Transforming growth factor β1 (TGFβ1) is a pluripotent cytokine that works in conjunction with other cytokines to modulate their effects on cell function. Our previous work demonstrated that the combination of TGFβ1 and 1α,25-dihydroxyvitamin D3 had a synergistic effect on alkaline phosphatase induction (500 to 700%) in human osteoblastic osteosarcoma cells (MG63). The current studies focused on the molecular basis of alkaline phosphatase induction, including the regulation of the signal transduction and modification of 1α,25-dihydroxyvitamin D3 receptors (VDR). We demonstrated that alkaline phosphatase activity was regulated at the transcription level. TGFβ1 at 1 ng/ml alone had little effect on alkaline phosphatase mRNA induction and 1α,25-dihydroxy vitamin D3 at 10-8 M increased alkaline phosphatase mRNA to about 200% over the control value. The combination of TGFβ1 and 1α,25-dihydroxyvitamin D3 significantly increased alkaline phosphatase mRNA about 800% over the control. The peak response was at 24 hours. Studies of the signal transduction mechanism provided evidence that the protein kinase C pathway was involved in the alkaline phosphatase stimulation by the combination of TGFβ1 and 1α,25-dihydroxyvitamin D3; MG63 cells express at least seven protein kinase C isoforms and PKCy was activated by TGFβ1 or 1α,25-dihydroxyvitamin D3 after 30 minute treatment. Studies on the VDR demonstrated that TGFβ1 or its combination with 1α,25-dihydroxyvitamin D3 significantly increased VDR mRNA about 300% and 500% respectively over the control by 3 hours. 1α,25-dihydroxyvitamin D3 increased VDR mRNA about 200% by 24 hour. The VDR protein level was also significantly elevated by the combination of TGFβ1 with 1α,25-dihydroxyvitamin D3. The peak response at 6 hours was 300% above the control level. Our studies further showed that a 2 hour treatment with TGFβ1 and 1α,25-dihydroxy vitamin D3 significantly stimulated VDR phosphorylation to 700% and 300% above the control, respectively. When cells were treated with the combination of TGFβ1 and 1α,25-dihydroxyvitamin D3, there was an additive effect on VDR phosphorylation to about 1000% over the control value. Conclusions: (1) PKCy is involved in the TGFβ and 1α, 25-dihydroxyvitamin D3 signal transduction pathway. (2) TGFβ potentiates the action of 1α,25-dihydroxyvitamin D3 by stimulation of VDR mRNA, VDR protein and VDR phosphorylation. These changes further enhance the effect of 1α,25-dihydroxy vitamin D3 on the cellular levels of alkaline phosphatase mRNA and alkaline phosphatase activity.
","abstract_html":"<p>Transforming growth factor β<sub>1 </sub>(TGFβ<sub>1</sub>) is a pluripotent cytokine that works in conjunction with other cytokines to modulate their effects on cell function. Our previous work demonstrated that the combination of TGFβ<sub>1</sub> and 1α,25-dihydroxyvitamin D<sub>3</sub> had a synergistic effect on alkaline phosphatase induction (500 to 700%) in human osteoblastic osteosarcoma cells (MG63). The current studies focused on the molecular basis of alkaline phosphatase induction, including the regulation of the signal transduction and modification of 1α,25-dihydroxyvitamin D<sub>3</sub> receptors (VDR). We demonstrated that alkaline phosphatase activity was regulated at the transcription level. TGFβ<sub>1</sub> at 1 ng/ml alone had little effect on alkaline phosphatase mRNA induction and 1α,25-dihydroxy vitamin D<sub>3</sub> at 10<sup>-8</sup> M increased alkaline phosphatase mRNA to about 200% over the control value. The combination of TGFβ<sub>1</sub> and 1α,25-dihydroxyvitamin D<sub>3</sub> significantly increased alkaline phosphatase mRNA about 800% over the control. The peak response was at 24 hours. Studies of the signal transduction mechanism provided evidence that the protein kinase C pathway was involved in the alkaline phosphatase stimulation by the combination of TGFβ<sub>1</sub> and 1α,25-dihydroxyvitamin D3; MG63 cells express at least seven protein kinase C isoforms and PKC<sub>y</sub> was activated by TGFβ<sub>1</sub> or 1α,25-dihydroxyvitamin D<sub>3</sub> after 30 minute treatment. Studies on the VDR demonstrated that TGFβ<sub>1</sub> or its combination with 1α,25-dihydroxyvitamin D<sub>3</sub> significantly increased VDR mRNA about 300% and 500% respectively over the control by 3 hours. 1α,25-dihydroxyvitamin D<sub>3</sub> increased VDR mRNA about 200% by 24 hour. The VDR protein level was also significantly elevated by the combination of TGFβ<sub>1</sub> with 1α,25-dihydroxyvitamin D3. The peak response at 6 hours was 300% above the control level. Our studies further showed that a 2 hour treatment with TGFβ<sub>1</sub> and 1α,25-dihydroxy vitamin D<sub>3</sub> significantly stimulated VDR phosphorylation to 700% and 300% above the control, respectively. When cells were treated with the combination of TGFβ<sub>1</sub> and 1α,25-dihydroxyvitamin D<sub>3,</sub> there was an additive effect on VDR phosphorylation to about 1000% over the control value. Conclusions: (1) PKC<sub>y</sub> is involved in the TGFβ and 1α, 25-dihydroxyvitamin D<sub>3</sub> signal transduction pathway. (2) TGFβ potentiates the action of 1α,25-dihydroxyvitamin D<sub>3</sub> by stimulation of VDR mRNA, VDR protein and VDR phosphorylation. These changes further enhance the effect of 1α,25-dihydroxy vitamin D<sub>3</sub> on the cellular levels of alkaline phosphatase mRNA and alkaline phosphatase activity.</p>","abstract_has_math":false,"creators":["Song, XinDe"],"institution":null,"degree_name":"Doctor of Philosophy (PhD)","degree_level":"Dissertation","degree_discipline":"Biochemistry","degree_department":null,"school":null,"contributors":["Jon E. Wergedal","Thomas A. Linkhart","Lora M. Green","E. Clifford Herrmann","Kelvin A. W. Hill"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":1996,"date_issued":"1996-03-01T08:00:00Z","date_published":"1996-03-01T08:00:00Z","updated_at":"2026-07-24T02:53:37Z","subjects":["Biochemistry","Osteosarcoma; Transforming Growth Factor beta; Calcitriol"],"languages":["English"],"rights":["This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights."],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://scholarsrepository.llu.edu/etd/987","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Jon E. Wergedal","Thomas A. Linkhart","Lora M. Green","E. Clifford Herrmann","Kelvin A. W. Hill"]},{"key":"dc:creator","label":"Author","values":["Song, XinDe"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"thesis:degree_discipline","label":"Discipline","values":["Biochemistry"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Doctor of Philosophy (PhD)"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Biochemistry","Osteosarcoma; Transforming Growth Factor beta; Calcitriol"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["English"]},{"key":"dc:rights","label":"Dc Rights","values":["This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights."]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://scholarsrepository.llu.edu/etd/987"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Transforming growth factor β1 (TGFβ1) is a pluripotent cytokine that works in conjunction with other cytokines to modulate their effects on cell function. Our previous work demonstrated that the combination of TGFβ1 and 1α,25-dihydroxyvitamin D3 had a synergistic effect on alkaline phosphatase induction (500 to 700%) in human osteoblastic osteosarcoma cells (MG63). The current studies focused on the molecular basis of alkaline phosphatase induction, including the regulation of the signal transduction and modification of 1α,25-dihydroxyvitamin D3 receptors (VDR). We demonstrated that alkaline phosphatase activity was regulated at the transcription level. TGFβ1 at 1 ng/ml alone had little effect on alkaline phosphatase mRNA induction and 1α,25-dihydroxy vitamin D3 at 10-8 M increased alkaline phosphatase mRNA to about 200% over the control value. The combination of TGFβ1 and 1α,25-dihydroxyvitamin D3 significantly increased alkaline phosphatase mRNA about 800% over the control. The peak response was at 24 hours. Studies of the signal transduction mechanism provided evidence that the protein kinase C pathway was involved in the alkaline phosphatase stimulation by the combination of TGFβ1 and 1α,25-dihydroxyvitamin D3; MG63 cells express at least seven protein kinase C isoforms and PKCy was activated by TGFβ1 or 1α,25-dihydroxyvitamin D3 after 30 minute treatment. Studies on the VDR demonstrated that TGFβ1 or its combination with 1α,25-dihydroxyvitamin D3 significantly increased VDR mRNA about 300% and 500% respectively over the control by 3 hours. 1α,25-dihydroxyvitamin D3 increased VDR mRNA about 200% by 24 hour. The VDR protein level was also significantly elevated by the combination of TGFβ1 with 1α,25-dihydroxyvitamin D3. The peak response at 6 hours was 300% above the control level. Our studies further showed that a 2 hour treatment with TGFβ1 and 1α,25-dihydroxy vitamin D3 significantly stimulated VDR phosphorylation to 700% and 300% above the control, respectively. When cells were treated with the combination of TGFβ1 and 1α,25-dihydroxyvitamin D3, there was an additive effect on VDR phosphorylation to about 1000% over the control value. Conclusions: (1) PKCy is involved in the TGFβ and 1α, 25-dihydroxyvitamin D3 signal transduction pathway. (2) TGFβ potentiates the action of 1α,25-dihydroxyvitamin D3 by stimulation of VDR mRNA, VDR protein and VDR phosphorylation. These changes further enhance the effect of 1α,25-dihydroxy vitamin D3 on the cellular levels of alkaline phosphatase mRNA and alkaline phosphatase activity.
"]},{"key":"dc:title","label":"Title","values":["Regulation of Human Osteosarcoma Cell Differentiation by Transforming Growth Factor B1 (TGFB and 1a,25- Dihydroxyvitamin D3 : the Mechanism of TGFB1 Potentiation of 1,25D3-induced Alkaline Phosphatase Activity in Human MG63 Osteosarcoma Cell"]}]}],"canonical_facts":{"dc:contributor":["Jon E. Wergedal","Thomas A. Linkhart","Lora M. Green","E. Clifford Herrmann","Kelvin A. W. Hill"],"dc:creator":["Song, XinDe"],"dc:description.abstract":["Transforming growth factor β1 (TGFβ1) is a pluripotent cytokine that works in conjunction with other cytokines to modulate their effects on cell function. Our previous work demonstrated that the combination of TGFβ1 and 1α,25-dihydroxyvitamin D3 had a synergistic effect on alkaline phosphatase induction (500 to 700%) in human osteoblastic osteosarcoma cells (MG63). The current studies focused on the molecular basis of alkaline phosphatase induction, including the regulation of the signal transduction and modification of 1α,25-dihydroxyvitamin D3 receptors (VDR). We demonstrated that alkaline phosphatase activity was regulated at the transcription level. TGFβ1 at 1 ng/ml alone had little effect on alkaline phosphatase mRNA induction and 1α,25-dihydroxy vitamin D3 at 10-8 M increased alkaline phosphatase mRNA to about 200% over the control value. The combination of TGFβ1 and 1α,25-dihydroxyvitamin D3 significantly increased alkaline phosphatase mRNA about 800% over the control. The peak response was at 24 hours. Studies of the signal transduction mechanism provided evidence that the protein kinase C pathway was involved in the alkaline phosphatase stimulation by the combination of TGFβ1 and 1α,25-dihydroxyvitamin D3; MG63 cells express at least seven protein kinase C isoforms and PKCy was activated by TGFβ1 or 1α,25-dihydroxyvitamin D3 after 30 minute treatment. Studies on the VDR demonstrated that TGFβ1 or its combination with 1α,25-dihydroxyvitamin D3 significantly increased VDR mRNA about 300% and 500% respectively over the control by 3 hours. 1α,25-dihydroxyvitamin D3 increased VDR mRNA about 200% by 24 hour. The VDR protein level was also significantly elevated by the combination of TGFβ1 with 1α,25-dihydroxyvitamin D3. The peak response at 6 hours was 300% above the control level. Our studies further showed that a 2 hour treatment with TGFβ1 and 1α,25-dihydroxy vitamin D3 significantly stimulated VDR phosphorylation to 700% and 300% above the control, respectively. When cells were treated with the combination of TGFβ1 and 1α,25-dihydroxyvitamin D3, there was an additive effect on VDR phosphorylation to about 1000% over the control value. Conclusions: (1) PKCy is involved in the TGFβ and 1α, 25-dihydroxyvitamin D3 signal transduction pathway. (2) TGFβ potentiates the action of 1α,25-dihydroxyvitamin D3 by stimulation of VDR mRNA, VDR protein and VDR phosphorylation. These changes further enhance the effect of 1α,25-dihydroxy vitamin D3 on the cellular levels of alkaline phosphatase mRNA and alkaline phosphatase activity.
"],"dc:identifier":["https://scholarsrepository.llu.edu/etd/987"],"dc:language":["English"],"dc:rights":["This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights."],"dc:subject":["Biochemistry","Osteosarcoma; Transforming Growth Factor beta; Calcitriol"],"dc:title":["Regulation of Human Osteosarcoma Cell Differentiation by Transforming Growth Factor B1 (TGFB and 1a,25- Dihydroxyvitamin D3 : the Mechanism of TGFB1 Potentiation of 1,25D3-induced Alkaline Phosphatase Activity in Human MG63 Osteosarcoma Cell"],"thesis:degree_discipline":["Biochemistry"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Doctor of Philosophy (PhD)"]},"updated_at":"2026-07-24T02:53:37Z"}