Cbfa1 isoform overexpression upregulates osteocalcin gene expression in non-osteoblastic and pre-osteoblastic cells

Research output: Contribution to journalArticle

95 Citations (Scopus)

Abstract

The mouse Cbfa1 gene potentially encodes several proteins that differ in their N-terminal sequences, including an osteoblast-specific transcription factor, Cbfa1/Osf2, a Cbfa1 isoform (Cbfa1/iso), and the originally described Cbfa 1 gene product (Cbfa 1/org). Uncertainty exists about the function of these potential isoforms of the Cbfa 1 gene. To examine the transactivation potential of different Cbfa 1 gene products, we compared the ability of Cbfa 1/Osf2, Cbfa 1/iso, and Cbfa 1/org overexpression to activate an osteocalcin promoter/reporter construct in NIH3T3 fibroblasts, C3H10T1/2 pluripotent cells and MC3T3-E1 pre-osteoblasts. These three cell lines were transiently cotransfected with a 1.3-kb mouse osteocalcin promoter luciferase-fusion construct (p1.3OC-luc) and different amounts of expression vectors containing the respective full-length Cbfa 1 isoform cDNAs. Using transfection protocols with lower amounts of expression plasmid DNAs, we found that all three Cbfa 1 isoforms stimulated osteocalcin promoter activity in each of the cell types, consistent with the their ability to induce expression of an osteoblast- specific gene both in non-osteoblast cells and in osteoblast cell lines. However, using transfection protocols with higher amounts of expression plasmids containing Cbfa1 cDNAs, we found that the Cbfa1/Osf2 and Cbfa1/org had less transactivating potential compared with Cbfa 1/iso. Our studies suggest that the 87-amino acid N-terminus of Cbfa 1/Osf2 is not crucial for optimal transactivation, whereas the 19-amino acid N-terminal sequence of Cbfa1/iso augments transcriptional activation only at high doses of the expression plasmid. The physiological significance of these in vitro findings remain to be determined.

Original languageEnglish (US)
Pages (from-to)596-605
Number of pages10
JournalJournal of Cellular Biochemistry
Volume74
Issue number4
DOIs
StatePublished - Sep 15 1999
Externally publishedYes

Fingerprint

Osteocalcin
Gene expression
Osteoblasts
Protein Isoforms
Up-Regulation
Genes
Gene Expression
Transcriptional Activation
Plasmids
Transfection
Core Binding Factor Alpha 1 Subunit
Complementary DNA
Cells
Amino Acids
Cell Line
Fibroblasts
Luciferases
Uncertainty
Transcription Factors
Fusion reactions

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Cell Biology

Cite this

@article{5d225f8117ef4779bada6611a5e6d925,
title = "Cbfa1 isoform overexpression upregulates osteocalcin gene expression in non-osteoblastic and pre-osteoblastic cells",
abstract = "The mouse Cbfa1 gene potentially encodes several proteins that differ in their N-terminal sequences, including an osteoblast-specific transcription factor, Cbfa1/Osf2, a Cbfa1 isoform (Cbfa1/iso), and the originally described Cbfa 1 gene product (Cbfa 1/org). Uncertainty exists about the function of these potential isoforms of the Cbfa 1 gene. To examine the transactivation potential of different Cbfa 1 gene products, we compared the ability of Cbfa 1/Osf2, Cbfa 1/iso, and Cbfa 1/org overexpression to activate an osteocalcin promoter/reporter construct in NIH3T3 fibroblasts, C3H10T1/2 pluripotent cells and MC3T3-E1 pre-osteoblasts. These three cell lines were transiently cotransfected with a 1.3-kb mouse osteocalcin promoter luciferase-fusion construct (p1.3OC-luc) and different amounts of expression vectors containing the respective full-length Cbfa 1 isoform cDNAs. Using transfection protocols with lower amounts of expression plasmid DNAs, we found that all three Cbfa 1 isoforms stimulated osteocalcin promoter activity in each of the cell types, consistent with the their ability to induce expression of an osteoblast- specific gene both in non-osteoblast cells and in osteoblast cell lines. However, using transfection protocols with higher amounts of expression plasmids containing Cbfa1 cDNAs, we found that the Cbfa1/Osf2 and Cbfa1/org had less transactivating potential compared with Cbfa 1/iso. Our studies suggest that the 87-amino acid N-terminus of Cbfa 1/Osf2 is not crucial for optimal transactivation, whereas the 19-amino acid N-terminal sequence of Cbfa1/iso augments transcriptional activation only at high doses of the expression plasmid. The physiological significance of these in vitro findings remain to be determined.",
author = "Zhousheng Xiao and Hinson, {T. K.} and Leigh Quarles",
year = "1999",
month = "9",
day = "15",
doi = "10.1002/(SICI)1097-4644(19990915)74:4<596::AID-JCB9>3.0.CO;2-F",
language = "English (US)",
volume = "74",
pages = "596--605",
journal = "Journal of Cellular Biochemistry",
issn = "0730-2312",
publisher = "Wiley-Liss Inc.",
number = "4",

}

TY - JOUR

T1 - Cbfa1 isoform overexpression upregulates osteocalcin gene expression in non-osteoblastic and pre-osteoblastic cells

AU - Xiao, Zhousheng

AU - Hinson, T. K.

AU - Quarles, Leigh

PY - 1999/9/15

Y1 - 1999/9/15

N2 - The mouse Cbfa1 gene potentially encodes several proteins that differ in their N-terminal sequences, including an osteoblast-specific transcription factor, Cbfa1/Osf2, a Cbfa1 isoform (Cbfa1/iso), and the originally described Cbfa 1 gene product (Cbfa 1/org). Uncertainty exists about the function of these potential isoforms of the Cbfa 1 gene. To examine the transactivation potential of different Cbfa 1 gene products, we compared the ability of Cbfa 1/Osf2, Cbfa 1/iso, and Cbfa 1/org overexpression to activate an osteocalcin promoter/reporter construct in NIH3T3 fibroblasts, C3H10T1/2 pluripotent cells and MC3T3-E1 pre-osteoblasts. These three cell lines were transiently cotransfected with a 1.3-kb mouse osteocalcin promoter luciferase-fusion construct (p1.3OC-luc) and different amounts of expression vectors containing the respective full-length Cbfa 1 isoform cDNAs. Using transfection protocols with lower amounts of expression plasmid DNAs, we found that all three Cbfa 1 isoforms stimulated osteocalcin promoter activity in each of the cell types, consistent with the their ability to induce expression of an osteoblast- specific gene both in non-osteoblast cells and in osteoblast cell lines. However, using transfection protocols with higher amounts of expression plasmids containing Cbfa1 cDNAs, we found that the Cbfa1/Osf2 and Cbfa1/org had less transactivating potential compared with Cbfa 1/iso. Our studies suggest that the 87-amino acid N-terminus of Cbfa 1/Osf2 is not crucial for optimal transactivation, whereas the 19-amino acid N-terminal sequence of Cbfa1/iso augments transcriptional activation only at high doses of the expression plasmid. The physiological significance of these in vitro findings remain to be determined.

AB - The mouse Cbfa1 gene potentially encodes several proteins that differ in their N-terminal sequences, including an osteoblast-specific transcription factor, Cbfa1/Osf2, a Cbfa1 isoform (Cbfa1/iso), and the originally described Cbfa 1 gene product (Cbfa 1/org). Uncertainty exists about the function of these potential isoforms of the Cbfa 1 gene. To examine the transactivation potential of different Cbfa 1 gene products, we compared the ability of Cbfa 1/Osf2, Cbfa 1/iso, and Cbfa 1/org overexpression to activate an osteocalcin promoter/reporter construct in NIH3T3 fibroblasts, C3H10T1/2 pluripotent cells and MC3T3-E1 pre-osteoblasts. These three cell lines were transiently cotransfected with a 1.3-kb mouse osteocalcin promoter luciferase-fusion construct (p1.3OC-luc) and different amounts of expression vectors containing the respective full-length Cbfa 1 isoform cDNAs. Using transfection protocols with lower amounts of expression plasmid DNAs, we found that all three Cbfa 1 isoforms stimulated osteocalcin promoter activity in each of the cell types, consistent with the their ability to induce expression of an osteoblast- specific gene both in non-osteoblast cells and in osteoblast cell lines. However, using transfection protocols with higher amounts of expression plasmids containing Cbfa1 cDNAs, we found that the Cbfa1/Osf2 and Cbfa1/org had less transactivating potential compared with Cbfa 1/iso. Our studies suggest that the 87-amino acid N-terminus of Cbfa 1/Osf2 is not crucial for optimal transactivation, whereas the 19-amino acid N-terminal sequence of Cbfa1/iso augments transcriptional activation only at high doses of the expression plasmid. The physiological significance of these in vitro findings remain to be determined.

UR - http://www.scopus.com/inward/record.url?scp=0033567874&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0033567874&partnerID=8YFLogxK

U2 - 10.1002/(SICI)1097-4644(19990915)74:4<596::AID-JCB9>3.0.CO;2-F

DO - 10.1002/(SICI)1097-4644(19990915)74:4<596::AID-JCB9>3.0.CO;2-F

M3 - Article

VL - 74

SP - 596

EP - 605

JO - Journal of Cellular Biochemistry

JF - Journal of Cellular Biochemistry

SN - 0730-2312

IS - 4

ER -