T Kobayashi1, G Papaioannou2, F Mirzamohammadi3, E Kozhemyakina4, M Zhang5, R Blelloch6, M W Chong7. 1. Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA. Electronic address: tkobayashi1@mgh.harvard.edu. 2. Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA. Electronic address: GPAPAIOANNOU@mgh.harvard.edu. 3. Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA. Electronic address: FMIRZAMOHAMMADI@mgh.harvard.edu. 4. Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA. Electronic address: eKozhemyakina@dresourcesgroup.com. 5. Department of Orthopaedic Surgery, Boston Children's Hospital, Boston, MA 02115, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA. Electronic address: Minjie.Zhang@childrens.harvard.edu. 6. The Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, Center for Reproductive Sciences, University of California, San Francisco, San Francisco, CA 94143, USA. Electronic address: blellochr@stemcell.ucsf.edu. 7. Genomics and Immunology Laboratory, St. Vincent's Institute of Medical Research, and Department of Medicine, University of Melbourne, Fitzroy, VIC 3065, Australia. Electronic address: mchong@svi.edu.au.
Abstract
OBJECTIVE: In growth plate chondrocytes, loss of Dicer, a microRNA (miRNA)-processing enzyme, causes defects in proliferation and differentiation, leading to a lethal skeletal dysplasia. However roles of miRNAs in articular chondrocytes have not been defined in vivo. To investigate the role of miRNAs in articular chondrocytes and to explore the possibility of generating a novel mouse osteoarthritis (OA) model caused by intrinsic cellular dysfunction, we ablated Drosha, another essential enzyme for miRNA biogenesis, exclusively in articular chondrocytes of postnatal mice. DESIGN: First, to confirm that the essential role of miRNAs in skeletal development, we ablated the miRNA biogenesis pathway by deleting Drosha or DGCR8 in growth plate chondrocytes. Next, to investigate the role of miRNAs in articular cartilage, we deleted Drosha using Prg4-CreER(T) transgenic mice expressing a tamoxifen-activated Cre recombinase (CreER(T)) exclusively in articular chondrocytes. Tamoxifen was injected at postnatal days, 7, 14, 21, and 28 to ablate Drosha. RESULTS: Deletion of Drosha or DGCR8 in growth plate chondrocytes caused a lethal skeletal defect similar to that of Dicer deletion, confirming the essential role of miRNAs in normal skeletogenesis. Early postnatal Drosha deletion in articular chondrocytes significantly increased cell death and decreased Safranin-O staining. Mild OA-like changes, including surface erosion and cleft formation, were found in male mice at 6 months of age; however such changes in females were not observed even at 9 months of age. CONCLUSIONS: Early postnatal Drosha deficiency induces articular chondrocyte death and can cause a mild OA-like pathology.
OBJECTIVE: In growth plate chondrocytes, loss of Dicer, a microRNA (miRNA)-processing enzyme, causes defects in proliferation and differentiation, leading to a lethal skeletal dysplasia. However roles of miRNAs in articular chondrocytes have not been defined in vivo. To investigate the role of miRNAs in articular chondrocytes and to explore the possibility of generating a novel mouseosteoarthritis (OA) model caused by intrinsic cellular dysfunction, we ablated Drosha, another essential enzyme for miRNA biogenesis, exclusively in articular chondrocytes of postnatal mice. DESIGN: First, to confirm that the essential role of miRNAs in skeletal development, we ablated the miRNA biogenesis pathway by deleting Drosha or DGCR8 in growth plate chondrocytes. Next, to investigate the role of miRNAs in articular cartilage, we deleted Drosha using Prg4-CreER(T) transgenic mice expressing a tamoxifen-activated Cre recombinase (CreER(T)) exclusively in articular chondrocytes. Tamoxifen was injected at postnatal days, 7, 14, 21, and 28 to ablate Drosha. RESULTS: Deletion of Drosha or DGCR8 in growth plate chondrocytes caused a lethal skeletal defect similar to that of Dicer deletion, confirming the essential role of miRNAs in normal skeletogenesis. Early postnatal Drosha deletion in articular chondrocytes significantly increased cell death and decreased Safranin-O staining. Mild OA-like changes, including surface erosion and cleft formation, were found in male mice at 6 months of age; however such changes in females were not observed even at 9 months of age. CONCLUSIONS: Early postnatal Drosha deficiency induces articular chondrocyte death and can cause a mild OA-like pathology.
Authors: Tatsuya Kobayashi; Jun Lu; Bradley S Cobb; Stephen J Rodda; Andrew P McMahon; Ernestina Schipani; Matthias Merkenschlager; Henry M Kronenberg Journal: Proc Natl Acad Sci U S A Date: 2008-01-31 Impact factor: 11.205
Authors: Ryan B Rountree; Michael Schoor; Hao Chen; Melissa E Marks; Vincent Harley; Yuji Mishina; David M Kingsley Journal: PLoS Biol Date: 2004-10-19 Impact factor: 8.029