scholarly journals Inhibition of MAP/ERK kinase prevents IGF-I-induced hypertrophy in rat muscles

2004 ◽  
Vol 96 (1) ◽  
pp. 203-210 ◽  
Author(s):  
Fadia Haddad ◽  
Gregory R. Adams
Keyword(s):  
Cell Proliferation ◽  
Muscle Protein ◽  
In Vitro Studies ◽  
Ras Pathway ◽  
Igf I ◽  
Phosphoinositide 3 Kinase ◽  
Kinase Pathway ◽  
Erk Kinase

Insulin-like growth factor-I (IGF-I) has been shown to stimulate a hypertrophy response in skeletal muscles in vivo. In vitro studies have delineated two primary intracellular pathways that appear to mediate the effects of IGF-I in skeletal muscle: the Ras-ERK pathway and the phosphoinositide-3 kinase pathway. In vitro, the Ras pathway appears to regulate the mitogenic effects of IGF-I signaling, whereas the phosphoinositide-3 kinase pathway is associated with cellular differentiation. On the basis of the results from in vitro studies, we hypothesized that the coinfusion of both IGF-I and an inhibitor of the Ras pathway would result in some increase in muscle protein but an inhibition of cell proliferation. Our results show that 14 days of coinfusion of MAPK/ERK kinase inhibitor PD-098059 (PD) limited the phosphorylation of ERK and prevented IGF-I induced increases in protein (18%, P < 0.05 vs. 7%, not significant) or myofibrillar protein (23%, P < 0.01 vs. 5%, not significant). However, there were similar increases in indicators of cell proliferation (e.g., total DNA, 50 and 52%, P < 0.001) in both the IGF- and IGF+PD-infused muscles. The most notable impact on IGF-I signaling was a significant blunting of IGF-I induced increase in S6K1 phosphorylation by PD-98059 coinfusion (∼5-fold, P < 0.001 vs. 3-fold, P < 0.01). These results suggest that there are interactions between the various pathways down stream of the IGF-I receptor that may behave differently in vivo than in myogenic cell lines in vitro.

scholarly journals Synergistic Autophagy Effect of miR-212-3p in Zoledronic Acid-Treated In Vitro and Orthotopic In Vivo Models and in Patient-Derived Osteosarcoma Cells

Cancers ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1812 ◽  
Author(s):  
Ju Oh ◽  
Eun Kim ◽  
Yeon-Joo Lee ◽  
Sei Sai ◽  
Sun Lim ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Zoledronic Acid ◽  
Mammalian Target Of Rapamycin ◽  
In Vivo Models ◽  
Extracellular Signal Regulated Kinase ◽  
Extracellular Signal ◽  
Kinase Pathway ◽  
Autophagy Inhibition

Osteosarcoma (OS) originates from osteoid bone tissues and is prone to metastasis, resulting in a high mortality rate. Although several treatments are available for OS, an effective cure does not exist for most patients with advanced OS. Zoledronic acid (ZOL) is a third-generation bisphosphonate that inhibits osteoclast-mediated bone resorption and has shown efficacy in treating bone metastases in patients with various types of solid tumors. Here, we sought to clarify the mechanisms through which ZOL inhibits OS cell proliferation. ZOL treatment inhibited OS cell proliferation, viability, and colony formation. Autophagy inhibition by RNA interference against Beclin-1 or ATG5 inhibited ZOL-induced OS cell death. ZOL induced autophagy by repressing the protein kinase B/mammalian target of rapamycin/p70S6 kinase pathway and extracellular signal-regulated kinase signaling-dependent autophagy in OS cell lines and patient-derived OS cells. Microarrays of miRNA showed that ZOL increased the levels of miR-212-3p, which is known to play an important role in autophagy, in OS in vitro and in vivo systems. Collectively, our data provided mechanistic insight into how increased miR-212-3p through ZOL treatment induces autophagy synergistically in OS cells, providing a preclinical rationale for conducting a broad-scale clinical evaluation of ZOL + miR-212-3p in treating OS.

The potential of stromal cell-derived factor-1 delivery using a collagen membrane for bone regeneration

2017 ◽  
Vol 31 (7) ◽  
pp. 1049-1061 ◽  
Author(s):  
Tadahiro Takayama ◽  
Jisen Dai ◽  
Keita Tachi ◽  
Ryutaro Shohara ◽  
Hironori Kasai ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Growth Factor ◽  
Bone Formation ◽  
Bone Regeneration ◽  
Stromal Cell ◽  
In Vitro Studies ◽  
New Bone Formation ◽  
Stromal Cell Derived Factor

Stromal cell-derived factor-1 (SDF-1) is a cytokine that is important in stem and progenitor cell recruitment in tissue repair after injury. Regenerative procedures using collagen membranes (CMs) are presently well established in periodontal and implant dentistry. The objective of this study is to test the subsequent effects of the released SDF-1 from a CM on bone regeneration compared to platelet-derived growth factor (PDGF) in vitro and in vivo. For in vitro studies, cell proliferation, alkaline phosphatase activity, and osteoblastic differentiation marker genes were assessed after MC3T3-E1 mouse preosteoblasts were cultured with CMs containing factors. In vivo effects were investigated by placement of CMs containing SDF-1 or PDGF using a rat mandibular bone defect model. At 4 weeks after the surgery, the new bone formation was measured using micro-computed tomography (µCT) and histological analysis. The results of in vitro studies revealed that CM delivery of SDF-1 significantly induced cell proliferation, ALP activity, and gene expression of all osteogenic markers compared to the CM alone or control, similar to PDGF. Quantitative and qualitative µCT analysis for volume of new bone formation and the percentage of new bone area showed that SDF-1-treated groups significantly increased and accelerated bone regeneration compared to control and CM alone. The enhancement of bone formation in SDF-1-treated animals was dose-dependent and with levels similar to those measured with PDGF. These results suggest that a CM with SDF-1 may be a great candidate for growth factor delivery that could be a substitute for PDGF in clinical procedures where bone regeneration is necessary.

scholarly journals Viral expression of insulin-like growth factor I E-peptides increases skeletal muscle mass but at the expense of strength

2014 ◽  
Vol 306 (8) ◽  
pp. E965-E974 ◽  
Author(s):  
Becky K. Brisson ◽  
Janelle Spinazzola ◽  
SooHyun Park ◽  
Elisabeth R. Barton
Keyword(s):  
Skeletal Muscle ◽  
Cell Proliferation ◽  
Growth Factor ◽  
Muscle Mass ◽  
Insulin Like Growth Factor ◽  
Factor I ◽  
Igf I ◽  
Growth Factor I

Insulin-like growth factor I (IGF-I) is a protein that regulates and promotes growth in skeletal muscle. The IGF-I precursor polypeptide contains a COOH-terminal extension called the E-peptide. Alternative splicing in the rodent produces two isoforms, IA and IB, where the mature IGF-I in both isoforms is identical yet the E-peptides, EA and EB, share less than 50% homology. Recent in vitro studies show that the E-peptides can enhance IGF-I signaling, leading to increased myoblast cell proliferation and migration. To determine the significance of these actions in vivo and to evaluate if they are physiologically beneficial, EA and EB were expressed in murine skeletal muscle via viral vectors. The viral constructs ensured production of E-peptides without the influence of additional IGF-I through an inactivating mutation in mature IGF-I. E-peptide expression altered ERK1/2 and Akt phosphorylation and increased satellite cell proliferation. EB expression resulted in significant muscle hypertrophy that was IGF-I receptor dependent. However, the increased mass was associated with a loss of muscle strength. EA and EB have similar effects in skeletal muscle signaling and on satellite cells, but EB is more potent at increasing muscle mass. Although sustained EB expression may drive hypertrophy, there are significant physiological consequences for muscle.

Uncoupling between proliferation and differentiation of ovine granulosa cells in vitro

1994 ◽  
Vol 142 (3) ◽  
pp. 497-510 ◽  
Author(s):  
D Monniaux ◽  
C Pisselet ◽  
J Fontaine
Keyword(s):  
Cell Proliferation ◽  
Granulosa Cell ◽  
Granulosa Cells ◽  
Follicular Growth ◽  
Proliferating Cells ◽  
Progesterone Secretion ◽  
Proliferation And Differentiation ◽  
Igf I

Abstract Granulosa cells of ovarian follicles both proliferate and undergo differentiation. In vivo, an inverse relationship between proliferation and steroidogenesis is observed. However, both processes can be enhanced by insulin-like growth factor-I (IGF-I) in vitro. Studies were undertaken in the ewe to understand the mechanisms controlling the balance between proliferation and differentiation in cultured granulosa cells from antral follicles better. For this purpose, granulosa cells from ovine small follicles (1–3 mm in diameter) and large follicles (5–7 mm in diameter) were compared for progesterone secretion, cytochrome P450 side-chain cleavage (P450scc) expression and their proportions of non-proliferating (G0) cells, in response to IGF-I and FSH stimulation in vitro. IGF-I mainly enhanced the proliferation of granulosa cells from small follicles but it strongly increased progesterone secretion and P450scc expression in granulosa cells from large follicles, in synergy with FSH. Blocking granulosa cell proliferation by the administration of colcemid or aphidicolin had no effect or a weak stimulating effect on progesterone secretion. At the beginning of the culture period, the proportion of non-proliferating cells, estimated by continuous [3H]thymidine labelling experiments, was clearly higher in large than in small follicles (91% vs 30%, P<0·001). For both cell types, treatment with IGF-I in vitro reduced the proportion of non-proliferating cells at 72 h of culture (40% vs 70% respectively in IGF-I-stimulated and unstimulated cells from large follicles, P<0·001, and 17% vs 30% respectively in IGF-I-stimulated and unstimulated cells from small follicles, P<0·001). Treatment with FSH had no effect on the proportion of non-proliferating cells. As revealed by immunohistochemistry experiments, IGF-I, in synergy with FSH, clearly increased the percentage of cells expressing P450scc enzyme and the intensity of staining in granulosa cells from large follicles. Unexpectedly, heavily stained cells in mitosis were observed in IGF-I-stimulated cells from large follicles after 96 h of culture, suggesting that dividing cells might also produce progesterone. Overall, these results support the hypothesis that the growth-promoting and the cytodifferentiative effects of IGF-I are clearly distinct. Moreover, they suggest that uncoupling between proliferation and steroidogenesis may occur in cultured ovine granulosa cells. The loss of proliferative activity accompanying terminal follicular growth in vivo could be reversed in vitro. During terminal follicular growth in vivo, the existence of an active mechanism inhibiting granulosa cell proliferation, and unrelated to terminal differentiation, is therefore strongly suspected. Journal of Endocrinology (1994) 142, 497–510

scholarly journals Akt1 and Akt2 Isoforms Play Distinct Roles in Regulating the Development of Inflammation and Fibrosis Associated with Alcoholic Liver Disease

Cells ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 1337 ◽  
Author(s):  
Karina Reyes-Gordillo ◽  
Ruchi Shah ◽  
Jaime Arellanes-Robledo ◽  
Ying Cheng ◽  
Joseph Ibrahim ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Liver Disease ◽  
Alcoholic Liver Disease ◽  
Kupffer Cells ◽  
Mammalian Target Of Rapamycin ◽  
Akt Isoforms ◽  
And Migration ◽  
Phosphoinositide 3 Kinase

Akt kinase isoforms (Akt1, Akt2, and Akt3) have generally been thought to play overlapping roles in phosphoinositide 3-kinase (PI3K)-mediated-signaling. However, recent studies have suggested that they display isoform-specific roles in muscle and fat. To determine whether such isoform-specificity is observed with respect to alcoholic liver disease (ALD) progression, we examined the role of Akt1, Akt2, and Akt3 in hepatic inflammation, and pro-fibrogenic proliferation and migration using Kupffer cells, hepatic stellate cells (HSC), and hepatocytes in an ethanol and lipopolysaccharide (LPS)-induced two-hit model in vitro and in vivo. We determined that siRNA-directed silencing of Akt2, but not Akt1, significantly suppressed cell inflammatory markers in HSC and Kupffer cells. Although both Akt1 and Akt2 inhibited cell proliferation in HSC, only Akt2 inhibited cell migration. Both Akt1 and Akt2, but not Akt3, inhibited fibrogenesis in hepatocytes and HSC. In addition, our in vivo results show that administration of chronic ethanol, binge ethanol and LPS (EBL) in wild-type C57BL/6 mice activated all three Akt isoforms with concomitant increases in activated forms of phosphoinositide dependent kinase-1 (PDK1), mammalian target-of-rapamycin complex 2 (mTORC2), and PI3K, resulting in upregulation in expression of inflammatory, proliferative, and fibrogenic genes. Moreover, pharmacological blocking of Akt2, but not Akt1, inhibited EBL-induced inflammation while blocking of both Akt1 and Akt2 inhibited pro-fibrogenic marker expression and progression of fibrosis. Our findings indicate that Akt isoforms play unique roles in inflammation, cell proliferation, migration, and fibrogenesis during EBL-induced liver injury. Thus, close attention must be paid when targeting all Akt isoforms as a therapeutic intervention.

Inhibiting the phosphoinositide 3-kinase pathway for cancer treatment

2004 ◽  
Vol 32 (2) ◽  
pp. 393-396 ◽  
Author(s):  
P. Workman
Keyword(s):  
Cancer Treatment ◽  
Gene Knockout ◽  
Genomic Analysis ◽  
Gene Knockout Mouse ◽  
Show Evidence ◽  
In Vivo Animal Models ◽  
Phosphoinositide 3 Kinase ◽  
Kinase Pathway

There is extensive evidence from the molecular and genomic analysis of human cancers that the PI 3-kinase (phosphoinositide 3-kinase)–Akt/PKB (protein kinase B) pathway is deregulated in malignant progression. Furthermore, the causal involvement of PI 3-kinase is supported by gene-knockout mouse models. Prototype inhibitors show evidence of anticancer activity in vitro and in vivo animal models. The recent development of isoform-selective inhibitors shows considerable promise for cancer treatment.

Small-molecule agonists of SHIP1 inhibit the phosphoinositide 3-kinase pathway in hematopoietic cells

Blood ◽  
2007 ◽  
Vol 110 (6) ◽  
pp. 1942-1949 ◽  
Author(s):  
Christopher J. Ong ◽  
Andrew Ming-Lum ◽  
Matt Nodwell ◽  
Ali Ghanipour ◽  
Lu Yang ◽  
...  
Keyword(s):  
Small Molecule ◽  
Hematopoietic Cells ◽  
Pi3k Pathway ◽  
Cellular Activation ◽  
Phosphoinositide 3 Kinase ◽  
Identification And Characterization ◽  
Kinase Pathway

Abstract Because phosphoinositide 3-kinase (PI3K) plays a central role in cellular activation, proliferation, and survival, pharmacologic inhibitors targeting components of the PI3K pathway are actively being developed as therapeutics for the treatment of inflammatory disorders and cancer. These targeted drugs inhibit the activity of either PI3K itself or downstream protein kinases. However, a previously unexplored, alternate strategy is to activate the negative regulatory phosphatases in this pathway. The SH2-containing inositol-5′-phosphatase SHIP1 is a normal physiologic counter-regulator of PI3K in immune/hematopoietic cells that hydrolyzes the PI3K product phosphatidylinositiol-3,4,5-trisphosphate (PIP3). We now describe the identification and characterization of potent and specific small-molecule activators of SHIP1. These compounds represent the first small-molecule activators of a phosphatase, and are able to activate recombinant SHIP1 enzyme in vitro and stimulate SHIP1 activity in intact macrophage and mast cells. Mechanism of activation studies with these compounds suggest that they bind a previously undescribed, allosteric activation domain within SHIP1. Furthermore, in vivo administration of these compounds was protective in mouse models of endotoxemia and acute cutaneous anaphylaxis, suggesting that SHIP1 agonists could be used therapeutically to inhibit the PI3K pathway.

Sign in / Sign up

Export Citation Format

Share Document