1
|
Shaikh A, Wesner AA, Abuhattab M, Kutty RG, Premnath P. Cell cycle regulators and bone: development and regeneration. Cell Biosci 2023; 13:35. [PMID: 36810262 PMCID: PMC9942316 DOI: 10.1186/s13578-023-00988-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 02/13/2023] [Indexed: 02/24/2023] Open
Abstract
Cell cycle regulators act as inhibitors or activators to prevent cancerogenesis. It has also been established that they can play an active role in differentiation, apoptosis, senescence, and other cell processes. Emerging evidence has demonstrated a role for cell cycle regulators in bone healing/development cascade. We demonstrated that deletion of p21, a cell cycle regulator acting at the G1/S transition enhanced bone repair capacity after a burr-hole injury in the proximal tibia of mice. Similarly, another study has shown that inhibition of p27 can increase bone mineral density and bone formation. Here, we provide a concise review of cell cycle regulators that influence cells like osteoblasts, osteoclasts, and chondrocytes, during development and/or healing of bone. It is imperative to understand the regulatory processes that govern cell cycle during bone healing and development as this will pave the way to develop novel therapies to improve bone healing after injury in instances of aged or osteoporotic fractures.
Collapse
Affiliation(s)
- Alisha Shaikh
- grid.267468.90000 0001 0695 7223Department of Biomedical Engineering, University of Wisconsin-Milwaukee, College of Engineering and Applied Sciences, 3200 N Cramer St, Milwaukee, WI 53211 USA
| | - Austin A. Wesner
- grid.267468.90000 0001 0695 7223Department of Biomedical Engineering, University of Wisconsin-Milwaukee, College of Engineering and Applied Sciences, 3200 N Cramer St, Milwaukee, WI 53211 USA
| | - Mohanad Abuhattab
- grid.267468.90000 0001 0695 7223Department of Biomedical Engineering, University of Wisconsin-Milwaukee, College of Engineering and Applied Sciences, 3200 N Cramer St, Milwaukee, WI 53211 USA
| | - Raman G. Kutty
- Department of Internal Medicine, White River Health System, Batesville, AR USA
| | - Priyatha Premnath
- Department of Biomedical Engineering, University of Wisconsin-Milwaukee, College of Engineering and Applied Sciences, 3200 N Cramer St, Milwaukee, WI, 53211, USA.
| |
Collapse
|
2
|
Abstract
PURPOSE OF REVIEW Enchondroma is a common cartilage benign tumor that develops from dysregulation of chondrocyte terminal differentiation during growth plate development. Here we provide an overview of recent progress in understanding causative mutations for enchondroma, dysregulated signaling and metabolic pathways in enchondroma, and the progression from enchondroma to malignant chondrosarcoma. RECENT FINDINGS Several signaling pathways that regulate chondrocyte differentiation are dysregulated in enchondromas. Somatic mutations in the metabolic enzymes isocitrate dehydrogenase 1 and 2 (IDH1/2) are the most common findings in enchondromas. Mechanisms including metabolic regulation, epigenetic regulation, and altered signaling pathways play a role in enchondroma formation and progression. Multiple pathways regulate growth plate development in a coordinated manner. Deregulation of the process can result in chondrocytes failing to undergo differentiation and the development of enchondroma.
Collapse
Affiliation(s)
- Hongyuan Zhang
- Department of Orthopaedic Surgery, Duke University School of Medicine, Durham, NC, 27710, USA
- Department of Cell Biology, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Benjamin A Alman
- Department of Orthopaedic Surgery, Duke University School of Medicine, Durham, NC, 27710, USA.
- Department of Cell Biology, Duke University School of Medicine, Durham, NC, 27710, USA.
| |
Collapse
|
3
|
Marín-Llera JC, Garciadiego-Cázares D, Chimal-Monroy J. Understanding the Cellular and Molecular Mechanisms That Control Early Cell Fate Decisions During Appendicular Skeletogenesis. Front Genet 2019; 10:977. [PMID: 31681419 PMCID: PMC6797607 DOI: 10.3389/fgene.2019.00977] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 09/13/2019] [Indexed: 12/02/2022] Open
Abstract
The formation of the vertebrate skeleton is orchestrated in time and space by a number of gene regulatory networks that specify and position all skeletal tissues. During embryonic development, bones have two distinct origins: bone tissue differentiates directly from mesenchymal progenitors, whereas most long bones arise from cartilaginous templates through a process known as endochondral ossification. Before endochondral bone development takes place, chondrocytes form a cartilage analgen that will be sequentially segmented to form joints; thus, in the cartilage template, either the cartilage maturation programme or the joint formation programme is activated. Once the cartilage differentiation programme starts, the growth plate begins to form. In contrast, when the joint formation programme is activated, a capsule begins to form that contains special articular cartilage and synovium to generate a functional joint. In this review, we will discuss the mechanisms controlling the earliest molecular events that regulate cell fate during skeletogenesis in long bones. We will explore the initial processes that lead to the recruitment of mesenchymal stem/progenitor cells, the commitment of chondrocyte lineages, and the formation of skeletal elements during morphogenesis. Thereafter, we will review the process of joint specification and joint morphogenesis. We will discuss the links between transcription factor activity, cell–cell interactions, cell–extracellular matrix interactions, growth factor signalling, and other molecular interactions that control mesenchymal stem/progenitor cell fate during embryonic skeletogenesis.
Collapse
Affiliation(s)
- Jessica Cristina Marín-Llera
- Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, Mexico City, Mexico
| | | | - Jesús Chimal-Monroy
- Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, Mexico City, Mexico
| |
Collapse
|
4
|
Hu H, Zhao X, Ma J, Shangguan Y, Pan Z, Chen L, Zhang X, Wang H. Prenatal nicotine exposure retards osteoclastogenesis and endochondral ossification in fetal long bones in rats. Toxicol Lett 2018; 295:249-255. [PMID: 29981921 DOI: 10.1016/j.toxlet.2018.07.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 06/06/2018] [Accepted: 07/04/2018] [Indexed: 12/21/2022]
Abstract
This study investigated the mechanisms underlying the retarded development of long bone in fetus by prenatal nicotine exposure (PNE) which had been demonstrated by our previous work. Nicotine (2.0 mg/kg.d) or saline was injected subcutaneously into pregnant rats every morning from gestational day (GD) 9 to 20. Fetal femurs or tibias were harvested for analysis on GD 20. We found massive accumulation of hypertrophic chondrocytes and a delayed formation of primary ossification center (POC) in the fetal femur or tibia of rat fetus after PNE, which was accompanied by a decreased amount of osteoclasts in the POC and up-regulated expression of osteoprotegerin (OPG) but by no obvious change in the expression of receptor activator of NF-κB ligand (RANKL). In primary osteoblastic cells, both nicotine (0, 162, 1620, 16,200 ng/ml) and corticosterone (0, 50, 250, 1250 nM) promoted the mRNA expression of OPG but concentration-dependently suppressed that of RANKL. Furthermore, blocking α4β2-nicotinic acetylcholine receptor (α4β2-nAChR) or glucocorticoid receptor rescued the above effects of nicotine and corticosterone, respectively. In conclusion, retarded osteoclastogenesis may contribute to delayed endochondral ossification in long bone in fetal rats with PNE. The adverse effects of PNE may be mediated via the direct effect of nicotine and indirect effect of maternal corticosterone on osteoblastic cells.
Collapse
Affiliation(s)
- Hang Hu
- Department of Pharmacology, Basic Medical School of Wuhan University, Hubei Provincial Key Laboratory of Developmentally Originated Disease, Wuhan 430071, China; Department of Physiology, Basic Medical School of Wuhan University, Wuhan 430071, China
| | - Xin Zhao
- Department of Physiology, Basic Medical School of Wuhan University, Wuhan 430071, China
| | - Jing Ma
- Department of Pharmacology, Basic Medical School of Wuhan University, Hubei Provincial Key Laboratory of Developmentally Originated Disease, Wuhan 430071, China; Department of Physiology, Basic Medical School of Wuhan University, Wuhan 430071, China
| | - Yangfan Shangguan
- Department of Pharmacology, Basic Medical School of Wuhan University, Hubei Provincial Key Laboratory of Developmentally Originated Disease, Wuhan 430071, China; Department of Orthopaedic Surgery, Zhongnan Hospital of Wuhan University, Wuhan 430071, China
| | - Zhengqi Pan
- Department of Pharmacology, Basic Medical School of Wuhan University, Hubei Provincial Key Laboratory of Developmentally Originated Disease, Wuhan 430071, China; Department of Orthopaedic Surgery, Zhongnan Hospital of Wuhan University, Wuhan 430071, China
| | - Liaobin Chen
- Department of Orthopaedic Surgery, Zhongnan Hospital of Wuhan University, Wuhan 430071, China
| | - Xianrong Zhang
- Department of Orthopaedics and Traumatology, Nanfang Hospital, Southern Medical University, Guangdong Provincial Key Laboratory of Bone and Cartilage Regenerative Medicine, Nanfang Hospital, Southern Medical University, No.1838 North of Guangzhou Avenue, Guangzhou, 510515, China.
| | - Hui Wang
- Department of Pharmacology, Basic Medical School of Wuhan University, Hubei Provincial Key Laboratory of Developmentally Originated Disease, Wuhan 430071, China.
| |
Collapse
|
5
|
Zhang J, Qin L, Han L, Zhao Y, Jing H, Song W, Shi H. Role of MicroRNA-93 I in Pathogenesis of Left Ventricular Remodeling via Targeting Cyclin-D1. Med Sci Monit 2017; 23:3981-3988. [PMID: 28817550 PMCID: PMC5572780 DOI: 10.12659/msm.897542] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Background The objective of this study was to identify the pathway responsible for ventricular remodeling. Material/Methods We collected remodeling myocardium tissue (n=18) and control myocardium tissue (n=22), and detected the expression of 4 miRNAs in these 2 groups using real-time PCR. We then searched the miRNA database online to find the candidate genes of miR-93. Real-time PCR and Western blot analysis were used to confirm the regulatory relationship. Results We found that only miR-93 was decreased in remodeling myocardium tissue, and validated CCND1 to be the direct target gene of miR-93, with the “seed sequence” located within the 3′-UTR of the target gene via luciferase reporter assay system. Furthermore, we established the negative regulatory relationship between miR-93 and CCND1 by determining the relative luciferase activity of cells transfected with wild-type or mutant 3′-UTR of CCND1. We also found that The CCND1 protein and mRNA expression level of HL-1 cells treated with 50 nM miR-93 mimics were apparently lower than the scramble control, and those of the cells treated with 100 nM miR-93 mimics and CCND1 siRNA (100 nM) were even lower than those in the 50 nM treatment group. Meanwhile, cells transfected with miR-93 mimics (50 nM) showed evidently downregulated viability when compared with the scramble controls, while cells transfected with (100 nM) and CCND1 siRNA (100nM) showed even lower viability. Conclusions We showed that CCND1 is a direct target of miR-93, and the dysregulation of the miR-93/CCND1 signaling pathway is responsible for the development of ventricular remodeling.
Collapse
Affiliation(s)
- Jingjing Zhang
- Department of Cardiology, Central Hospital of Zhengzhou University, Zhengzhou, Henan, China (mainland)
| | - Li Qin
- Department of Cardiology, Central Hospital of Zhengzhou University, Zhengzhou, Henan, China (mainland)
| | - Ling Han
- Department of Cardiology, Central Hospital of Zhengzhou University, Zhengzhou, Henan, China (mainland)
| | - Ying Zhao
- Department of Cardiology, No. 1 Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China (mainland)
| | - Hongfeng Jing
- Department of Radiology, Central Hospital of Zhengzhou University, Zhengzhou, Henan, China (mainland)
| | - Wei Song
- Department of Pathology, Affiliated Tumor Hospital of Zhengzhou University, Zhengzhou, Henan, China (mainland)
| | - Haili Shi
- Department of Cardiology, Central Hospital of Zhengzhou University, Zhengzhou, Henan, China (mainland)
| |
Collapse
|
6
|
Cell Death in Chondrocytes, Osteoblasts, and Osteocytes. Int J Mol Sci 2016; 17:ijms17122045. [PMID: 27929439 PMCID: PMC5187845 DOI: 10.3390/ijms17122045] [Citation(s) in RCA: 107] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Revised: 11/13/2016] [Accepted: 11/23/2016] [Indexed: 12/04/2022] Open
Abstract
Cell death in skeletal component cells, including chondrocytes, osteoblasts, and osteocytes, plays roles in skeletal development, maintenance, and repair as well as in the pathogenesis of osteoarthritis and osteoporosis. Chondrocyte proliferation, differentiation, and apoptosis are important steps for endochondral ossification. Although the inactivation of P53 and RB is involved in the pathogenesis of osteosarcomas, the deletion of p53 and inactivation of Rb are insufficient to enhance chondrocyte proliferation, indicating the presence of multiple inhibitory mechanisms against sarcomagenesis in chondrocytes. The inflammatory processes induced by mechanical injury and chondrocyte death through the release of danger-associated molecular patterns (DAMPs) are involved in the pathogenesis of posttraumatic osteoarthritis. The overexpression of BCLXL increases bone volume with a normal structure and maintains bone during aging by inhibiting osteoblast apoptosis. p53 inhibits osteoblast proliferation and enhances osteoblast apoptosis, thereby reducing bone formation, but also exerts positive effects on osteoblast differentiation through the Akt–FoxOs pathway. Apoptotic osteocytes release ATP, which induces the receptor activator of nuclear factor κ-B ligand (Rankl) expression and osteoclastogenesis, from pannexin 1 channels. Osteocyte death ultimately results in necrosis; DAMPs are released to the bone surface and promote the production of proinflammatory cytokines, which induce Rankl expression, and osteoclastogenesis is further enhanced.
Collapse
|
7
|
Pan Z, Zhang X, Shangguan Y, Hu H, Chen L, Wang H. Suppressed osteoclast differentiation at the chondro-osseous junction mediates endochondral ossification retardation in long bones of Wistar fetal rats with prenatal ethanol exposure. Toxicol Appl Pharmacol 2016; 305:234-241. [DOI: 10.1016/j.taap.2016.06.021] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Revised: 06/17/2016] [Accepted: 06/18/2016] [Indexed: 02/02/2023]
|
8
|
Verschoyle RD, Edwards R, Nolan B, Greaves P. Articular Chondromatosis and Chrondroid Metaplasia in Transgenic TAg Mice. Toxicol Pathol 2016; 32:22-5. [PMID: 14713544 DOI: 10.1080/01926230490260691] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The C3(1)/SV40 T antigen transgenic mouse model for which rapid mammary and prostate tumor development has been documented uses the FVB/N mouse as a background strain. In this study, where the background strain used was the C57BL/6J mouse, neither mammary nor prostate tumors developed over periods of up to 40 weeks. However, a disturbance of hyaline cartilage in joints was observed similar to that found in synovial chondromatosis in humans. In addition, cartilage thickening in the external ears and cartilaginous metaplasia of the ascending aorta also occurred. This suggests that rearrangement of the transgene occurred in breeding on the C57BL background, thus modifying its expression. It raises the possibility that the genetic changes induced by the SV40 T antigen transforming sequence are important in cartilage homeostasis.
Collapse
Affiliation(s)
- Richard D Verschoyle
- Department of Oncology, University of Leicester, Leicester LE2 7LX, United Kingdom
| | | | | | | |
Collapse
|
9
|
Zhang X, Shang-Guan Y, Ma J, Hu H, Wang L, Magdalou J, Chen L, Wang H. Mitogen-inducible gene-6 partly mediates the inhibitory effects of prenatal dexamethasone exposure on endochondral ossification in long bones of fetal rats. Br J Pharmacol 2016; 173:2250-62. [PMID: 27128203 DOI: 10.1111/bph.13506] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 04/05/2016] [Accepted: 04/18/2016] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND AND PURPOSE Prenatal exposure to dexamethasone slows down fetal linear growth and bone mineralization but the regulatory mechanism remains unknown. Here we assessed how dexamethasone regulates bone development in the fetus. EXPERIMENTAL APPROACH Dexamethasone (1 mg·kg(-1) ·day(-1) ) was injected subcutaneously every morning in pregnant rats from gestational day (GD)9 to GD20. Fetal femurs and tibias were harvested at GD20 for histological and gene expression analysis. Femurs of 12-week-old female offspring were harvested for microCT (μCT) measurement. Primary chondrocytes were treated with dexamethasone (10, 50, 250 and 1000 nM). KEY RESULTS Prenatal dexamethasone exposure resulted in accumulation of hypertrophic chondrocytes and delayed formation of the primary ossification centre in fetal long bone. The retardation was accompanied by reduced maturation of hypertrophic chondrocytes, decreased osteoclast number and down-regulated expression of osteocalcin and bone sialoprotein in long bone. In addition, the mitogen-inducible gene-6 (Mig6) and osteoprotegerin (OPG) expression were stimulated, and the receptor activator of NF-κB ligand (RANKL) expression was repressed. Moreover, dexamethasone activated OPG and repressed RANKL expression in both primary chondrocytes and primary osteoblasts, and the knockdown of Mig6 abolished the effect of dexamethasone on OPG expression. Further, μCT measurement showed loss of bone mass in femur of 12-week-old offspring with prenatal dexamethasone exposure. CONCLUSIONS AND IMPLICATIONS Prenatal dexamethasone exposure delays endochondral ossification by suppressing chondrocyte maturation and osteoclast differentiation, which may be partly mediated by Mig6 activation in bone. Bone development retardation in the fetus may be associated with reduced bone mass in later life.
Collapse
Affiliation(s)
- Xianrong Zhang
- Department of Physiology, School of Basic Medical Sciences, Wuhan University, Wuhan, China.,Hubei Provincial Key Laboratory of Developmentally Originated Disease, Wuhan, China
| | - Yangfan Shang-Guan
- Hubei Provincial Key Laboratory of Developmentally Originated Disease, Wuhan, China.,Department of Orthopedic Surgery, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Jing Ma
- Department of Physiology, School of Basic Medical Sciences, Wuhan University, Wuhan, China.,Hubei Provincial Key Laboratory of Developmentally Originated Disease, Wuhan, China
| | - Hang Hu
- Hubei Provincial Key Laboratory of Developmentally Originated Disease, Wuhan, China.,Department of Orthopedic Surgery, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Linlong Wang
- Hubei Provincial Key Laboratory of Developmentally Originated Disease, Wuhan, China.,Department of Orthopedic Surgery, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Jacques Magdalou
- Faculté de Médicine, UMR 7561 CNRS-NancyUniversité, Vandoeuvre-lès-Nancy, France
| | - Liaobin Chen
- Hubei Provincial Key Laboratory of Developmentally Originated Disease, Wuhan, China.,Department of Orthopedic Surgery, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Hui Wang
- Department of Pharmacology, School of Basic Medical Sciences, Wuhan University, Wuhan, China.,Hubei Provincial Key Laboratory of Developmentally Originated Disease, Wuhan, China
| |
Collapse
|
10
|
Tsang KY, Tsang SW, Chan D, Cheah KSE. The chondrocytic journey in endochondral bone growth and skeletal dysplasia. ACTA ACUST UNITED AC 2015; 102:52-73. [PMID: 24677723 DOI: 10.1002/bdrc.21060] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2014] [Accepted: 02/23/2014] [Indexed: 12/29/2022]
Abstract
The endochondral bones of the skeleton develop from a cartilage template and grow via a process involving a cascade of chondrocyte differentiation steps culminating in formation of a growth plate and the replacement of cartilage by bone. This process of endochondral ossification, driven by the generation of chondrocytes and their subsequent proliferation, differentiation, and production of extracellular matrix constitute a journey, deviation from which inevitably disrupts bone growth and development, and is the basis of human skeletal dysplasias with a wide range of phenotypic severity, from perinatal lethality to progressively deforming. This highly coordinated journey of chondrocyte specification and fate determination is controlled by a myriad of intrinsic and extrinsic factors. SOX9 is the master transcription factor that, in concert with varying partners along the way, directs the different phases of the journey from mesenchymal condensation, chondrogenesis, differentiation, proliferation, and maturation. Extracellular signals, including bone morphogenetic proteins, wingless-related MMTV integration site (WNT), fibroblast growth factor, Indian hedgehog, and parathyroid hormone-related peptide, are all indispensable for growth plate chondrocytes to align and organize into the appropriate columnar architecture and controls their maturation and transition to hypertrophy. Chondrocyte hypertrophy, marked by dramatic volume increase in phases, is controlled by transcription factors SOX9, Runt-related transcription factor, and FOXA2. Hypertrophic chondrocytes mediate the cartilage to bone transition and concomitantly face a live-or-die situation, a subject of much debate. We review recent insights into the coordination of the phases of the chondrocyte journey, and highlight the need for a systems level understanding of the regulatory networks that will facilitate the development of therapeutic approaches for skeletal dysplasia.
Collapse
Affiliation(s)
- Kwok Yeung Tsang
- Department of Biochemistry, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong, China
| | | | | | | |
Collapse
|
11
|
Cheng X, Chen JL, Ma ZL, Zhang ZL, Lv S, Mai DM, Liu JJ, Chuai M, Lee KKH, Wan C, Yang X. Biphasic influence of dexamethasone exposure on embryonic vertebrate skeleton development. Toxicol Appl Pharmacol 2014; 281:19-29. [DOI: 10.1016/j.taap.2014.09.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Revised: 08/31/2014] [Accepted: 09/26/2014] [Indexed: 12/26/2022]
|
12
|
Abstract
Mammalian DREAM is a conserved protein complex that functions in cellular quiescence. DREAM contains an E2F, a retinoblastoma (RB)-family protein, and the MuvB core (LIN9, LIN37, LIN52, LIN54, and RBBP4). In mammals, MuvB can alternatively bind to BMYB to form a complex that promotes mitotic gene expression. Because BMYB-MuvB is essential for proliferation, loss-of-function approaches to study MuvB have generated limited insight into DREAM function. Here, we report a gene-targeted mouse model that is uniquely deficient for DREAM complex assembly. We have targeted p107 (Rbl1) to prevent MuvB binding and combined it with deficiency for p130 (Rbl2). Our data demonstrate that cells from these mice preferentially assemble BMYB-MuvB complexes and fail to repress transcription. DREAM-deficient mice show defects in endochondral bone formation and die shortly after birth. Micro-computed tomography and histology demonstrate that in the absence of DREAM, chondrocytes fail to arrest proliferation. Since DREAM requires DYRK1A (dual-specificity tyrosine phosphorylation-regulated protein kinase 1A) phosphorylation of LIN52 for assembly, we utilized an embryonic bone culture system and pharmacologic inhibition of (DYRK) kinase to demonstrate a similar defect in endochondral bone growth. This reveals that assembly of mammalian DREAM is required to induce cell cycle exit in chondrocytes.
Collapse
|
13
|
|
14
|
Overexpression of Cdk6 and Ccnd1 in chondrocytes inhibited chondrocyte maturation and caused p53-dependent apoptosis without enhancing proliferation. Oncogene 2013; 33:1862-71. [PMID: 23624920 DOI: 10.1038/onc.2013.130] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Revised: 02/21/2013] [Accepted: 03/04/2013] [Indexed: 12/21/2022]
Abstract
Cell proliferation and differentiation are closely coupled. However, we previously showed that overexpression of cyclin-dependent kinase (Cdk6) blocks chondrocyte differentiation without affecting cell-cycle progression in vitro. To investigate whether Cdk6 inhibits chondrocyte differentiation in vivo, we generated chondrocyte-specific Cdk6 transgenic mice using Col2a1 promoter. Unexpectedly, differentiation and cell-cycle progression of chondrocytes in the Cdk6 transgenic mice were similar to those in wild-type mice. Then, we generated chondrocyte-specific Ccnd1 transgenic mice and Cdk6/Ccnd1 double transgenic mice to investigate the possibility that Cdk6 inhibits chondrocyte differentiation through E2f activation. Bromodeoxyuridine (BrdU)-positive chondrocytes and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive chondrocytes were increased in number, and chondrocyte maturation was inhibited only in Cdk6/Ccnd1 transgenic mice (K6(H)/D1(H) mice), which showed dwarfism. Retinoblastoma protein (pRb) was highly phosphorylated but p107 was upregulated, and the expression of E2f target genes was dysregulated as shown by upregulation of Cdc6 but downregulation of cyclin E, dihydrofolate reductase (dhfr), Cdc25a and B-Myb in chondrocytes of K6(H)/D1(H) mice. Similarly, overexpression of Cdk6/Ccnd1 in a chondrogenic cell line ATDC5 highly phosphorylated pRb, upregulated p107, induced apoptosis, upregulated Cdc6 and downregulated cyclin E, dhfr and B-Myb and p107 small interfering RNA reversed the expression of downregulated genes. Further, introduction of kinase-negative Cdk6 and cyclin D1 abolished all effects by Cdk6/cyclin D1 in ATDC5 cells, indicating the requirement of the kinase activity on these effects. p53 deletion partially restored the size of the skeleton and almost completely rescued chondrocyte apoptosis, but failed to enhance chondrocyte proliferation in K6(H)/D1(H) mice. These findings indicated that Cdk6/Ccnd1 overexpression inhibited chondrocyte maturation and enhanced G1/S cell-cycle transition by phosphorylating pRb, but the chondrocytes failed to accomplish the cell cycle, and underwent p53-dependent apoptosis probably due to the dysregulation of E2f target genes. Our findings also indicated that p53 deletion in addition to the inactivation of Rb was not sufficient to accelerate chondrocyte proliferation, suggesting the resistance of chondrocytes to sarcomagenesis.
Collapse
|
15
|
Bergwitz C, Wee MJ, Sinha S, Huang J, DeRobertis C, Mensah LB, Cohen J, Friedman A, Kulkarni M, Hu Y, Vinayagam A, Schnall-Levin M, Berger B, Perkins LA, Mohr SE, Perrimon N. Genetic determinants of phosphate response in Drosophila. PLoS One 2013; 8:e56753. [PMID: 23520455 PMCID: PMC3592877 DOI: 10.1371/journal.pone.0056753] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Accepted: 01/14/2013] [Indexed: 11/30/2022] Open
Abstract
Phosphate is required for many important cellular processes and having too little phosphate or too much can cause disease and reduce life span in humans. However, the mechanisms underlying homeostatic control of extracellular phosphate levels and cellular effects of phosphate are poorly understood. Here, we establish Drosophila melanogaster as a model system for the study of phosphate effects. We found that Drosophila larval development depends on the availability of phosphate in the medium. Conversely, life span is reduced when adult flies are cultured on high phosphate medium or when hemolymph phosphate is increased in flies with impaired Malpighian tubules. In addition, RNAi-mediated inhibition of MAPK-signaling by knockdown of Ras85D, phl/D-Raf or Dsor1/MEK affects larval development, adult life span and hemolymph phosphate, suggesting that some in vivo effects involve activation of this signaling pathway by phosphate. To identify novel genetic determinants of phosphate responses, we used Drosophila hemocyte-like cultured cells (S2R+) to perform a genome-wide RNAi screen using MAPK activation as the readout. We identified a number of candidate genes potentially important for the cellular response to phosphate. Evaluation of 51 genes in live flies revealed some that affect larval development, adult life span and hemolymph phosphate levels.
Collapse
Affiliation(s)
- Clemens Bergwitz
- Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts, United States of America.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Landman AS, Danielian PS, Lees JA. Loss of pRB and p107 disrupts cartilage development and promotes enchondroma formation. Oncogene 2012; 32:4798-805. [PMID: 23146901 DOI: 10.1038/onc.2012.496] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Revised: 08/22/2012] [Accepted: 08/30/2012] [Indexed: 01/20/2023]
Abstract
The pocket proteins pRB, p107 and p130 have established roles in regulating the cell cycle through the control of E2F activity. The pocket proteins regulate differentiation of a number of tissues in both cell cycle-dependent and -independent manners. Prior studies showed that mutation of p107 and p130 in the mouse leads to defects in cartilage development during endochondral ossification, the process by which long bones form. Despite evidence of a role for pRB in osteoblast differentiation, it is unknown whether it functions during cartilage development. Here, we show that mutation of Rb in the early mesenchyme of p107-mutant mice results in severe cartilage defects in the growth plates of long bones. This is attributable to inappropriate chondrocyte proliferation that persists after birth and leads to the formation of enchondromas in the growth plates as early as 8 weeks of age. Genetic crosses show that development of these tumorigenic lesions is E2f3 dependent. These results reveal an overlapping role for pRB and p107 in cartilage development, endochondral ossification and enchondroma formation that reflects their coordination of cell-cycle exit at appropriate developmental stages.
Collapse
Affiliation(s)
- A S Landman
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA
| | | | | |
Collapse
|
17
|
Miller ES, Berman SD, Yuan TL, Lees JA. Disruption of calvarial ossification in E2f4 mutant embryos correlates with increased proliferation and progenitor cell populations. Cell Cycle 2011; 9:2620-8. [PMID: 20581455 DOI: 10.4161/cc.9.13.12108] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The E2F family of transcription factors, in association with pocket protein family members, are important for regulating genes required for cellular proliferation. The most abundant E2F, E2F4, is implicated in maintaining the G(0)/G(1) cell cycle state via transcriptional repression of genes that encode proteins required for S-phase progression. Here, we investigate E2F4's role in bone development using E2f4 germline mutant mice. We find that mutation of E2f4 impairs the formation of several bones that arise through intramembranous or endochondral ossification. The most severe defect occurred in the calvarial bones of the skull where we observed a striking delay in their ossification. In vivo and in vitro analyses established that E2F4 loss did not block the intrinsic differentiation potential of calvarial osteoblast progenitors. However, our data showed that E2f4 mutation elevated proliferation in the developing calvaria in vivo and it increased the endogenous pool of undifferentiated progenitor cells. These data suggest that E2F4 plays an important role in enabling osteoblast progenitors to exit the cell cycle and subsequently differentiate thereby contributing to the commitment of these cells to the bone lineage.
Collapse
Affiliation(s)
- Emily S Miller
- David H. Koch Institute for Integrative Cancer Research, MIT, Cambridge, MA, USA
| | | | | | | |
Collapse
|
18
|
Kim HA, Jung HA, Kim TY. Identification of Genes Regulated by IL-1β Using Integrative microRNA and mRNA Genomic Analysis in Human Articular Chondrocytes. JOURNAL OF RHEUMATIC DISEASES 2011. [DOI: 10.4078/jrd.2011.18.4.264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Hyun Ah Kim
- Department of Internal Medicine, Hallym University Sacred Heart Hospital, Anyang, Korea
| | - Hyun A Jung
- Department of Internal Medicine, Hallym University Sacred Heart Hospital, Anyang, Korea
| | - Tae Young Kim
- Department of Orthopedic Surgery, Hallym University Sacred Heart Hospital, Anyang, Korea
| |
Collapse
|
19
|
Wirt SE, Sage J. p107 in the public eye: an Rb understudy and more. Cell Div 2010; 5:9. [PMID: 20359370 PMCID: PMC2861648 DOI: 10.1186/1747-1028-5-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2010] [Accepted: 04/02/2010] [Indexed: 11/25/2022] Open
Abstract
p107 and its related family members Rb and p130 are critical regulators of cellular proliferation and tumorigenesis. Due to the extent of functional overlap within the Rb family, it has been difficult to assess which functions are exclusive to individual members and which are shared. Like its family members, p107 can bind a variety of cellular proteins to affect the expression of many target genes during cell cycle progression. Unlike Rb and p130, p107 is most highly expressed during the G1 to S phase transition of the cell cycle in actively dividing cells and accumulating evidence suggests a role for p107 during DNA replication. The specific roles for p107 during differentiation and development are less clear, although emerging studies suggest that it can cooperate with other Rb family members to control differentiation in multiple cell lineages. As a tumor suppressor, p107 is not as potent as Rb, yet studies in knockout mice have revealed some tumor suppressor functions in mice, depending on the context. In this review, we identify the unique and overlapping functions of p107 during the cell cycle, differentiation, and tumorigenesis.
Collapse
Affiliation(s)
- Stacey E Wirt
- Departments of Pediatrics and Genetics, Stanford Medical School, Stanford, CA 94305, USA.
| | | |
Collapse
|
20
|
Wuelling M, Vortkamp A. Transcriptional networks controlling chondrocyte proliferation and differentiation during endochondral ossification. Pediatr Nephrol 2010; 25:625-31. [PMID: 19949815 DOI: 10.1007/s00467-009-1368-6] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2009] [Revised: 10/23/2009] [Accepted: 10/28/2009] [Indexed: 12/11/2022]
Abstract
During endochondral ossification bones are formed as cartilage templates in which chondrocytes proliferate, differentiate into hypertrophic chondrocytes and are gradually replaced by bone. Postnatally, remnants of embryonic chondrocytes remain in a restricted domain between the ossified regions of the bones forming the growth plate. The coordinated proliferation and differentiation of chondrocytes ensures the continuous elongation of the epiphyseal growth plates. The sequential changes between proliferation and differentiation are tightly regulated by secreted growth factors, which activate chondrocyte-specific transcription factors. Transcription factors that play critical roles in regulating cell-type-specific gene expression include Sox9, Gli2/3, and Runx2. The interaction of these transcription factors with general transcriptional regulators like histone-modifying enzymes provides an additional level of regulation to fine-tune the expression of target genes in different chondrocyte populations. This review will outline recent advances in the analysis of the complex transcriptional network that regulates the distinct steps of chondrocyte differentiation.
Collapse
Affiliation(s)
- Manuela Wuelling
- Department of Developmental Biology, Center for Medical Biotechnology, University Duisburg-Essen, 45117 Essen, Germany
| | | |
Collapse
|
21
|
Lassová L, Niu Z, Golden EB, Cohen AJ, Adams SL. Thyroid hormone treatment of cultured chondrocytes mimics in vivo stimulation of collagen X mRNA by increasing BMP 4 expression. J Cell Physiol 2009; 219:595-605. [PMID: 19170125 DOI: 10.1002/jcp.21704] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
During endochondral bone formation, chondrocytes undergo terminal differentiation, during which the rate of proliferation decreases, cells become hypertrophic, and the extracellular matrix is altered by production of collagen X, as well as proteins required for matrix mineralization. This maturation process is responsible for most longitudinal bone growth, both during embryonic development and in postnatal long bone growth plates. Among the major signaling molecules implicated in regulation of this process are the positive regulators thyroid hormone (T3) and bone morphogenetic proteins (BMPs). Both T3 and BMPs are essential for endochondral bone formation and cannot compensate for each other, suggesting interaction of the two signaling pathways. We have analyzed the temporal and spatial expression patterns of numerous genes believed to play a role in chondrocyte maturation. Our results show that T3 stimulates collagen X gene expression in cultured chondrocytres with kinetics and magnitude similar to those observed in vivo. Stimulation of collagen X gene expression by T3 occurs only after a significant delay, implying that this hormone may act indirectly. We show further that T3 rapidly stimulates production of BMP 4, concomitant with a decrease in the BMP inhibitor Noggin, potentially resulting in a net increase in BMP signaling. Finally, inhibition of BMP signaling with exogenous Noggin prevents T3 stimulation of collagen X expression, indicating that BMP signaling is essential for this process. These data position thyroid hormone at the top of a T3/BMP cascade, potentially explaining why both pathways are essential for chondrocyte maturation. J. Cell. Physiol. 219: 595-605, 2009. (c) 2009 Wiley-Liss, Inc.
Collapse
Affiliation(s)
- Luisa Lassová
- Department of Biochemistry, University of Pennsylvania School of Dental Medicine, Philadelphia, Pennsylvania, USA.
| | | | | | | | | |
Collapse
|
22
|
Hirata M, Kugimiya F, Fukai A, Ohba S, Kawamura N, Ogasawara T, Kawasaki Y, Saito T, Yano F, Ikeda T, Nakamura K, Chung UI, Kawaguchi H. C/EBPbeta Promotes transition from proliferation to hypertrophic differentiation of chondrocytes through transactivation of p57. PLoS One 2009; 4:e4543. [PMID: 19229324 PMCID: PMC2638010 DOI: 10.1371/journal.pone.0004543] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2008] [Accepted: 01/06/2009] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Although transition from proliferation to hypertrophic differentiation of chondrocytes is a crucial step for endochondral ossification in physiological skeletal growth and pathological disorders like osteoarthritis, the underlying mechanism remains an enigma. This study investigated the role of the transcription factor CCAAT/enhancer-binding protein beta (C/EBPbeta) in chondrocytes during endochondral ossification. METHODOLOGY/PRINCIPAL FINDINGS Mouse embryos with homozygous deficiency in C/EBPbeta (C/EBPbeta-/-) exhibited dwarfism with elongated proliferative zone and delayed chondrocyte hypertrophy in the growth plate cartilage. In the cultures of primary C/EBPbeta-/- chondrocytes, cell proliferation was enhanced while hypertrophic differentiation was suppressed. Contrarily, retroviral overexpression of C/EBPbeta in chondrocytes suppressed the proliferation and enhanced the hypertrophy, suggesting the cell cycle arrest by C/EBPbeta. In fact, a DNA cell cycle histogram revealed that the C/EBPbeta overexpression caused accumulation of cells in the G0/G1 fraction. Among cell cycle factors, microarray and real-time RT-PCR analyses have identified the cyclin-dependent kinase inhibitor p57(Kip2) as the transcriptional target of C/EBPbeta. p57(Kip2) was co-localized with C/EBPbeta in late proliferative and pre-hypertrophic chondrocytes of the mouse growth plate, which was decreased by the C/EBPbeta deficiency. Luciferase-reporter and electrophoretic mobility shift assays identified the core responsive element of C/EBPbeta in the p57(Kip2) promoter between -150 and -130 bp region containing a putative C/EBP motif. The knockdown of p57(Kip2) by the siRNA inhibited the C/EBPbeta-induced chondrocyte hypertrophy. Finally, when we created the experimental osteoarthritis model by inducing instability in the knee joints of adult mice of wild-type and C/EBPbeta+/- littermates, the C/EBPbeta insufficiency caused resistance to joint cartilage destruction. CONCLUSIONS/SIGNIFICANCE C/EBPbeta transactivates p57(Kip2) to promote transition from proliferation to hypertrophic differentiation of chondrocytes during endochondral ossification, suggesting that the C/EBPbeta-p57(Kip2) signal would be a therapeutic target of skeletal disorders like growth retardation and osteoarthritis.
Collapse
Affiliation(s)
- Makoto Hirata
- Departments of Sensory & Motor System Medicine, Faculty of Medicine, University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Fumitaka Kugimiya
- Departments of Sensory & Motor System Medicine, Faculty of Medicine, University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Atsushi Fukai
- Departments of Sensory & Motor System Medicine, Faculty of Medicine, University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Shinsuke Ohba
- Center for Disease Biology and Integrative Medicine, Faculty of Medicine, University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Naohiro Kawamura
- Departments of Sensory & Motor System Medicine, Faculty of Medicine, University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Toru Ogasawara
- Departments of Sensory & Motor System Medicine, Faculty of Medicine, University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Yosuke Kawasaki
- Departments of Sensory & Motor System Medicine, Faculty of Medicine, University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Taku Saito
- Departments of Sensory & Motor System Medicine, Faculty of Medicine, University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Fumiko Yano
- Center for Disease Biology and Integrative Medicine, Faculty of Medicine, University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Toshiyuki Ikeda
- Departments of Sensory & Motor System Medicine, Faculty of Medicine, University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Kozo Nakamura
- Departments of Sensory & Motor System Medicine, Faculty of Medicine, University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Ung-il Chung
- Center for Disease Biology and Integrative Medicine, Faculty of Medicine, University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Hiroshi Kawaguchi
- Departments of Sensory & Motor System Medicine, Faculty of Medicine, University of Tokyo, Bunkyo-ku, Tokyo, Japan
- * E-mail:
| |
Collapse
|
23
|
Checa S, Prendergast PJ. A Mechanobiological Model for Tissue Differentiation that Includes Angiogenesis: A Lattice-Based Modeling Approach. Ann Biomed Eng 2008; 37:129-45. [DOI: 10.1007/s10439-008-9594-9] [Citation(s) in RCA: 134] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2008] [Accepted: 10/29/2008] [Indexed: 11/30/2022]
|
24
|
Berman SD, Yuan TL, Miller ES, Lee EY, Caron A, Lees JA. The retinoblastoma protein tumor suppressor is important for appropriate osteoblast differentiation and bone development. Mol Cancer Res 2008; 6:1440-51. [PMID: 18819932 DOI: 10.1158/1541-7786.mcr-08-0176] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Mutation of the retinoblastoma (RB) tumor suppressor gene is strongly linked to osteosarcoma formation. This observation and the documented interaction between the retinoblastoma protein (pRb) and Runx2 suggests that pRb is important in bone development. To assess this hypothesis, we used a conditional knockout strategy to generate pRb-deficient embryos that survive to birth. Analysis of these embryos shows that Rb inactivation causes the abnormal development and impaired ossification of several bones, correlating with an impairment in osteoblast differentiation. We further show that Rb inactivation acts to promote osteoblast differentiation in vitro and, through conditional analysis, establish that this occurs in a cell-intrinsic manner. Although these in vivo and in vitro differentiation phenotypes seem paradoxical, we find that Rb-deficient osteoblasts have an impaired ability to exit the cell cycle both in vivo and in vitro that can explain the observed differentiation defects. Consistent with this observation, we show that the cell cycle and the bone defects in Rb-deficient embryos can be suppressed by deletion of E2f1, a known proliferation inducer that acts downstream of Rb. Thus, we conclude that pRb plays a key role in regulating osteoblast differentiation by mediating the inhibition of E2F and consequently promoting cell cycle exit.
Collapse
Affiliation(s)
- Seth D Berman
- David H. Koch Institute for Integrative Cancer Research at MIT, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | | | | | | | | | | |
Collapse
|
25
|
Vale-Cruz DS, Ma Q, Syme J, LuValle PA. Activating transcription factor-2 affects skeletal growth by modulating pRb gene expression. Mech Dev 2008; 125:843-56. [DOI: 10.1016/j.mod.2008.06.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2007] [Revised: 06/17/2008] [Accepted: 06/22/2008] [Indexed: 11/29/2022]
|
26
|
Abstract
PURPOSE Central to the use of murine models of disease is the ability to derive reproducible data. The purpose of this study was to determine factors contributing to variability in our murine model of small bowel resection (SBR). METHODS Male C57Bl/6 mice were randomized to sham or 50% SBR. The effect of housing type (pathogen-free vs standard housing), nutrition (reconstituted powder vs tube feeding formulation), and correlates of intestinal morphology with gene expression changes were investigated. Multiple linear regression modeling or 1-way analysis of variance was used for data analysis. RESULTS Pathogen-free mice had significantly shorter ileal villi at baseline and demonstrated greater villus growth after SBR compared to mice housed in standard rooms. Food type did not affect adaptation. Gene expression changes were more consistent and significant in isolated crypt cells that demonstrated adaptive growth when compared with crypts that did not deepen after SBR. CONCLUSION Maintenance of mice in pathogen-free conditions and restricting gene expression analysis to individual animals exhibiting morphologic adaptation enhances sensitivity and specificity of data derived from this model. These refinements will minimize experimental variability and lead to improved understanding of the complex process of intestinal adaptation.
Collapse
|
27
|
Geris L, Gerisch A, Sloten JV, Weiner R, Oosterwyck HV. Angiogenesis in bone fracture healing: a bioregulatory model. J Theor Biol 2007; 251:137-58. [PMID: 18155732 DOI: 10.1016/j.jtbi.2007.11.008] [Citation(s) in RCA: 148] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2007] [Revised: 11/07/2007] [Accepted: 11/09/2007] [Indexed: 12/26/2022]
Abstract
The process of fracture healing involves the action and interaction of many cells, regulated by biochemical and mechanical signals. Vital to a successful healing process is the restoration of a good vascular network. In this paper, a continuous mathematical model is presented that describes the different fracture healing stages and their response to biochemical stimuli only (a bioregulatory model); mechanoregulatory effects are excluded here. The model consists of a system of nonlinear partial differential equations describing the spatiotemporal evolution of concentrations and densities of the cell types, extracellular matrix types and growth factors indispensable to the healing process. The model starts after the inflammation phase, when the fracture callus has already been formed. Cell migration is described using not only haptokinetic, but also chemotactic and haptotactic influences. Cell differentiation is controlled by the presence of growth factors and sufficient vascularisation. Matrix synthesis and growth factor production are controlled by the local cell and matrix densities and by the local growth factor concentrations. Numerical simulations of the system, using parameter values based on experimental data obtained from literature, are presented. The simulation results are corroborated by comparison with experimental data from a standardised rodent fracture model. The results of sensitivity analyses on the parameter values as well as on the boundary and initial conditions are discussed. Numerical simulations of compromised healing situations showed that the establishment of a vascular network in response to angiogenic growth factors is a key factor in the healing process. Furthermore, a correct description of cell migration is also shown to be essential to the prediction of realistic spatiotemporal tissue distribution patterns in the fracture callus. The mathematical framework presented in this paper can be an important tool in furthering the understanding of the mechanisms causing compromised healing and can be applied in the design of future fracture healing experiments.
Collapse
Affiliation(s)
- Liesbet Geris
- Division of Biomechanics and Engineering Design, Katholieke Universiteit Leuven, Celestijnenlaan 300C (PB 2419), 3001 Leuven, Belgium.
| | | | | | | | | |
Collapse
|
28
|
Woei Ng K, Speicher T, Dombrowski C, Helledie T, Haupt LM, Nurcombe V, Cool SM. Osteogenic differentiation of murine embryonic stem cells is mediated by fibroblast growth factor receptors. Stem Cells Dev 2007; 16:305-18. [PMID: 17521241 DOI: 10.1089/scd.2006.0044] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The mechanisms involved in the control of embryonic stem (ES) cell differentiation are yet to be fully elucidated. However, it has become clear that the family of fibroblast growth factors (FGFs) are centrally involved. In this study we examined the role of the FGF receptors (FGFRs 1-4) during osteogenesis in murine ES cells. Single cells were obtained after the formation of embryoid bodies, cultured on gelatin-coated plates, and coaxed to differentiate along the osteogenic lineage. Upregulation of genes was analyzed at both the transcript and protein levels using gene array, relative-quantitative PCR (RQ-PCR), and Western blotting. Deposition of a mineralized matrix was evaluated with Alizarin Red staining. An FGFR1-specific antibody was generated and used to block FGFR1 activity in mES cells during osteogenic differentiation. Upon induction of osteogenic differentiation in mES cells, all four FGFRs were clearly upregulated at both the transcript and protein levels with a number of genes known to be involved in osteogenic differentiation including bone morphogenetic proteins (BMPs), collagen I, and Runx2. Cells were also capable of depositing a mineralized matrix, confirming the commitment of these cells to the osteogenic lineage. When FGFR1 activity was blocked, a reduction in cell proliferation and a coincident upregulation of Runx2 with enhanced mineralization of cultures was observed. These results indicate that FGFRs play critical roles in cell recruitment and differentiation during the process of osteogenesis in mES cells. In particular, the data indicate that FGFR1 plays a pivotal role in osteoblast lineage determination.
Collapse
Affiliation(s)
- Kee Woei Ng
- Stem Cell and Tissue Repair Laboratory, Institute of Molecular and Cell Biology, Proteos, Singapore 138673
| | | | | | | | | | | | | |
Collapse
|
29
|
Massip L, Ectors F, Deprez P, Maleki M, Behets C, Lengelé B, Delahaut P, Picard J, Rezsöhazy R. Expression of Hoxa2 in cells entering chondrogenesis impairs overall cartilage development. Differentiation 2007; 75:256-67. [PMID: 17359301 DOI: 10.1111/j.1432-0436.2006.00132.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Vertebrate Hox genes act as developmental architects by patterning embryonic structures like axial skeletal elements, limbs, brainstem territories, or neural crest derivatives. While active during the patterning steps of development, these genes turn out to be down-regulated in specific differentiation programs like that leading to chondrogenesis. To investigate why chondrocyte differentiation is correlated to the silencing of a Hox gene, we generated transgenic mice allowing Cre-mediated conditional misexpression of Hoxa2 and induced this gene in Collagen 2 alpha 1-expressing cells committed to enter chondrogenesis. Persistent Hoxa2 expression in chondrogenic cells resulted in overall chondrodysplasia with delayed cartilage hypertrophy, mineralization, and ossification but without proliferation defects. The absence of skeletal patterning anomaly and the regular migration of precursor cells indicated that the condensation step of chondrogenesis was normal. In contrast, closer examination at the differentiation step showed severely impaired chondrocyte differentiation. In addition, this inhibition affected structures independently of their embryonic origin. In conclusion, for the first time here, by a cell-type specific misexpression, we precisely uncoupled the patterning function of Hoxa2 from its involvement in regulating differentiation programs per se and demonstrate that Hoxa2 displays an anti-chondrogenic activity that is distinct from its patterning function.
Collapse
Affiliation(s)
- Laurent Massip
- Developmental Genetics Unit, Université catholique de Louvain, Brussels, Belgium.
| | | | | | | | | | | | | | | | | |
Collapse
|
30
|
Yeh N, Miller JP, Gaur T, Capellini TD, Nikolich-Zugich J, de la Hoz C, Selleri L, Bromage TG, van Wijnen AJ, Stein GS, Lian JB, Vidal A, Koff A. Cooperation between p27 and p107 during endochondral ossification suggests a genetic pathway controlled by p27 and p130. Mol Cell Biol 2007; 27:5161-71. [PMID: 17502351 PMCID: PMC1951950 DOI: 10.1128/mcb.02431-06] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2006] [Revised: 02/21/2007] [Accepted: 05/02/2007] [Indexed: 02/05/2023] Open
Abstract
Pocket proteins and cyclin-dependent kinase (CDK) inhibitors negatively regulate cell proliferation and can promote differentiation. However, which members of these gene families, which cell type they interact in, and what they do to promote differentiation in that cell type during mouse development are largely unknown. To identify the cell types in which p107 and p27 interact, we generated compound mutant mice. These mice were null for p107 and had a deletion in p27 that prevented its binding to cyclin-CDK complexes. Although a fraction of these animals survived into adulthood and looked similar to single p27 mutant mice, a larger number of animals died at birth or within a few weeks thereafter. These animals displayed defects in chondrocyte maturation and endochondral bone formation. Proliferation of chondrocytes was increased, and ectopic ossification was observed. Uncommitted mouse embryo fibroblasts could be induced into the chondrocytic lineage ex vivo, but these cells failed to mature normally. These results demonstrate that p27 carries out overlapping functions with p107 in controlling cell cycle exit during chondrocyte maturation. The phenotypic similarities between p107(-/-) p27(D51/D51) and p107(-/-) p130(-/-) mice and the cells derived from them suggest that p27 and p130 act in an analogous pathway during chondrocyte maturation.
Collapse
Affiliation(s)
- Nancy Yeh
- Sloan-Kettering Institute, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10021, USA
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
31
|
Adams SL, Cohen AJ, Lassová L. Integration of signaling pathways regulating chondrocyte differentiation during endochondral bone formation. J Cell Physiol 2007; 213:635-41. [PMID: 17886256 DOI: 10.1002/jcp.21262] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
During endochondral bone formation, chondrocytes undergo a process of terminal differentiation or maturation, during which the rate of proliferation decreases, cells become hypertrophic, and the extracellular matrix is altered by production of a unique protein, collagen X, as well as proteins that promote mineralization. The matrix surrounding the hypertrophic chondrocytes eventually becomes mineralized, and the mineralized matrix serves as a template for bone deposition. This process is responsible for most longitudinal bone growth, both during embryonic development and in the postnatal long bone growth plates. Chondrocyte maturation must be precisely controlled, balancing proliferation with terminal differentiation; changes in the rate of either proliferation or differentiation result in shortened bones. Numerous signaling molecules have been implicated in regulation of this process. These include the negative regulators Indian hedgehog (Ihh) and parathyroid hormone-related protein (PTHrP; Pthlh, PTH-like hormone), as well as a number of positive regulators. This review will focus on several positive regulators which exert profound effects on chondrocyte maturation: the thyroid hormones T3 and T4, retinoic acid (the major active metabolite of vitamin A) and bone morphogenetic proteins (BMPs), as well as the transcription factor Runx2. Each of these molecules is essential for endochondral bone formation and cannot compensate for the others; abrogation of any one of them prevents differentiation. The important features of each of these signaling pathways will be discussed as they relate to chondrocyte maturation, and a model will be proposed suggesting how these pathways may converge to regulate this process.
Collapse
Affiliation(s)
- Sherrill L Adams
- Department of Biochemistry, University of Pennsylvania School of Dental Medicine, Philadelphia, Pennsylvania 19104-6030, USA.
| | | | | |
Collapse
|
32
|
Qiao M, Shapiro P, Fosbrink M, Rus H, Kumar R, Passaniti A. Cell cycle-dependent phosphorylation of the RUNX2 transcription factor by cdc2 regulates endothelial cell proliferation. J Biol Chem 2006; 281:7118-28. [PMID: 16407259 DOI: 10.1074/jbc.m508162200] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
RUNX2 is a member of the runt family of DNA-binding transcription factors. RUNX2 mediates endothelial cell migration and invasion during tumor angiogenesis and is expressed in metastatic breast and prostate tumors. Our published studies showed that RUNX2 DNA-binding activity is low during growth arrest, but elevated in proliferating endothelial cells. To investigate its role in cell proliferation and cell cycle regulation, RUNX2 was depleted in human bone marrow endothelial cells using RNA interference. Specific RUNX2 depletion inhibited DNA-binding activity as measured by electrophoretic mobility shift assay resulting in inhibition of cell proliferation. Cells were synchronized at the G(1)/S boundary with excess thymidine or in mitosis (M phase) with nocodazole. Endogenous or ectopic RUNX2 activity was maximal at late G(2) and during M phase. Inhibition of RUNX2 expression by RNA interference delayed entry into and exit out of the G(2)/M phases of the cell cycle. RUNX2 was coimmunoprecipitated with cyclin B1 in mitotic cells, which further supported a role for RUNX2 in cell cycle progression. Moreover, in vitro kinase assays using recombinant cdc2 kinase showed that RUNX2 was phosphorylated at Ser(451). The cdc2 inhibitor roscovitine dose dependently inhibited in vivo RUNX2 DNA-binding activity during mitosis and the RUNX2 mutant S451A exhibited lower DNA-binding activity and reduced stimulation of anchorage-independent growth relative to wild type RUNX2. These results suggest for the first time that RUNX2 phosphorylation by cdc2 may facilitate cell cycle progression possibly through regulation of G(2) and M phases, thus promoting endothelial cell proliferation required for tumor angiogenesis.
Collapse
Affiliation(s)
- Meng Qiao
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD 21201, USA
| | | | | | | | | | | |
Collapse
|
33
|
Fisher MC, Meyer C, Garber G, Dealy CN. Role of IGFBP2, IGF-I and IGF-II in regulating long bone growth. Bone 2005; 37:741-50. [PMID: 16183342 DOI: 10.1016/j.bone.2005.07.024] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2005] [Revised: 04/20/2005] [Accepted: 07/05/2005] [Indexed: 01/15/2023]
Abstract
The IGF axis is important for long bone development, homeostasis and disease. The activities of IGF-I and IGF-II are regulated by IGF binding proteins (IGFBPs). IGF-I and IGFBP2 are co-expressed in dynamic fashions in the developing long bones of the chick wing, and we have found that IGF-II is present in the cartilage model and surrounding perichondrium, proliferative and hypertrophic chondrocytes and developing periosteum. To gain insight into endogenous roles of IGF-I, IGF-II and IGFBP2 in long bone development, we have overexpressed IGFBP2 in the developing skeletal elements of the embryonic chick wing in vivo, using an RCAS retroviral vector. IGFBP2 overexpression led to an obvious shortening of the long bones of the wing. We have investigated, at the cellular and molecular levels, the mechanism of action whereby IGFBP2 overexpression impairs long bone development in vivo. At an early stage, IGFBP2 excess dramatically inhibits proliferation by the chondrocytes of the cartilage models that prefigure the developing long bones. Later, IGFBP2 excess also reduces proliferation of the maturing chondrocytes and attenuates proliferation by the perichondrium/developing periosteum. IGFBP2 excess does not affect morphological or molecular indicators of chondrocyte maturation, osteoblast differentiation or cell/matrix turnover, such as expression of Ihh, PTHrP, type X collagen and osteopontin, or distribution and relative abundance of putative clast cells. We also have found that IGFBP2 blocks the ability of IGF-I and IGF-II to promote proliferation and matrix synthesis by wing chondrocytes in vitro. Together, our results suggest that the mechanism of action whereby IGFBP2 excess impairs long bone development is to inhibit IGF-mediated proliferation and matrix synthesis by the cartilage model; reduce the proliferation and progression to hypertrophy by the maturing chondrocytes; and attenuate proliferation and formation of the periosteal bony collar. These actions retard the growth and longitudinal expansion of the developing long bones, resulting in shortened wing skeletal elements. Our results emphasize the importance of a balance of IGF/IGFBP2 action at several stages during normal long bone development.
Collapse
Affiliation(s)
- Melanie C Fisher
- Center for Limb and Skeletal Development, Department of BioStructure and Function, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06030, USA
| | | | | | | |
Collapse
|
34
|
Abstract
The retinoblastoma protein (pRB) and the pRB-related p107 and p130 comprise the 'pocket protein' family of cell cycle regulators. These proteins are best known for their roles in restraining the G1-S transition through the regulation of E2F-responsive genes. pRB and the p107/p130 pair are required for the repression of distinct sets of genes, potentially due to their selective interactions with E2Fs that are engaged at specific promoter elements. In addition to regulating E2F-responsive genes in a reversible manner, pocket proteins contribute to silencing of such genes in cells that are undergoing senescence or differentiation. Pocket proteins also affect the G1-S transition through E2F-independent mechanisms, such as by inhibiting Cdk2 or by stabilizing p27(Kip1), and they are implicated in the control of G0 exit, the spatial organization of replication, and genomic rereplication. New insights into pocket protein regulation have also been obtained. Kinases previously thought to be crucial to pocket protein phosphorylation have been shown to be redundant, and new modes of phosphorylation and dephosphorylation have been identified. Despite these advances, much remains to be learned about the pocket proteins, particularly with regard to their developmental and tumor suppressor functions. Thus continues the story of the pocket proteins and the cell cycle.
Collapse
Affiliation(s)
- David Cobrinik
- Dyson Vision Research Institute and Department of Ophthalmology, Weill Medical College of Cornell University, 1300 York Avenue, LC303, New York, NY 10021, USA.
| |
Collapse
|
35
|
MacLean HE, Kronenberg HM. Localization of Indian hedgehog and PTH/PTHrP receptor expression in relation to chondrocyte proliferation during mouse bone development. Dev Growth Differ 2005; 47:59-63. [PMID: 15771625 DOI: 10.1111/j.1440-169x.2004.00781.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have developed a useful approach to examine the pattern of gene expression in comparison to cell proliferation, using double in situ hybridization and immunofluorescence. Using this system, we examined the expression of Indian hedgehog (Ihh) and PTH/PTHrP receptor (PPR) mRNA in relation to chondrocyte proliferation during embryonic mouse bone development. Both genes are expressed strongly in prehypertrophic and early hypertrophic chondrocytes, and there is a strong correlation between upregulation of both Ihh and PPR expression and chondrocyte cell cycle arrest. At embryonic day (E14.5), PPR mRNA upregulation begins in the columnar chondrocytes just prior to cell cycle exit, but at later time points expression is only observed in the postproliferative region. In contrast, Ihh mRNA expression overlaps slightly with the region of columnar proliferating chondrocytes at all stages. This study provides further evidence that in the developing growth plate, cell cycle exit and upregulation of Ihh and PPR mRNA expression are coupled.
Collapse
Affiliation(s)
- Helen E MacLean
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA
| | | |
Collapse
|
36
|
Moro T, Ogasawara T, Chikuda H, Ikeda T, Ogata N, Maruyama Z, Komori T, Hoshi K, Chung UI, Nakamura K, Okayama H, Kawaguchi H. Inhibition of Cdk6 expression through p38 MAP kinase is involved in differentiation of mouse prechondrocyte ATDC5. J Cell Physiol 2005; 204:927-33. [PMID: 15795936 DOI: 10.1002/jcp.20350] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Because a temporal arrest in the G1-phase of the cell cycle is a prerequisite for cell differentiation, this study investigated the involvement of cell cycle factors in the differentiation of cultured mouse prechondrocyte cell line ATDC5. Among the G1 cell cycle factors examined, both protein and mRNA levels of cyclin-dependent kinase (Cdk6) were downregulated during the culture in a differentiation medium. The protein degradation of Cdk6 was not involved in this downregulation because proteasome inhibitors did not reverse the protein level. When inhibitors of p38 MAPK, ERK-1/2, and PI3K/Akt were added to the culture, only a p38 MAPK inhibitor SB203580 blocked the decrease in the Cdk6 protein level by the differentiation medium, indicating that the Cdk6 inhibition was mediated by p38 MAPK pathway. In fact, p38 MAPK was confirmed to be phosphorylated during differentiation of ATDC5 cells. Enforced expression of Cdk6 in ATDC5 cells blocked the chondrocyte differentiation and inhibited Sox5 and Sox6 expressions. However, the Cdk6 overexpression did not affect the proliferation or the cell cycle progression, suggesting that the inhibitory effect of Cdk6 on the differentiation was exerted by a mechanism largely independent of its cell cycle regulation. These results indicate that Cdk6 may be a regulator of chondrocyte differentiation and that its p38-mediated downregulation is involved in the efficient differentiation.
Collapse
Affiliation(s)
- Toru Moro
- Department of Sensory and Motor System Medicine, Faculty of Medicine, University of Tokyo, Japan
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
37
|
Litovchick L, Chestukhin A, DeCaprio JA. Glycogen synthase kinase 3 phosphorylates RBL2/p130 during quiescence. Mol Cell Biol 2004; 24:8970-80. [PMID: 15456871 PMCID: PMC517894 DOI: 10.1128/mcb.24.20.8970-8980.2004] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Phosphorylation of the retinoblastoma-related or pocket proteins RB1/pRb, RBL1/p107, and RBL2/p130 regulates cell cycle progression and exit. While all pocket proteins are phosphorylated by cyclin-dependent kinases (CDKs) during the G1/S-phase transition, p130 is also specifically phosphorylated in G0-arrested cells. We have previously identified several phosphorylated residues that match the consensus site for glycogen synthase kinase 3 (GSK3) in the G0 form of p130. Using small-molecule inhibitors of GSK3, site-specific mutants of p130, and phospho-specific antibodies, we demonstrate here that GSK3 phosphorylates p130 during G0. Phosphorylation of p130 by GSK3 contributes to the stability of p130 but does not affect its ability to interact with E2F4 or cyclins. Regulation of p130 by GSK3 provides a novel link between growth factor signaling and regulation of the cell cycle progression and exit.
Collapse
Affiliation(s)
- Larisa Litovchick
- Dana-Farber Cancer Institute, Mayer 457, 44 Binney St., Boston, MA 02115, USA
| | | | | |
Collapse
|
38
|
Nilsson O, Baron J. Fundamental limits on longitudinal bone growth: growth plate senescence and epiphyseal fusion. Trends Endocrinol Metab 2004; 15:370-4. [PMID: 15380808 DOI: 10.1016/j.tem.2004.08.004] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Longitudinal bone growth occurs rapidly in early life but then slows and, eventually, ceases. The decline in growth rate is caused primarily by a decrease in the rate of chondrocyte proliferation and is accompanied by structural changes in growth plate cartilage. This programmed senescence does not appear to be caused by hormonal or other systemic mechanisms but is intrinsic to the growth plate itself. In particular, recent evidence indicates that senescence might occur because stem-like cells in the resting zone have a finite proliferative capacity, which is exhausted gradually. In some mammals, including humans, proliferative exhaustion is followed by epiphyseal fusion, an abrupt event in which the growth plate cartilage is replaced completely by bone.
Collapse
Affiliation(s)
- Ola Nilsson
- Developmental Endocrinology Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | | |
Collapse
|
39
|
Garciadiego-Cázares D, Rosales C, Katoh M, Chimal-Monroy J. Coordination of chondrocyte differentiation and joint formation byα5β1 integrin in the developing appendicular skeleton. Development 2004; 131:4735-42. [PMID: 15329344 DOI: 10.1242/dev.01345] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The control point by which chondrocytes take the decision between the cartilage differentiation program or the joint formation program is unknown. Here, we have investigated the effect of α5β1 integrin inhibitors and bone morphogenetic protein (BMP) on joint formation. Blocking ofα5β1 integrin by specific antibodies or RGD peptide(arginine-glycine-aspartic acid) induced inhibition of pre-hypertrophic chondrocyte differentiation and ectopic joint formation between proliferating chondrocytes and hypertrophic chondrocytes. Ectopic joint expressed Wnt14,Gdf5, chordin, autotaxin, type I collagen and CD44, while expression of Indian hedgehog and type II collagen was downregulated in cartilage. Expression of these interzone markers confirmed that the new structure is a new joint being formed. In the presence of BMP7, inhibition of α5β1 integrin function still induced the formation of the ectopic joint between proliferating chondrocytes and hypertrophic chondrocytes. By contrast,misexpression of α5β1 integrin resulted in fusion of joints and formation of pre-hypertrophic chondrocytes. These facts indicate that the decision of which cell fate to make pre-joint or pre-hypertrophic is made on the basis of the presence or absence of α5β1 integrin on chondrocytes.
Collapse
Affiliation(s)
- David Garciadiego-Cázares
- Departamento de Biología Celular y Fisiología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | | | | | | |
Collapse
|
40
|
MacLean HE, Guo J, Knight MC, Zhang P, Cobrinik D, Kronenberg HM. The cyclin-dependent kinase inhibitor p57(Kip2) mediates proliferative actions of PTHrP in chondrocytes. J Clin Invest 2004; 113:1334-43. [PMID: 15124025 PMCID: PMC398433 DOI: 10.1172/jci21252] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2004] [Accepted: 03/08/2004] [Indexed: 01/17/2023] Open
Abstract
Parathyroid hormone-related peptide (PTHrP) is a positive regulator of chondrocyte proliferation during bone development. In embryonic mice lacking PTHrP, chondrocytes stop proliferating prematurely, with accelerated differentiation. Because the bone phenotype of mice lacking the cyclin-dependent kinase inhibitor p57(Kip2) is the opposite of the PTHrP-null phenotype, we hypothesized that PTHrP's proliferative actions in chondrocytes might be mediated by opposing p57. We generated p57/PTHrP-null embryos, which showed partial rescue of the PTHrP-null phenotype. There was reversal of the loss of proliferative chondrocytes in most bones, with reversal of the accelerated differentiation that occurs in the PTHrP-null phenotype. p57 mRNA and protein were upregulated in proliferative chondrocytes in the absence of PTHrP. Metatarsal culture studies confirmed the action of PTHrP to decrease p57 mRNA and protein levels in a model in which parathyroid hormone (PTH), used as an analog of PTHrP, increased chondrocyte proliferation rate and the length of the proliferative domain. PTH treatment of p57-null metatarsals had no effect on proliferation rate in round proliferative chondrocytes but still stimulated proliferation in columnar chondrocytes. These studies suggest that the effects of PTHrP on both the rate and extent of chondrocyte proliferation are mediated, at least in part, through suppression of p57 expression.
Collapse
Affiliation(s)
- Helen E MacLean
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114, USA
| | | | | | | | | | | |
Collapse
|
41
|
MacLean HE, Guo J, Knight MC, Zhang P, Cobrinik D, Kronenberg HM. The cyclin-dependent kinase inhibitor p57Kip2 mediates proliferative actions of PTHrP in chondrocytes. J Clin Invest 2004. [DOI: 10.1172/jci200421252] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
|
42
|
Wang G, Woods A, Sabari S, Pagnotta L, Stanton LA, Beier F. RhoA/ROCK Signaling Suppresses Hypertrophic Chondrocyte Differentiation. J Biol Chem 2004; 279:13205-14. [PMID: 14726536 DOI: 10.1074/jbc.m311427200] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Coordinated proliferation and differentiation of growth plate chondrocytes is required for normal growth and development of the endochondral skeleton, but little is known about the intracellular signal transduction pathways regulating these processes. We have investigated the roles of the GTPase RhoA and its effector kinases ROCK1/2 in hypertrophic chondrocyte differentiation. RhoA, ROCK1, and ROCK2 are expressed throughout chondrogenic differentiation. RhoA overexpression in chondrogenic ATDC5 cells results in increased proliferation and a marked delay of hypertrophic differentiation, as shown by decreased induction of alkaline phosphatase activity, mineralization, and expression of the hypertrophic markers collagen X, bone sialoprotein, and matrix metalloproteinase 13. These effects are accompanied by activation of cyclin D1 transcription and repression of the collagen X promoter by RhoA. In contrast, inhibition of Rho/ROCK signaling by the pharmacological inhibitor Y27632 inhibits chondrocyte proliferation and accelerates hypertrophic differentiation. Dominant-negative RhoA also inhibits induction of the cyclin D1 promoter by parathyroid hormone-related peptide. Finally, Y27632 treatment partially rescues the effects of RhoA overexpression. In summary, we identify the RhoA/ROCK signaling pathway as a novel and important regulator of chondrocyte proliferation and differentiation.
Collapse
Affiliation(s)
- Guoyan Wang
- Department of Physiology and Pharmacology, Canadian Institutes of Health Research Group in Skeletal Development and Remodeling, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | | | | | | | | | | |
Collapse
|
43
|
Stewart MC, Kadlcek RM, Robbins PD, MacLeod JN, Ballock RT. Expression and activity of the CDK inhibitor p57Kip2 in chondrocytes undergoing hypertrophic differentiation. J Bone Miner Res 2004; 19:123-32. [PMID: 14753744 DOI: 10.1359/jbmr.0301209] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
UNLABELLED Growth plates of p57-null mice exhibit several abnormalities, including loss of collagen type X (CollX) expression. The phenotypic consequences of p57 expression were assessed in an in vitro model of hypertrophic differentiation. Adenoviral p57 expression was not sufficient for CollX expression but did augment induction of CollX by BMP-2. INTRODUCTION During hypertrophic differentiation, chondrocytes pass from an actively proliferative state to a postmitotic, hypertrophic phenotype. The induction of growth arrest is a central feature of this phenotypic transition. Mice lacking the cyclin dependent-kinase inhibitor p57Kip2 exhibit several developmental abnormalities including chondrodysplasia. Although growth plate chondrocytes in p57-null mice undergo growth arrest, they do not express collagen type X, a specific marker of the hypertrophic phenotype. This study was carried out to investigate the link between p57 expression and the induction of collagen type X in chondrocytes and to determine whether p57 overexpression is sufficient for the induction of hypertrophic differentiation. MATERIALS AND METHODS Neonatal rat epiphyseal or growth plate chondrocytes were maintained in an aggregate culture model, in defined, serum-free medium. Protein and mRNA levels were monitored by Western and Northern blot analyses, respectively. Proliferative activity was assessed by fluorescent measurement of total DNA and by 3H-thymidine incorporation rates. An adenoviral vector was used to assess the phenotypic consequences of p57 expression. RESULTS AND CONCLUSIONS During in vitro hypertrophic differentiation, levels of p57 mRNA and protein were constant despite changes in chondrocyte proliferative activity and the induction of hypertrophic-specific genes in response to bone morphogenetic protein (BMP)-2. Adenoviral p57 overexpression induced growth arrest in prehypertrophic epiphyseal chondrocytes in a dose-dependent manner but was not sufficient for the induction of collagen type X, either alone or when coexpressed with the related CDKI p21Cip1. Similar results were obtained with more mature tibial growth plate chondrocytes. p57 overexpression did augment collagen type X induction by BMP-2. These data indicate that p57-mediated growth arrest is not sufficient for expression of the hypertrophic phenotype, but rather it occurs in parallel with other aspects of the differentiation pathway. Our findings also suggest a contributing role for p57 in the regulation of collagen type X expression in differentiating chondrocytes.
Collapse
Affiliation(s)
- Matthew C Stewart
- Department of Veterinary Clinical Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois 61802, USA.
| | | | | | | | | |
Collapse
|
44
|
Abstract
The longitudinal growth of endochondral bones is governed by proliferation and hypertrophic differentiation of growth plate chondrocytes. Numerous growth factors and hormones have been implicated in the regulation of these processes, but the intracellular mechanisms involved remain much less understood. We had suggested a role of cell-cycle genes in the integration of these diverse extracellular signals and their translation into coordinated proliferation and differentiation of chondrocytes. Numerous recent studies have provided support for such a scenario and provide novel insights into the regulation and function of cell-cycle genes in chondrocytes. This review article summarizes recent progress in the field.
Collapse
Affiliation(s)
- Frank Beier
- CIHR Group in Skeletal Development and Remodeling, Department of Physiology and Pharmacology, and School of Dentistry, University of Western Ontario, London, Ontario, Canada.
| |
Collapse
|
45
|
Topol L, Jiang X, Choi H, Garrett-Beal L, Carolan PJ, Yang Y. Wnt-5a inhibits the canonical Wnt pathway by promoting GSK-3-independent beta-catenin degradation. J Cell Biol 2003; 162:899-908. [PMID: 12952940 PMCID: PMC2172823 DOI: 10.1083/jcb.200303158] [Citation(s) in RCA: 580] [Impact Index Per Article: 27.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Wnts are secreted signaling molecules that can transduce their signals through several different pathways. Wnt-5a is considered a noncanonical Wnt as it does not signal by stabilizing beta-catenin in many biological systems. We have uncovered a new noncanonical pathway through which Wnt-5a antagonizes the canonical Wnt pathway by promoting the degradation of beta-catenin. This pathway is Siah2 and APC dependent, but GSK-3 and beta-TrCP independent. Furthermore, we provide evidence that Wnt-5a also acts in vivo to promote beta-catenin degradation in regulating mammalian limb development and possibly in suppressing tumor formation.
Collapse
Affiliation(s)
- Lilia Topol
- Genetic Disease Research Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | | | | | | | | | | |
Collapse
|
46
|
Dailey L, Laplantine E, Priore R, Basilico C. A network of transcriptional and signaling events is activated by FGF to induce chondrocyte growth arrest and differentiation. J Cell Biol 2003; 161:1053-66. [PMID: 12821644 PMCID: PMC2172997 DOI: 10.1083/jcb.200302075] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Activating mutations in FGF receptor 3 (FGFR3) cause several human dwarfism syndromes by affecting both chondrocyte proliferation and differentiation. Using microarray and biochemical analyses of FGF-treated rat chondrosarcoma chondrocytes, we show that FGF inhibits chondrocyte proliferation by initiating multiple pathways that result in the induction of antiproliferative functions and the down-regulation of growth-promoting molecules. The initiation of growth arrest is characterized by the rapid dephosphorylation of the retinoblastoma protein (pRb) p107 and repression of a subset of E2F target genes by a mechanism that is independent of cyclin E-Cdk inhibition. In contrast, hypophosphorylation of pRb and p130 occur after growth arrest is first detected, and may contribute to its maintenance. Importantly, we also find a number of gene expression changes indicating that FGF promotes many aspects of hypertrophic differentiation, a notion supported by in situ analysis of developing growth plates from mice expressing an activated form of FGFR3. Thus, FGF may coordinate the onset of differentiation with chondrocyte growth arrest in the developing growth plate.
Collapse
Affiliation(s)
- Lisa Dailey
- Dept. of Microbiology, New York University School of Medicine, New York, NY 10016, USA.
| | | | | | | |
Collapse
|
47
|
Scheijen B, Bronk M, van der Meer T, Bernards R. Constitutive E2F1 overexpression delays endochondral bone formation by inhibiting chondrocyte differentiation. Mol Cell Biol 2003; 23:3656-68. [PMID: 12724423 PMCID: PMC164752 DOI: 10.1128/mcb.23.10.3656-3668.2003] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2002] [Revised: 09/06/2002] [Accepted: 02/28/2003] [Indexed: 12/28/2022] Open
Abstract
Longitudinal bone growth results from endochondral ossification, a process that requires proliferation and differentiation of chondrocytes. It has been shown that proper endochondral bone formation is critically dependent on the retinoblastoma family members p107 and p130. However, the precise functional roles played by individual E2F proteins remain poorly understood. Using both constitutive and conditional E2F1 transgenic mice, we show that ubiquitous transgene-driven expression of E2F1 during embryonic development results in a dwarf phenotype and significantly reduced postnatal viability. Overexpression of E2F1 disturbs chondrocyte maturation, resulting in delayed endochondral ossification, which is characterized by reduced hypertrophic zones and disorganized growth plates. Employing the chondrogenic cell line ATDC5, we investigated the effects of enforced E2F expression on the different phases of chondrocyte maturation that are normally required for endochondral ossification. Ectopic E2F1 expression strongly inhibits early- and late-phase differentiation of ATDC5 cells, accompanied by diminished cartilage nodule formation as well as decreased type II collagen, type X collagen, and aggrecan gene expression. In contrast, overexpression of E2F2 or E2F3a results in only a marginal delay of chondrocyte maturation, and increased E2F4 levels have no effect. These data are consistent with the notion that E2F1 is a regulator of chondrocyte differentiation.
Collapse
Affiliation(s)
- Blanca Scheijen
- Division of Molecular Carcinogenesis and Center for Biomedical Genetics, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
| | | | | | | |
Collapse
|
48
|
Cormier SA, Mello MA, Kappen C. Normal proliferation and differentiation of Hoxc-8 transgenic chondrocytes in vitro. BMC DEVELOPMENTAL BIOLOGY 2003; 3:4. [PMID: 12713673 PMCID: PMC156609 DOI: 10.1186/1471-213x-3-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2002] [Accepted: 04/24/2003] [Indexed: 12/14/2022]
Abstract
BACKGROUND Hox genes encode transcription factors that are involved in pattern formation in the skeleton, and recent evidence suggests that they also play a role in the regulation of endochondral ossification. To analyze the role of Hoxc-8 in this process in more detail, we applied in vitro culture systems, using high density cultures of primary chondrocytes from neonatal mouse ribs. RESULTS Cultured cells were characterized on the basis of morphology (light microscopy) and production of cartilage-specific extracellular matrix (sulfated proteoglycans and type II Collagen). Hypertrophy was demonstrated by increase in cell size, alkaline phosphatase activity and type X Collagen immunohistochemistry. Proliferation was assessed by BrdU uptake and flow cytometry. Unexpectedly, chondrocytes from Hoxc-8 transgenic mice, which exhibit delayed cartilage maturation in vivo 1, were able to proliferate and differentiate normally in our culture systems. This was the case even though freshly isolated Hoxc-8 transgenic chondrocytes exhibited significant molecular differences as measured by real-time quantitative PCR. CONCLUSIONS The results demonstrate that primary rib chondrocytes behave similar to published reports for chondrocytes from other sources, validating in vitro approaches for studies of Hox genes in the regulation of endochondral ossification. Our analysis of cartilage-producing cells from Hoxc-8 transgenic mice provides evidence that the cellular phenotype induced by Hoxc-8 overexpression in vivo is reversible in vitro.
Collapse
Affiliation(s)
- Stephania A Cormier
- Samuel C. Johnson Medical Research Center, Mayo Clinic Scottsdale, Scottdale, AZ 85259, USA
| | - Maria Alice Mello
- Center for Human Molecular Genetics, Munroe-Meyer Institute, University of Nebraska Medical Center, Omaha, NE 68198, USA
- Current address: NIAMS/NIH, Cartilage Biology and Orthopedics Branch, Bethesda, MD 20892-8022, USA
| | - Claudia Kappen
- Samuel C. Johnson Medical Research Center, Mayo Clinic Scottsdale, Scottdale, AZ 85259, USA
- Center for Human Molecular Genetics, Munroe-Meyer Institute, University of Nebraska Medical Center, Omaha, NE 68198, USA
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical School, Omaha, NE 68198, USA
| |
Collapse
|
49
|
Landsberg RL, Sero JE, Danielian PS, Yuan TL, Lee EY, Lees JA. The role of E2F4 in adipogenesis is independent of its cell cycle regulatory activity. Proc Natl Acad Sci U S A 2003; 100:2456-61. [PMID: 12604789 PMCID: PMC151362 DOI: 10.1073/pnas.0138064100] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2002] [Accepted: 12/31/2002] [Indexed: 01/04/2023] Open
Abstract
The E2F and pocket protein families are known to play an important role in the regulation of both cellular proliferation and terminal differentiation. In this study, we have used compound E2F and pocket protein mutant mouse embryonic fibroblasts to dissect the role of these proteins in adipogenesis. This analysis shows that loss of E2F4 allows cells to undergo spontaneous differentiation. The ability of E2F4 to prevent adipogenesis seems to be quite distinct from the known properties of E2F. First, it can be separated from any change in either E2F-responsive gene expression or cell cycle regulation. Second, it is a specific property of E2F4, and not other E2Fs, and it occurs independently of E2F4's ability to interact with pocket proteins. In addition, E2F4 loss does not override the differentiation defect resulting from pRB loss even though it completely suppresses the proliferation defect of Rb(-/-) mouse embryonic fibroblasts. This finding definitively separates the known, positive role of pRB in adipogenesis from its cell cycle function and shows that this pocket protein is required to act downstream of E2F4 in the differentiation process.
Collapse
Affiliation(s)
- Rebecca L Landsberg
- Center for Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | | | | | | | | | | |
Collapse
|
50
|
Laplantine E, Rossi F, Sahni M, Basilico C, Cobrinik D. FGF signaling targets the pRb-related p107 and p130 proteins to induce chondrocyte growth arrest. J Cell Biol 2002; 158:741-50. [PMID: 12177046 PMCID: PMC2174007 DOI: 10.1083/jcb.200205025] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Unregulated FGF signaling affects endochondral ossification and long bone growth, causing several genetic forms of human dwarfism. One major mechanism by which FGFs regulate endochondral bone growth is through their inhibitory effect on chondrocyte proliferation. Because mice with targeted mutations of the retinoblastoma (Rb)-related proteins p107 and p130 present severe endochondral bone defects with excessive chondrocyte proliferation, we have investigated the role of the Rb family of cell cycle regulators in the FGF response. Using a chondrocyte cell line, we found that FGF induced a rapid dephosphorylation of all three proteins of the Rb family (pRb, p107, and p130) and a blockade of the cells in the G1 phase of the cell cycle. This cell cycle block was reversed by inactivation of Rb proteins with viral oncoproteins such as polyoma large T (PyLT) antigen and Adenovirus E1A. Expression of a PyLT mutant that efficiently binds pRb, but not p107 and p130, allowed the cells to be growth inhibited by FGF, suggesting that pRb itself is not involved in the FGF response. To investigate more precisely the role of the individual Rb family proteins in FGF-mediated growth inhibition, we used chondrocyte micromass culture of limb bud cells isolated from mice lacking Rb proteins individually or in combination. Although wild-type as well as Rb-/- chondrocytes were similarly growth inhibited by FGF, chondrocytes null for p107 and p130 did not respond to FGF. Furthermore, FGF treatment of metatarsal bone rudiments obtained from p107-/-;p130-/- embryos failed to inhibit proliferation of growth plate chondrocytes, whereas rudiments from p107-null or p130-null embryos showed only a slight inhibition of growth. Our findings indicate that p107 and p130, but not pRb, are critical effectors of FGF-mediated growth inhibition in chondrocytes.
Collapse
Affiliation(s)
- Emmanuel Laplantine
- Department of Microbiology, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA
| | | | | | | | | |
Collapse
|