Osteoclast-stimulating factor interacts with the spinal muscular atrophy gene product to stimulate osteoclast formation.
We have recently identified and cloned an intracellular peptide termed osteoclast-stimulating factor (OSF) that increases osteoclast (OCL) formation and bone resorption through a cellular signal transduction cascade, possibly through its interaction with c-Src or related family members. To further identify participants in the OSF signaling cascade, we used yeast two-hybrid screening with Saccharomyces cerevisiae, and we found that the 40-kDa spinal muscular atrophy disease-determining gene product, survival motor neuron (SMN), interacts with the OSF-Src homology 3 domain. Reverse transcription-polymerase chain reaction analysis of SMN mRNA expression in cells of the OCL lineage demonstrates that expression of the exon 7 splice variant of SMN is restricted to mature OCLs, whereas the unspliced transcript was expressed in OCL precursors as well as mature OCLs. Treatment of murine bone marrow cultures with conditioned media (5% (v/v)) from 293 cells transiently expressing the SMN cDNA significantly increased OCL formation, compared with treatment with conditioned media from mock-transfected cells. Furthermore, OCL-stimulatory activity by OSF or SMN was abolished by antisense constructs to SMN or OSF, respectively. These data confirm the participation of SMN in the OSF-enhanced expression of an OCL stimulator. OSF-SMN interaction may provide more insights into novel cellular signaling mechanisms that may play an important role in congenital bone fractures associated with type I spinal muscular atrophy disease.
Kurihara
N
N
Department of Medicine/Hematology, The University of Texas Health Science Center, San Antonio, Texas 78229, USA.
Menaa
C
C
Maeda
H
H
Haile
D J
DJ
Reddy
S V
SV
D000818:Animals; D001483:Base Sequence; D017362:Cyclic AMP Response Element-Binding Protein; D017931:DNA Primers; D018076:DNA, Complementary; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D008810:Mice, Inbred C57BL; D009419:Nerve Tissue Proteins / Q000378:metabolism / Q000502:physiology*; D010010:Osteoclasts / Q000166:cytology*; D010455:Peptides / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D011485:Protein Binding; D016601:RNA-Binding Proteins; D020133:Reverse Transcriptase Polymerase Chain Reaction; D055532:SMN Complex Proteins; D020798:Two-Hybrid System Techniques
D017362:Cyclic AMP Response Element-Binding Protein; D017931:DNA Primers; D018076:DNA, Complementary; D047908:Intracellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins; D010455:Peptides; D016601:RNA-Binding Proteins; D055532:SMN Complex Proteins; C408994:osteoclast stimulating factor