Effects of electroacupuncture on the expression of p70 ribosomal protein S6 kinase and ribosomal protein S6 in the hippocampus of rats with vascular dementia

This study investigated the mechanism underlying electroacupuncture therapy for vascular dementia through electroacupuncture at the acupoints of Baihui （DU20）, Dazhui （DU14）, and bilateral Shenshu （BL23） in a rat model of vascular dementia produced by bilateral middle cerebral artery occlusion. Morris water maze test showed that electroacupuncture improved the learning ability of vascular dementia rats. Western blot assay revealed that the expression of p70 ribosomal protein S6 kinase and ribosomal protein S6 in vascular dementia rats was significantly increased after electroacupuncture, compared with the model group that was not treated with acupuncture. The average escape latency was also shortened after electroacupuncture, and escape strategies in the spatial probe test improved from edge and random searches, to linear and trending swim pathways. The experimental findings indicate that electroacupuncture improves learning and memory ability by up-regulating expression of p70 ribosomal protein S6 kinase and ribosomal protein S6 in the hippocampus of vascular dementia rats.

蟾蜍令灵对裸鼠食管鳞癌原位移植瘤中P70S6K表达的影响

背景食管癌是世界上最常见的消化道恶性肿瘤之一,近年研究发现,核糖体蛋白S6激酶(P70S6K)与其发生密切相关。笔者前期的研究表明,蟾蜍令灵(Bufalin)有明显的抗肿瘤作用。目的探讨Bufalin对裸鼠食管鳞癌原位移植瘤中P70S6K表达的影响。方法 Nu/Nu健康裸鼠36只,雌雄各半,采用随机数字表法分为4组,每组9只,即对照组(0.9%氯化钠溶液)、Bufalin低剂量(0.5 mg/kg,BL)组、Bufalin中剂量(1.0 mg/kg,BM)组、Bufalin高剂量(1.5 mg/kg,BH)组。观察经Bufalin治疗后裸鼠肿瘤生长情况;反转录PCR(RT-PCR)法检测裸鼠原位移植瘤中P70S6K mRNA的表达,Western blotting及免疫组化法检测裸鼠原位移植瘤中P70S6K和p-P70S6K相对表达量。结果 4组治疗前及治疗后第1天裸鼠体质量比较,差异无统计学意义(P>0.05)。4组治疗前肿瘤体积比较,差异无统计学意义(P>0.05);治疗后第15天肿瘤体积比较,差异有统计学意义(P<0.05)。治疗后第15天,BM组、BH组肿瘤体积均低于BL组和对照组(P<0.05)。3组肿瘤抑制率比较,差异有统计学意义(P<0.05)。4组P70S6K mRNA及P70S6K相对表达量比较,差异无统计学意义(F=0.634、0.119,P>0.05)。4组p-P70S6K相对表达量比较,差异有统计学意义(F=233.005,P<0.05)。结论 Bufalin对裸鼠食管鳞癌原位移植瘤具有抑制作用;Bufalin可以下调P70S6K的磷酸化水平,而P70S6K则不受影响,提示Bufalin可能通过抑制P70S6K活化而发挥作用。

Inhibitory effects of rapamycin on the different stages of hepatic fibrosis

AIM: To investigate and compare the inhibitory effects of rapamycin in the different stages of liver fibrosis.

Effect of moxibustion on mTOR-mediated autophagy in rotenone-induced Parkinson's disease model rats

Defects in autophagy-mediated clearance of α-synuclein may be one of the key factors leading to progressive loss of dopaminergic neurons in the substantia nigra. Moxibustion therapy for Parkinson’s disease has been shown to have a positive effect, but the underlying mechanism remains unknown. Based on this, we explored whether moxibustion could protect dopaminergic neurons by promoting autophagy mediated by mammalian target of rapamycin （mTOR）, with subsequent elimination of α-syn. A Parkinson’s disease model was induced in rats by subcutaneous injection of rotenone at the back of their necks, and they received moxibustion at Zusanli （ST36）, Guanyuan （CV4）and Fengfu （GV16）, for 10 minutes at every point, once per day, for 14 consecutive days. Model rats without any treatment were used as a sham control. Compared with the Parkinson’s disease group, the moxibustion group showed significantly greater tyrosine hydroxylase immunoreactivity and expression of light chain 3-II protein in the substantia nigra, and their behavioral score, α-synuclein immunoreactivity,the expression of phosphorylated mTOR and phosphorylated ribosomal protein S6 kinase （p-p70S6K） in the substantia nigra were significantly lower. These results suggest that moxibustion can promote the autophagic clearance of α-syn and improve behavioral performance in Parkinson’s disease model rats. The protective mechanism may be associated with suppression of the mTOR/p70S6K pathway.

AMPK-associated signaling to bridge the gap between fuel metabolism and hepatocyte viability

The adenosine monophosphate-activated protein kinase (AMPK) and p70 ribosomal S6 kinase-1 pathway may serve as a key signaling flow that regulates energy metabolism; thus, this pathway becomes an attractive target for the treatment of liver diseases that result from metabolic derangements. In addition, AMPK emerges as a kinase that controls the redox-state and mitochondrial function, whose activity may be modulated by antioxidants. A close link exists between fuel metabolism and mitochondrial biogenesis. The relationship between fuel metabolism and cell survival strongly implies the existence of a shared signaling network, by which hepatocytes respond to challenges of external stimuli. The AMPK pathway may belong to this network. A series of drugs and therapeutic candidates enable hepatocytes to protect mitochondria from radical stress and increase cell viability, which may be associated with the activation of AMPK, liver kinase B1, and other molecules or components. Consequently, the components downstream of AMPK may contribute to stabilizing mitochondrial membrane potential for hepatocyte survival. In this review, we discuss the role of the AMPK pathway in hepatic energy metabolism and hepatocyte viability. This information may help identify ways to prevent and/or treat hepatic diseases caused by the metabolic syndrome. Moreover, clinical drugs and experimental therapeutic candidates that directly or indirectly modulate the AMPK pathway in distinct manners are discussed here with particular emphasis on their effects on fuel metabolism and mitochondrial function.

p85S6K sustains synaptic GluA1 to ameliorate cognitive deficits in Alzheimer’s disease

Background Ribosomal protein S6 kinase 1(S6K1)is a serine-threonine kinase that has two main isoforms:p70S6K(70-kDa isoform)and p85S6K(85-kDa isoform).p70S6K,with its upstream mammalian target of rapamycin(mTOR),has been shown to be involved in learning and memory and participate in the pathophysiology of Alzheimer’s dis-ease(AD).However,the function of p85S6K has long been neglected due to its high similarity to p70S6k.The role of p85S6K in learning and memory is still largely unknown.Methods We fractionated the postsynaptic densities to illustrate the differential distribution of p85S6K and p70S6K.Coimmunoprecipitation was performed to unveil interactions between p85S6K and the GluA1 subunit of AMPA receptor.The roles of p85S6K in synaptic targeting of GluA1 and learning and memory were evaluated by specific knockdown or overexpression of p85S6K followed by a broad range of methodologies including immunofluorescence,Western blot,in situ proximity ligation assay,morphological staining and behavioral examination.Further,the expression level of p85S6K was measured in brains from AD patients and AD model mice.Results p85S6K,but not p70S6K,was enriched in the postsynaptic densities.Moreover,knockdown of p85S6K resulted in defective spatial and recognition memory.In addition,p85S6K could interact with the GluA1 subunit of AMPA receptor through synapse-associated protein 97 and A-kinase anchoring protein 79/150.Mechanistic studies demonstrated that p85S6K could directly phosphorylate GluA1 at Ser845 and increase the amount of GluA1 in syn-apses,thus sustaining synaptic function and spine densities.Moreover,p85S6K was found to be specifically decreased in the synaptosomal compartment in the brains of AD patients and AD mice.Overexpression of p85S6K ameliorated the synaptic deficits and cognitive impairment in transgenic AD model mice.Conclusions These results strongly imply a significant role for p85S6K in maintaining synaptic and cognitive function by interacting with GluA1.The findings provide an insight into the rational targeting of p85S6K as a therapeutic potential for AD.

Effect of Metformin-Induced Stimulation on the Expression of Insulin Receptor Substrate 1 through Negative Regulation of P70S6k

Objective:The aim is to study the effects of metformin on the expression of 70 kDa ribosomal protein S6 kinase(P70S6k),insulin receptor substrate 1(IRS-1),and IRS-1Ser307 phosphorylation in human luteinized granulosa cells.Methods:Granulosa cells in the experimental group were cultured in M199 medium containing 0.1 mmol/L metformin for 24 h and those in control group were cultured in M199 medium.The expression levels of P70S6k and IRS-1 mRNA were detected by reverse-transcriptiom polymerase chain reaction(RT-PCR)and real-time PCR.P70S6k,IRS-1,p-ser307-IRS-1,and p-thr389-P70S6k protein expression levels were detected by immunofluorescence and western blotting.Results:P70S6k mRNA level was higher and IRS-1 was significantly lower in the experimental group than those in the control group.IRS-1 and p-ser307-IRS-1 were expressed in cell plasma,and P70S6k and p-thr389-P70S6k were expressed in cell nucleus.The results of Western blot analysis indicated that the expression levels of P70S6k,p-thr389-P70S6k,IRS-1,and p-ser307-IRS-1 proteins had significant difference between the experimental group and the control group.Compared to the control group,the relative intensity illustrated that the expression levels of P70S6K and p-thr389-P70S6k significantly increased in the experimental group;however,those of IRS-1 and p-ser307-IRS-1 proteins significantly decreased.Conclusion:Metformin can inhibit the P70S6k mRNA and protein expression levels in the granulosa cells and improve insulin sensitivity by regulating IRS-1 expression through Akt/P70S6k/IRS-1-dependent pathway.

Activation of mammalian target of rapamycin contributes to pain nociception induced in rats by BmK I, a sodium channel-specific modulator

The mammalian target of rapamycin （mTOR） pathway is essential for maintenance of the sensitivity of certain adult sensory neurons. Here, we investigated whether the mTOR cascade is involved in scorpion envenomation-induced pain hypersensitivity in rats. The results showed that intraplantar injection of a neurotoxin from Buthus martensii Karsch, BmK I （10 pg）, induced the activation of mTOR, as well as its downstream molecules p70 ribosomal S6 protein kinase （p70 S6K） and eukaryotic initiation factor 4E-binding protein 1 （4E-BP1）, in lumbar 5-6 dorsal root ganglia neurons on both sides in rats. The activation peaked at 2 h and recovered 1 day after injection. Compared with the control group, the ratios of p-mTOR/p-p70 S6K/p-4E- BP1 in three types of neurons changed significantly. The cell typology of p-mTOR/p-p70 S6K/p-4E-BP1 immuno-reactive neurons also changed. Intrathecal administration of deforolimus, a specific inhibitor of mTOR, attenuated BmK I-induced pain responses （spontaneous flinching, paroxysmal pain-like behavior, and mechanical hypersensitivity）. Together, these results imply that the mTOR signaling pathway is mobilized by and contributes to experimental scorpion sting-induced pain.

Oral everolimus inhibits intimal proliferation in injured carotid artery in rats

Background Everolimus, a derivative of sirolimus, is a potent immunosuppressant that has important anti-proliferative properties. In the present study, we demonstrated the inhibiting neointimal hyperplasia in injured carotid arteries in rats by using two different doses of everolimus administrated via the oral route for a long time. Methods A rat model of carotid artery injury was established by balloon inflation. Eighty rats were randomly divided into the sham-operated group （n=20）, injury group （n=20）, low dosage of everolimus group （n=20）, and high dosage of everolimus group （n=20）. The low close of everolimus （1.5 mg/kg） was given one day before injuring the carotid artery by balloon, followed by 0.75 mg/kg per day for 28 days via intragastric gavage. High dose everolimus （2.5 mg/kg） was given one day before injuring the carotid artery by balloon, followed by 1 mg/kg per day for 28 days. Expression of eukaryotic translation initiation factor 4E （elF-4E） and phosphorylation of ribosomal proteinS6 kinase 1 （P70S6K） were determined by reverse transcription-polymerase chain reaction and Western blotting analysis. Results In the injured carotid artery, neointimal hyperplasia was normally observed four weeks after injury. Everolimus inhibited neointimal hyperplasia after balloon injury in a dose dependent manner. At the same time, the study demonstrated that everolimus reduced the expression of P-P70S6K, elF-4E, transforming growth factor （TGF）-131 and of proliferating cell nuclear antigen （PCNA）. Conclusions Everolimus significantly inhibited neointimal hyperplasia of the injured carotid artery. The effect depended on dosaqe and was associated with the reduction of phosphorylation of P70S6K and the elF-4E expression level.