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Chang WW, Thies AB, Tresguerres M, Hu MY. Soluble adenylyl cyclase coordinates intracellular pH homeostasis and biomineralization in calcifying cells of a marine animal. Am J Physiol Cell Physiol 2023; 324:C777-C786. [PMID: 36779665 DOI: 10.1152/ajpcell.00524.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
Biomineralizing cells concentrate dissolved inorganic carbon (DIC) and remove protons from the site of mineral precipitation. However, the molecular regulatory mechanisms that orchestrate pH homeostasis and biomineralization of calcifying cells are poorly understood. Here, we report that the acid-base sensing enzyme soluble adenylyl cyclase (sAC) coordinates intracellular pH (pHi) regulation in the calcifying primary mesenchyme cells (PMCs) of sea urchin larvae. Single-cell transcriptomics, in situ hybridization, and immunocytochemistry elucidated the spatiotemporal expression of sAC during skeletogenesis. Live pHi imaging of PMCs revealed that the downregulation of sAC activity with two structurally unrelated small molecules inhibited pHi regulation of PMCs, an effect that was rescued by the addition of cell-permeable cAMP. Pharmacological sAC inhibition also significantly reduced normal spicule growth and spicule regeneration, establishing a link between PMC pHi regulation and biomineralization. Finally, increased expression of sAC mRNA was detected during skeleton remineralization and exposure to CO2-induced acidification. These findings suggest that transcriptional regulation of sAC is required to promote remineralization and to compensate for acidic stress. This work highlights the central role of sAC in coordinating acid-base regulation and biomineralization in calcifying cells of a marine animal.
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Affiliation(s)
| | - Angus B Thies
- Scripps Institution of Oceanography, University of California San Diego, California, United States
| | - Martin Tresguerres
- Scripps Institution of Oceanography, University of California San Diego, California, United States
| | - Marian Y Hu
- Institute of Physiology, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
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2
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Wang C, Du R, Jin J, Dong Y, Liu J, Fan L, Xiang R. Use of whole-exome sequencing to identify a novel ADCY10 mutation in a patient with nephrolithiasis. Am J Transl Res 2020; 12:4576-4581. [PMID: 32913531 PMCID: PMC7476115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 07/19/2020] [Indexed: 06/11/2023]
Abstract
Nephrolithiasis is a prevalent condition with high morbidity, and the incidence and prevalence of nephrolithiasis have been increasing worldwide. Although dozens of monogenic reason of nephrolithiasis have been identified, the fraction of the disease caused by single genes has not been determined. In this study, employing total exon sequencing technology, we investigated two patients in south-central China with primary nephrolithiasis and identified a novel ADCY10 mutation c.2186G > A (p.G729E) and a known ADCY10 mutation c.2182G > A (p.E728K). The results of our study suggest that ADCY10 plays an important role in nephrolithiasis.
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Affiliation(s)
- Chenyu Wang
- Department of Nephrology, The Third Xiangya Hospital of Central South UniversityChangsha 410013, China
- Department of Cell Biology, The School of Life Sciences, Central South UniversityChangsha 410013, China
| | - Ran Du
- Department of Cell Biology, The School of Life Sciences, Central South UniversityChangsha 410013, China
| | - Jieyuan Jin
- Department of Cell Biology, The School of Life Sciences, Central South UniversityChangsha 410013, China
| | - Yi Dong
- Department of Cell Biology, The School of Life Sciences, Central South UniversityChangsha 410013, China
| | - Jishi Liu
- Department of Nephrology, The Third Xiangya Hospital of Central South UniversityChangsha 410013, China
| | - Liangling Fan
- Department of Cell Biology, The School of Life Sciences, Central South UniversityChangsha 410013, China
- Hunan Key Laboratory of Animal for Human Disease, School of Life Sciences, Central South UniversityChangsha 410013, China
| | - Rong Xiang
- Department of Cell Biology, The School of Life Sciences, Central South UniversityChangsha 410013, China
- Hunan Key Laboratory of Animal for Human Disease, School of Life Sciences, Central South UniversityChangsha 410013, China
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Wang YY, Pu XY, Shi WG, Fang QQ, Chen XR, Xi HR, Gao YH, Zhou J, Xian CJ, Chen KM. Pulsed electromagnetic fields promote bone formation by activating the sAC-cAMP-PKA-CREB signaling pathway. J Cell Physiol 2019; 234:2807-2821. [PMID: 30067871 DOI: 10.1002/jcp.27098] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2018] [Accepted: 06/28/2018] [Indexed: 02/06/2023]
Abstract
The application of pulsed electromagnetic fields (PEMFs) in the prevention and treatment of osteoporosis has long been an area of interest. However, the clinical application of PEMFs remains limited because of the poor understanding of the PEMF action mechanism. Here, we report that PEMFs promote bone formation by activating soluble adenylyl cyclase (sAC), cyclic adenosine monophosphate (cAMP), protein kinase A (PKA), and cAMP response element-binding protein (CREB) signaling pathways. First, it was found that 50 Hz 0.6 millitesla (mT) PEMFs promoted osteogenic differentiation of rat calvarial osteoblasts (ROBs), and that PEMFs activated cAMP-PKA-CREB signaling by increasing intracellular cAMP levels, facilitating phosphorylation of PKA and CREB, and inducing nuclear translocation of phosphorylated (p)-CREB. Blocking the signaling by adenylate cyclase (AC) and PKA inhibitors both abolished the osteogenic effect of PEMFs. Second, expression of sAC isoform was found to be increased significantly by PEMF treatment. Blocking sAC using sAC-specific inhibitor KH7 dramatically inhibited the osteogenic differentiation of ROBs. Finally, the peak bone mass of growing rats was significantly increased after 2 months of PEMF treatment with 90 min/day. The serum cAMP content, p-PKA, and p-CREB as well as the sAC protein expression levels were all increased significantly in femurs of treated rats. The current study indicated that PEMFs promote bone formation in vitro and in vivo by activating sAC-cAMP-PKA-CREB signaling pathway of osteoblasts directly or indirectly.
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Affiliation(s)
- Yuan-Yuan Wang
- Department of Bioengineering, School of Life Science and Engineering, Lanzhou University of Technology, Lanzhou, China
- Institute of Orthopaedics, Lanzhou General Hospital of CPLA, Lanzhou, China
| | - Xiu-Ying Pu
- Department of Bioengineering, School of Life Science and Engineering, Lanzhou University of Technology, Lanzhou, China
| | - Wen-Gui Shi
- Institute of Orthopaedics, Lanzhou General Hospital of CPLA, Lanzhou, China
| | - Qing-Qing Fang
- Institute of Orthopaedics, Lanzhou General Hospital of CPLA, Lanzhou, China
| | - Xin-Ru Chen
- Department of Biology, College of Life Sciences, Northwest A & F University, Yanglin, China
| | - Hui-Rong Xi
- Institute of Orthopaedics, Lanzhou General Hospital of CPLA, Lanzhou, China
| | - Yu-Hai Gao
- Institute of Orthopaedics, Lanzhou General Hospital of CPLA, Lanzhou, China
| | - Jian Zhou
- Institute of Orthopaedics, Lanzhou General Hospital of CPLA, Lanzhou, China
| | - Cory J Xian
- Sansom Institute for Health Research, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, South Australia, Australia
| | - Ke-Ming Chen
- Institute of Orthopaedics, Lanzhou General Hospital of CPLA, Lanzhou, China
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Li WY, Li XY, Tian YH, Chen XR, Zhou J, Zhu BY, Xi HR, Gao YH, Xian CJ, Chen KM. Pulsed electromagnetic fields prevented the decrease of bone formation in hindlimb-suspended rats by activating sAC/cAMP/PKA/CREB signaling pathway. Bioelectromagnetics 2018; 39:569-584. [PMID: 30350869 DOI: 10.1002/bem.22150] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2018] [Accepted: 09/30/2018] [Indexed: 12/21/2022]
Abstract
Microgravity is one of the main threats to the health of astronauts. Pulsed electromagnetic fields (PEMFs) have been considered as one of the potential countermeasures for bone loss induced by space flight. However, the optimal therapeutic parameters of PEMFs have not been obtained and the action mechanism is still largely unknown. In this study, a set of optimal therapeutic parameters for PEMFs (50 Hz, 0.6 mT 50% duty cycle and 90 min/day) selected based on high-throughput screening with cultured osteoblasts was used to prevent bone loss in rats induced by hindlimb suspension, a commonly accepted animal model to simulate the space environment. It was found that hindlimb suspension for 4 weeks led to significant decreases in femoral and vertebral bone mineral density (BMD) and their maximal loads, severe deterioration in bone micro-structure, and decreases in levels of bone formation markers and increases in bone resorption markers. PEMF treatment prevented about 50% of the decreased BMD and maximal loads, preserved the microstructure of cancellous bone and thickness of cortical bone, and inhibited decreases in bone formation markers. Histological analyses revealed that PEMFs significantly alleviated the reduction in osteoblast number and inhibited the increase in adipocyte number in the bone marrow. PEMFs also blocked decreases in serum levels of parathyroid hormone and its downstream signal molecule cAMP, and maintained the phosphorylation levels of protein kinase A (PKA) and cAMP response element-binding protein (CREB). The expression level of soluble adenylyl cyclases (sAC) was also maintained. It therefore can be concluded that PEMFs partially prevented the bone loss induced by weightless environment by maintaining bone formation through signaling of the sAC/cAMP/PKA/CREB pathway. Bioelectromagnetics. 39:569-584, 2018. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- Wen-Yuan Li
- School of Life Science and Engineering, Lanzhou University of Technology, Lanzhou, China.,Institute of Orthopaedics, Lanzhou General Hospital of CPLA, Lanzhou, China
| | - Xue-Yan Li
- School of Life Science and Engineering, Lanzhou University of Technology, Lanzhou, China
| | - Yong-Hui Tian
- School of Life Science and Engineering, Lanzhou University of Technology, Lanzhou, China
| | - Xin-Ru Chen
- College of Life Sciences, Northwest A & F University, Yanglin, China
| | - Jian Zhou
- Institute of Orthopaedics, Lanzhou General Hospital of CPLA, Lanzhou, China
| | - Bao-Ying Zhu
- Institute of Orthopaedics, Lanzhou General Hospital of CPLA, Lanzhou, China
| | - Hui-Rong Xi
- Institute of Orthopaedics, Lanzhou General Hospital of CPLA, Lanzhou, China
| | - Yu-Hai Gao
- Institute of Orthopaedics, Lanzhou General Hospital of CPLA, Lanzhou, China
| | - Cory J Xian
- Sansom Institute for Health Research, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, Australia
| | - Ke-Ming Chen
- Institute of Orthopaedics, Lanzhou General Hospital of CPLA, Lanzhou, China
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Xi HR, Ma HP, Yang FF, Gao YH, Zhou J, Wang YY, Li WY, Xian CJ, Chen KM. Total flavonoid extract of Epimedium herb increases the peak bone mass of young rats involving enhanced activation of the AC10/cAMP/PKA/CREB pathway. JOURNAL OF ETHNOPHARMACOLOGY 2018; 223:76-87. [PMID: 29783019 DOI: 10.1016/j.jep.2018.05.023] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2018] [Revised: 05/09/2018] [Accepted: 05/17/2018] [Indexed: 06/08/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Epimedium sagittatum brevicornum Maxim. is an important traditional Chinese herb that has long been used to promote bone fracture healing and treat osteoporosis. AIM OF THE STUDY Achieving peak bone mass by adolescence has now been accepted to be fundamental for preventing osteoporosis in adulthood life. This study investigated the possibility of increasing peak bone mass in young rats using the total flavonoid extract of Epimedium herb (TFE). MATERIALS AND METHODS TFE was intragastrically administered to one-month-old Wistar rats at a low (100 mg/kg), middle (200 mg/kg) or high dose (400 mg/kg). Whole body bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry every two weeks. When BMD of any one of TFE groups was found to be significantly higher than that of the control, all rats were sacrificed, serum samples were collected for bone turnover biochemical assays, and femurs, tibiae and vertebrae were isolated and used in BMD, mechanical, micro-structural, histomorphometric and mechanistic studies. RESULTS Administration of TFE at middle and high doses for two months significantly increased the whole body, femoral and vertebral BMDs, and improved the bone mechanical and micro-architectural properties. The serum turnover biochemical results and the enhanced expression levels of bone-formation regulatory genes (Runx-2, OSX, and BMP-2) demonstrated that TFE administration increased bone formation but had no effect on bone resorption. The increased phosphorylation levels in femurs of PKA and CREB and expression of AC10 (the only soluble form of adenylyl cyclase) and the increased serum cAMP level after 4 h of TFE administration indicated that TFE promoted bone formation by activating the AC10/cAMP/PKA/CREB pathway in vivo. CONCLUSIONS Oral administration of TFE at 200 mg/kg for two months can increase the peak bone mass of growing rats, suggesting the possibility of using total flavonoid extract of Epimedium herb to increase the peak bone mass in adolescence which is important for preventing osteoporosis in adult life.
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Affiliation(s)
- Hui-Rong Xi
- School of Pharmacy, Ningxia Medical University, Yinchuan 750004, PR China; Institute of Orthopaedics, Lanzhou General Hospital of CPLA, Lanzhou 730050, PR China
| | - Hui-Ping Ma
- School of Pharmacy, Ningxia Medical University, Yinchuan 750004, PR China; Department of Pharmacy, Lanzhou General Hospital of CPLA, Lanzhou 730050, PR China.
| | - Fang-Fang Yang
- Institute of Orthopaedics, Lanzhou General Hospital of CPLA, Lanzhou 730050, PR China
| | - Yu-Hai Gao
- Institute of Orthopaedics, Lanzhou General Hospital of CPLA, Lanzhou 730050, PR China
| | - Jian Zhou
- Institute of Orthopaedics, Lanzhou General Hospital of CPLA, Lanzhou 730050, PR China
| | - Yuan-Yuan Wang
- Institute of Orthopaedics, Lanzhou General Hospital of CPLA, Lanzhou 730050, PR China
| | - Wen-Yuan Li
- Institute of Orthopaedics, Lanzhou General Hospital of CPLA, Lanzhou 730050, PR China
| | - Cory J Xian
- Sansom Institute for Health Research, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA 5001, Australia
| | - Ke-Ming Chen
- Institute of Orthopaedics, Lanzhou General Hospital of CPLA, Lanzhou 730050, PR China.
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Shi W, Gao Y, Wang Y, Zhou J, Wei Z, Ma X, Ma H, Xian CJ, Wang J, Chen K. The flavonol glycoside icariin promotes bone formation in growing rats by activating the cAMP signaling pathway in primary cilia of osteoblasts. J Biol Chem 2017; 292:20883-20896. [PMID: 29089388 PMCID: PMC5743065 DOI: 10.1074/jbc.m117.809517] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 10/29/2017] [Indexed: 11/06/2022] Open
Abstract
Icariin, a prenylated flavonol glycoside isolated from the herb Epimedium, has been considered as a potential alternative therapy for osteoporosis. Previous research has shown that, unlike other flavonoids, icariin is unlikely to act via the estrogen receptor, but its exact mechanism of action is unknown. In this study, using rat calvarial osteoblast culture and rat bone growth models, we demonstrated that icariin promotes bone formation by activating the cAMP/protein kinase A (PKA)/cAMP response element-binding protein (CREB) pathway requiring functional primary cilia of osteoblasts. We found that icariin increases the peak bone mass attained by young rats and promotes the maturation and mineralization of rat calvarial osteoblasts. Icariin activated cAMP/PKA/CREB signaling of the osteoblasts by increasing intracellular cAMP levels and facilitating phosphorylation of both PKA and CREB. Blocking cAMP/PKA/CREB signaling with inhibitors of the cAMP-synthesizing adenylyl cyclase (AC) and PKA inhibitors significantly inhibited the osteogenic effect of icariin in the osteoblasts. Icariin-activated cAMP/PKA/CREB signaling was localized to primary cilia, as indicated by localization of soluble AC and phosphorylated PKA. Furthermore, blocking ciliogenesis via siRNA knockdown of a cilium assembly protein, IFT88, inhibited icariin-induced PKA and CREB phosphorylation and also abolished icariin's osteogenic effect. Finally, several of these outcomes were validated in icariin-treated rats. Together, these results provide new insights into icariin function and its mechanisms of action and strengthen existing ties between cAMP-mediated signaling and osteogenesis.
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Affiliation(s)
| | - Yuhai Gao
- From the Institute of Orthopaedics and
| | | | - Jian Zhou
- From the Institute of Orthopaedics and
| | | | - Xiaoni Ma
- From the Institute of Orthopaedics and
| | - Huiping Ma
- the Department of Pharmacy, Lanzhou General Hospital of CPLA, Lanzhou 730050, China
| | - Cory J Xian
- the Sansom Institute for Health Research, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA 5001, Australia, and
| | - Jufang Wang
- the Key Laboratory of Space Radiobiology of Gansu Province, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
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Li J, Huang Q, Ge L, Xu J, Shi X, Xie W, Liu X, Liu X. Identification of genetic variations of a Chinese family with paramyotonia congenita via whole exome sequencing. GENOMICS DATA 2015; 4:65-8. [PMID: 26484179 PMCID: PMC4535863 DOI: 10.1016/j.gdata.2015.03.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Revised: 03/03/2015] [Accepted: 03/03/2015] [Indexed: 11/09/2022]
Abstract
Paramyotonia congenita (PC) is a rare autosomal dominant neuromuscular disorder characterized by juvenile onset and development of cold-induced myotonia after repeated activities. The disease is mostly caused by genetic mutations of the sodium channel, voltage-gated, type IV, alpha subunit (SCN4A) gene. This study intended to systematically identify the causative genetic variations of a Chinese Han PC family. Seven members of this PC family, including four patients and three healthy controls, were selected for whole exome sequencing (WES) using the Illumina HiSeq platform. Sequence variations were identified using the SoftGenetics program. The mutation R1448C of SCN4A was found to be the only causative mutation. This study applied WES technology to sequence multiple members of a large PC family and was the first to systematically confirm that the genetic change in SCN4A is the only causative variation in this PC family and the SCN4A mutation is sufficient to lead to PC.
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Affiliation(s)
- Jinxin Li
- Key Laboratory of Developmental Genes and Human Diseases, Institute of Life Sciences, Southeast University, Nanjing 210096, China
| | - Qinghai Huang
- Key Laboratory of Developmental Genes and Human Diseases, Institute of Life Sciences, Southeast University, Nanjing 210096, China
| | - Liang Ge
- Key Laboratory of Developmental Genes and Human Diseases, Institute of Life Sciences, Southeast University, Nanjing 210096, China
| | - Jing Xu
- Key Laboratory of Developmental Genes and Human Diseases, Institute of Life Sciences, Southeast University, Nanjing 210096, China
| | - Xingjuan Shi
- Key Laboratory of Developmental Genes and Human Diseases, Institute of Life Sciences, Southeast University, Nanjing 210096, China
| | - Wei Xie
- Key Laboratory of Developmental Genes and Human Diseases, Institute of Life Sciences, Southeast University, Nanjing 210096, China
| | - Xiang Liu
- Hainan Medical University, Hainan 571199, China
| | - Xiangdong Liu
- Key Laboratory of Developmental Genes and Human Diseases, Institute of Life Sciences, Southeast University, Nanjing 210096, China
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Schmitz B, Brand SM, Brand E. Aldosterone signaling and soluble adenylyl cyclase-a nexus for the kidney and vascular endothelium. Biochim Biophys Acta Mol Basis Dis 2014; 1842:2601-9. [PMID: 24907563 DOI: 10.1016/j.bbadis.2014.05.036] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 05/23/2014] [Accepted: 05/28/2014] [Indexed: 12/14/2022]
Abstract
The steroid hormone aldosterone regulates the reabsorption of water and ions in the kidney and plays a central role in blood pressure regulation and homeostasis. In recent years, the vascular endothelium has been established as an important aldosterone target organ with major implications in renal and cardiovascular health and disease. Different lines of evidence suggest that the calcium- and bicarbonate-activated soluble adenylyl cyclase (sAC) is a novel mediator of aldosterone signaling in both the kidney and vascular endothelium. This review summarizes our current understanding of the molecular mechanisms of sAC gene expression regulation in the kidney and vascular endothelium and outlines the potential clinical implications of sAC in chronic kidney disease and cardiovascular disease. This review is part of a special issue entitled: The role of soluble adenylyl cyclase in health and disease. This article is part of a Special Issue entitled: The role of soluble adenylyl cyclase in health and disease.
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Affiliation(s)
- Boris Schmitz
- Institute of Sports Medicine, Molecular Genetics of Cardiovascular Disease, University Hospital Muenster, Horstmarer Landweg 39, 48149 Muenster, Germany; Internal Medicine D, Department of Nephrology, Hypertension and Rheumatology, University Hospital Muenster, Albert-Schweitzer-Campus 1, 48149 Muenster, Germany
| | - Stefan-Martin Brand
- Institute of Sports Medicine, Molecular Genetics of Cardiovascular Disease, University Hospital Muenster, Horstmarer Landweg 39, 48149 Muenster, Germany
| | - Eva Brand
- Internal Medicine D, Department of Nephrology, Hypertension and Rheumatology, University Hospital Muenster, Albert-Schweitzer-Campus 1, 48149 Muenster, Germany.
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Buck J, Levin LR. Physiological sensing of carbon dioxide/bicarbonate/pH via cyclic nucleotide signaling. SENSORS 2012; 11:2112-28. [PMID: 21544217 PMCID: PMC3085406 DOI: 10.3390/s110202112] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Carbon dioxide (CO2) is produced by living organisms as a byproduct of metabolism. In physiological systems, CO2 is unequivocally linked with bicarbonate (HCO3−) and pH via a ubiquitous family of carbonic anhydrases, and numerous biological processes are dependent upon a mechanism for sensing the level of CO2, HCO3, and/or pH. The discovery that soluble adenylyl cyclase (sAC) is directly regulated by bicarbonate provided a link between CO2/HCO3/pH chemosensing and signaling via the widely used second messenger cyclic AMP. This review summarizes the evidence that bicarbonate-regulated sAC, and additional, subsequently identified bicarbonate-regulate nucleotidyl cyclases, function as evolutionarily conserved CO2/HCO3/pH chemosensors in a wide variety of physiological systems.
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Affiliation(s)
- Jochen Buck
- Department of Pharmacology, Weill Medical College of Cornell University, 1300 York Avenue, New York, NY 10065, USA.
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Abstract
Nephrolithiasis remains a formidable health problem in the United States and worldwide. A very important but underaddressed area in nephrolithiasis is the accompanying bone disease. Epidemiologic studies have shown that osteoporotic fractures occur more frequently in patients with nephrolithiasis than in the general population. Decreased bone mineral density and defects in bone remodeling are commonly encountered in patients with calcium nephrolithiasis. The pathophysiologic connection of bone defects to kidney stones is unknown. Hypercalciuria and hypocitraturia are two important risk factors for stone disease, and treatments with thiazide diuretics and alkali, respectively, have been shown to be useful in preventing stone recurrence in small prospective trials. However, no studies have examined the efficacy of these agents or other therapies in preventing continued bone loss in calcium stone formers. This manuscript reviews the epidemiology, pathophysiology, and potential treatments of bone disease in patients with nephrolithiasis.
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11
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Xu XH, Dong SS, Guo Y, Yang TL, Lei SF, Papasian CJ, Zhao M, Deng HW. Molecular genetic studies of gene identification for osteoporosis: the 2009 update. Endocr Rev 2010; 31:447-505. [PMID: 20357209 PMCID: PMC3365849 DOI: 10.1210/er.2009-0032] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2009] [Accepted: 02/02/2010] [Indexed: 12/12/2022]
Abstract
Osteoporosis is a complex human disease that results in increased susceptibility to fragility fractures. It can be phenotypically characterized using several traits, including bone mineral density, bone size, bone strength, and bone turnover markers. The identification of gene variants that contribute to osteoporosis phenotypes, or responses to therapy, can eventually help individualize the prognosis, treatment, and prevention of fractures and their adverse outcomes. Our previously published reviews have comprehensively summarized the progress of molecular genetic studies of gene identification for osteoporosis and have covered the data available to the end of September 2007. This review represents our continuing efforts to summarize the important and representative findings published between October 2007 and November 2009. The topics covered include genetic association and linkage studies in humans, transgenic and knockout mouse models, as well as gene-expression microarray and proteomics studies. Major results are tabulated for comparison and ease of reference. Comments are made on the notable findings and representative studies for their potential influence and implications on our present understanding of the genetics of osteoporosis.
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Affiliation(s)
- Xiang-Hong Xu
- Institute of Molecular Genetics, Xi'an Jiaotong University, Shaanxi, People's Republic of China
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12
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Frick KK, Bushinsky DA. Effect of metabolic and respiratory acidosis on intracellular calcium in osteoblasts. Am J Physiol Renal Physiol 2010; 299:F418-25. [PMID: 20504884 DOI: 10.1152/ajprenal.00136.2010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In vivo, metabolic acidosis {decreased pH from decreased bicarbonate concentration ([HCO(3)(-)])} increases urine calcium (Ca) without increased intestinal Ca absorption, resulting in a loss of bone Ca. Conversely, respiratory acidosis [decreased pH from increased partial pressure of carbon dioxide (Pco(2))] does not appreciably alter Ca homeostasis. In cultured bone, chronic metabolic acidosis (Met) significantly increases cell-mediated net Ca efflux while isohydric respiratory acidosis (Resp) does not. The proton receptor, OGR1, appears critical for cell-mediated, metabolic acid-induced bone resorption. Perfusion of primary bone cells or OGR1-transfected Chinese hamster ovary (CHO) cells with Met induces transient peaks of intracellular Ca (Ca(i)). To determine whether Resp increases Ca(i), as does Met, we imaged Ca(i) in primary cultures of bone cells. pH for Met = 7.07 ([HCO(3)(-)] = 11.8 mM) and for Resp = 7.13 (Pco(2) = 88.4 mmHg) were similar and lower than neutral (7.41). Both Met and Resp induced a marked, transient increase in Ca(i) in individual bone cells; however, Met stimulated Ca(i) to a greater extent than Resp. We used OGR1-transfected CHO cells to determine whether OGR1 was responsible for the greater increase in Ca(i) in Met than Resp. Both Met and Resp induced a marked, transient increase in Ca(i) in OGR1-transfected CHO cells; however, in these cells Met was not different than Resp. Thus, the greater induction of Ca(i) by Met in primary bone cells is not a function of OGR1 alone, but must involve H(+) receptors other than OGR1, or pathways sensitive to Pco(2), HCO(3)(-), or total CO(2) that modify the effect of H(+) in primary bone cells.
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Affiliation(s)
- Kevin K Frick
- Department of Medicine, University of Rochester School of Medicine and Dentistry, New York 14642, USA.
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13
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Zerwekh JE. Bone disease and hypercalciuria in children. Pediatr Nephrol 2010; 25:395-401. [PMID: 19885683 DOI: 10.1007/s00467-009-1338-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2009] [Revised: 10/05/2009] [Accepted: 10/05/2009] [Indexed: 10/20/2022]
Abstract
There have been relatively few studies of bone mass in children with idiopathic hypercalciuria (IH). When performed, bone mineral density (BMD) measurements have consistently disclosed decreased Z-scores for children with IH at the lumbar spine and, to a lesser extent, at the femoral neck. Few investigations have delineated the nature of the mechanism(s) that may contribute to the bone loss in these children. Some studies have been consistent, showing increased bone resorption as the probable mechanism of bone loss. To date, there have been no reports regarding the assessment of biochemical markers specific for bone formation in children with IH. However, since most of the children with IH in these reports had demonstrated normal longitudinal growth, it seems less likely that there is an alteration in bone formation. The causes for increased bone resorption also are not firmly established, but genetics, dietary indiscretions, and altered cytokine production have been proposed as being contributory to the decreased BMD observed in these children with IH. Optimal bone mineral accretion during childhood and adolescence is important in attaining peak bone mass and may serve to prevent the development of osteoporosis in adulthood. Thus, a better understanding of bone loss in children with IH is warranted.
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Affiliation(s)
- Joseph E Zerwekh
- Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-8885, USA.
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