Ono -- PTH-Pthrp Receptor Signaling in Osterix-Expressing Progenitors.Pdf

3/27/14 Root forma)on Cementum Dentin <ul style="display: flex;"><li style="flex:1">Cementoblast </li><li style="flex:1">Odontoblast </li></ul>Role of PTH/PTHrP Receptor Signaling on Root Formaꢀon Epithelial rests of Malassez (ERM) Dental papilla cells Wanida Ono AGE Orthodonꢀcs, Department of Developmental Biology, Harvard School of Dental Medicine Endocrine Unit, MassachuseLs General Hospital and Harvard Medical School Dental follicle cells Hertwig’s epithelial root sheath (HERS) Osterix PTHrP-PPR system PTHrP •ꢀ Transcrip)on factor essenꢀal to osteoblast differenꢀaꢀon (Nakashima K et al. 2002) PTH/PTHrP receptor (PPR) •ꢀ Expressed in odontoblasts and alveolar osteoblasts during Gαs Gq tooth development (Chen S et al. 2009) •ꢀ Controls cellular cementum formaꢀon (Cao Z et al. 2012) •ꢀ Mediates epithelial-mesenchymal interac)ons •ꢀ Osterix-expressing precursors in the perichondrium move to bone marrow and become osteoblasts during fetal •ꢀ PTHrP is expressed in enamel epithelia/HERS? •ꢀ PPR is expressed in dental mesenchymes (Beck et al 1995; Lee Deeds and Segre 1995; Liu et al 1998) development (Maes C, Kronenberg HM et al. 2010) •ꢀ PTHrP is required for tooth erupꢀon in mice (Philbrick WM, Karaplis AC et al. PNAS 1998) Osterix+ cells Root-forming progenitors •ꢀ PPR haploinsufficiency is associated with primary ?failure of tooth erupꢀon (PFE) in humans (Decker E, Weber BH et al. Am J Hum Gen 2008) PTHrP expression paꢀern during root morphogenesis Aims of this study •ꢀ Idenꢀfy how osterix-expressing progenitors contribute PTHrPLacZ/+ x40 <ul style="display: flex;"><li style="flex:1">P7 </li><li style="flex:1">P14 </li><li style="flex:1">P49 </li></ul>to murine root morphogenesis •ꢀ Understand how PTH/PTHrP receptor signal regulates root-forming progenitors PTHrP--acZ <ul style="display: flex;"><li style="flex:1">x200 </li><li style="flex:1">x400 </li></ul><ul style="display: flex;"><li style="flex:1">P7 </li><li style="flex:1">P14 </li></ul>PTHrP Epithelial root sheath ?PPR PTHrP--acZ Osx+ progenitors Odontoblast Cementoblast PTHrP parꢀcipates in …….. -ꢀdental (root) development -ꢀhomeostasis of root-bone interface (composed by PDL, cementum) Dental follicle/papilla cells 1 3/27/14 Experimental approach (1) Working hypothesis •ꢀ Idenꢀfy how osterix-expressing progenitors contribute to murine root forma)on PTHrP HERS (Epithelial root sheath) Tamoxifen Osx-CreERT2 ?Molar root forma+on PPR P3 P4 P7 <ul style="display: flex;"><li style="flex:1">P11 </li><li style="flex:1">P25 </li></ul>Root-forming progenitors CAG Cementoblast Tomato loxP Stop loxP XDental follicle cells Cre CAG Tomato Rosa26-Tomato Osx+ cells are root-forming progenitors In vivo fate mapping of Osx+ cells Tam <ul style="display: flex;"><li style="flex:1">P3 P4 </li><li style="flex:1">P7 </li></ul>Osx+ cells <ul style="display: flex;"><li style="flex:1">P14 </li><li style="flex:1">P25 </li></ul>Dental pulp cells Osx-CreER; Tomato P4 (+1d) Dental papilla Odontoblasts Osx+ cells Periodontal ligament cells Dental follicle Postnatal day 4 Mandibular M1, mid-sagiLal secꢀon Cementoblasts Alveolar osteoblasts Experimental approach (2) <ul style="display: flex;"><li style="flex:1">Osx-Cre ; PPRflox /+ </li><li style="flex:1">PPRflox/flox </li></ul>X•ꢀ Understand how PTH/PTHrP receptor signal (PPR) regulates root-forming progenitors P7 <ul style="display: flex;"><li style="flex:1">Control </li><li style="flex:1">CondiIonal Het </li></ul>CondiIonal KO Osx-Cre ; PPRflox/+ PTH/PTHrP receptor (PPR) locus <ul style="display: flex;"><li style="flex:1">E1 </li><li style="flex:1">E2 </li></ul>PPR floxed allele Cre (Kobayashi T, Kronenberg HM et al. 2002) XE2 PPR null allele PPRflox/flox <ul style="display: flex;"><li style="flex:1">Osx-Cre ; PPRflox/+ </li><li style="flex:1">Osx-Cre; PPRflox/flox </li></ul>PPRflox/flox 2 3/27/14 PPR signal in Osx+ progenitors are essen)al for root forma)on Conclusion •ꢀ Osterix-expressing cells are dental root-forming progenitors during morphogenesis: Osx+ cells become dental pulp cells and odontoblasts, Osx+ cells PPR signal Periodontal ligament cells periodontal ligament cells, cementoblasts and alveolar osteoblasts •ꢀ Deleꢀon of PTH/PTHrP receptor in Osx+ cells leads to Dental follicle dental root malforma)on and failure of erup)on Cementoblasts 1)ꢀ Truncaꢀon of the dental root 2)ꢀ Hypogenesis of periodontal ligament 3)ꢀ Ankylosis of cementum to bone 4)ꢀ Underdeveloped mandible PPR signal 5)ꢀ Failure of molar erupꢀon “malformed/ truncated root” Acknowledgement Endocrine Unit / MassachuseLs General Hospitalꢀ Hank Kronenberg Noriaki Ono Shigeki Nishimori Tatsuya Kobayashi Marc Wein Forest Lai Everyone in the Endocrine Unit HSDM AGE Orthodonꢀcs Program Acknowledgement for Important Mice…ꢀ Arthur Broadus PTHrP-LacZ Andrew McMahon Osx-Cre::GFP 3

Ono -- PTH-Pthrp Receptor Signaling in Osterix-Expressing Progenitors.Pdf

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