title: Calmodulin interacts with Rab3D and modulates osteoclastic bone resorption.
abstract: Calmodulin is a highly versatile protein that regulates intracellular calcium homeostasis and is involved in a variety of cellular functions including cardiac excitability, synaptic plasticity and signaling transduction. During osteoclastic bone resorption, calmodulin has been reported to concentrate at the ruffled border membrane of osteoclasts where it is thought to modulate bone resorption activity in response to calcium. Here we report an interaction between calmodulin and Rab3D, a small exocytic GTPase and established regulator osteoclastic bone resorption. Using yeast two-hybrid screening together with a series of protein-protein interaction studies, we show that calmodulin interacts with Rab3D in a calcium dependent manner. Consistently, expression of a calcium insensitive form of calmodulin (i.e. CaM1234) perturbs calmodulin-Rab3D interaction as monitored by bioluminescence resonance energy transfer (BRET) assays. In osteoclasts, calmodulin and Rab3D are constitutively co-expressed during RANKL-induced osteoclast differentiation, co-occupy plasma membrane fractions by differential gradient sedimentation assay and colocalise in the ruffled border as revealed by confocal microscopy. Further, functional blockade of calmodulin-Rab3D interaction by calmidazolium chloride coincides with an attenuation of osteoclastic bone resorption. Our data imply that calmodulin- Rab3D interaction is required for efficient bone resorption by osteoclasts in vitro.
authors.affiliation: Department of Orthopaedics, The Second Affiliated Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, 325027 China.|School of Pathology and Laboratory Medicine, The University of Western Australia, Perth, WA 6009, Australia.
authors.forename: Sipin
authors.initials: S
authors.lastname: Zhu
authors.affiliation: School of Pathology and Laboratory Medicine, The University of Western Australia, Perth, WA 6009, Australia.
authors.forename: Shek Man
authors.initials: SM
authors.lastname: Chim
authors.affiliation: Centre for Orthopaedic Research, School of Surgery, The University of Western Australia, Perth, WA 6009, Australia.
authors.forename: Taksum
authors.initials: T
authors.lastname: Cheng
authors.affiliation: School of Dentistry, Oral Biology Research Laboratory, The University of Western Australia, Perth, WA 6009, Australia.
authors.forename: Estabelle
authors.initials: E
authors.lastname: Ang
authors.affiliation: School of Pathology and Laboratory Medicine, The University of Western Australia, Perth, WA 6009, Australia.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Ng
authors.affiliation: School of Pathology and Laboratory Medicine, The University of Western Australia, Perth, WA 6009, Australia.
authors.forename: Baysie
authors.initials: B
authors.lastname: Lim
authors.affiliation: School of Pathology and Laboratory Medicine, The University of Western Australia, Perth, WA 6009, Australia.
authors.forename: Kai
authors.initials: K
authors.lastname: Chen
authors.affiliation: School of Pathology and Laboratory Medicine, The University of Western Australia, Perth, WA 6009, Australia.
authors.forename: Heng
authors.initials: H
authors.lastname: Qiu
authors.affiliation: School of Pathology and Laboratory Medicine, The University of Western Australia, Perth, WA 6009, Australia.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Tickner
authors.affiliation: Department of Orthopaedics, The Second Affiliated Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, 325027 China.
authors.forename: Huazi
authors.initials: H
authors.lastname: Xu
authors.affiliation: Centre for Orthopaedic Research, School of Surgery, The University of Western Australia, Perth, WA 6009, Australia.
authors.forename: Nathan
authors.initials: N
authors.lastname: Pavlos
authors.affiliation: Department of Orthopaedics, The Second Affiliated Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, 325027 China.|School of Pathology and Laboratory Medicine, The University of Western Australia, Perth, WA 6009, Australia.
authors.forename: Jiake
authors.initials: J
authors.lastname: Xu
mesh_terms: D000818:Animals; D001862:Bone Resorption / Q000378:metabolism / Q000473:pathology*; D002147:Calmodulin / Q000378:metabolism*; D002454:Cell Differentiation; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D051379:Mice; D010010:Osteoclasts / Q000378:metabolism / Q000473:pathology*; D020798:Two-Hybrid System Techniques; D020692:rab3 GTP-Binding Proteins / Q000378:metabolism*
chemical_list: D002147:Calmodulin; C116711:Rab3d protein, mouse; D020692:rab3 GTP-Binding Proteins