Role Of Autophagy In Development Research Articles

The role of autophagy in acute myeloid leukemia development

ABSTRACT Introduction Autophagy is a highly conservative self-degradative process. It aims at elimination-impaired proteins and cellular organelles. Previous research confirmed the autophagy role in cancer pathogenesis. Areas covered This article discusses the role of autophagy in the development of AML. Autophagy seems to be a ‘double-sword’ mechanism, hence, either its suppression or induction could promote neoplasm growth. This mechanism could also be the aim of the ‘molecular targeted therapy.’ Chemo- and radiotherapy induce cellular stress in neoplasm cells with subsequent autophagy suppression. Simultaneously, it is claimed that the autophagy suppression increases chemosensitivity ’in neoplastic cells. Some agents, like bortezomib, in turn could promote autophagy process, e.g. in AML (acute myeloid leukemia). However, currently there are not many studies focusing on the role of autophagy in patients suffering for AML. In this review, we summarize the research done so far on the role of autophagy in the development of AML. Expert opinion The analysis of autophagy genes expression profiling in AML could be a relevant factor in the diagnostic process and treatment ‘individualization.’ Autophagy modulation seems to be a relevant target in the oncological therapy – it could limit disease progression and increase the effectiveness of treatment.

Role of autophagy in response of epithelial ovarian cancer cells to cisplatin treatment and cisplatin resistance

Ovarian cancer survival rate is inversely associated with the extent of tumor metastasis. One of the main treatment approaches against ovarian cancer is employment of platinum based therapies, including cisplatin. Majority of ovarian cancer patients develop cisplatin resistance. We aimed to investigate roles for macroautophagy in response of epithelial ovarian cancer cells to cisplatin, including changes in cell motility, as well as in development of cisplatin resistance. Cisplatin treatment induced autophagy in Caov-3 cells in vitro, as well as resulted in increased cell motility. Pharmacologic inhibition of autophagy by wortmannin eliminated the effect of cisplatin on cell motility. We further selected Caov-3 cells with acquired cisplatin resistance and observed elevated baseline expression of autophagy markers in the resistant cells. Our data indicate a role for autophagy in development of cisplatin resistance by the EOC cells, as well as a potential role for cisplatin-induced autophagy in ovarian tumor metastasis.

Aedes albopictus Autophagy-Related Gene 8 (AaAtg8) Is Required to Confer Anti-Bacterial Gut Immunity.

Autophagy is an important process by which pathogens and damaged or unused organelles are eliminated. The role of autophagy in development and the immune response to pathogens is well established. Autophagy-related protein 8 (Atg8) is involved in the formation of the autophagosome and, with the help of the serine protease Atg4, mediates the delivery of both vesicles and the autophagosome to the vacuole. Here, we cloned the Aedes albopictus autophagy-related protein 8 (AaAtg8) gene and characterized its role in the innate immunity of the mosquito against microbial infections. AaAtg8 is comprised of an open reading frame (ORF) region of 357 bp encoding a polypeptide of 118 amino acid residues. A domain analysis of AaAtg8 revealed an Atg8 ubiquitin-like domain, Atg7/Atg4 interaction sites, and peptide binding sites. The AaAtg8 mRNA expression was high in the Malpighian tubules and heads of both sugar-fed and blood-fed adult female mosquitoes. The expression level of AaAtg8 mRNA increased in the midgut and abdominal carcass following being challenged with Listeria monocytogenes. To investigate the role of AaAtg8 in the innate immune responses of Ae. albopictus, AaAtg8 gene-silenced adult mosquitoes were challenged by injection or by being fed microorganisms in blood. High mortality rates were observed in mosquitoes in which AaAtg8 was silenced after challenges of microorganisms to the host by blood feeding. This suggests that Atg8-autophagy plays a critical role in the gut immunity in Ae. albopictus.

Regulatory role of autophagy in development of pulmonary artery hypertension

Pulmonary arterial hypertension (PAH) is a multi-etiological chronic disease characterized by a progressive elevation in pulmonary resistance and vascular remodeling. Its pathogenesis is complicated. Recently, emerging researches suggest that autophagy, as a self-protection mechanism maintaining the intracellular environment homeostasis in eukaryotes, participate in the occurrence and development of various types of PAH. Autophagy can regulate the survival, apoptosis of pulmonary vascular wall cells and secretion of vasoactive substances and inflammatory cytokines, thus influencing pulmonary vascular homeostasis. Some drugs based on regulating autophagy activity can effectively improve the prognosis of PAH. In this article, the regulatory role of autophagy on the development of pulmonary hypertension is reviewed to provide insight into PAH and its treatment.

Autophagy, programmed cell death and reactive oxygen species in sexual reproduction in plants.

Autophagy is one of the major cellular processes of recycling of proteins, metabolites and intracellular organelles, and plays crucial roles in the regulation of innate immunity, stress responses and programmed cell death (PCD) in many eukaryotes. It is also essential in development and sexual reproduction in many animals. In plants, although autophagy-deficient mutants of Arabidopsis thaliana show phenotypes in abiotic and biotic stress responses, their life cycle seems normal and thus little had been known until recently about the roles of autophagy in development and reproduction. Rice mutants defective in autophagy show sporophytic male sterility and immature pollens, indicating crucial roles of autophagy during pollen maturation. Enzymatic production of reactive oxygen species (ROS) by respiratory burst oxidase homologues (Rbohs) play multiple roles in regulating anther development, pollen tube elongation and fertilization. Significance of autophagy and ROS in the regulation of PCD of transient cells during plant sexual reproduction is discussed in comparison with animals.

Role of autophagy in development of inflammatory pain in rats

Objective To evaluate the role of autophagy in the development of inflammatory pain in the rats. Methods Twenty-four healthy adult male Sprague-Dawley rats, weighing 180-240 g, were randomly divided into 4 groups (n=6 each) by using a random number table: control group (group C), inflammatory pain group (group IP), dimethyl sulfoxide (DMSO) group (group D), and rapamycin (autophagy inducer) group (group R). Inflammatory pain was produced by injecting 50 μl bee venom into the plantar surface of the left hindpaw.In group C, 0.9% normal saline was injected into the plantar surface of the left hindpaw.In group D, 2% DMSO was injected through a gastric tube into the stomach 1 ml per day for 3 consecutive days, and the model was established at 1 h after injection on 3rd day.In group R, rapamycin 10 mg/kg (in 2% DMSO) was injected through a gastric tube into stomach 1 ml per day for 3 consecutive days, and the model was established at 1 h after injection on 3rd day.The mechanical paw withdrawal threshold (MWT) and thermal paw withdrawal latency (TWL) were measured at 2 h after the model was established.After measurement of the pain threshold, the dorsal horn of the spinal cord was removed for determination of the expression of microtubule-associated protein 1 light chain 3 Ⅱ (LC3 Ⅱ), Beclin-1 and p62 by Western blot. Results Compared with group C, the MWT was significantly decreased, the TWL was significantly shortened in IP and D groups, and the expression of LC3Ⅱ, Beclin-1 and p62 in the dorsal horn of the spinal cord was significantly up-regulated in IP, D and R groups (P 0.05). Conclusion Autophagy disorders are involved in the development of inflammatory pain in the rats. Key words: Autophagy; Inflammatory; Pain

The roles of autophagy in development and stress responses in Arabidopsis thaliana

Autophagy is a dynamic process that involves the recycling process of the degradation of intracellular materials. Over the past decade, our molecular and physiological understanding of plant autophagy has greatly been increased. Most essential autophagic machineries are conserved from yeast to plants. The roles that autophagy-related genes (ATGs) family play in the lifecycle of the Arabidopsis are proved to be similar to that in mammal. Autophagy is activated during certain stages of development, senescence or in response to starvation, or environmental stress in Arabidopsis. In the progression of autophagy, ATGs act as central signaling regulators and could develop sophisticated mechanisms to survive when plants are suffering unfavorable environments. It will facilitate further understanding of the molecular mechanisms of autophagy in plant. In this review, we will discuss recent advances in our understanding of autophagy in Arabidopsis, areas of controversy, and highlight potential future directions in autophagy research.

Role of autophagy in development of neuropathic pain in rats

Objective To evaluate the role of autophagy in the development of neuropathic pain (NP) in rats.Methods Thirty male Sprague-Dawley rats,weighing 200-220 g,were randomly divided into 3 groups (n =10 each) using a random number table:sham operation group (sham group),NP group and rapamycin (autophagy inducer) group (Rap group).Intrathecal catheter was inserted into the subarachnoid space and advanced caudally until the tip reached L4,5 segment.NP was induced by ligation of the left L5 spinal nerve (SNL) in NP and Rap groups.The L5 spinal nerve was only exposed,but not ligated in group sham.At 30 min before ligation and 2 days after operation,rapamycin 60 μg was injected intrathecally via the intrathecal catheter in Rap group,while the equal volume of vehicle (5％ dimethyl sulfoxide) was injected in sham and NP groups.The mechanical and thermal pain thresholds were measured on 1,3,5 and 7 days after ligation (T-4).The rats were sacrificed after the last measurement of pain threshold at T4.The ipsilateral L5 segment of spinal dorsal horn was removed for examination of autophagosomes (using transmission electron microscope) and for determination of the expression of LC3 Ⅱ and p62 (by Western blot) and content of IL-1β (by ELISA).Results Compared with sham group,the mechanical pain threshold at each time point and thermal pain threshold at T2-4 were significantly decreased,and the LC3 Ⅱ and p62 expression and IL-1β content were increased at T4 in group NP (P ＜ 0.05).Compared with NP group,the mechanical pain threshold at each time point,thermal pain threshold at T2-4 and LC3 Ⅱ expression at T4 were significantly increased,and the p62 expression and IL-1β content were decreased at T4 in group Rap (P ＜ 0.05).Microscopic examination showed that autophagosomes were observed in the spinal dorsal horn in NP and Rap groups,and the damage to organelles was lighter in Rap group than in NP group.Conclusion The development of NP is related to autophagic dysfunction in rats. Key words: Autophagy; Neuralgia

Emerging role of autophagy in pediatric neurodegenerative and neurometabolic diseases

Pediatric neurodegenerative diseases are a heterogeneous group of diseases that result from specific genetic and biochemical defects. In recent years, studies have revealed a wide spectrum of abnormal cellular functions that include impaired proteolysis, abnormal lipid trafficking, accumulation of lysosomal content, and mitochondrial dysfunction. Within neurons, elaborated degradation pathways such as the ubiquitin-proteasome system and the autophagy-lysosomal pathway are critical for maintaining homeostasis and normal cell function. Recent evidence suggests a pivotal role for autophagy in major adult and pediatric neurodegenerative diseases. We herein review genetic, pathological, and molecular evidence for the emerging link between autophagy dysfunction and lysosomal storage disorders such as Niemann-Pick type C, progressive myoclonic epilepsies such as Lafora disease, and leukodystrophies such as Alexander disease. We also discuss the recent discovery of genetically deranged autophagy in Vici syndrome, a multisystem disorder, and the implications for the role of autophagy in development and disease. Deciphering the exact mechanism by which autophagy contributes to disease pathology may open novel therapeutic avenues to treat neurodegeneration. To this end, an outlook on novel therapeutic approaches targeting autophagy concludes this review.

Abstract 1684: Autophagy inhibition as an effective strategy for sensitizing triple-negative breast cancer cells to chemotherapy.

Abstract Introduction: Triple-negative breast cancer (TNBC), defined by a lack of expression of the estrogen, progesterone and HER-2 receptors, remains a major clinical challenge due to higher recurrence rates and poorer prognosis compared to other subtypes of breast cancer. Tumors that initially respond to chemotherapy - the core treatment option for the patients with an advanced disease - eventually develop resistance. New therapeutic options are urgently required for TNBC. Autophagy, a lysosome-mediated degradation and recycling process, has been shown to function as an adaptive survival response during chemotherapy. Previous studies in other cancer subtypes have indicated that autophagy inhibition can restore chemotherapeutic sensitivity and enhance treatment response. Objective: Generate proof-of-principle evidence for autophagy inhibition as an effective treatment strategy for TNBC. Experimental Design: We are employing in vitro models using TNBC lines MDA-MB-231 and SUM159PT, as well as their derivative lines (R8 and R75, respectively) resistant to Epirubicin (EPI) and other anthracyclines. In vivo xenograft mouse models of MDA-MB-231 and R8 are being used to evaluate the effects of combinatorial therapy with EPI and autophagy inhibitor hydroxychloroquine (HCQ). Methods: We assessed levels of autophagy in TNBC cell lines treated with EPI, developed EPI- resistant sub-lines, and compared basal autophagy levels in parental and resistant lines, using autophagy flux (degradative completion of autophagy) assays. We evaluated the effects of chemotherapy alone and in combination with autophagy inhibitors (HCQ or siRNAs targeting autophagy-related (Atg) proteins) on both parent and resistant sub-lines by assessing their viability. For in vivo studies, MDA-MB-231 cells were injected subcutaneously in Rag2M mice. After tumor formation, mice were treated with EPI, HCQ or their combination, and treatment efficacy was evaluated by tumor volume measurements. Autophagy levels in tumors were also assessed. Results: TNBC cells demonstrated increased autophagy in response to EPI treatment in vitro and in vivo. EPI- resistant lines showed at least 1.5 fold increased basal autophagy levels compared to their parental lines suggesting a possible adaptive role for autophagy in development of chemoresistance. Knock-down of Atg proteins by siRNA dramatically reduced the viability of EPI-resistant sub-lines, which indicates dependence of drug-resistant cells on autophagy for survival. Resistance of MDA-MB-231-R8 cells to EPI was reverted by autophagy inhibition in vitro. Combination of EPI with HCQ in vivo showed an enhanced tumor response to treatment compared to monotherapy with EPI. Additional in vivo studies are in progress. Conclusion: Our preliminary results suggest that autophagy inhibition may be an effective strategy for the treatment of chemo-refractory TNBC cells. Citation Format: Svetlana Bortnik, Suganthi Chittaranjan, Wieslawa H. Dragowska, Namal Abeysundara, Amy Chen, Lindsay DeVorkin, Nancy Dos Santos, Nancy Erro Go, Amy Leung, Dana Masin, Maria Rizza, Dita Strutt, Sherry Weppler, Jing Xu, Hong Yan, Karen Gelmon, Donald Yapp, Marcel Bally, Sharon M. Gorski. Autophagy inhibition as an effective strategy for sensitizing triple-negative breast cancer cells to chemotherapy. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1684. doi:10.1158/1538-7445.AM2013-1684

Pattern recognition receptor and autophagy gene variants are associated with development of antimicrobial antibodies in Crohnʼs disease

We sought to investigate whether variants in genes involved in bacterial sensing and autophagy (NOD2, TLR5, IRGM, ATG16L1) and the interleukin-23 signaling pathway (IL12B, IL23R, STAT3) were associated with development of antimicrobial antibodies in patients with Crohn's disease (CD). A cohort of 616 CD patients from a tertiary referral hospital (Mount Sinai Hospital, Toronto) was evaluated. DNA was tested for three CD-associated NOD2 variants (3020insC, G908R, R702W), variants in IRGM, ATG16L1, IL12B, IL23R, STAT3, and a TLR5-stop mutation. Serum was analyzed by enzyme-linked immunosorbent assay (ELISA) for anti-Saccharomyces cerevisiae (ASCA) IgG and IgA, anti-outer membrane porin C (anti-ompC), anti-Cbir1 flagellin, and anti-Pseudomonas fluorescens (anti-I2). NOD2 3020insC was associated with cumulative seroreactivity by quartile sum (P = 0.003) and number of positive antibodies (P = 0.02). NOD2 G908R was also associated with quartile sum (P = 0.05). Increased ASCA seropositivity was associated with NOD2 3020insC (odds ratio [OR] = 1.9, P = 0.02) and G908R (OR = 1.8, P = 0.05), and ATG16L1 T300A (OR = 1.4, P = 0.01) variants; ASCA-positive patients had an increased cumulative number of NOD2 3020insC and ATG16L1 T300A variants (P = 0.007). TLR5-stop mutation abrogated development of anti-flagellin in a dominant-negative fashion (OR = 0.5, P = 0.009). The IRGM CD risk variant was associated with increased anti-flagellin seropositivity (OR = 1.5, P = 0.03). IL12B, IL23R, and STAT3 variants did not contribute to development of antimicrobial antibodies. Variants in innate immune genes involved in pattern recognition and autophagy but not the interleukin-23 signaling pathway influence antimicrobial seroreactivity in CD. In particular, the additive effect of NOD2 3020insC and ATG16L1 T300A suggests a role for autophagy in development of ASCA.

Crucial role for autophagy in degranulation of mast cells

Autophagy plays a crucial role in controlling various biological responses including starvation, homeostatic turnover of long-lived proteins, and invasion of bacteria. However, a role for autophagy in development and/or function of mast cells is unknown. To investigate a role for autophagy in mast cells, we generated bone marrow-derived mast cells (BMMCs) from mice lacking autophagy related gene (Atg) 7, an essential enzyme for autophagy induction. Bone marrow-derived mast cells were generated from bone marrow cells of control and IFN-inducible Atg7-deficient mice, and morphologic and functional analyses were performed. We found that conversion of type I to type II light chain (LC3)-II, a hallmark of autophagy, was constitutively induced in mast cells under full nutrient conditions, and LC3-II localized in secretory granules of mast cells. Although deletion of Atg7 did not impair the development of BMMCs, Atg7(-/-) BMMCs showed severe impairment of degranulation, but not cytokine production on FcεRI cross-linking. Intriguingly, LC3-II but not LC3-I was co-localized with CD63, a secretory lysosomal marker, and was released extracellularly along with degranulation in Atg7(+/+) but not Atg7(-/-) BMMCs. Moreover, passive cutaneous anaphylaxis reactions were severely impaired in mast cell-deficient WBB6F1-W/W(V) mice reconstituted with Atg7(-/-) BMMCs compared with Atg7(+/+) BMMCs. These results suggest that autophagy is not essential for the development but plays a crucial role in degranulation of mast cells. Thus, autophagy might be a potential target to treat allergic diseases in which mast cells are critically involved.