الملخص
Obiective Alzheimer’s disease (AD) is a degenerative disease of the central nervous system (CNS) caused by a variety of risk factors. There are various pathological changes, but apoptosis of the neurological meridian cells is one of the most important pathological bases. Hyperlipidemia is a high-risk factor for the development of AD, which can lead to increased levels of oxidized low-density lipoprotein (ox-LDL) in brain tissues. PCSK9 is a protease closely related to lipid metabolism, but studies have shown that it may be related to the development of AD. LRP1 is abundantly expressed in neuronal cells, and it is an important transporter for the clearance of Aβ. There is now a large amount of literature confirming that PCSK9 can induce the degradation of LRP1. PI3K/AKT is an important signaling pathway in vivo, which plays an important role in apoptosis, and there is now a large amount of literature confirming that LRP1 activates the PI3K/AKT pathway, which has an anti-apoptotic effect. So can PCSK9 affect the PI3K/AKT pathway through LRP1 and thus regulate neuronal apoptosis? This deserves further investigation.The aim of this study was to explore the role of PCSK9 in mediating ox-LDL pro-apoptotic neuronal cell death and its mechanism, and then further elaborate the mechanism of hyperlipidemia leading to neurodegenerative diseases such as AD. MethodsFirstly, PC12 cells were treated with different concentrations of ox-LDL (0, 25, 50, 75 and 100 mg/L) for 24 h. Oil red O staining was used to detect lipid accumulation in PC12 cells, Hoechst33258 staining and flow cytometry to detect apoptosis in PC12 cells, ELISA to detect the content of Aβ secreted by PC12, Western blot to detect expression of SREBP2, PCSK9 and LRP1. Then PC12 cells were treated with 75 mg/L ox-LDL for different times (0, 6, 12, 24, 48 h), and Western blot were performed to detect the expression of SREBP2, PCSK9 and LRP1. Finally, after transfecting 100 nmol/L PCSK9 siRNA into PC12 cells for 48 h, PC12 cells were treated with 75 mg/L ox-LDL for 24 h, Hoechst33258 staining and flow cytometry to detect apoptosis rate of PC12 cells, and Western blot to detect PCSK9, LRP1, PI3K, AKT, P-PI3K , P-AKT, NF-κB, Bcl-2, Bax, Caspase-9 and Caspase-3 expression, and ELISA detected Aβ content secreted by PC12 cells. Resultsox-LDL increased lipid accumulation and promoted apoptosis and Aβ secretion in PC12 cells, as well as increasing the expression of SREBP2 and PCSK9 and decreasing the expression of LRP1 in PC12 cells. pCsk9 siRNA could be inhibited through the PI3K/AKT pathway and the NF-κB-Bcl-2/Bax-Caspase-9/3 pathway to inhibit ox-LDL-induced apoptosis in PC12 cells while increasing Aβ secretion in PC12 cells. Conclusionox-LDL plays a bidirectional regulatory role in ox-LDL-induced apoptosis of PC12 cells by inducing an increase in PCSK9 expression and a decrease in LRP1 expression in PC12 cells, which in turn affects different signaling pathways downstream.
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Objective:To investigate the impact of matrix metalloproteinase 13 (MMP13) and low-density lipoprotein receptor-related protein 1 (LRP1) on autophagy of articular chondrocytes in patients with Kashin-Beck disease (KBD).Methods:Human articular cartilage samples obtained from 4 KBD patients and 4 control subjects were collected from Shaanxi Institute for Endemic Disease Prevention and Control, and the expression levels of MMP13 and LRP1 in cartilage tissue were determined using immunohistochemistry (IHC). Chondrocytes were extracted and cultured in vitro, the mRNA and protein expression levels of LRP1 and the autophagy related genes [Beclin 1 (BECN1), microtubule associated protein 1 light chain 3 (LC3)], cartilage injury related genes [MMP13, caspase-3 (CASP3)], chondrocyte differentiation related genes [collagen type Ⅱ alpha 1 chain (COL2A1), and SRY-box transcription factor 9 (SOX9)] were detected by real-time fluorescence quantitative PCR (qRT-PCR) and Western blot (WB), respectively. Chondrocytes from 3 KBD patients were extracted, and MMP13 gene silencing experiment was performed by RNA interference (RNAi) technology, the mRNA and protein expression levels of the above genes were detected by qRT-PCR and WB, respectively. In addition, the antagonist receptor associated protein (RAP) of LRP1 was used to block the LRP1 of human normal chondrocytes (C28/I2 cells), and qRT-PCR and WB were used to detect the mRNA and protein expression levels of LRP1, chondrocyte autophagy, differentiation and cartilage injury related genes, respectively. Results:The IHC results showed that the expression levels of MMP13 (1.67 ± 0.21, 0.59 ± 0.15, 0.51 ± 0.12) in the surface, middle, and deep layers of cartilage tissue of KBD patients were significantly higher than those of control subjects (0.25 ± 0.03, 0.26 ± 0.04, 0.06 ± 0.01), and the differences were statistically significant ( t = - 11.38, P < 0.001; t = - 3.82, - 6.26, P = 0.019, 0.003). The expression levels of LRP1 (0.10 ± 0.02, 0.03 ± 0.01, 0.17 ± 0.03) were significantly lower than those of control subjects (1.63 ± 0.40, 0.44 ± 0.12, 0.34 ± 0.08), and the differences were statistically significant ( t = 6.61, 5.61, 3.64, P = 0.003, 0.005, 0.022). The mRNA and protein expression levels of MMP13, CASP3, SOX9 in chondrocytes of KBD patients were significantly higher than those of control subjects, and the differences were statistically significant ( P < 0.05). The mRNA expression levels of LRP1, LC3, COL2A1 were significantly lower than those of control subjects, and the differences were statistically significant ( P < 0.05). After silencing the MMP13 gene in chondrocytes of KBD patients, there were no significant differences in the mRNA and protein expression levels of LRP1, BECN1, LC3, CASP3, COL2A1, and SOX9 ( P > 0.05). After blocking LRP1 with RAP, the protein expression levels of LRP1, BECN1, LC3, MMP13, COL2A1 and SOX9 in chondrocytes were significantly lower than those in control group ( P < 0.05). Conclusions:There is no direct correlation between MMP13 and abnormal autophagy of articular chondrocytes in KBD patients. After blocking LRP1, the expression of the autophagy related genes BECN1 and LC3 in chondrocytes is decreased.
الملخص
Low-density lipoprotein receptor-related protein 1B (LRP1B) is defined as a potential cancer suppressor since it was discovered, and it has been found to be silencing in multiple tumors, and its main pathogenic mechanisms include gene mutations, epigenetic modifications in the promoter region and regulation by microRNA (miRNA). Recent studies showed that LRP1B played an important role in the occurrence and development of digestive system tumors. Combined with domestic and international research advances, this review summarizes the structure and function of LRP1B and its effect on digestive system tumors, further reveals its potential value as a marker of immunotherapy, and explores its transition from cancer inhibitor to cancer promotor in different tumors, with the aim of helping the subsequent research on the mechanism.
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ObjectiveTo investigate the protective effect of Liuwei Dihuangwan on neurovascular injury in SAMP8 mice. MethodThe Alzheimer's disease （AD） model with insufficiency of kidney essence was induced in 75 SAMP8 mice aging 6 months. The model mice were divided into model group， positive control group （donepezil hydrochloride， 0.747 mg·kg-1·d-1）， and high-， medium-， and low-dose Liuwei Dihuangwan groups （2.700， 1.350， 0.675 g·kg-1·d-1）， with 15 mice in each group. Fifteen SAMR1 mice were assigned to a normal control group. All mice were administered continuously for 2 months. The spatial memory of mice was tested by the Morris water maze. Hematoxylin-eosin （HE） staining was used to observe the pathological changes in the hippocampus and cortex of brain tissues. The immunohistochemical method （IHC） was used to detect the deposition of amyloid β-protein （Aβ） and the expression of von Willebrand factor （vWF） and CD34 in the hippocampus and cortex of brain tissues. Electron microscopy was used to observe the ultrastructural changes in cerebral microvessels. Western blot was used to detect the protein expression levels of the receptor of advanced glycation endproduct （RAGE）， low-density lipoprotein receptor-related protein 1 （LRP1）， vascular endothelial growth factor A （VEGF-A）， and P-selection in the hippocampus and cortex of brain tissues. ResultCompared with the normal control group， the model group showed prolonged escape latency and swimming distance （P<0.01）， increased number of glial cells， decreased number of nerve cells， blurred tight junctions or enlarged gap of the brain microvascular endothelial cells， severely injured membrane structure， swollen mitochondria of endothelial cells， ruptured membrane， massive dissolution in cristae， increased protein expression of Aβ and vWF in the hippocampus and cortex （P<0.01）， reduced protein expression of CD34 （P<0.05）， elevated protein expression of RAGE and P-selection in the cortex （P<0.01）， and decreased protein expression level of LRP1 and VEGF-A （P<0.01）. Compared with the model group， the Liuwei Dihuangwan groups showed shortened escape latency and swimming distance （P<0.05）， reduced number of glial cells in the cortex and hippocampus， increased number of microvessels in the cortex， clear double-layer membrane structure in tight junctions between the microvascular endothelial cells， increased number of mitochondria with intact membrane and recovered mitochondrial cristae， decreased protein expression of Aβ， vWF， RAGE， and P-selection in the hippocampus and cortex （P<0.05）， and increased protein expression of CD34， LRP1， and VEGF-A （P<0.05）. ConclusionLiuwei Dihuangwan can regulate Aβ metabolism through the RAGE/LRP1 receptor system and promote cerebral microvascular angiogenesis by inhibiting vWF expression and increasing VEGF-A and CD34， thereby improving cerebral microvascular injury in SAMP8 mice.
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Objective: To uncover the time-dependent expression pattern of ptk2b gene and ptk2b-encoded protein, protein tyrosine kinase 2 beta(PTK2B), in the brain tissues of transgenic animal models of Alzheimer's disease (AD) and its relationship with the levels of Aβ1-42, phosphorylation of Tau (p-Tau) and low density lipoprotein receptor-related protein-1(LRP-1) in blood and brain tissues. Methods: In this study, 5-, 10- and 15-month-old APPswe/PS1dE9 double-transgenic mice harboring the genotype of AD confirmed by the gene test were divided into the 5-, 10- and 15-month-old experiment groups, and simultaneously, age-matched C57BL/6J mice were placed into the corresponding control groups, with 8 mice in each group. All mice were subjected to the Morris Water Maze for test of cognitive and behavioral ability. Expression profiles of PTK2B, Aβ1-42, p-Tau/Tau and LRP-1 in the hippocampus or blood of mice were quantified by using the immunohistochemistry staining, Western blot or enzyme-linked immunosorbent assay (ELISA), while the mRNA expression of ptk2b in the hippocampus was quantified by using the real-time quantitative polymerase chain reaction (qRT-PCR). Results: Results of experiment groups demonstrated that as mice aged, the expression levels of PTK2B, ptk2b mRNA, Aβ1-42 and p-Tau/Tau in the hippocampus were increased, and the expression of LRP-1 was decreased gradually. While in the blood, the level of Aβ1-42 was decreased, and the cognitive and behavioral ability was decreased in an age-dependent manner (all P＜ 0.05). However, comparisons among the control groups, only the age-dependent downregulation of LRP-1 were observed in hippocampus(P＜0.05), but other indicators had no significant differences (P＞0.05). Conclusion: In the hippocampus of APP/PS1 double-transgenic mice, the expressions of PTK2B, Aβ1-42 and p-Tau/Tau are upregulated, LRP-1 is downregulated, while cognitive and behavioral ability is decreased, and such changes are presented in a time-dependent manner.
الموضوعات
Animals , Mice , Alzheimer Disease/metabolism , Amyloid beta-Peptides , Amyloid beta-Protein Precursor/genetics , Focal Adhesion Kinase 2/metabolism , Hippocampus/metabolism , Low Density Lipoprotein Receptor-Related Protein-1 , Maze Learning , Mice, Inbred C57BL , Mice, Transgenic , RNA, Messengerالملخص
OBJECTIVES@#To study the role of the low-density lipoprotein receptor-related protein 1 (LRP1)-proline-rich tyrosine kinase 2 phosphorylation (pPyk2)-matrix metalloproteinases 9 (MMP9) pathway in hyperoxia-induced lung injury in neonatal rats.@*METHODS@#A total of 16 neonatal rats were randomly placed in chambers containing room air (air group) or 95% medical oxygen (hyperoxia group) immediately after birth, with 8 rats in each group. All of the rats were sacrificed on day 8 of life. Hematoxylin and eosin staining was used to observe the pathological changes of lung tissue. ELISA was used to measure the levels of soluble LRP1 (sLRP1) and MMP9 in serum and bronchoalveolar lavage fluid (BALF). Western blot was used to measure the protein expression levels of LRP1, MMP9, Pyk2, and pPyk2 in lung tissue. RT-PCR was used to measure the mRNA expression levels of LRP1 and MMP9 in lung tissue.@*RESULTS@#The hyperoxia group had significantly higher levels of sLRP1 and MMP9 in serum and BALF than the air group (@*CONCLUSIONS@#The activation of the LRP1-pPyk2-MMP9 pathway is enhanced in hyperoxia-induced lung injury in neonatal rats, which may be involved in the pathogenesis of bronchopulmonary dysplasia.
الموضوعات
Animals , Rats , Animals, Newborn , Hyperoxia/complications , Lung , Lung Injury/etiology , Matrix Metalloproteinase 9/geneticsالملخص
Objective::To observe the neuroprotective effect and potential mechanism of Zhenxin Shengshui Yizhi Fang(XSF) aqueous extract on human brain microvascular endothelial cells (HBMEC) injury induced by amyloid-β protein(Aβ)25-35. Method::HBMEC cells damage induced by Aβ25-35 was used as Alzheimer' s disease(AD) cell model. The study included control group, Aβ25-35 group, and low, medium and high-dose XSF aqueous extract groups (125, 250, 500 mg·L-1). After treatment, the cytotoxicity of different concentrations of drugs and Aβ25-35 was determined by methyl thiazolyl tetrazolium(MTT) colorimetry. Apoptosis was observed by Hoechst-33258 staining. The activity of Caspase-3 was detected by colorimetry. Western blot was used to detect the expression levels of the receptor of advanced glycation end products (RAGE) and low-density lipoprotein receptor-related protein (LRP1). Result::Compared with the control group, the cell viability of Aβ25-35 group was significantly decreased (P<0.01). Hoechst-33258 staining showed bright blue fluorescence, chromatin condensation, dense staining or fragmentation dense staining, whitening in color, and significant increase of the percentage of apoptotic cells (P<0.01). Caspase-3 activity increased significantly (P<0.01). Western blot showed that RAGE protein expression increased significantly (P<0.01), while low-density lipoprotein receptor-related protein(LRP1), glucose transporter 1(GLUT1) and GLUT3 protein expressions decreased significantly (P<0.01). Compared with the Aβ25-35 group, the cell viability of XSF aqueous extract groups was significantly increased in a dose-dependent manner. The XSF aqueous extract had a more significant protective effect of than the other groups (P<0.05). The XSF aqueous extract group (500 mg·L-1) significantly inhibited the number of apoptotic cells (P<0.01), but significantly reduced the Caspase-3 activity (P<0.01). RAGE protein expression was not significantly decreased in XSF aqueous extract group (125 mg·L-1), but significantly decreased in XSF aqueous extract group (250, 500 mg·L-1, P<0.01), while LRP1, GLUT1 and GLUT3 protein expression significantly increased (P<0.05, P<0.01) in a dose-dependent manner. Conclusion::XSF aqueous extract can attenuate the cytotoxicity of HBMEC induced by Aβ25-35 oligomer, inhibit apoptosis, decrease caspase-3 activity and RAGE protein expression, increase LRP1, GLUT1 and GLUT3 protein expressions, and reduce the abnormal accumulation and deposition of Aβ in the brain, which may be its mechanisms for prevention and treatment of AD.
الملخص
According to traditional Chinese medicine, "spleen transport" is closely related to the metabolism of substance and energy. Studies have shown that Alzheimer's disease(AD) is a disease related to glucose and lipid metabolism and energy metabolism. The traditional Chinese medicine Jiangpi Recipe can improve the learning ability and memory of AD animal model. Sijunzi Decoction originated from Taiping Huimin Hefang Prescription is the basic prescription for strengthening and nourishing the spleen, with the effects of nourishing Qi and strengthening the spleen. In this experiment, human brain microvascular endothelial cells(HBMEC) and Sijunzi Decoction water extract(0.25, 0.5, 1 mg·L~(-1)) were pre-incubated for 2 h, and then Aβ_(25-35) oligomers(final concentration 40 μmol·L~(-1)) was added for co-culture for 22 hours. The effect of Sijunzi Decoction on the activity of Aβ_(25-35) oligomer injured cells and the expression of related proteins were investigated. Q-TOF-LC-MS was used first for principal component analysis of Sijunzi Decoction water extract. Then MTT assay was used to investigate the effect of Sijunzi Decoction water extract on the proliferation of HBMEC cells. Real-time fluorescence quantitative PCR(RT-qPCR) was employed to detect the mRNA expression of GLUT1, RAGE, and LRP1. The expression of Aβ-related proteins across blood-brain barrier(RAGE, LRP1) was detected by Western blot. The results showed that 40 μmol·L~(-1) Aβ_(25-35) oligomers could induce endothelial cell damage, reduce cell survival, increase expression of RAGE mRNA and RAGE protein, and reduce expression of GLUT1 mRNA, LRP1 mRNA, and LRP1 protein. Sijunzi Decoction water extract could reduce the Aβ_(25-35) oligomer-induced cytotoxicity of HBMEC, decrease the expression of RAGE mRNA and RAGE protein, and increase the expression of GLUT1 mRNA, LRP1 mRNA and LRP1 protein. The results indicated that Sijunzi Decoction could reduce the injury of HBMEC cells induced by Aβ_(25-35) oligomer, and regulate the transport-related proteins GLUT1, RAGE and LRP1, which might be the mechanism of regulating Aβ_(25-35) transport across the blood-brain barrier.
الموضوعات
Animals , Humans , Amyloid beta-Peptides , Blood-Brain Barrier , Drugs, Chinese Herbal , Endothelial Cellsالملخص
Almost all active immunotherapy attempts which targeted at clearing or reducing β-amyloid (Aβ) plaques in brains of patients with Alzheimer'disease (AD) were fallen into unprecedented difficulties,because of unsatisfactory curative effects.Recently,more and more evidences support that low density lipoprotein receptor related protein 1 (LRP1) is involved in Aβ production and clearance through multiple non-immune pathways,which has showed the potential as a whole-new interference target different with classical Aβ immunotherapies.So,we try to summarize the research developments of roles of LRP1 in Aβ metabolic process in physiological and AD conditions,and look forward to its possible applications in the prevention and treatment of AD.
الملخص
Present study investigated the role of mesenchyme homeobox 2 (MEOX2) gene in neurovascular dysfunction in Alzheimer's disease (AD) model rats by bilateral intracerebroventricular injection of Aβ1-42. One week after surgery, Morris water maze, immunohistochemistry, biochemical detection, Western blot and real-time PCR were used to detect the indexes. The animal studies were conducted in accordance with the Regulations of Experimental Animal Administration issued by the State Committee of Science and Technology of the People's Republic of China. Compared to the Sham-operated rats, Aβ1-42-operated rats showed obviously cognitive dysfunction, accompanied by increased Aβ, glial fibrillary acidic protein (GFAP), allograft inflammatory factor 1 (AIF1), endothelial nitric oxide synthase (eNOS) and decreased neuron specific enolase (NSE), synaptophysin (SYN), CD34, vascular endothelial growth factor (VEGF) expressions of brain. Aβ1-42-operated rats also increased the endothelin (ET) level and decreased nitric oxide (NO) level in brain tissue. Moreover, MEOX2 expression was decreased correlated with low density lipoprotein receptor-related protein 1 (LRP-1) decreasing and receptor for advanced glycation end products (RAGE) increasing in brain tissues of AD model rats. We found the correlation between MEOX2 gene expression and neurovascular dysfunction, in addition, the decreased MEOX2 may involve in increasing the accumulation of Aβ in brain by relating to the decreased LRP-1 and increased RAGE which is located in blood-brain barrier (BBB) in senescence-accelerated mice.
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Low-density lipoprotein receptor-related protein-1 (LRP-1) is a transmembrane receptor protein locatedon the plasma membrane of the cells and involved in receptor-mediated endocytosis.LRP-1 binds to distinct ligandsthat are structurally and functionally unrelated, which makes it not only mediates endocytosis, but also regulates cell surfaceproteolytic activity and specific intracellular signaling pathways related to multiple links in the process of developmentof atherosclerosis.Moreover, LRP-1 plays an important role in maintaining vascular stability.This review focuses on theprogress in LRP-1-regulated vascular integrity, and provides new insights to the target of the blood vessel diseases.
الملخص
? amyloid protein(A?) including A?40 and A?42 are the important bioactive substances in vivo.Their toxic and beneficial attributes in the body depend on its concentration.The brain A? level is maintained by two balances under the physiological condition.The first balance is the generation involved in ?-secretase and ?-secretase and the degradation involved in neprilysin(NEP) and insulin-degrading enzyme(IDE) of A?. The second one is the balance between the receptor for advanced end glycation products(RAGE)-mediated influx and low-density lipoprotein receptor related protein 1(LRP1)-mediated efflux of A? across the blood-brain barrier(BBB).Breakdowning any one of the two balances would result in the aggregation and precipitation of A? in the brain,which is a crucial event in the pathogenesis of Alzheimer's disease(AD).This paper reviews the regulation of brain A? level under the physiological condition and the reducing strategies on the level of brain A? under the pathological condition for developing new drugs in the treatment of AD.