Association of CFH and MAP1LC3B gene polymorphisms with age-related macular degeneration in a high-altitude population

AIM: To evaluate the association of complement factor H(CFH) and microtubule-associated protein 1 light chain 3 beta(MAP1LC3B) gene polymorphisms with the risk of age-related macular degeneration(AMD) in a high-altitude population. METHODS: The study group consisted of 172 participants with symptoms of AMD who were examined and diagnosed between January 2019 and June 2020. The control group was composed of 120 healthy individuals. Each participant was required to provide two milliliters of peripheral blood for DNA extraction. Two single nucleotide polymorphisms(SNPs) of CFH(rs1061170 and rs800292) and two SNPs of MAP1LC3B(rs8044820 and rs9903) were genotyped. The genotypes and allele frequencies of the SNPs in the study and control groups were further compared using Chi-square and Fisher’s exact tests. RESULTS: In a high-altitude population, the nominally significant differences of rs800292 and rs9903’s genotype AG frequencies were observed in the AMD group(P=0.034 and 0.004, respectively). The frequencies of allele G of rs800292 and allele A of rs9903 were also significantly dif ferent in the AMD group compared to the control [(P=0.034, OR=0.70, 95%CI: 0.50-0.98) and(P=0.004, OR=1.60, 95%CI: 1.15-2.22), respectively]. No significant differences in the genotype distributions(P=0.16 and 0.40, respectively) and allele frequencies(P>0.05) of rs1061170 and rs8044820 were observed in the AMD group.CONCLUSION: Genotype AG of rs800292 may be a protective factor for AMD. Conversely, rs9903 seems to be a risk factor for AMD. Therefore, allele G of rs800292 may be a protective factor, and allele A of rs9903, a risk factor for AMD in Qinghai high-altitude population.

ROS-mediated BNIP3-dependent mitophagy promotes coelomocyte survival in Apostichopus japonicus in response to Vibrio splendidus infection

Organisms produce high levels of reactive oxygen species(ROS)to kill pathogens or act as signaling molecules to induce immune responses;however,excessive ROS can result in cell death.To maintain ROS balance and cell survival,mitophagy selectively eliminates damaged mitochondria via mitophagy receptors in vertebrates.In marine invertebrates,however,mitophagy and its functions remain largely unknown.In the current study,Vibrio splendidus infection damaged mitochondrial morphology in coelomocytes and reduced mitochondrial membrane potential(ΔΨm)and mitophagosome formation.The colocalization of mitochondria and lysosomes further confirmed that lipopolysaccharide(LPS)treatment increased mitophagy flux.To explore the regulatory mechanism of mitophagy,we cloned Bcl2/adenovirus E1 B 19 kDa protein-interacting protein 3(BNIP3),a common mitophagy receptor,from sea cucumber Apostichopus japonicus(Aj BNIP3)and confirmed that Aj BNIP3 was significantly induced and accumulated in mitochondria after V.splendidus infection and LPS exposure.At the mitochondrial membrane,Aj BNIP3 interacts with microtubule-associated protein 1 light chain 3(LC3)on phagophore membranes to mediate mitophagy.After Aj BNIP3 interference,mitophagy flux decreased significantly.Furthermore,Aj BNIP3-mediated mitophagy was activated by ROS following the addition of exogenous hydrogen peroxide(H2 O2),ROS scavengers,and ROS inhibitors.Finally,inhibition of BNIP3-mediated mitophagy by Aj BNIP3 small interfering RNA(si RNA)or high concentrations of lactate increased apoptosis and decreased coelomocyte survival.These findings highlight the essential role of Aj BNIP3 in damaged mitochondrial degradation during mitophagy.This mitophagy activity is required for coelomocyte survival in A.japonicus against V.splendidus infection.

A novel mechanism of PHB2-mediated mitophagy participating in the development of Parkinson's disease

Endoplasmic reticulum stress and mitochondrial dysfunction play important roles in Parkinson s disease,but the regulato ry mechanism remains elusive.Prohibitin-2(PHB2)is a newly discove red autophagy receptor in the mitochondrial inner membrane,and its role in Parkinson’s disease remains unclear.Protein kinase R(PKR)-like endoplasmic reticulum kinase(PERK)is a factor that regulates cell fate during endoplasmic reticulum stress.Parkin is regulated by PERK and is a target of the unfolded protein response.It is unclear whether PERK regulates PHB2-mediated mitophagy thro ugh Parkin.In this study,we established a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine(MPTP)-induced mouse model of Parkinson’s disease.We used adeno-associated virus to knockdown PHB2 expression.Our res ults showed that loss of dopaminergic neurons and motor deficits were aggravated in the MPTP-induced mouse model of Parkinson’s disease.Ove rexpression of PHB2 inhibited these abnormalities.We also established a 1-methyl-4-phenylpyridine(MPP+)-induced SH-SY5Y cell model of Parkinson’s disease.We found that ove rexpression of Parkin increased co-localization of PHB2 and microtubule-associated protein 1 light chain 3,and promoted mitophagy.In addition,MPP+regulated Parkin involvement in PHB2-mediated mitophagy through phosphorylation of PERK.These findings suggest that PHB2 participates in the development of Parkinson’s disease by intera cting with endoplasmic reticulum stress and Parkin.

Structural insights of phosphorylated into the recognition FUNDC1 by LC3B in mitophagy

Mitophagy is an essential intracellular process that eliminates dysfunctional mitochondria and maintains cellular homeostasis. Mitophagy is regulated by the post-translational modification of mitophagy receptors. Fun14 domain-containing protein 1 （FUNDC1） was reported to be a new receptor for hypoxia-induced mitophagy in mammalian cells and interact with micro-tubule-associated protein light chain 3 beta （LC3B） through its LC3 interaction region （LIR）. Moreover, the phosphorylation modification of FUNDC1 affects its binding affinity for LC3B and regulates selective mitophagy. However, the structural basis of this regulation mechanism remains unclear. Here, we present the crystal structure of LC3B in complex with a FUNDCI LIR peptide phosphorylated at Ser17 （pS17）, demonstrating the key residues of LC3B for the specific recognition of the phosphorylated or dephosphorylated FUNDC1. Intriguingly, the side chain of LC3B Lys49 shifts remarkably and forms a hydrogen bond and electrostatic interaction with the phosphate group of FUNDC1 pS17. Alternatively, phosphorylated Tyr18 （PY18） and Ser13 （PS13） in FUNDC1 significantly obstruct their interaction with the hydrophobic pocket and Arg10 of LC3B, respectively. Structural observations are further validated by mutation and isothermal titration calorimetry （ITC） assays. Therefore, our structural and biochemical results reveal a working model for thespecific recognition of FUNDCI by LC3B and imply that the reversible phosphorylation modification of mitophagy receptors may be a switch for selective mitophagy.

Choline dehydrogenase interacts with SQSTM1 to activate mitophagy and promote coelomocyte survival in Apostichopus japonicus following Vibrio splendidus infection

Previous studies have shown that Vibrio splendidus infection causes mitochondrial damage in Apostichopus japonicus coelomocytes,leading to the production of excessive reactive oxygen species(ROS)and irreversible apoptotic cell death.Emerging evidence suggests that mitochondrial autophagy(mitophagy)is the most effective method for eliminating damaged mitochondria and ROS,with choline dehydrogenase(CHDH)identified as a novel mitophagy receptor that can recognize non-ubiquitin damage signals and microtubule-associated protein 1 light chain 3(LC3)in vertebrates.However,the functional role of CHDH in invertebrates is largely unknown.In this study,we observed a significant increase in the mRNA and protein expression levels of A.japonicus CHDH(AjCHDH)in response to V.splendidus infection and lipopolysaccharide(LPS)challenge,consistent with changes in mitophagy under the same conditions.Notably,AjCHDH was localized to the mitochondria rather than the cytosol following V.splendidus infection.Moreover,AjCHDH knockdown using si RNA transfection significantly reduced mitophagy levels,as observed through transmission electron microscopy and confocal microscopy.Further investigation into the molecular mechanisms underlying CHDH-regulated mitophagy showed that AjCHDH lacked an LC3-interacting region(LIR)for direct binding to LC3 but possessed a FB1 structural domain that binds to SQSTM1.The interaction between AjCHDH and SQSTM1 was further confirmed by immunoprecipitation analysis.Furthermore,laser confocal microscopy indicated that SQSTM1 and LC3 were recruited by AjCHDH in coelomocytes and HEK293T cells.In contrast,AjCHDH interference hindered SQSTM1 and LC3 recruitment to the mitochondria,a critical step in damaged mitochondrial degradation.Thus,AjCHDH interference led to a significant increase in both mitochondrial and intracellular ROS,followed by increased apoptosis and decreased coelomocyte survival.Collectively,these findings indicate that AjCHDH-mediated mitophagy plays a crucial role in coelomocyte survival in A.japonicus following V.splendidus infection.

胍丁胺对吗啡耐受小鼠蓝斑核组织中μ-阿片受体和自噬相关蛋白的作用机制

目的探讨胍丁胺(AG)对吗啡(Mor)耐受小鼠蓝斑核(LC)组织中μ-阿片受体(MOR)和自噬相关蛋白的作用机制。方法40只成年健康雄性C57BL/6J小鼠随机分为生理盐水(NS)组、Mor组、AG-Mor组及AG组,皮下注射给药法建立小鼠慢性Mor耐受模型,采用温水甩尾法测定各组小鼠给药前及给药第1~7天的甩尾潜伏期(TFL);造模结束后麻醉处死小鼠、取脑组织,采用免疫荧光法、Western blot及荧光定量聚合酶链式反应(q-PCR)检测各组小鼠LC组织中MOR的表达,采用Western blot法检测各组小鼠LC组织中自噬蛋白微管相关蛋白1轻链3(LC3)、家蚕隔离体蛋白1(P62)的表达。结果与Mor组比较,AG-Mor组小鼠TFL下降趋势较缓慢,差异有统计学意义(P<0.05);与Mor组比较,AG-Mor组小鼠LC组织中MOR蛋白表达水平升高、P62含量明显下降,差异有统计学意义(P<0.05);与NS组比较,Mor组小鼠LC组织中LC3-Ⅱ/LC3-Ⅰ比值与P62含量均出现不同程度的升高,差异有统计学意义(P<0.05)。结论AG抗Mor耐受形成的机制可能与增加Mor耐受小鼠LC组织中MOR蛋白表达量、降低P62含量有关。

柯萨奇病毒B组3型2B蛋白诱导细胞自噬及其基序鉴定

目的 探讨柯萨奇病毒B组3型（CVB3） woodruff病毒2B蛋白对细胞自噬的诱导作用,及其自噬相关基序的鉴定.方法 分别构建增强型绿色荧光蛋白（EGFP）与CVB3 woodruff病毒2B蛋白及其9种截短蛋白的融合蛋白（EGFP-2B、EGFP-2B1-249、EGFP-2B1-201、EGFP-2B1-153、EGFP-2B1-105、EGFP-2B1-57、EGFP-2B106.201、EGFP-2B106-249、EGFP-2 B205-297、EGFP-2B106-201）真核表达载体,红色荧光蛋白（mCherry）与微管相关蛋白轻链3（LC3）的融合蛋白真核表达载体pmCherry-LC3;应用激光共聚焦与蛋白质免疫印迹（Western blot）检测病毒2B蛋白对宫颈癌细胞（HeLa） LC3表达的影响;荧光显微镜观察9种截短蛋白在HeLa细胞中的表达;Western blot检测pEGFP-2B和pEGFP-2B106-249转染细胞后LC3的表达;观察自噬抑制剂3-甲基腺苷（3-MA）处理后,pEGFP-2B和pEGFP-2B106-249诱导细胞自噬的情况.结果 CVB3攻击HeLa细胞后,mCherry-LC3呈现细胞核周点状聚集表达,Western blot检测出现清晰LC3-Ⅱ条带;pEGFP-2B与pmCherry-LC3共转染后也可见细胞核周围绿色荧光与红色荧光均成点状聚集并相互重叠,且LC3-Ⅱ条带明显;9种截短融合蛋白质粒分别转染HeLa细胞后,其中可见细胞核周围绿色荧光点状聚集的最短截短蛋白为EGFP-2B106-249;pEGFP-2B和pEGFP-2B106-249转染细胞后可检测出现清晰LC3-Ⅱ条带;3-MA处理后,pEGFP-2B和pEGFP-2B106-249分别与pmCherry-LC3共转染的细胞均未见绿色和红色荧光的核周点状聚集.结论 CVB3 woodruff病毒2B蛋白可以诱导宿主细胞发生自噬,其中截短蛋白2B106-249是病毒蛋白2B诱导HeLa细胞发生自噬的功能基序.

自噬体在紫绀型先天性心脏病患儿心肌中的表达

目的检测紫绀型先天性心脏病患儿心肌细胞中自噬体的表达,探讨细胞自噬作用在心肌慢性缺氧适应中的意义。方法入选行手术矫治的先天性心脏病患儿18例,其中紫绀型先天性心脏病患儿10例,非紫绀型先天性心脏病患儿8例。取手术中切除的右室流出道心肌组织作为标本,采用透射电镜技术观察心肌细胞超微结构的改变,应用Western blot检测自噬体特异性标志物LC3-Ⅱ的表达情况。结果紫绀组患儿术前血氧饱和度明显低于非紫绀组(P<0.01);紫绀组患儿心肌细线粒体数量增多、排列紊乱,内质网肿胀,可见典型自噬体形成;与非紫绀组相比,紫绀组患儿LC3-Ⅱ蛋白表达显著增高(P<0.01)。结论紫绀型先天性心脏病患儿心肌细胞自噬作用增强,可能参与慢性缺氧条件下心肌细胞的适应性调节。

瞬时受体电位通道蛋白在多功能性系统萎缩中的调控作用

多系统萎缩(multiple system atrophy,MSA)是一类神经系统退行性疾病,其病理特征是胶质细胞中出现含有不溶性α突触核蛋白(α-synuclein)的胞质包涵体.研究显示,α-synuclein在多系统萎缩的发病机制中有重要作用,但其毒性的分子机制目前还不清楚.本文在前期研究氧化应激条件下α-synuclein引起细胞内钙稳态失衡,提出了以氧化应激为连接的多系统萎缩中,胶质细胞死亡的新假说的基础上,深入分析了α-synuclein过表达导致U251细胞变性死亡的分子机制.首先证明过表达α-synuclein的U251细胞出现生长速度减慢、氧化应激水平增加和钙离子瞬时受体电位通道蛋白(transient receptor potential channel-1,TRPC1)表达量升高,而且细胞存活率的变化可通过下调TRPC1的表达得以恢复,说明TRPC1在α-synuclein过表达细胞死亡中发挥了重要作用;其次,研究发现α-synuclein稳转U251细胞中出现了明显的自噬水平增加和细胞凋亡的特征,表明α-synuclein通过作用于内质网钙泵以及细胞膜上的瞬时受体电位钙通道TRPC1,破坏了细胞内的钙稳态,进而影响自噬和凋亡,增加了U251细胞对于过氧化氢的敏感性,这可能是导致多系统萎缩病人脑内胶质细胞死亡的原因.

m TOR signaling in liver regeneration: Rapamycin combined with growth factor treatment

AIM: To investigate the effects of mammalian target of rapamycin(mT OR) inhibition on liver regeneration and autophagy in a surgical resection model.METHODS: C57BL/6 mice were subjected to a 70% partial hepatectomy(PH) and treated intraperitoneally every 24 h with a combination of the m TOR inhibitor rapamycin(2.5 mg/kg per day) and the steroid dexamethasone(2.0 mg/kg per day) in phosphate bufferedsaline(PBS) or with PBS alone as vehicle control. In the immunosuppressant group, part of the group was treated subcutaneously 4 h prior to and 24 h after PH with a combination of human recombinant interleukin 6(IL-6; 500 μg/kg per day) and hepatocyte growth factor(HGF; 100 μg/kg per day) in PBS. Animals were sacrificed 2, 3 or 5 d after PH and liver tissue and blood were collected for further analysis. Immunohistochemical staining for 5-Bromo-2'-deoxyuridine(Brd U) was used to quantify hepatocyte proliferation. Western blotting was used to detect hepatic microtubule-associated protein 1 light chain 3(LC3)-Ⅱ protein expression as a marker for autophagy. Hepatic gene expression levels of proliferation-, inflammation- and angiogenesisrelated genes were examined by real-time reverse transcription-polymerase chain reaction and serum bilirubin and transaminase levels were analyzed at the clinical chemical core facility of the Erasmus MC-University Medical Center.RESULTS: m TOR inhibition significantly suppressed regeneration, shown by decreased hepatocyte proliferation(2% vs 12% Brd U positive hepatocyte nuclei at day 2, P < 0.01; 0.8% vs 1.4% at day 5, P = 0.02) and liver weight reconstitution(63% vs 76% of initial total liver weight at day 3, P = 0.04), and furthermore increased serum transaminase levels(aspartate aminotransferase 641 U/L vs 185 U/L at day 2, P = 0.02). Expression of the autophagy marker LC3-Ⅱ, which was reduced during normal liver regeneration, increased after mT OR inhibition(46% increase at day 2, P = 0.04). Hepatic gene expression showed an increased inflammation-related response [tumor necrosis factor(TNF)-α 3.2-fold upregulation at day 2, P = 0.03; IL-1Ra 6.0-fold upregulation at day 2 and 42.3-fold upregulation at day 5, P < 0.01] and a reduced expression of cell cycle progression and angiogenesis-related factors(HGF 40% reduction at day 2; vascular endothelial growth factor receptor 2 50% reduction at days 2 and 5; angiopoietin 1 60% reduction at day 2, all P ≤ 0.01). Treatmentwith the regeneration stimulating cytokine IL-6 and growth factor HGF could overcome the inhibitory effect on liver weight(75% of initial total liver weight at day 3, P = 0.02 vs immunosuppression alone and P = 0.90 vs controls) and partially reversed gene expression changes caused by rapamycin(TNF-α and IL-1Ra levels at day 2 were restored to control levels). However, no significant changes in hepatocyte proliferation, serum injury markers or autophagy were found.CONCLUSION: mT OR inhibition severely impairs liver regeneration and increases autophagy after PH. These effects are partly reversed by stimulation of the IL-6 and HGF pathways.

Micro RNA-9 promotes the neuronal differentiation of rat bone marrow mesenchymal stem cells by activating autophagy

MicroRNA-9 （miR-9） has been shown to promote the differentiation of bone marrow mesen-chymal stem cells into neuronal cells, but the precise mechanism is unclear. Our previous study conifrmed that increased autophagic activity improved the efifciency of neuronal differentiation in bone marrow mesenchymal stem cells. Accumulating evidence reveals that miRNAs adjust the autophagic pathways. This study used miR-9-1 lentiviral vector and miR-9-1 inhibitor to modulate the expression level of miR-9. Autophagic activity and neuronal differentiation were measured by the number of light chain-3 （LC3）-positive dots, the ratio of LC3-II/LC3, and the expression levels of the neuronal markers enolase and microtubule-associated protein 2. Re-sults showed that LC3-positive dots, the ratio of LC3-II/LC3, and expression of neuron speciifc enolase and microtubule-associated protein 2 increased in the miR-9＋ group. The above results suggest that autophagic activity increased and bone marrow mesenchymal stem cells were prone to differentiate into neuronal cells when miR-9 was overexpressed, demonstrating that miR-9 can promote neuronal differentiation by increasing autophagic activity.

Mutant alpha-synuclein and autophagy in PC12 cells

Several studies have demonstrated that overexpression of mutant a-synuclein in PC12 cells is related to occurrence of autophagy. The present study established mutant α-synuclein （A30P） -transfected PC12 cells and treated them with the autophagy inducer rapamycin and autophagy inhibitor wortmannin, respectively. Results demonstrated that mutant a-synuclein resulted in cell death via autophagy and involved a-synuclein accumulation, membrane lipid oxidation, and loss of plasma membrane integrity. Mutant a-synuclein （A30P） also mediated toxicity of 1-methyl-4-phenylpyridinium ion. Moreover, rapamycin inhibited a-synuclein aggregation, while wortmannin promoted α-synuclein aggregation and cell death. To further determine the role of autophagy due to mutant α-synuclein, the present study measured expression of microtubule-associated protein light chain 3. Results revealed that wortmannin and 1-methyl-4-phenylpyridinium ion inhibited expression of microtubule-associated protein light chain 3 while rapamycin promoted its expression. These findings suggested that abnormal aggregation of a-synuclein induced autophagic programmed cell death in PC12 cells.

Regulation of autophagy:a promising therapeutic target for the treatment of hearing loss

Autophagy,a ubiquitous cellular biological behavior that features a lysosome-dependent degradation pathway,is an important mechanism for cellular self-protection in eukaryotes.Autophagy plays essential roles in cell survival,renewal,material reuse and the maintenance of homeostasis.This paper reviews recent advances in understanding the physiological function of autophagy and its possible roles in auditory diseases.We focused our review on original publications on animal models,drug models,and molecular mechanisms of hearing impairment involved in the dysregulation of autophagy.As research on the mechanisms of autophagy has deepened,it has become obvious that autophagy plays essential roles not only in cell survival,but the occurrence and development of a variety of auditory-related disorder,including aminoglycoside-induced hearing loss,age-related hearing loss,and noise-induced hearing loss.While clinical treatment of such conditions via regulation of the development of autophagy is a novel idea,more time is needed to fully elucidate the specific regulatory pathways and modes of autophagy in auditory diseases.The continued study of the mechanisms and regulation of autophagy in auditory diseases will be of great significance for the future treatment and prevention of these conditions.