Roles of neuronal lysosomes in the etiology of Parkinson’s disease

Therapeutic progress in neurodegenerative conditions such as Parkinson’s disease has been hampered by a lack of detailed knowledge of its molecular etiology.The advancements in genetics and genomics have provided fundamental insights into specific protein players and the cellular processes involved in the onset of disease.In this respect,the autophagy-lysosome system has emerged in recent years as a strong point of convergence for genetics,genomics,and pathologic indications,spanning both familial and idiopathic Parkinson’s disease.Most,if not all,genes linked to familial disease are involved,in a regulatory capacity,in lysosome function(e.g.,LRRK2,alpha-synuclein,VPS35,Parkin,and PINK1).Moreover,the majority of genomic loci associated with increased risk of idiopathic Parkinson’s cluster in lysosome biology and regulation(GBA as the prime example).Lastly,neuropathologic evidence showed alterations in lysosome markers in autoptic material that,coupled to the alpha-synuclein proteinopathy that defines the disease,strongly indicate an alteration in functionality.In this Brief Review article,I present a personal perspective on the molecular and cellular involvement of lysosome biology in Parkinson’s pathogenesis,aiming at a larger vision on the events underlying the onset of the disease.The attempts at targeting autophagy for therapeutic purposes in Parkinson’s have been mostly aimed at“indiscriminately”enhancing its activity to promote the degradation and elimination of aggregate protein accumulations,such as alpha-synuclein Lewy bodies.However,this approach is based on the assumption that protein pathology is the root cause of disease,while pre-pathology and pre-degeneration dysfunctions have been largely observed in clinical and pre-clinical settings.In addition,it has been reported that unspecific boosting of autophagy can be detrimental.Thus,it is important to understand the mechanisms of specific autophagy forms and,even more,the adjustment of specific lysosome functionalities.Indeed,lysosomes exert fine signaling capacities in addition to their catabolic roles and might participate in the regulation of neuronal and glial cell functions.Here,I discuss hypotheses on these possible mechanisms,their links with etiologic and risk factors for Parkinson’s disease,and how they could be targeted for disease-modifying purposes.

Role of lysosomal trafficking regulator in autophagic lysosome reformation in neurons:a disease perspective

Lysosomes are discrete organelles that act as recycling centers for extracellular and intracellular materials,playing a pivotal role in maintaining cellular homeostasis.Their acidic environment,maintained by numerous hydrolytic enzymes,facilitates substrate degradation.Dysfunction in lysosomal processes can lead to abnormal substrate degradation,significantly impacting cellular homeostasis.High energy-demanding cells,such as post-mitotic neurons,are especially vulnerable to these changes,often resulting in neurological diseases.Autophagy,a conserved catabolic process,requires extensive lysosomal utilization.It plays a key role in removing unnecessary intracellular components,ensuring cellular homeostasis,and promoting cell survival during stress conditions such as starvation,infection,or cellular damage.

Nanomaterials-mediated lysosomal regulation:a robust protein-clearance approach for the treatment of Alzheimer’s disease

Alzheimer’s disease is a debilitating,progressive neurodegenerative disorder characterized by the progressive accumulation of abnormal proteins,including amyloid plaques and intracellular tau tangles,primarily within the brain.Lysosomes,crucial intracellular organelles responsible for protein degradation,play a key role in maintaining cellular homeostasis.Some studies have suggested a link between the dysregulation of the lysosomal system and pathogenesis of neurodegenerative diseases,including Alzheimer’s disease.Restoring the normal physiological function of lysosomes hold the potential to reduce the pathological burden and improve the symptoms of Alzheimer’s disease.Currently,the efficacy of drugs in treating Alzheimer’s disease is limited,with major challenges in drug delivery efficiency and targeting.Recently,nanomaterials have gained widespread use in Alzheimer’s disease drug research owing to their favorable physical and chemical properties.This review aims to provide a comprehensive overview of recent advances in using nanomaterials(polymeric nanomaterials,nanoemulsions,and carbon-based nanomaterials)to enhance lysosomal function in treating Alzheimer’s disease.This review also explores new concepts and potential therapeutic strategies for Alzheimer’s disease through the integration of nanomaterials and modulation of lysosomal function.In conclusion,this review emphasizes the potential of nanomaterials in modulating lysosomal function to improve the pathological features of Alzheimer’s disease.The application of nanotechnology to the development of Alzheimer’s disease drugs brings new ideas and approaches for future treatment of this disease.

Enhanced autophagic clearance of amyloid-βvia histone deacetylase 6-mediated V-ATPase assembly and lysosomal acidification protects against Alzheimer's disease in vitro and in vivo

Recent studies have suggested that abnormal acidification of lysosomes induces autophagic accumulation of amyloid-βin neurons,which is a key step in senile plaque formation.Therefore,resto ring normal lysosomal function and rebalancing lysosomal acidification in neurons in the brain may be a new treatment strategy for Alzheimer's disease.Microtubule acetylation/deacetylation plays a central role in lysosomal acidification.Here,we show that inhibiting the classic microtubule deacetylase histone deacetylase 6 with an histone deacetylase 6 shRNA or thehistone deacetylase 6 inhibitor valproic acid promoted lysosomal reacidification by modulating V-ATPase assembly in Alzheimer's disease.Fu rthermore,we found that treatment with valproic acid markedly enhanced autophagy.promoted clearance of amyloid-βaggregates,and ameliorated cognitive deficits in a mouse model of Alzheimer's disease.Our findings demonstrate a previously unknown neuroprotective mechanism in Alzheimer's disease,in which histone deacetylase 6 inhibition by valproic acid increases V-ATPase assembly and lysosomal acidification.

S100A8/A9 induces autophagy and apoptosis via ROS-mediated cross-talk between mitochondria and lysosomes that involves BNIP3

The complex formed by two members of the S100 calcium-binding protein family, S100A8/A9, exerts apoptosisinducing activity in various cells of different origins. Here, we present evidence that the underlying molecular mechanisms involve both programmed cell death I （PCD I, apoptosis） and PCD II （autophagy）-like death. Treatment of cells with S100A8/A9 caused the increase of Beclin-1 expression as well as Atgl2-Atg5 formation. S100A8/A9-induced cell death was partially inhibited by the specific PI3-kinase class Ⅲ inhibitor, 3-methyladenine （3-MA）, and by the vacuole H＋-ATPase inhibitor, bafilomycin-A1 （Baf-A1）. S100A8/A9 provoked the translocation of BNIP3, a BH3 only pro-apoptotic Bcl2 family member, to mitochondria. Consistent with this finding, ATM-BNIP3 overexpression partially inhibited S100A8/A9-induced cell death, decreased reactive oxygen species （ROS） generation, and partially pro- tected against the decrease in mitochondrial transmembrane potential in S100A8/A9-treated ceils. In addition, either ATM-BNIP3 overexpression or N-acetyl-L-cysteine co-treatment decreased lysosomal activation in cells treated with S100A8/A9. Our data indicate that S100A8/A9-promoted cell death occurs through the cross-talk of mitochondria and lysosomes via ROS and the process involves BNIP3.

Enhancement of lysosome biogenesis as a potential therapeutic approach for neurodegenerative diseases

Millions of people are suffering from Alzheimer’s disease globally,but there is still no effective treatment for this neurodegenerative disease.Thus,novel therapeutic approaches for Alzheimer’s disease are needed,which requires further evaluation of the regulato ry mechanisms of protein aggregate degradation.Lysosomes are crucial degradative organelles that maintain cellular homeostasis.Transcription factor EB-mediated lysosome biogenesis enhances autolysosomedependent degradation,which subsequently alleviates neurodege nerative diseases,including Alzheimer’s disease,Parkinson’s disease,and Huntington’s disease.In this review,we start by describing the key features of lysosomes,including their roles in nutrient sensing and degradation,and their functional impairments in different neurodegenerative diseases.We also explain the mechanisms—especially the post-translational modifications—which impact transcription factor EB and regulate lysosome biogenesis.Next,we discuss strategies for promoting the degradation of toxic protein aggregates.We describe Proteolysis-Ta rgeting Chimera and related technologies for the targeted degradation of specific proteins.We also introduce a group of LYsosome-Enhancing Compounds,which promote transcription factor EB-mediated lysosome biogenesis and improve learning,memory,and cognitive function in APP-PSEN1 mice.In summary,this review highlights the key aspects of lysosome biology,the mechanisms of transcription factor EB activation and lysosome biogenesis,and the promising strategies which are emerging to alleviate the pathogenesis of neurodegenerative diseases.

SIRT1 facilitates amyloid beta peptide degradation by upregulating lysosome number in primary astrocytes

Previous studies have shown that sirtuin 1（SIRT1） reduces the production of neuronal amyloid beta（Aβ） and inhibits the inflammatory response of glial cells, thereby generating a neuroprotective effect against Aβ neurotoxicity in animal models of Alzheimer＇s disease. However, the protective effect of SIRT1 on astrocytes is still under investigation. This study established a time point model for the clearance of Aβ in primary astrocytes. Results showed that 12 hours of culture was sufficient for endocytosis of oligomeric Aβ, and 36 hours sufficient for effective degradation. Immunofluorescence demonstrated that Aβ degradation in primary astrocytes relies on lysosome function. Enzymatic agonists or SIRT1 inhibitors were used to stimulate cells over a concentration gradient. Aβ was co-cultured for 36 hours in medium. Western blot assay results under different conditions revealed that SIRT1 relies on its deacetylase activity to promote intracellular Aβ degradation. The experiment further screened SIRT1 using quantitative proteomics to investigate downstream, differentially expressed proteins in the Aβ degradation pathway and selected the ones related to enzyme activity of SIRT1. Most of the differentially expressed proteins detected are close to the primary astrocyte lysosomal pathway. Immunofluorescence staining demonstrated that SIRT1 relies on its deacetylase activity to upregulate lysosome number in primary astrocytes. Taken together, these findings confirm that SIRT1 relies on its deacetylase activity to upregulate lysosome number, thereby facilitating oligomeric Aβ degradation in primary astrocytes.

KCNJ15 deficiency promotes drug resistance via affecting the function of lysosomes

The altered lysosomal function can induce drug redistribution which leads to drug resistance and poor prognosis for cancer patients.V-ATPase,an ATP-driven proton pump positioned at lysosomal surfaces,is responsible for maintaining the stability of lysosome.Herein,we reported that the potassium voltage-gated channel subfamily J member 15(KCNJ15)protein,which may bind to V-ATPase,can regulate the function of lysosome.The deficiency of KCNJ15 protein in breast cancer cells led to drug aggregation as well as reduction of drug efficacy.The application of the V-ATPase inhibitor could inhibit the binding between KCNJ15 and V-ATPase,contributing to the amelioration of drug resistance.Clinical data analysis revealed that KCNJ15 deficiency was associated with higher histological grading,advanced stages,more metastases of lymph nodes,and shorter disease free survival of patients with breast cancer.KCNJ15 expression level is positively correlated with a high response rate after receiving neoadjuvant chemotherapy.Moreover,we revealed that the small molecule drug CMA/BAF can reverse drug resistance by disrupting the interaction between KCNJ15 and lysosomes.In conclusion,KCNJ15 could be identified as an underlying indicator for drug resistance and survival of breast cancer,which might guide the choice of therapeutic strategies.

Association of Lysosome Associated Protein Transmembrane 4 Beta Gene Polymorphism with the Risk of Pancreatic Cancer

Objective： Lysosome associated protein transmembrane 4 beta （LAPTM4B） was originally identified as a gene in human hepatocellular carcinoma （HCC）. It was successfully cloned by fluorescence differential display, rapid amplification of cDNA ends （RACE） and reverse transcription polymerase chain reaction （RT-PCR）. Previous study showed that the novel gene played an important role in the occurrence, development, migration and prognosis of tumors. Pancreatic cancer is an aggressive malignancy with the majority of patients dying within one year after diagnosis. This study tries to find out the relationship between lysosome associated protein transmembrane 4 beta gene polymorphism and the susceptibility of pancreatic cancer. Methods： A case-control study was conducted in China, including 58 pancreatic cancer cases and 156 healthy controls. Human genomic DNA was used as the template, polymerase chain reaction （PCR） was used to detect the distribution of LAPTM4B genotype. Analyses Odds ratio （OR） and corresponding 95% confidence interval （95%CI） with logistic regression were performed. Results： Two alleles of LAPTM4B generated three kinds of genotypes in population, ＊1/1, ＊1/2, and ＊2/2. The genotype frequency of ＊1/1, ＊1/2 and ＊2/2 in the pancreatic cancer group were 41.4%, 44.8% and 13.8% respectively, which were not significantly different from those of healthy group （47.4%, 42.9%, 9.6%） （P=0.773, P=0.291）. Also the ＊2 allele frequency of LAPTM4B among pancreatic cancer had no significantly difference with the controls （P=0.354）. When compared to the ＊1 allele, the people with ＊2 allele had no increased risk of pancreatic cancer. Conclusion： The gene polymorphism of LAPTM4B may not influence the susceptibility of pancreatic cancer.

Enhanced lysosome escape mediated by 1,2-dicarboxylic-cyclohexene anhydride-modified poly-L-lysine dendrimer as a gene delivery system

Antisense oligodeoxynucleotide(ASODN)can directly interfere a series of biological events of the target RNA derived from tumor cells through Watson-Crick base pairing,in turn,plays antitumor therapeutic roles.In the study,a novel HIF-1αASODN-loaded nanocomposite was formulated to efficiently deliver gene to the target RNA.The physicochemical properties of nanocomposite were characterized using TEM,FTIR,DLS and zeta potentials.The mean diameter of resulting GEL-DGL-FA-ASODN-DCA nanocomposite was about 170–192 nm,and according to the agarose gel retardation assay,the loading amount of ASODN accounted for 166.7 mg/g.The results of cellular uptake showed that the nanocomposite could specifically target to HepG2 and Hela cells.The cytotoxicity assay demonstrated that the toxicity of vectors was greatly reduced by using DCA to reversibly block the cationic DGL.The subcellular distribution images clearly displayed the lysosomal escape ability of the DCA-modified nanocomposite.In vitro exploration of molecular mechanism indicated that the nanocomposite could inhibit m RNA expression and HIF-1αprotein translation at different levels.In vivo optical images and quantitative assay testified that the formulation accumulated preferentially in the tumor tissue.In vivo antitumor efficacy research confirmed that this nanocomposite had significant antitumor activity and the tumor inhibitory rate was 77.99%.These results manifested that the GEL-DGL-FA-ASODNDCA nanocomposite was promising in gene therapeutics for antitumor by interacting directly with target RNA.

Combination of kaempferol and chloroquine induces glioma cell death via expansion and subsequent rupture of lysosomes

OBJECTIVE Chloroquine is considered as a potential chemotherapy and radiotherapy sensitizer,but the anticancer effect of chloroquine alone is limited.Since we found that the flavonoid kaempferol effectively sensitizes glioma cells to chloroquine-mediated cell death,we investigated the underlying mechanisms of glioma cell death induced by the combination of kaempferol and chloroquine.METHODS To examine the effect of kaempferol and/or chloroquine on various glioma cells,cell viability assay using calcein-AM and EthD-1was performed.The changes in the lysosomal structures following treatment with kaempferol and/or chloroquine were observed by electron microscopy and fluorescence microscopy using acridine orange or Lyso-tracker Red.The changes in cathepsin D proteins were analyzed by Western blotting,immunocytochemistry,and fluorescence microscopy using BODIPY FL-pepstatin.RESULTS Treatment with subtoxic doses of chloroquine,when combined with kaempferol,effectively induced cell death in various glioma cells,but not in normal astrocytes.While kaempferol treatment increased the numbers of lysosome,chloroquine treatment increased lysosomal masses.Combined treatment with kaempferol and chloroquine induced the expansion and subsequent rupture of lysosomes,leading to the spillage of the lysosomal contents into the cytosol.We found that while kaemfperol treatment increased the active mature forms of cathepsin D,chloroquine treatment completely blocked the processing of cathepsin D.The processing of cathepsin D was also blocked by the combined treatment,but the activity of cathepsin D,which was released from the lysosomes,was restored.The cell death induced by kaempferol and chloroquine in U251 MG cells was accompanied by mitochondrial dysfunction,ER stress,and DNA damage.CONCLUSION Disruption of lysosomal membrane integrity and a resultant release of lysosomal proteases may critically contribute to the irreparable damage of various organelles and glioma cell death by chloroquine plus kaempferol.

Detection of distribution of copper inside and outside of lysosomes in cultured hepatolenticular degeneration fibroblasts by electron probe X-ray microanalysis

OBJECTIVE: To observe the distribution of copper in the subcellular structure for the understanding of primary pathogenesis of hepatolenticular degeneration (HLD). METHODS: Skin fibroblasts taken from HLD patients were cultured as an in vitro model of HLD, and the control cells taken from healthy volunteers were clutured in the same way. The distribution of copper inside and outside of lysosomes in fibroblasts was detected by quantitative electron probe X-ray microanalysis. The relationship between the subcellular location of copper and the genotype of the patients, and relationship between the distribution of copper and the course of the disease were analyzed. RESULTS: The content of Cu^(2+) inside lysosomes of HLD cells (14.6±2.1 mmol/kg) and of heterozygote cells (11.6±0.6 mmol/kg) was higher than that of normal cells (4.5±1.2 mmol/kg) (P<0.01). The content of Cu^(2+) outside lysosomes of HLD cells (17.5±4.2 mmol/kg) and of heterozygote cells (12.0±0.9 mmol/kg) was higher than that of normal cells (4.7±1.2 mmol/kg) (P<0.01). The distribution of copper in the subcellular structure was correlated with disease courses of HLD patients. With the progression of the disease, more copper was deposited in lysosomes (r=0.85, P<0.01). The content of copper in the diffused cytoplasmic compartment in HLD cells was correlated with that of sulfur (r=0.86, P<0.05), but not in heterozygote and normal cells. CONCLUSIONS: In the early stage of HLD, copper is accumulated outside lysosome, which is paralleled with increase of metallothionein-like proteins (copper and sulfur-binding proteins). With the development of the disease, more copper is deposited inside lysosome than outside lysosome. We conclude that the up-regulation expression of copper and sulfur-binding proteins and copper accumulation in lysosomes may play an important role in lowering the ATP7B gene mutation-induced toxic effects of free copper on the cell.

Anti-sense RNA Inhibits the Expression of Synaptotagmin Ⅱ in RBL-2H3 and Enhances the Exocytosis of Lysosomes in RBL-2H3

Summary: The expression of synaptotagmin Ⅱ(Syt2) in RBL-2H3 (RBL) and its role during exocytosis of RBL was investigated. The expression of Syt2 in RBL was detected by western blot and Syt2 gene was amplified by PCR. The anti-sense full length Syt2 cDNA expression vector was constructed with pEGFP-N1 and transfected into RBL by electroporation, and stable transfectants were selected by using G418. To analyze the role of Syt2 during exocytosis of RBL, the release of cathepsin D was assayed by immunoblotting. The results showed that Syt2 was expressed in RBL. The anti-sense expression vector pEGFP-N1-Syt2-AS was constructed and the sequence of insertion was completely consistent with rat Syt2 (accession number in GeneBank : NM012665). The stable transfectants (RBL-Syt2-AS) were obtained. Western blot showed that RBL-Syt2-AS expressed a lower level of Syt2 (8 % and 10 % of control cells), indicating that the expression of Syt2 in RBL-Syt2-AS was markedly down-regulated by anti-RNA. Compared with control, the release of cathepsin D by RBL-Syt2-AS was increased. It was concluded that Syt2 expressed in RBL and could inhibit exocytosis of lysosomes in RBL.

Concluding Step in Cell Restitution Cycle: ER Transport Vesicles with Sphingolipids in the Outer Leaflet of the Membrane Restore Lysosomes

Restitution of the cell organelles and the membrane implicates serine palmitoyltransferase (SPT) in signal-specific and selective assembly of the transport vesicles. Here, we reveal that SPT, embedded in the outer leaflet (OL) of endoplasmic reticulum (ER), is engaged in the synthesis of ER transport vesicles that recondition cell organelles, and the inner leaflet (IL) SPT in the restitution of the cell membrane. The OL SPT impacts assembly of sphingomyelinase (SMase)—susceptible ER vesicles but not the SMase-resistant and sphingolipid (SPhL) core—carrying vesicles that refurbish the cell membrane. The investigation of the SPT-initiated differences in the placement of SPhL in vesicular membranes by utilizing ER depleted of OL SPT, allows us to conclude that the restitution of endosomal and lysosomal membranes is achieved with the involvement of OL SPT, whereas the IL SPT is involved in formation of the lipid core for glycosphingolipids (GSL) and sphingomyelin (SM) of the apical and basolateral cell membrane. These findings along with our previously published report (Slomiany and Slomiany, Advances in Biological Chemistry, 2013, 3, 275-287), provide a clear distinction between the processes that renovate cell membrane and its organelles from that of the endocytotic cell debridement, and show that vesicles are navigated to the specific organelles and the cell membrane by the biomembrane constituents programmed in ER.

Isoform-and cell-state-specific APOE homeostasis and function

Apolipoprotein E is the major lipid transporter in the brain and an important player in neuron-astrocyte metabolic coupling.It ensures the survival of neurons under stressful conditions and hyperactivity by nourishing and detoxifying them.Apolipoprotein E polymorphism,combined with environmental stresses and/or age-related alterations,influences the risk of developing late-onset Alzheimer’s disease.In this review,we discuss our current knowledge of how apolipoprotein E homeostasis,i.e.its synthesis,secretion,degradation,and lipidation,is affected in Alzheimer’s disease.

Role of lipids in the control of autophagy and primary cilium signaling in neurons

The brain is,after the adipose tissue,the organ with the greatest amount of lipids and diversity in their composition in the human body.In neurons,lipids are involved in signaling pathways controlling autophagy,a lysosome-dependent catabolic process essential for the maintenance of neuronal homeostasis and the function of the primary cilium,a cellular antenna that acts as a communication hub that transfers extracellular signals into intracellular responses required for neurogenesis and brain development.A crosstalk between primary cilia and autophagy has been established;however,its role in the control of neuronal activity and homeostasis is barely known.In this review,we briefly discuss the current knowledge regarding the role of autophagy and the primary cilium in neurons.Then we review the recent literature about specific lipid subclasses in the regulation of autophagy,in the control of primary cilium structure and its dependent cellular signaling in physiological and pathological conditions,specifically focusing on neurons,an area of research that could have major implications in neurodevelopment,energy homeostasis,and neurodegeneration.

Protective effect of Liangxue Huayu decoction on human retinal pigment epithelial cell(ARPE-19)injury induced by hypoxia through autophagy pathway

Background:Exploring the protective mechanism of the Liangxue Huayu(LXHY)decoction on human retinal pigment epithelial(RPE)cells induced by hypoxia through the autophagy pathway.Methods:The appropriate LXHY decoction concentration was determined by CCK-8.ARPE-19 cells were divided into the normal control group(A group),CoCl_(2)group(B group),3-Methyladenine(3-MA)group(treated with 3-MA(the inhibition of autophagy pathway))(C group),blank serum(BS)group(D group),LXHY drug-contained serum(DCS)group(E group),and Rapamycin(RAP)group[treated with LXHY drug-contained serum combined with rapamycin group(the activation of autophagy pathway)](F group).Counting the number of autophagosomes and autolysosomes in each group of cells under transmission electron microscopy.After infection of cells in each group by mRFP-GFP-LC3 fusion protein adenovirus,the strength of autophagic flux was detected.The mRNA expression levels of LC3 and Beclin-1 were detected by Q-PCR.Results:CCK-8 assay results showed that LXHY DCS could inhibit the cell proliferation of ARPE-19 under hypoxia(all P<0.05).As the transmission electron microscopy assay result showed,compared with the normal control group,the number of autolysosomes was significantly increased in the CoCl_(2)group(P<0.05).Compared with CoCl_(2)group,the number of autolysosomes was significantly reduced the 3-Methyladenine group,blank serum group and LXHY drug-contained serum group(all P<0.001).As autophagic flux assay result showed,compared with the normal control group,the level of autophagosomes and autolysosomes were significantly risen in CoCl_(2)group(all P<0.001).Compared with the CoCl_(2)group,the level of autophagosomes and autolysosomes were significantly fell down in 3-Methyladenine group,blank serum group and LXHY drug-contained serum group(all P<0.05).The level of autolysosomes in the LXHY drug-contained serum group was lower than in the blank serum group(P<0.05).Compared with the LXHY drug-contained serum group,the levels of autophagosomes and autolysosomes were significantly risen in the LXHY drug-contained serum combined with the rapamycin group(all P<0.05).As the Q-PCR result showed,compared with the normal control group,the expression of LC3 and Beclin-1 mRNA were significantly reduced in the CoCl_(2)group(all P<0.001).Compared with the CoCl_(2)group,the expression of LC3 mRNA were significantly increased in the 3-Methyladenine group,blank serum group and LXHY drug-contained serum group(all P<0.001).Beclin-1 mRNA expression was increased significantly(all P<0.001)in the blank serum group and the LXHY drug-contained serum group.And Beclin-1 mRNA expression in the LXHY drug-contained serum group was statistically significant increased than blank serum group(P<0.001).In the LXHY drug-contained serum combined with the rapamycin group,the LC3 and Beclin-1 mRNA expression was reduced significantly compared with the LXHY drug-contained serum group(all P<0.001).Conclusion:The LXHY DCS has the ability to protect the human retinal pigment epithelial cell(ARPE-19)damage under hypoxia through the autophagy pathway.

Mechanisms of lysosomal proteases participating in cerebral ischemia-induced neuronal death

There are three different types of cell death, including apoptosis （Type I）, autophagic cell death （Type II）, and necrosis （Type III）. Ischemic neuronal death influences stroke development and progression. Lysosomes are important organelles having an acidic milieu to maintain cellular metabolism by degrading unneeded extra- and intracellular substances. Lysosomal enzymes, including cathepsins and some lipid hydrolases, when secreted following rupture of the lysosomal membrane, can be very harmful to their environment, which results in pathological destruction of cellular structures. Since lysosomes contain catalytic enzymes for degrading proteins, carbohydrates and lipids, it seems natural that they should participate in cellular death and dismantling. In this review, we discuss the recent developments in ischemic neuronal death, and present the possible molecular mechanisms that the lysosomal enzymes participate in the three different types of cell death in ischemic brain damage. Moreover, the research related to the selective cathepsin inhibitors may provide a novel therapeutic target for treating stroke and promoting recovery.

微量元素铜与人体健康

本文综述了微量元素铜在体内的生理作用,阐明了对病理过程影响的生理机制,并从预防医学的角度提出了防止铜缺乏或过多的一些有效的可行性措施。

Physiological functions of Atg6/Beclin 1： a unique autophagy-related protein

The most striking morphological feature of eukaryotic cells is the presence of various membrane-enclosed compartments. These compartments, including organelles and transient transport intermediates, are not static. Rather, dynamic exchange of proteins and membrane is needed to maintain cellular homeostasis. One of the most dramatic examples of membrane mobilization is seen during the process ofmacroautophagy. Macroautophagy is the primary cellular pathway for degradation of long-lived proteins and organelles. In response to environmental cues, such as starvation or other types of stress, the cell produces a unique membrane structure, the phagophore. The phagophore sequesters cytoplasm as it forms a double-membrane cytosolic vesicle, an autophagosome. Upon completion, the autophagosome fuses with a lysosome or a vacuole in yeast, which delivers hydrolases that break down the inner autophagosome membrane along with its cargo, and the resulting macromolecules are released back into the cytosol for reuse. Autophagy is therefore a recycling process, allowing cells to survive periods of nutrient limitation; however, it has a wider physiological role, participating in development and aging, and also in protection against pathogen invasion, cancer and certain neurodegenerative diseases. In many cases, the role ofautophagy is identified through studies of an autophagy-related protein, Atg6/Beclin 1. This protein is part of a lipid kinase complex, and recent studies suggest that it plays a central role in coordinating the cytoprotective function ofautophagy and in opposing the cellular death process of apoptosis. Here, we summarize our current knowledge ofAtg6/Beclin 1 in different model organisms and its unique function in the cell.