OBJECTIVETo study the role of mammalian target of rapamycin (mTOR) and p70 S6 kinase (p70 S6K) in periodontal tissues remodeling during orthodontic tooth movement.

METHODSTwenty-four rabbits were chosen to establish rabbit models for the study. The right maxillary teeth of each animal treated by orthodontics were the test sides, and the untreated left teeth were the control sides. The animals were sacrificed at 3, 5, 7, 14 d, respectively. The prepared tissue specimens were processed for the study of the change in the histologic morphology with HE staining and the expression of p70 S6K in periodontal tissues by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot techniques.

RESULTSIn the test side, the tranecula of bone became porous and cells arrayed disorderly, resorption of alveolar bone was observed in histological study. There were many holes in the alveolar bone, osteoblasts were occasionally observed. RT-PCR showed that the expression of p70 S6K mRNA dramatically changed at 3 d. The expression of p70 S6K mRNA in treating periodontal tissues was higher than the control side, especially at 7 d, and then decreased. Compared with the control side, there was significant difference in statistical analysis (P<0.01). The expression of Western blot was same as the RT-PCR.

CONCLUSIONHigher expression of mTOR and p70 S6K during orthodontic tooth movement especially plays an important role in the process of periodontium remodeling.

Animals ; Osteoblasts ; Periodontal Ligament ; Rabbits ; Ribosomal Protein S6 Kinases, 70-kDa ; Sirolimus ; TOR Serine-Threonine Kinases ; Tooth Movement Techniques

p70 ribosomal protein S6 kinase (p70S6K), an important member of AGC family, is a kind of multifunctional Ser/Thr kinases, which plays an important role in mTOR signaling cascade. The p70 ribosomal protein S6 kinase is closely associated with diverse cellular processes such as protein synthesis, mRNA processing, glucose homeostasis, cell growth and apoptosis. Recent studies have highlighted the important role of S6K in cancer, which arose interests of scientific researchers for the design and discovery of anti-cancer agents. Herein, the mechanisms of S6K and available inhibitors are reviewed.
Antineoplastic Agents ; Humans ; Protein Kinase Inhibitors ; chemistry ; Ribosomal Protein S6 Kinases, 70-kDa ; antagonists & inhibitors ; metabolism ; Signal Transduction ; TOR Serine-Threonine Kinases

OBJECTIVEThe aim of this study was to observe the expression of mTOR (mammalian target of rapamycin) and its substrates in oral squamous cell carcinoma.

METHODSmTOR and its substrates alpha1, alpha2, beta1, beta2 isoforms of p70 S6 kinase (p70S6k) and 4EBP1 were examined by means of RT-PCR, Western-blot test.

RESULTSThe result of RT-PCR showed that in poorly differentiated tissue, the expression level of mTOR and its substrates alpha1, alpha2, beta1, beta2 isoforms of p70S6k increased obviously, while that of 4EBP1 decreased, while that in well differentiated tissue was second to it, the normal oral tissue was the last. The expression of Western-blot was the same as the RT-PCR.

CONCLUSIONThe expression of mTOR and its substrates differs in different types of oral squamous cell carcinoma. The result suggests that mTOR, p70S6K and 4EBP1 might play important roles in oral squamous cell carcinoma. It may be an important target protein to treat tumor in the future.

Adaptor Proteins, Signal Transducing ; metabolism ; Carcinoma, Squamous Cell ; metabolism ; Humans ; Mouth Neoplasms ; metabolism ; Phosphoproteins ; metabolism ; Ribosomal Protein S6 Kinases, 70-kDa ; metabolism ; TOR Serine-Threonine Kinases ; metabolism

Obesity is a prevalent metabolic disorder, which seriously affects human health and has become the world's public health problem. Kinase S6K1, an important downstream effector of mammalian target of rapamycin (mTOR), influences specific pathological responses, including obesity, type 2 diabetes and cancer. Presently, S6K1 has become an attractive therapeutic target in the treatment of these disorders. Here, the functions of kinase S6K1, its molecular regulation mechanisms, related pathogenesis of disease and relevant small molecular inhibitors are reviewed. Finally, the prospect of research toward S6K1 is expected as well.
Animals ; Diabetes Mellitus, Type 2 ; Humans ; Neoplasms ; Obesity ; Ribosomal Protein S6 Kinases, 70-kDa ; metabolism ; Signal Transduction ; TOR Serine-Threonine Kinases ; metabolism

Eukaryotic translation initiation factor 4B (eIF4B) plays an important role in mRNA translation initiation, cell survival and proliferation in vitro, but the in vivo function is poorly understood. In this study, via various experimental techniques such as hematoxylin-eosin (HE) staining, flow cytometry, Western blotting, and immunohistochemistry, we investigated the role of eIF4B in mouse embryo development using an eIF4B knockout (KO) mouse model and explored the mechanism. We found that the livers, but not lungs, brain, stomach, or pancreas, derived from eIF4B KO mouse embryos displayed severe pathological changes characterized by enhanced apoptosis and necrosis. Accordingly, high expression of cleaved-caspase 3, and excessive activation of mTOR signaling as evidenced by increased expression and phosphorylation of p70S6K and enhanced phosphorylation of 4EBP1, were observed in mouse embryonic fibroblasts and fetal livers from eIF4B KO mice. These results uncover a critical role of eIF4B in mouse embryo development and provide important insights into the biological functions of eIF4B in vivo.
Animals ; Apoptosis/genetics* ; Caspase 3 ; Eosine Yellowish-(YS) ; Eukaryotic Initiation Factors/metabolism* ; Fibroblasts ; Hematoxylin ; Liver/metabolism* ; Mice ; Ribosomal Protein S6 Kinases, 70-kDa/genetics* ; TOR Serine-Threonine Kinases

OBJECTIVETo illustrate the molecular mechanism of skeletal muscle growth by examining the effect of swimming training on skeletal muscle growth and p70s6k, rpS6 protein expression.

METHODSTwenty four male SD rats were used to establish swimming training models with a 15% body mass load. The training protocol adopted interval swimming training (every other day with 8 weeks). The gastrocnemius and soleus muscle were collected and weighed after training, and the protein expression of p70s6k, rpS6 and their phosphorylated forms were examined.

RESULTSAfter 8 weeks treatment, no significant change was observed in skeletal muscle mass between training group (T) and control group (C) (P > 0.05), but muscle mass in training rapamycin (TR) group has a significantly decrease compared with that in T and C groups (P < 0.05). Soleus and gastrocnemius muscle mass index in T group increased significantly compared with C group (P < 0.05). Compared with the C group, the ratio of P-p70s6k/p70s6k in T group increased with significant difference (P < 0.05), but the ratio in TR group was significantly reduced (P < 0.05). The ratio of P-rpS6/rpS6 had a significant difference between TR and T group (P < 0.05).

CONCLUSIONThese results suggest that the interval training protocol is helpful to increase the relative muscle hypertrophy, and has a role in promoting the expression of p70s6k and rpS6.

Animals ; Male ; Muscle, Skeletal ; growth & development ; metabolism ; physiology ; Physical Conditioning, Animal ; Rats ; Rats, Sprague-Dawley ; Ribosomal Protein S6 Kinases, 70-kDa ; metabolism ; Swimming

OBJECTIVETo explore the effects of rapamycin on the proliferation of prostate cancer cell line 22RV1 and the activity of S6K1.

METHODSProstate cancer 22RV1 cells cultured in vitro were treated with rapamycin at the concentrations of 0, 50, 100, 200 and 400 nmol/L. The inhibition rate of the cells'proliferation was detected by MTT, and the activity of S6K1 was determined by liquid scintillation counting.

RESULTSRapamycin significantly inhibited the proliferation of the prostate cancer 22RV1 cells and the activity of S6K1 in a dose- dependent manner, most obviously at 400 nmol/L (P<0.01).

CONCLUSIONRapamycin can effectively suppress the proliferation of prostate cancer 22RV1 cells by regulating the expression of S6K1, the downstream protein of mammalian target of rapamycin (mTOR).

Cell Line, Tumor ; Cell Proliferation ; drug effects ; Humans ; Male ; Prostate ; metabolism ; Prostatic Neoplasms ; metabolism ; pathology ; Ribosomal Protein S6 Kinases, 70-kDa ; metabolism ; Sirolimus ; pharmacology

OBJECTIVETo determine the spatio-temporal expression of p70S6k activation in hippocampus in mesial temporal lobe epilepsy.

METHODSTemporal lobe epilepsy model was established by stereotaxically unilateral and intrahippocampal injection of kainite acid (KA) in adult male C57BL/6 mice. Latent and chronic epileptogenesis were represented by mice 5 days after KA injection (n = 5) and mice 5 weeks after KA injection (n = 8), respectively. Control mice (n = 5) were injected with saline. Immunohistochemical assays were performed on brain sections of the mice.

RESULTSHippocampus both ipsilateral and contralateral to the KA injection displayed significantly up-regulated pS6 immunoreactivity in dispersed granule cells in 5-day and 5-week model mice.

CONCLUSIONThe activation of p70S6k is mainly located in the dentate gyrus in KA-induced mouse model of temporal lobe epilepsy, indicating that the activation may be related with the disperse degree and hypertrophy of granule cells.

Animals ; Epilepsy, Temporal Lobe ; enzymology ; Hippocampus ; enzymology ; Immunohistochemistry ; Male ; Mice ; Mice, Inbred C57BL ; Phosphorylation ; Ribosomal Protein S6 Kinases, 70-kDa ; analysis ; metabolism

OBJECTIVETo investigate the effect of rapamycin on the proliferation of rat valvular interstitial cells in primary culture.

METHODSThe interstitial cells isolated from rat aortic valves were cultured and treated with rapamycin, and the cell growth and cell cycle changes were analyzed using MTT assay and flow cytometry, respectively. RT-PCR was used to detect mRNA expression levels of S6 and P70S6K in cells, and the protein expressions level of S6, P70S6K, P-S6, and P-P70S6K were detected using Western blotting.

RESULTSRat aortic valvular interstitial cells was isolated successfully. The rapamycin-treated cells showed a suppressed proliferative activity (P<0.05), but the cell cycle distribution remained unaffected. Rapamycin treatment resulted in significantly decreased S6 and P70S6K protein phosphorylation level in the cells (P<0.05).

CONCLUSIONThe mechanism by which rapamycin inhibits the proliferation of valvular interstitial cells probably involves suppression of mTOR to lower S6 and P70S6K phosphorylation level but not direct regulation of the cell cycle.

Animals ; Blotting, Western ; Cell Cycle ; Cell Proliferation ; drug effects ; Cells, Cultured ; Heart Valves ; cytology ; Phosphorylation ; Rats ; Ribosomal Protein S6 Kinases, 70-kDa ; metabolism ; Sirolimus ; pharmacology

Chronic cerebral hypoperfusion (CCH), which is associated with onset of vascular dementia, causes cognitive impairment and neuropathological alterations in the brain. In the present study, we examined the neuroprotective effect of duloxetine (DXT), a potent and balanced serotonin/norepinephrine reuptake inhibitor, on CCH-induced neuronal damage in the hippocampal CA1 region using a rat model of permanent bilateral common carotid arteries occlusion. We found that treatment with 20 mg/kg DXT could attenuate the neuronal damage, the reduction of phosphorylations of mTOR and p70S6K as well as the elevations of TNF-α and IL-1β levels in the hippocampal CA1 region at 28 days following CCH. These results indicate that DXT displays the neuroprotective effect against CCH-induced hippocampal neuronal death, and that neuroprotective effect of DXT may be closely related with the attenuations of CCH-induced decrease of mTOR/p70S6K signaling pathway as well as CCH-induced neuroinflammatory process.
Brain ; CA1 Region, Hippocampal ; Carotid Artery, Common ; Cognition Disorders ; Dementia, Vascular ; Duloxetine Hydrochloride* ; Models, Animal ; Neurons* ; Neuroprotection ; Neuroprotective Agents* ; Phosphorylation ; Ribosomal Protein S6 Kinases, 70-kDa