scholarly journals Smad2/3 Activation Regulates Smad1/5/8 Signaling via a Negative Feedback Loop to Inhibit 3T3-L1 Adipogenesis

2021 ◽  
Vol 22 (16) ◽  
pp. 8472
Author(s):  
Senem Aykul ◽  
Jordan Maust ◽  
Vijayalakshmi Thamilselvan ◽  
Monique Floer ◽  
Erik Martinez-Hackert
Keyword(s):  
Negative Feedback ◽  
Feedback Loop ◽  
Negative Feedback Loop ◽  
Adipose Tissues ◽  
Family Growth ◽  
Simultaneous Activation ◽  
Adipocyte Hypertrophy ◽  
Adipocyte Development ◽  
Energy Surplus

Adipose tissues (AT) expand in response to energy surplus through adipocyte hypertrophy and hyperplasia. The latter, also known as adipogenesis, is a process by which multipotent precursors differentiate to form mature adipocytes. This process is directed by developmental cues that include members of the TGF-β family. Our goal here was to elucidate, using the 3T3-L1 adipogenesis model, how TGF-β family growth factors and inhibitors regulate adipocyte development. We show that ligands of the Activin and TGF-β families, several ligand traps, and the SMAD1/5/8 signaling inhibitor LDN-193189 profoundly suppressed 3T3-L1 adipogenesis. Strikingly, anti-adipogenic traps and ligands engaged the same mechanism of action involving the simultaneous activation of SMAD2/3 and inhibition of SMAD1/5/8 signaling. This effect was rescued by the SMAD2/3 signaling inhibitor SB-431542. By contrast, although LDN-193189 also suppressed SMAD1/5/8 signaling and adipogenesis, its effect could not be rescued by SB-431542. Collectively, these findings reveal the fundamental role of SMAD1/5/8 for 3T3-L1 adipogenesis, and potentially identify a negative feedback loop that links SMAD2/3 activation with SMAD1/5/8 inhibition in adipogenic precursors.

scholarly journals TGF-Β Family Inhibitors Blunt Adipogenesis Via Non-Canonical Regulation Of SMAD Pathways

2020 ◽  
Author(s):  
Senem Aykul ◽  
Jordan Maust ◽  
Monique Floer ◽  
Erik Martinez-Hackert
Keyword(s):  
Growth Factors ◽  
Signaling Pathways ◽  
Intracellular Signaling ◽  
Feedback Loop ◽  
Adipose Tissues ◽  
Intracellular Signaling Pathways ◽  
Family Growth ◽  
Pathological Conditions ◽  
Adipocyte Hypertrophy ◽  
Energy Surplus

ABSTRACTAdipose tissues (AT) expand in response to energy surplus through adipocyte hypertrophy and hyperplasia (i.e., adipogenesis). The latter is a process by which multipotent precursors differentiate into mature adipocytes. This process is directed by growth factors and cytokines, including members of the TGF-β family, which regulate intracellular signaling pathways that control adipogenic transcriptional programs. As ectopic adipogenesis has been linked with metabolic syndrome and other pathological conditions, we undertook to establish how TGF-β family growth factors and their inhibitors regulate this process in a 3T3-L1 adipogenesis model. We found that intracellular SMAD1/5/8 signaling pathways are activated while SMAD2/3 pathways are suppressed in differentiating cells. Addition of SMAD1/5/8 pathway activating ligands promoted cell proliferation, while SMAD2/3 pathway activating ligands suppressed adipocyte formation. We identified several ligand traps that blunted 3T3-L1 adipogenesis. Strikingly, anti-adipogenic traps and ligands exploited the same mechanism of regulation involving a negative feedback loop that links SMAD2/3 activation with SMAD1/5/8 hyper-phosphorylation, cytoplasmic retention, and reduced signaling. The identified anti-adipogenic traps could be used to control hyperplastic AT expansion and its associated pathological conditions.

The role of Alx-4 in the establishment of anteroposterior polarity during vertebrate limb development

Development ◽  
1998 ◽  
Vol 125 (22) ◽  
pp. 4417-4425 ◽  
Author(s):  
M. Takahashi ◽  
K. Tamura ◽  
D. Buscher ◽  
H. Masuya ◽  
S. Yonei-Tamura ◽  
...  
Keyword(s):  
Negative Feedback ◽  
Limb Development ◽  
Feedback Loop ◽  
Limb Bud ◽  
Negative Regulator ◽  
Negative Feedback Loop ◽  
Vertebrate Limb ◽  
Limb Outgrowth ◽  
Vertebrate Limb Development

We have determined that Strong's Luxoid (lstJ) [corrected] mice have a 16 bp deletion in the homeobox region of the Alx-4 gene. This deletion, which leads to a frame shift and a truncation of the Alx-4 protein, could cause the polydactyly phenotype observed in lstJ [corrected] mice. We have cloned the chick homologue of Alx-4 and investigated its expression during limb outgrowth. Chick Alx-4 displays an expression pattern complementary to that of shh, a mediator of polarizing activity in the limb bud. Local application of Sonic hedgehog (Shh) and Fibroblast Growth Factor (FGF), in addition to ectodermal apical ridge removal experiments suggest the existence of a negative feedback loop between Alx-4 and Shh during limb outgrowth. Analysis of polydactylous mutants indicate that the interaction between Alx-4 and Shh is independent of Gli3, a negative regulator of Shh in the limb. Our data suggest the existence of a negative feedback loop between Alx-4 and Shh during vertebrate limb outgrowth.

scholarly journals RAC1/miR-3613/RAC1 feedback loop contributes to ovarian cancer progression

2021 ◽  
Author(s):  
Changzhong Li ◽  
Ruobing Leng ◽  
Yunfang Meng ◽  
Na Li ◽  
Feifei Li ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Cancer Progression ◽  
Negative Feedback ◽  
Feedback Loop ◽  
Inhibitory Effect ◽  
Ovarian Cancer Cells ◽  
Negative Feedback Loop

Abstract The RAC1 signal pathway is involved in various tumor cell biological processes. Here, the role of RAC1-miR-3613-RAC1 negative feedback loop in ovarian cancer was explored. Results showed that RAC1 knockdown up-regulated miR-3613, which in turn inhibited RAC1 expression. RAC1 counteracted the inhibitory effect of miR-3613 on the proliferation and invasion of ovarian cancer cells in vitro and on the tumor growth in vivo. In ovarian cancer, miR-3613 expression was negatively correlated with RAC1, and patients with low miR-3613 expression had poor prognosis. These findings indicate the role of RAC1-miR-3613-RAC1 negative feedback loop in the malignant progression of ovarian cancer and its possible therapeutic values.

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