vitro study. Cultivated skin fibroblasts from the patients and the healthy controls were used for the experiments. Proliferation rates of fibroblasts were measured in the presence or absence of recombinant human IGF-I and IGF-II using the commercially available 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) test. PI3K (phosphoinositide 3-kinase) assay and NF-κB transcription factor assay were performed using ELISA in order to estimate the IGF-I-stimulated Akt phosphorylation and IκB phosphorylation, respectively. RESULTS Fibroblasts from SRS patients and fibroblasts from control individuals showed a comparable potential to proliferate in serum-free medium when stimulated with IGFs. No significant differences were found between both groups concerning Akt phosphorylation and IκB phosphorylation rates. CONCLUSIONS The results of the in-vitro study do not support the hypothesis that IGF-I/IGF-II resistance is a major pathogenetic mechanism responsible for the growth failure in the subgroup of SRS children with IGF2/H19 hypomethylation.
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Affiliation(s)
- D I Iliev
- University Children's Hospital, Pediatric Endocrinology and Diabetology, Hoppe-Seyler-Str. 1, D-72076 Tuebingen, Germany
| | - K Kannenberg
- University Children's Hospital, Pediatric Endocrinology and Diabetology, Hoppe-Seyler-Str. 1, D-72076 Tuebingen, Germany
| | - K Weber
- University Children's Hospital, Pediatric Endocrinology and Diabetology, Hoppe-Seyler-Str. 1, D-72076 Tuebingen, Germany
| | - G Binder
- University Children's Hospital, Pediatric Endocrinology and Diabetology, Hoppe-Seyler-Str. 1, D-72076 Tuebingen, Germany.
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13
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Chia DJ. Minireview: mechanisms of growth hormone-mediated gene regulation. Mol Endocrinol 2014; 28:1012-25. [PMID: 24825400 DOI: 10.1210/me.2014-1099] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
GH exerts a diverse array of physiological actions that include prominent roles in growth and metabolism, with a major contribution via stimulating IGF-1 synthesis. GH achieves its effects by influencing gene expression profiles, and Igf1 is a key transcriptional target of GH signaling in liver and other tissues. This review examines the mechanisms of GH-mediated gene regulation that begin with signal transduction pathways activated downstream of the GH receptor and continue with chromatin events at target genes and additionally encompasses the topics of negative regulation and cross talk with other cellular inputs. The transcription factor, signal transducer and activator of transcription 5b, is regarded as the major signaling pathway by which GH achieves its physiological effects, including in stimulating Igf1 gene transcription in liver. Recent studies exploring the mechanisms of how activated signal transducer and activator of transcription 5b accomplishes this are highlighted, which begin to characterize epigenetic features at regulatory domains of the Igf1 locus. Further research in this field offers promise to better understand the GH-IGF-1 axis in normal physiology and disease and to identify strategies to manipulate the axis to improve human health.
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Affiliation(s)
- Dennis J Chia
- Department of Pediatrics, Icahn School of Medicine at Mt Sinai, New York, New York 10029
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14
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Clayton P, Bonnemaire M, Dutailly P, Maisonobe P, Naudin L, Pham E, Zhang Z, Grupe A, Thiagalingam A, Denèfle P. Characterizing short stature by insulin-like growth factor axis status and genetic associations: results from the prospective, cross-sectional, epidemiogenetic EPIGROW study. J Clin Endocrinol Metab 2013; 98:E1122-30. [PMID: 23596138 DOI: 10.1210/jc.2012-4283] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Serum IGF-I levels are often low in patients with short stature (SS) without defined etiology. Hence, genetic investigations have focused on the GH-IGF-I axis. OBJECTIVE Our objectives were to characterize IGF-I axis status and search for a broader range of genetic associations in children with SS and normal GH. DESIGN AND SETTING We conducted a prospective, cross-sectional, epidemiogenetic case-control study in 9 European countries (2008-2010). PARTICIPANTS Children (n = 275) aged ≥2 years with SS without defined etiology (≤-2.5 height SD score [SDS]) and ≥1 peak GH ≥7 μg/L) were recruited. METHODS Serum IGF-I, IGF-binding protein-3 (IGFBP-3), and acid-labile subunit (ALS) levels were measured in a central laboratory. Candidate gene exome sequencing was performed in this cohort and ethnicity-matched controls. RESULTS Serum IGF-I, IGFBP-3, and ALS levels were highly correlated, but there was a discrepancy between prevalence of IGF-I, IGFBP-3, and ALS deficiencies (53%, 30%, and 0.8%, respectively). An insertion-deletion (Indel) on the IGF1 gene (P = 1.2 × 10(-5), Bonferroni-corrected; case vs control frequency: 0.04 vs 0.112), an Indel on NFKB1 (P = 1.36 × 10(-10); case vs control frequency: 0.464 vs 0.272), and 2 single-nucleotide polymorphisms on ZBTB38 (P < 2.3 × 10(-6)) were associated with SS. At P < 10(-4), single-nucleotide polymorphisms on genes related to protein kinase regulation, MAPK, and Fanconi pathways were also associated with SS. CONCLUSIONS IGF-I deficiency is a common feature in SS without defined etiology; an Indel in the IGF1 gene was associated with SS. However, genes involved in transcriptional regulation (NFKB1 and ZBTB38) and growth factor signaling were also associated, providing further candidates for genetic investigations on individual patients.
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Affiliation(s)
- Peter Clayton
- University of Manchester, Manchester Academic Health Sciences Centre, Pediatric Endocrinology, Fifth Floor (Research), Royal Manchester Children's Hospital, Oxford Road, Manchester M13 9WL, United Kingdom.
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15
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Mul D, Wu S, de Paus RA, Oostdijk W, Lankester AC, Duyvenvoorde HAV, Ruivenkamp CAL, Losekoot M, Tol MJDV, De Luca F, van de Vosse E, Wit JM. A mosaic de novo duplication of 17q21-25 is associated with GH insensitivity, disturbed in vitro CD28-mediated signaling, and decreased STAT5B, PI3K, and NF-κB activation. Eur J Endocrinol 2012; 166:743-52. [PMID: 22214923 DOI: 10.1530/eje-11-0774] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
OBJECTIVE The established causes of GH insensitivity include defects of the GH receptor and STAT5B. The latter condition is also characterized by severe immunodeficiency. A recent case with short stature, GH resistance, and immunodeficiency due to an IκB mutation suggests that the NF-κB pathway may interact with STAT5B signaling. DESIGN Here, we present a case of a short child with several congenital anomalies as well as GH insensitivity and mild immunodeficiency associated with a mosaic de novo duplication of chromosome 17q21-25, suggesting that overexpression of one of the duplicated genes may be implicated in GH resistance. METHODS AND RESULTS In vitro studies on blood lymphocytes showed disturbed signaling of the CD28 pathway, involving NF-κB and related proteins. Functional studies on cultured skin fibroblasts revealed that NF-κB activation, PI3K activity, and STAT5 phosphorylation in response to GH were suppressed, while the sensitivity to GH in terms of MAPK phosphorylation was increased. An in silico analysis of the duplicated genes showed that MAP3K3 and PRKCA are associated with the NF-κB pathway. Baseline MAP3K3 expression in T-cell blasts (TCBs) was normal, but PRKCA expression in TCBs and fibroblasts was significantly higher than that in control cells. CONCLUSIONS We conclude that the 17q21-25 duplication is associated with GH insensitivity and disturbed STAT5B, PI3K, and NF-κB signaling, possibly due to PRKCA mRNA overexpression.
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Affiliation(s)
- D Mul
- Department of Pediatrics, Leiden University Medical Center, Leiden, The Netherlands
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16
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Coutant R, Dörr HG, Gleeson H, Argente J. Diagnosis of endocrine disease: limitations of the IGF1 generation test in children with short stature. Eur J Endocrinol 2012; 166:351-7. [PMID: 22048966 DOI: 10.1530/eje-11-0618] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The IGF1 generation test (IGFGT) is often used during the assessment of suspected GH insensitivity (GHI). We report the results of a survey undertaken in 2010 to determine the use of IGFGT amongst members of the European Society for Paediatric Endocrinology to evaluate suspected GHI. The literature surrounding the usefulness and limitations of IGFGT are reviewed, and recommendations provided for its use. Of 112 paediatric endocrinologists from 30 countries who responded to the survey, 91 (81%) reported that they had used the IGFGT in the previous 2 years; >10 IGFGT protocols were used. The IGFGT impacted treatment decisions for 97% of the respondents and was a prerequisite for recombinant human IGF1 treatment for 45% of respondents. From a literature review, sensitivity of the IGFGT was evaluated as 77-91% in molecularly proven cases of GHI; specificity was ≤97%, depending on the protocol. The positive predictive value of the IGFGT is likely to be low, as the frequency of normality is predictably higher than that of abnormality in GH signalling. Given the limitations of the IGFGT in the most severe cases of GHI syndrome (GHIS), the ability of the IGFGT to detect less severe GHIS is doubtful. In a pragmatic approach, the IGFGT may not be useful for the diagnosis of GHIS.
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Affiliation(s)
- Régis Coutant
- Endocrinologie Diabétologie Pédiatrique, Pôle Enfant, CHU Angers, 4 rue Larrey, 49933 Angers, Cedex 9, France
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17
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Wu S, Morrison A, Sun H, De Luca F. Nuclear factor-kappaB (NF-kappaB) p65 interacts with Stat5b in growth plate chondrocytes and mediates the effects of growth hormone on chondrogenesis and on the expression of insulin-like growth factor-1 and bone morphogenetic protein-2. J Biol Chem 2011; 286:24726-34. [PMID: 21592969 DOI: 10.1074/jbc.m110.175364] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Growth hormone (GH) stimulates growth plate chondrogenesis and longitudinal bone growth with its stimulatory effects primarily mediated by insulin-like growth factor-1 (IGF-1) both systemically and locally in the growth plate. It has been shown that the transcription factor Stat5b mediates the GH promoting effect on IGF-1 expression and on chondrogenesis, yet it is not known whether other signaling molecules are activated by GH in growth plate chondrocytes. We have previously demonstrated that nuclear factor-κB p65 is a transcription factor expressed in growth plate chondrocytes where it facilitates chondrogenesis. We have also shown that fibroblasts isolated from a patient with growth failure and a heterozygous mutation of inhibitor-κBα (IκB; component of the nuclear factor-κB (NF-κB) signaling pathway) exhibit GH insensitivity. In this study, we cultured rat metatarsal bones in the presence of GH and/or pyrrolidine dithiocarbamate (PDTC), a known NF-κB inhibitor. The GH-mediated stimulation of metatarsal longitudinal growth and growth plate chondrogenesis was neutralized by PDTC. In cultured chondrocytes isolated from rat metatarsal growth plates, GH induced NF-κB-DNA binding and chondrocyte proliferation and differentiation and prevented chondrocyte apoptosis. The inhibition of NF-κB p65 expression and activity (by NF-κB p65 siRNA and PDTC, respectively) in chondrocytes reversed the GH-mediated effects on chondrocyte proliferation, differentiation, and apoptosis. Lastly, the inhibition of Stat5b expression in chondrocytes prevented the GH promoting effects on NF-κB-DNA binding, whereas the inhibition of NF-κB p65 expression or activity prevented the GH-dependent activation of IGF-1 and bone morphogenetic protein-2 expression.
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Affiliation(s)
- Shufang Wu
- Section of Endocrinology and Diabetes, St. Christopher's Hospital for Children, Drexel University College of Medicine, Philadelphia, Pennsylvania 19134, USA
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Abstract
After a proper medical history, growth analysis and physical examination of a short child, followed by radiological and laboratory screening, the clinician may decide to perform genetic testing. We propose several clinical algorithms that can be used to establish the diagnosis. GH1 and GHRHR should be tested in children with severe isolated growth hormone deficiency and a positive family history. A multiple pituitary dysfunction can be caused by defects in several genes, of which PROP1 and POU1F1 are most common. GH resistance can be caused by genetic defects in GHR, STAT5B, IGF1, IGFALS, which all have their specific clinical and biochemical characteristics. IGF-I resistance is seen in heterozygous defects of the IGF1R. If besides short stature additional abnormalities are present, these should be matched with known dysmorphic syndromes. If no obvious candidate gene can be determined, a whole genome approach can be taken to check for deletions, duplications and/or uniparental disomies.
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Affiliation(s)
- J M Wit
- Department of Paediatrics, J6S Leiden University Medical Center, Leiden, The Netherlands.
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Chan L, Albertsson-Wikland K, Camacho-Hübner C, Hochberg Z. Signal transduction in child health: closing the gap between clinical and basic research. Sci Signal 2010; 3:mr3. [PMID: 20940424 DOI: 10.1126/scisignal.3143mr3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Although some diseases are specific to children, many diseases of adults, including obesity and the metabolic syndrome, often originate in childhood. Thus, understanding the mechanisms of disease onset and progression in children is vital not only for child health, but for adult health as well. The NICHe (New Inroads to Child Health) Conference series focuses on future directions in child health, by bringing together clinical and basic scientists with the aim of sharing knowledge to facilitate the development of new therapeutic approaches. This year's conference, entitled "Child Health and Signal Transduction," focused on G protein-coupled receptor and receptor tyrosine kinase pathways involved in endocrine signaling, how disruption of these pathways can lead to disease, and how understanding these pathways may guide drug discovery.
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Affiliation(s)
- Li Chan
- Centre for Endocrinology, William Harvey Research Institute, St. Bartholomew's and The Royal London School of Medicine and Dentistry, London, UK.
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Jia G, Mitra AK, Gangahar DM, Agrawal DK. Insulin-like growth factor-1 induces phosphorylation of PI3K-Akt/PKB to potentiate proliferation of smooth muscle cells in human saphenous vein. Exp Mol Pathol 2010; 89:20-6. [PMID: 20471974 DOI: 10.1016/j.yexmp.2010.04.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2009] [Revised: 04/30/2010] [Accepted: 04/30/2010] [Indexed: 11/26/2022]
Abstract
Coronary revascularization by coronary artery bypass grafting (CABG) is recommended in patients with recurrent myocardial ischemia. However, the long-term results of CABG using saphenous vein (SV) graft, compared to internal mammary artery (IMA) graft, have not been satisfactory. The SV graft failure is due to the development of intimal hyperplasia, a process characterized by abnormal migration and proliferation of smooth muscle cells (SMCs) in the intimal layer of the vein graft. Insulin growth factor 1 (IGF-1) is a major mitogenic growth factor released at the site of the shear stress-induced graft injury. This study, for the first time, compares the extent of IGF-1-PI3K-Akt activation in isolated human bypass graft conduits. Human SV and IMA vessels were collected and SMCs isolated and cultured. In cultured SMCs, effect of IGF-1 was examined on total and phosphorylated PI3K, Akt and IGF-1R by Western blot analysis. Cell proliferation was measured using BrdU ELISA. There was no significant difference in the basal expression of phosphorylated PI3K, Akt and IGF-1R in SV and IMA SMCs from human bypass conduits. However, we observed an upregulation of IGF-1 receptors in the SV SMCs in response to IGF-1 stimulation with no effect in IMA SMCs. Furthermore, the immunoblotting and cellular activation of signaling ELISA (CASE) assay demonstrated a significantly higher activity of both PI3K and Akt in IGF-1-stimulated SV SMCs than IMA. This was inhibited by an IGF-1R blocking antibody. IGF-1 induced proliferation in both SV and IMA SMCs was inhibited by a PI3K inhibitor, wortmannin. These data demonstrate differential activity of IGF-1-induced PI3K-Akt activation, which was quantitatively and temporally greater in SV SMCs than in the IMA. This, at least in part, could explain the greater propensity of the SV conduits than the IMA to undergo intimal hyperplasia following CABG.
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Affiliation(s)
- Guanghong Jia
- Center for Clinical and Translational Science, Creighton University School of Medicine, Omaha, NE 68178, USA.
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