Upregulation of signal transducer and activator of transcription 4 promotes osteoblast activity by activating AMP-activated protein kinase based on cationic liposome transfection

2020 ◽  
Vol 10 (11) ◽  
pp. 1836-1845
Author(s):  
Tao Jiang ◽  
Qingzhen Chen ◽  
Min Shao ◽  
Zhen Shen ◽  
Gang Wang ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Osteogenic Differentiation ◽  
Transcriptional Activity ◽  
Cationic Liposome ◽  
Promoter Sequence ◽  
Fluorescence Quantitative Pcr ◽  
Osteoblast Activity ◽  
Activity Factor ◽  
Proliferation And Differentiation ◽  
Amp Activated Protein Kinase

Activation of Protein Kinase AMP-Activated Catalytic Subunit Alpha (AMPKα) is an important regulatory pathway for osteogenic differentiation. STAT4 acts as a transcriptional activity factor to regulate the transcription of many genes and is potentially a regulatory factor for AMPKα transcription activity. To confirm the regulatory effect of STAT4 on AMPKα and the effect of STAT4 on osteogenic differentiation, the promoter sequence of AMPKα was analyzed via bioinformatics, the STAT4 overexpression vector was constructed and transfected into human osteoblast-like cells MG-63 by cationic liposome, fluorescence quantitative PCR (RT-qPCR) and western blotting technologies were used to detect the effect of STAT4 on the expression of AMPKα. MTT and ALP activity assays were also used to verify the effect of STAT4 on the proliferation and maturation of osteoblasts by regulating AMPKα expression. Our results showed that STAT4 was a co-transcriptional regulator of AMPKα1 and AMPKα2, which combined the enrichment region of CpG on the promoter sequence of AMPKα1/2. Overexpression of STAT4 significantly increased the expression of AMPKα1 and AMPKα2, which promoted the proliferation and maturation of osteoblasts. We concluded that STAT4 was a transcriptional activator of AMPKα and promoting STAT4 expression enhances the proliferation and differentiation activity of AMPKα in osteoblasts.

scholarly journals Activity of Retinoic Acid Receptor-alpha Is Directly Regulated at Its Protein Kinase A Sites in Response to Follicle-Stimulating Hormone Signaling

Endocrinology ◽  
2010 ◽  
Vol 151 (5) ◽  
pp. 2361-2372 ◽  
Author(s):  
Nadine C. Santos ◽  
Kwan Hee Kim
Keyword(s):  
Cell Proliferation ◽  
Retinoic Acid ◽  
Protein Kinase ◽  
Protein Kinase A ◽  
Nuclear Localization ◽  
Transcriptional Activity ◽  
Retinoic Acid Receptor ◽  
Cell Proliferation And Differentiation ◽  
Proliferation And Differentiation ◽  
Kinase A

Retinoic acid receptor-α (RARA) is crucial for germ cell development in the testis, as shown by the degenerated testis in Rara gene knockout mice, which are sterile. Similarly, FSH is known to regulate Sertoli cell proliferation and differentiation, indirectly controlling the quantity of the spermatogenic output. Interestingly, FSH inhibited, via activation of FSH receptor, cAMP, and protein kinase A (PKA), the nuclear localization and transcriptional activity of RARA. Given that retinoic acid, the ligand for RARA, is known to regulate cell proliferation and differentiation, we investigated whether FSH regulates RARA by a direct posttranslational phosphorylation mechanism. Mutagenesis of serine 219 (S219) and S369 at the PKA sites on RARA to either double alanines or double glutamic acids showed that both PKA sites are important for RARA activity. The negative charges at the PKA sites, whether they are from glutamic acids or phosphorylation of serines, decreased the nuclear localization of RARA, heterodimerization with retinoid X receptor-α, and the transcriptional activity of the receptor. On the other hand, the double-alanine mutant that cannot be phosphorylated at the 219 and 369 amino acid positions did not respond to cAMP and PKA activation. Wild-type and double-mutant RARA interacted with PKA, but only in the presence of cAMP or FSH. These results together suggest that FSH may regulate cell proliferation and differentiation of Sertoli cells, at least partially, by directly affecting the PKA sites of RARA and controlling the transcriptional function of the receptor.

scholarly journals Role of Metformin on Osteoblast Differentiation in Type 2 Diabetes

2019 ◽  
Vol 2019 ◽  
pp. 1-6 ◽  
Author(s):  
Lin Jiating ◽  
Ji Buyun ◽  
Zhang Yinchang
Keyword(s):  
Mineral Metabolism ◽  
Polycystic Ovary ◽  
Serum Levels ◽  
Osteoblast Activity ◽  
Extracellular Signal ◽  
Energy Sensor ◽  
Glycation End Products ◽  
Proliferation And Differentiation ◽  
Related Transcription Factor ◽  
Amp Activated Protein Kinase

Metformin, an effective hypoglycemic, can modulate different points of malignant mass, polycystic ovary syndrome (PCOS), cardiovascular diseases, tuberculosis, and nerve regeneration. Recently, the effect of metformin on bone metabolism has been analyzed. Metformin relies on organic cation transporters (OCT1), a polyspecific cell membrane of the solute carrier 22A (SLC22A) gene family, to facilitate its intracellular uptake and action on complex I of the respiratory chain of mitochondria. These changes activate the cellular energy sensor AMP-activated protein kinase (AMPK). Thus, the increased cellular AMP/ATP ratio causes a dramatic and progressive activation of insulin and lysosomes, resulting in a decrease in intracellular glucose level, which promotes osteoblast proliferation and differentiation. AMPK also phosphorylates runt-related transcription factor 2 (Runx2) at S118, the lineage-specific transcriptional regulators, to promote osteogenesis. Metformin phosphorylates extracellular signal-regulated kinase (ERK), stimulates endothelial and inducible nitric oxide synthases (e/iNOS), inhibits the GSK3β/Wnt/β-catenin pathway, and promotes osteogenic differentiation of osteoblasts. The effect of metformin on hyperglycemia decreases intracellular reactive oxygen species (ROS) and advanced glycation end-products (AGEs) in collagen, and reduced serum levels of insulin-like growth factors (IGF-1) were beneficial for bone formation. Metformin has a certain effect on microangiopathy and anti-inflammation, which can induce osteoporosis, activate the activity of osteoclasts, and inhibit osteoblast activity, and has demonstrated extensive alteration in bone and mineral metabolism. The aim of this review was to elucidate the mechanisms of metformin on osteoblasts in insulin-deficient diabetes.

scholarly journals Wnt-Independent Role of β-Catenin in Thyroid Cell Proliferation and Differentiation

2014 ◽  
Vol 28 (5) ◽  
pp. 681-695 ◽  
Author(s):  
Ana Sastre-Perona ◽  
Pilar Santisteban
Keyword(s):  
Cell Proliferation ◽  
Transcription Factor ◽  
Protein Kinase ◽  
Transcriptional Activity ◽  
Nuclear Accumulation ◽  
Cell Physiology ◽  
Thyroid Cell ◽  
Thyroid Cells ◽  
Cell Proliferation And Differentiation ◽  
Proliferation And Differentiation

Abstract The Wnt/β-catenin pathway has been associated with thyroid cell growth and tumorigenesis. However, little is known regarding its involvement in the response to the key regulators of thyroid cell proliferation and differentiation. Here we show that TSH and IGF-1 increase β-catenin nuclear accumulation and its transcriptional activity in differentiated thyroid cells. This effect takes place in a Wnt-independent manner because TSH and IGF-1, through the activation of protein kinase A and protein kinase B/Akt, phosphorylate β-catenin at S552 and S675, which results in β-catenin release from E-cadherin at the adherens junctions. Nuclear β-catenin regulates thyroid cell proliferation, because its silencing or the overexpression of a dominant-negative form of T-cell factor 4 resulted in reduced levels of cyclin D1 and DNA synthesis. Furthermore, the β-catenin silencing markedly reduced the expression of Pax8, the main transcription factor involved in epithelial thyroid cell differentiation. Finally, we observed that β-catenin physically interacts with the transcription factor Pax8, increasing its transcriptional activity on the sodium iodide symporter (NIS) gene, a critical gene required for thyroid cell physiology. Taken together, our findings show that β-catenin plays a not yet described role in thyroid function including a functional interaction with Pax8.

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