Role of TAFII-17, a VDR binding protein, in the increased osteoclast formation in Paget's Disease.
In contrast to normal OCL precursors, pagetic OCL precursors express MVNP and form OCL at physiologic concentrations of 1,25(OH)2D3, as do normal OCL precursors transfected with the MVNP gene. Using a GST-VDR chimeric protein, we identified TAFII-17 as VDR binding protein expressed by pagetic OCL precursors and MVNP transduced normal OCL precursors. TAF(II)-17 was in part responsible for the increased 1,25(OH)2D3 responsivity of pagetic OCL precursors.


BACKGROUND
Pagetic osteoclasts (OCLs) and their precursors express measles virus nucleocapsid protein (MVNP) and form large numbers of OCLs at low concentrations of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3]. Similarly, normal OCL precursors transfected with MVNP also form OCLs at low concentrations of 1,25(OH)2D3. These results suggest that expression of MVNP in OCL precursors enhances vitamin D receptor (VDR)-mediated gene transcription.


METHODS
To determine the mechanism for the increased OCL formation capacity of pagetic OCL precursors in response to 1,25(OH)2D3, lysates from pagetic and MVNP-transduced normal OCL precursors were incubated with a GST-VDR chimeric protein.


RESULTS
A 17-kDa peptide that bound VDR was detected in MVNP-transduced cells and pagetic OCL precursors treated with 1,25(OH)2D3. This peptide was identified as TAFII-17, a component of the TFIID transcription complex. Expression of increased levels of TAFII-17 in cells allowed TAFII-17 to bind to VDR at low concentrations of 1,25(OH)2D3. An antisense oligonucelotide (AS-ODN) to TAFII-17 significantly decreased OCL formation in response to 1,25(OH)2D3 in pagetic but not normal marrow cultures by approximately 40%. Transfection of TAFII-17 or MVNP into NIH3T3 cells increased VDR transcriptional activity as measured by DR-3 reporter assays.


CONCLUSIONS
These data show that expression of the MVNP gene in OCL precursors results in increased levels of TAFII-17. TAFII-17 can bind VDR at low concentrations of 1,25(OH)2D3. These results suggest that MVNP expression in Paget's OCL precursors increases expression of a component(s) of the VDR transcription complex that can increase OCL formation.
Kurihara
Noriyoshi
N
Department of Medicine/Hematology and Oncology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
Reddy
Sakamuri V
SV
Araki
Norie
N
Ishizuka
Seiichi
S
Ozono
Keiichi
K
Cornish
Jillian
J
Cundy
Tim
T
Singer
Frederick R
FR
Roodman
G David
GD
D001854:Bone Marrow Cells / Q000378:metabolism; D001862:Bone Resorption / Q000378:metabolism; D002460:Cell Line; D016373:DNA, Antisense / Q000494:pharmacology; D020868:Gene Silencing; D006801:Humans; D019590:Nucleocapsid Proteins; D009698:Nucleoproteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D010001:Osteitis Deformans / Q000378:metabolism*; D010010:Osteoclasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010455:Peptides; D025941:Protein Interaction Mapping; D018167:Receptors, Calcitriol / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D020539:Sequence Analysis, Protein; D035362:Transcription Factor TFIID / Q000032:analysis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014161:Transduction, Genetic; D014758:Viral Core Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000494:pharmacology
D016373:DNA, Antisense; D019590:Nucleocapsid Proteins; D009698:Nucleoproteins; D010455:Peptides; D018167:Receptors, Calcitriol; C494394:TAFII-17 protein, human; D035362:Transcription Factor TFIID; D014758:Viral Core Proteins; C118756:dihydroxy-vitamin D3; D014807:Vitamin D