Downregulation of cAMP-dependent protein kinase inhibitor γ is required for BMP-2-induced osteoblastic differentiation

Zhao, Li; Yang, Shengnan; Zhou, Guangqian; Yang, Jianyu; Ji, Dejun; Sabatakos, G.; Zhu, Tianhui

doi:10.1016/j.biocel.2006.05.015

Cited by 22 publications

(29 citation statements)

References 47 publications

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“…It is likely that signaling is mediated via the AP1 complex. Thus, following stimulation with BMP‐2 and TGF‐β, there was a concomitant increase in expression and activity of c‐Jun, an important constituent of the AP1 signaling complex 25, 26. That there was robust activation of AP1 was evident from studies of the activity of the AP1‐responsive reporter.…”

Section: Discussionmentioning

confidence: 98%

BMP-2 and TGF-β stimulate expression of β1,3-glucuronosyl transferase 1 (GlcAT-1) in nucleus pulposus cells through AP1, TonEBP, and Sp1: Role of MAPKs

Hiyama

Gogate

Gajghate

et al. 2010

Journal of Bone and Mineral Research

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The goal of the study was to investigate bone morphogenetic protein 2 (BMP-2) and transforming growth factor β (TGF-β) control of the expression of β1,3-glucuronosyl transferase 1 (GlcAT-1), an important regulator of chondroitin sulfate synthesis in cells of the nucleus pulposus. Treatment with both growth factors resulted in induction of GlcAT-1 expression and promoter activity. Deletion analysis indicated that promoter constructs lacking AP1 and TonE sites were unresponsive to growth factor treatment. Experiments using dominant-negative proteins showed that these transcription factors along with Sp1 were required for induction of GlcAT-1 promoter activity. Moreover, when either AP1 or TonE binding sites were mutated, induction was suppressed. Both BMP-2 and TGF-β increased c-Jun and TonEBP expression and phosphorylation of transactivation domains. We investigated the role of the mitogen-activated protein kinase (MAPK) signaling pathway following growth factor treatment; a robust and transient activation of ERK1/2, p38, and JNK was noted. Treatment with MAPK inhibitors blocked BMP-2- and TGF-β-induced AP1 reporter function, GlcAT-1 expression, and GAG accumulation. We found that DN-ERK1 but not DN-ERK2 resulted in suppression of growth factor–mediated induction of GlcAT-1 promoter activity; we also showed that p38δ was important in GlcAT-1 activation. Results of these studies demonstrate that BMP-2 and TGF-β regulate GlcAT-1 expression in nucleus pulposus cells through a signaling network comprising MAPK, AP1, Sp1, and TonEBP. It is concluded that by controlling both GAG and aggrecan synthesis, these growth factors positively influence disk cell function. © 2010 American Society for Bone and Mineral Research.

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Section: Discussionmentioning

confidence: 98%

BMP-2 and TGF-β stimulate expression of β1,3-glucuronosyl transferase 1 (GlcAT-1) in nucleus pulposus cells through AP1, TonEBP, and Sp1: Role of MAPKs

Hiyama

Gogate

Gajghate

et al. 2010

Journal of Bone and Mineral Research

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“…The effect of cAMP activation/inhibition in osteogenesis has also been examined, with most studies reporting a requirement for increased cAMP during osteogenesis [40–46]. However, these studies were conducted in preosteoblastic cells that were already committed to the osteoblast lineage.…”

Section: Discussionmentioning

confidence: 99%

Paternally Inherited Gsα Mutation Impairs Adipogenesis and Potentiates a Lean Phenotype In Vivo

et al. 2012

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Paternally inherited inactivating mutations of the GNAS gene have been associated with a rare and disabling genetic disorder, progressive osseous heteroplasia, in which heterotopic ossification occurs within extraskeletal soft tissues, such as skin, subcutaneous fat, and skeletal muscle. This ectopic bone formation is hypothesized to be caused by dysregulated mesenchymal progenitor cell differentiation that affects a bipotential osteogenic-adipogenic lineage cell fate switch. Interestingly, patients with paternally inherited inactivating mutations of GNAS are uniformly lean. Using a mouse model of Gsα-specific exon 1 disruption, we examined whether heterozygous inactivation of Gnas affects adipogenic differentiation of mesenchymal precursor cells from subcutaneous adipose tissues (fat pad). We found that paternally inherited Gsα inactivation (Gsα+/p−) impairs adipogenic differentiation of adipose-derived stromal cells (ASCs). The Gsα+/p− mutation in ASCs also decreased expression of the adipogenic factors CCAAT-enhancer-binding protein (C/EBP)β, C/EBPα, peroxisome proliferator-activated receptor gamma, and adipocyte protein 2. Impaired adipocyte differentiation was rescued by an adenylyl cyclase activator, forskolin, and provided evidence that Gsα-cAMP signals are necessary in early stages of this process. Supporting a role for Gnas in adipogenesis in vivo, fat tissue weight and expression of adipogenic genes from multiple types of adipose tissues from Gsα+/p− mice were significantly decreased. Interestingly, the inhibition of adipogenesis by paternally inherited Gsα mutation also enhances expression of the osteogenic factors, msh homeobox 2, runt-related transcription factor 2, and osteocalcin. These data support the hypothesis that Gsα plays a critical role in regulating the balance between fat and bone determination in soft tissues, a finding that has important implications for a wide variety of disorders of osteogenesis and adipogenesis.

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“…One of the factors known to regulate differentiation of MSCs is cAMP (Strickland et al, 1980;Zhao et al, 2006; for the indicated time periods. Total cell lysates were prepared in RIPA buffer before equal amounts of protein (50 g) were subjected to Western blot analysis using antibodies against the indicated proteins.…”

Section: Discussionmentioning

confidence: 99%

cAMP-mediated Induction of Cyclin E Sensitizes Growth-arrested Adipose Stem Cells to DNA Damage–induced Apoptosis

Ugland

Boquest

Naderi

et al. 2008

MBoC

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The differentiation capacity of mesenchymal stem cells has been extensively studied, but little is known on cell cycle-related events in the proliferation and differentiation phases of these cells. Here, we demonstrate that exposure to cAMP-increasing agents inhibits proliferation of adipose stem cells (ASCs). This antiproliferative effect is associated with both reduced cdk2 activity and pRB phosphorylation. Concomitantly, however, the level of cyclin E markedly increases upon cAMP induction, indicating that cyclin E may have cdk2-independent functions in these cells besides its role as a cdk2 activator. Indeed, we found indications of a cdk2-independent role of cyclin E in DNA damage-induced apoptosis. 8-CPT-cAMP sensitizes ASCs to ␥-irradiation-induced apoptosis, an effect abolished by knockdown of cyclin E. Moreover, cAMP induces early activation of ERK, leading to reduced degradation of cyclin E. The cAMP-mediated upregulation of cyclin E was blocked by knockdown of ERK or by an inhibitor of the ERK kinase MEK. We conclude that cAMP inhibits cdk2 activity and pRB phosphorylation, leading to reduced ASC proliferation. Concomitant with this growth inhibition, however, cyclin E levels are increased in a MEK/ERK-dependent manner. Our results suggest that cyclin E plays an important, cdk2-independent role in genotoxic stress-induced apoptosis in mesenchymal stem cells. INTRODUCTIONHuman mesenchymal stem cells (MSCs) have been shown to differentiate not only into mesenchymal lineages (such as osteogenic, chondrogenic, adipogenic, and myogenic), but also into neurogenic, angiogenic, and hepatic lineages (Zuk et al., 2002;Baksh et al., 2004;Boquest et al., 2006a;Schaffler and Buchler, 2007). The pluripotent nature of MSCs makes them potentially ideal candidates for tissue engineering, and they have already demonstrated some efficacy in cell therapy and regenerative medicine Kassem, 2004;Leo and Grande, 2006;Mimeault and Batra, 2006). Adipose tissue contains a supportive stroma that can be easily isolated and provides a rich source of MSCs (Zuk et al., 2002;Boquest et al., 2006a). Thus, adipose tissue represents a valuable source of multilineage stem cells. It is therefore important to understand the biology of adipose stem cells (ASCs).Cyclic AMP (cAMP) is a ubiquitous second messenger that regulates a number of different cellular processes, including metabolism, growth, differentiation, and gene regulation (Krebs and Beavo, 1979;McKnight, 1991;Vossler et al., 1997;Daniel et al., 1998;Kim et al., 2005). Most effects of cAMP are mediated through activation of protein kinase A (PKA) or the Epac (exchange protein directly activated by cAMP) family of exchange proteins (Walsh et al., 1968;Bos, 2003). Elevation of intracellular cAMP has both proliferative and antiproliferative effects depending on the cell type. For instance, cAMP stimulates the proliferation of thyroid cells, neurons, and Swiss 3T3 cells, while inhibiting the proliferation of lymphocytes, fibroblasts, and adipocytes (Rozengurt et al., 1981;Blomhoff et ...

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Downregulation of cAMP-dependent protein kinase inhibitor γ is required for BMP-2-induced osteoblastic differentiation

Cited by 22 publications

References 47 publications

BMP-2 and TGF-β stimulate expression of β1,3-glucuronosyl transferase 1 (GlcAT-1) in nucleus pulposus cells through AP1, TonEBP, and Sp1: Role of MAPKs

BMP-2 and TGF-β stimulate expression of β1,3-glucuronosyl transferase 1 (GlcAT-1) in nucleus pulposus cells through AP1, TonEBP, and Sp1: Role of MAPKs

Paternally Inherited Gsα Mutation Impairs Adipogenesis and Potentiates a Lean Phenotype In Vivo

cAMP-mediated Induction of Cyclin E Sensitizes Growth-arrested Adipose Stem Cells to DNA Damage–induced Apoptosis

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