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Rolipram, a phosphodiesterase 4 inhibitor, stimulates inducible cAMP early repressor expression in osteoblasts.

Cho ES, Yu JH, Kim MS, Yim M - Yonsei Med. J. (2005)

Bottom Line: This study investigated the effect of a PDE4 inhibitor on the expression of the inducible cAMP early repressor (ICER), which is an endogenous inhibitor of CRE- mediated transcription, in osteoblastic cells.RT-PCR analysis revealed that rolipram, a PDE4 inhibitor, stimulates the ICER mRNA in a dose dependent manner.The induction of ICER mRNA expression by rolipram was suppressed by the inhibitors of protein kinase A (PKA) and p38 MAPK, suggesting the involvement of PKA and p38 MAPK activation in ICER expression by rolipram.

View Article: PubMed Central - PubMed

Affiliation: College of Pharmacy, Sookmyung Women's University, Seoul 140-742, Korea.

ABSTRACT
Phosphodiesterase (PDE) 4 inhibitors have been shown to induce the cAMP-mediated signaling pathway by inhibiting cAMP hydrolysis. This study investigated the effect of a PDE4 inhibitor on the expression of the inducible cAMP early repressor (ICER), which is an endogenous inhibitor of CRE- mediated transcription, in osteoblastic cells. RT-PCR analysis revealed that rolipram, a PDE4 inhibitor, stimulates the ICER mRNA in a dose dependent manner. The induction of ICER mRNA expression by rolipram was suppressed by the inhibitors of protein kinase A (PKA) and p38 MAPK, suggesting the involvement of PKA and p38 MAPK activation in ICER expression by rolipram. It was previously shown that rolipram induced the expression of TNF-related activation-induced cytokine (TRANCE, also known as RANKL, ODF, or OPGL) in osteoblasts. This paper provides evidences that a transcriptional repressor like ICER might modulate TRANCE mRNA expression by rolipram in osteoblasts.

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The attenuation of rolipram-induced TRANCE mRNA expression requires the transcriptional repressor in osteoblasts. A. UAMS-32 cells were treated with 5 µM rolipram, 1 µg/ml cycloheximide (CHX) or rolipram and CHX (the CHX was added 1hr before the rolipram). The total RNA was extracted from the cells at the indicated times. Total RNA was analyzed by Northern blot using probes for TRANCE and GAPDH. B. primary mouse calvarial cells were treated in a similar manner shown in A.
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Figure 3: The attenuation of rolipram-induced TRANCE mRNA expression requires the transcriptional repressor in osteoblasts. A. UAMS-32 cells were treated with 5 µM rolipram, 1 µg/ml cycloheximide (CHX) or rolipram and CHX (the CHX was added 1hr before the rolipram). The total RNA was extracted from the cells at the indicated times. Total RNA was analyzed by Northern blot using probes for TRANCE and GAPDH. B. primary mouse calvarial cells were treated in a similar manner shown in A.

Mentions: It was previously reported that rolipram stimulates TRANCE mRNA expression in osteoblastic cells.22 In order to determine if intermediate gene expression is essential for the effects of rolipram on TRANCE expression, the UAMS-32 cells were treated with rolipram for 3, 9, 24 hrs in the presence or absence of the protein synthesis inhibitor, cycloheximide. Cycloheximide alone stimulated the TRANCE mRNA levels at 3 and 9 hrs but did not block the additional stimulatory action of rolipram in the UAMS-32 cells (Fig. 3A). This indicates that rolipram stimulates TRANCE mRNA expression in osteoblastic cells directly. The expression level of TRANCE mRNA by rolipram decreased at 9 hrs and returned almost to the baseline by 24 hrs (Fig. 3A). However, pretreatment of cycloheximide caused a continuing increase in the TRANCE mRNA expression level at 9 hrs, suggesting the possible involvement of a transcriptional repressor such as ICER on TRANCE expression in osteoblastic cells. Primary mouse calvarial cells were used in order to exclude the possibility that the effect of cycloheximide on rolipram-induced TRANCE expression is unique in UAMS-32 cells. As shown in Fig. 3B, similar results were also obtained in primary mouse calvarial cells.


Rolipram, a phosphodiesterase 4 inhibitor, stimulates inducible cAMP early repressor expression in osteoblasts.

Cho ES, Yu JH, Kim MS, Yim M - Yonsei Med. J. (2005)

The attenuation of rolipram-induced TRANCE mRNA expression requires the transcriptional repressor in osteoblasts. A. UAMS-32 cells were treated with 5 µM rolipram, 1 µg/ml cycloheximide (CHX) or rolipram and CHX (the CHX was added 1hr before the rolipram). The total RNA was extracted from the cells at the indicated times. Total RNA was analyzed by Northern blot using probes for TRANCE and GAPDH. B. primary mouse calvarial cells were treated in a similar manner shown in A.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2823041&req=5

Figure 3: The attenuation of rolipram-induced TRANCE mRNA expression requires the transcriptional repressor in osteoblasts. A. UAMS-32 cells were treated with 5 µM rolipram, 1 µg/ml cycloheximide (CHX) or rolipram and CHX (the CHX was added 1hr before the rolipram). The total RNA was extracted from the cells at the indicated times. Total RNA was analyzed by Northern blot using probes for TRANCE and GAPDH. B. primary mouse calvarial cells were treated in a similar manner shown in A.
Mentions: It was previously reported that rolipram stimulates TRANCE mRNA expression in osteoblastic cells.22 In order to determine if intermediate gene expression is essential for the effects of rolipram on TRANCE expression, the UAMS-32 cells were treated with rolipram for 3, 9, 24 hrs in the presence or absence of the protein synthesis inhibitor, cycloheximide. Cycloheximide alone stimulated the TRANCE mRNA levels at 3 and 9 hrs but did not block the additional stimulatory action of rolipram in the UAMS-32 cells (Fig. 3A). This indicates that rolipram stimulates TRANCE mRNA expression in osteoblastic cells directly. The expression level of TRANCE mRNA by rolipram decreased at 9 hrs and returned almost to the baseline by 24 hrs (Fig. 3A). However, pretreatment of cycloheximide caused a continuing increase in the TRANCE mRNA expression level at 9 hrs, suggesting the possible involvement of a transcriptional repressor such as ICER on TRANCE expression in osteoblastic cells. Primary mouse calvarial cells were used in order to exclude the possibility that the effect of cycloheximide on rolipram-induced TRANCE expression is unique in UAMS-32 cells. As shown in Fig. 3B, similar results were also obtained in primary mouse calvarial cells.

Bottom Line: This study investigated the effect of a PDE4 inhibitor on the expression of the inducible cAMP early repressor (ICER), which is an endogenous inhibitor of CRE- mediated transcription, in osteoblastic cells.RT-PCR analysis revealed that rolipram, a PDE4 inhibitor, stimulates the ICER mRNA in a dose dependent manner.The induction of ICER mRNA expression by rolipram was suppressed by the inhibitors of protein kinase A (PKA) and p38 MAPK, suggesting the involvement of PKA and p38 MAPK activation in ICER expression by rolipram.

View Article: PubMed Central - PubMed

Affiliation: College of Pharmacy, Sookmyung Women's University, Seoul 140-742, Korea.

ABSTRACT
Phosphodiesterase (PDE) 4 inhibitors have been shown to induce the cAMP-mediated signaling pathway by inhibiting cAMP hydrolysis. This study investigated the effect of a PDE4 inhibitor on the expression of the inducible cAMP early repressor (ICER), which is an endogenous inhibitor of CRE- mediated transcription, in osteoblastic cells. RT-PCR analysis revealed that rolipram, a PDE4 inhibitor, stimulates the ICER mRNA in a dose dependent manner. The induction of ICER mRNA expression by rolipram was suppressed by the inhibitors of protein kinase A (PKA) and p38 MAPK, suggesting the involvement of PKA and p38 MAPK activation in ICER expression by rolipram. It was previously shown that rolipram induced the expression of TNF-related activation-induced cytokine (TRANCE, also known as RANKL, ODF, or OPGL) in osteoblasts. This paper provides evidences that a transcriptional repressor like ICER might modulate TRANCE mRNA expression by rolipram in osteoblasts.

Show MeSH
Related in: MedlinePlus