Ioannis P. Nezis

The University of Warwick · School of Life Sciences

LC3 (microtubule-associated protein 1 light chain 3, called Atg8 in yeast and Drosophila), is one of the most well-studied autophagy-related proteins. LC3 controls selectivity of autophagic degradation by interacting with LIR (LC3-interacting region) motifs also known as AIM (Atg8-interacting motifs) on selective autophagy receptors that carry carg...

LIR motif-containing proteins (LIRCPs) bind to LDS (LIR motif docking site) of Atg8-family proteins. In this protocol, we describe steps to identify Drosophila LIRCPs, in Atg8a LDS mutants we have created, via label-free quantitative proteomic analysis. We detail steps for extraction of proteins from adult Drosophila heads, followed by liquid chrom...

Macroautophagy is a ubiquitous homeostasis and health-promoting recycling process of eukaryotic cells, targeting misfolded proteins, damaged organelles and intracellular infectious agents. Some intracellular pathogens such as Salmonella enterica serovar Typhimurium hijack this process during pathogenesis. Here we investigate potential protein-prote...

The LIR motif-docking site (LDS) of Atg8/LC3 proteins is essential for the binding of LC3-interacting region (LIR)-containing proteins and their subsequent degradation by macroautophagy/autophagy. In our recent study, we created a mutated LDS site in Atg8a, the Drosophila homolog of Atg8/LC3 and found that LDS mutants accumulate known autophagy sub...

Several selective macroautophagy receptor and adaptor proteins bind members of the Autophagy-related protein 8 (Atg8) family using short linear motifs (SLiMs), most often referred to as Atg8-interacting motifs (AIM) or LC3-interacting motifs (LIR). AIM/LIR-motifs have been extensively studied during the last fifteen years, since they can uncover th...

Selective autophagy receptors and adapters contain short linear motifs called LIR motifs (LC3-interacting region), which are required for the interaction with the Atg8-family proteins. LIR motifs bind to the hydrophobic pockets of the LIR motif docking site (LDS) of the respective Atg8-family proteins. The physiological significance of LDS docking...

Macroautophagy/autophagy-related protein Atg8/LC3 is important for autophagosome biogenesis and required for selective degradation of various substrates. In our recent study, we performed a yeast two-hybrid screening to identify proteins that interact with Atg8a, the Drosophila homolog of Atg8/LC3. The screening identified several Atg8a-interacting...

Selective autophagy is a catabolic route that turns over specific cellular material for degradation by lysosomes, and whose role in the regulation of innate immunity is largely unexplored. Here, we show that the apical kinase of the Drosophila immune deficiency (IMD) pathway Tak1, as well as its co-activator Tab2, are both selective autophagy subst...

Hunger drives food-seeking behaviour and controls adaptation of organisms to nutrient availability and energy stores. Lipids constitute an essential source of energy in the cell that can be mobilised during fasting by autophagy. Selective degradation of proteins by autophagy is made possible essentially by the presence of LIR and KFERQ-like motifs....

Autophagy has been described as a catabolic process in which cytoplasmic material is being recycled under various conditions of cellular stress, preventing cell damage and promoting cell survival. Drosophila has been demonstrated to provide an excellent animal model for the study of autophagy. Here, we provide a detailed experimental procedure for...

Despite the growing evidence that the macroautophagy/autophagy-related protein LC3 is localized in the nucleus, why and how it is targeted to the nucleus are poorly understood. In our recent study, we found that transcription factor seq (sequoia) interacts via its LIR motif with Atg8a, the Drosophila homolog of LC3, to negatively regulate the trans...

Autophagy is the degradation of cytoplasmic material through the lysosomal pathway. One of the most studied autophagy-related proteins is LC3. Despite growing evidence that LC3 is enriched in the nucleus, its nuclear role is poorly understood. Here, we show that Drosophila Atg8a protein, homologous to mammalian LC3, interacts with the transcription...

“Autophagy is the process by which cytoplasmic components are engulfed in double-membraned vesicles before being delivered to the lysosome to be degraded. Defective autophagy has been linked to a vast array of human pathologies. The molecular mechanism of the autophagic machinery is well-described and has been extensively investigated. However, und...

Age-related impairment of macroautophagy/autophagy and loss of cardiac tissue homeostasis contribute significantly to cardiovascular diseases later in life. MTOR (mechanistic target of rapamycin kinase) signaling is the most well-known regulator of autophagy, cellular homeostasis, and longevity. The MTOR signaling consists of two structurally and f...

Implication of autophagy in the downregulation of immune signaling pathways through the degradation of their components constitutes an emerging field of investigation. Our work showed that the selective interaction of Drosophila protein Kenny/IKKγ (CG16910) with the autophagic machinery is required for the degradation of the I-kappa B kinase comple...

Autophagy is a highly conserved catabolic process in which cytoplasmic material is recycled under various conditions of cellular stress, preventing cell damage and promoting survival in the event of energy or nutrient shortage, or in response to various cytotoxic insults. Autophagy is also responsible for the removal of aggregated proteins and dama...

Biometals such as iron, copper, potassium, and zinc are essential regulatory elements of several biological processes. The homeostasis of biometals is often affected in age-related pathologies. Notably, impaired iron metabolism has been linked to several neurodegenerative disorders. Autophagy, an intracellular degradative process dependent on the l...

Biometals such as iron, copper, potassium, and zinc are essential regulatory elements of several biological processes. The homeostasis of biometals is often affected in age-related pathologies. Notably, impaired iron metabolism has been linked to several neurodegenerative disorders. Autophagy, an intracellular degradative process dependent on the l...

Autophagy is a fundamental, evolutionarily conserved, process in which cytoplasmic material is degraded through the lysosomal pathway [1-7]. One of the most important and well-studied autophagy-related proteins is LC3 [Microtubule-associated protein 1 light chain 3, (called Atg8 in yeast and Drosophila)], which participates in autophagosome formati...

Due to the critical role played by autophagy in pathogen clearance, pathogens have developed diverse strategies to subvert it. Despite previous key findings of bacteria-autophagy interplay, asystems-level insight into selective targeting by the host and autophagy modulation by the pathogens is lacking. We predicted potential interactions between hu...

Autophagy is a central pathway utilized by many eukaryotic cells in order to recycle intracellular constituents, particularly under periods of nutrient scarcity or cellular damage. The process is evolutionarily conserved from yeast to mammals and can be highly selective with regard to the contents that are targeted for degradation. The availability...

Age-dependent loss of cardiac tissue homeostasis largely impacts heart performance and contributes significantly to cardiovascular diseases later in life. Cellular quality control machinery, such as autophagy/lysosome system, plays a crucial role in maintaining cardiac health and preventing age-induced cardiomyopathy and heart failure. However, how...

Autophagy is the process by which cytoplasmic components are sequestered in autophagosomal vesicles and delivered to the lysosome for degradation. Defective autophagy has been linked to a vast array of human pathologies. The molecular mechanism of the autophagic machinery is well-described and has been extensively investigated. However, understandi...

Accumulation of ubiquitinated protein aggregates is a hallmark of most aging-related neurodegenerative disorders. Autophagy has been found to be involved in the selective clearance of these protein aggregates, and this process is called aggrephagy. Here we provide two protocols for the investigation of protein aggregation and their removal by autop...

Selective autophagy is a catabolic process with which cellular material is specifically targeted for degradation by lysosomes. The function of selective autophagic degradation of self-components in the regulation of innate immunity is still unclear. Here we show that Drosophila Kenny, the homolog of mammalian IKKγ, is a selective autophagy receptor...

Macroautophagy/autophagy has been shown to mediate the selective lysosomal degradation of pathogenic bacteria and viruses (xenophagy), and to contribute to the activation of innate and adaptative immune responses. Autophagy can serve as an antiviral defense mechanism but also as a pro-viral process during infection. Atg8-family proteins play a cent...

Caspases are a family of cysteine proteases widely known as the principal mediators of the apoptotic cell death response, but considerably less so as the contributors to the regulation of pathways outside cellular demise. In regards to autophagy, the modulatory roles of caspases have only recently begun to be adequately described. In contrast to ap...

Study focussing in the molecular warfare between bacterial pathogens and host autophagy investigated using a combination of computational and experimental techniques.

Targeted interplay between bacterial pathogens and autophagy

Oogenesis is a fundamental biological process for the transmission of genetic information to the next generations. Drosophila has proven to be a valuable model for elucidating the molecular and cellular mechanisms involved in this developmental process. It has been shown that autophagy participates in the maturation of the egg chamber. Here we prov...

Transmission Electron Microscopy (TEM) provides high resolution and accuracy at the subcellular level for observing and investigating cellular structures. This is essential for understanding a large variety of cellular processes. In this chapter, we describe a detailed protocol for preparing Drosophila follicles in order to be used as a specimen fo...

Detecting the localization of cellular components using gold nanoparticles has come to offer tremendous advantages in cell biology, allowing for the high resolution imaging of the cellular organization at the subcellular level. This is further aided by the breakthroughs in the cryopreparation of samples, which focus at the retention of antigenicity...

Atg8-family proteins are the best-studied proteins of the core autophagic machinery. They are essential for the elongation and closure of the phagophore into a proper autophagosome. Moreover, Atg8-family proteins are associated with the phagophore from the initiation of the autophagic process to, or just prior to, the fusion between autophagosomes...

In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring au...

Abscission is the final step of cytokinesis that involves the cleavage of the intercellular bridge connecting the two daughter cells. Recent studies have given novel insight into the spatiotemporal regulation and molecular mechanisms controlling abscission in cultured yeast and human cells. The mechanisms of abscission in living metazoan tissues ar...

The discovery of evolutionarily conserved Atg genes required for autophagy in yeast truly revolutionized this research field and made it possible to carry out functional studies on model organisms. Insects including Drosophila are classical and still popular models to study autophagy, starting from the 1960s. This review aims to summarize past achi...

Autophagy is a mechanism of cellular self-degradation that is very important for cellular homeostasis and differentiation. Components of the endosomal sorting complex required for transport (ESCRT) machinery are required for endosomal sorting and also for autophagy and the completion of cytokinesis. Here we show that the ESCRT-III subunit CHMP4B no...

Macroautophagy was initially considered to be a nonselective process for bulk breakdown of cytosolic material. However, recent evidence points toward a selective mode of autophagy mediated by the so-called selective autophagy receptors (SARs). SARs act by recognizing and sorting diverse cargo substrates (e.g., proteins, organelles, pathogens) to th...

Autophagy is a process of cellular self-degradation and is a major pathway for elimination of cytoplasmic material by the lysosomes. Autophagy is responsible for the degradation of damaged organelles and protein aggregates and therefore plays a significant role in cellular homeostasis. Despite the initial belief that autophagy is a nonselective bul...

Autophagy is an evolutionarily conserved process of cellular self-eating and is a major pathway for degradation of cytoplasmic material by the lysosomal machinery. Autophagy functions as a cellular response in nutrient starvation, but it is also associated with the removal of protein aggregates and damaged organelles and therefore plays an importan...

Sequestosome 1 (p62/SQSTM1) is a multifunctional adapter protein implicated in selective autophagy, cell signaling pathways, and tumorigenesis. RECENT ADVANCES: Recent evidence has revealed that p62/SQSTM1 has a critical role in an oxidative stress response pathway by its direct interaction with the ubiquitin ligase adaptor Kelch-like ECH-associate...

Suppression of macroautophagy, due to mutations or through processes linked to aging, results in the accumulation of cytoplasmic substrates that are normally eliminated by the pathway. This is a significant problem in long-lived cells like neurons, where pathway defects can result in the accumulation of aggregates containing ubiquitinated proteins....

FYVE-CENT and Beclin 1 expression in HCC-1395 and HCC-1954 breast cancer cells. (A) Whole cell lysates from HCC-1395 and HCC-1954 (FYVE-CENT R1945Q mutant) cell lines were analyzed by immunoblotting with the indicated antibodies. Equal amounts of cell lysates (as measured by protein content) from control and mutant cells were loaded in triplicates....

Back-transfection of R1945Q FYVE-CENT mutant C terminus (1807–2539) transgene does not rescue cytokinesis arrest caused by siRNA compared to FYVE-CENT C terminus (1807–2539). Hela cells were tranfected with myc- FYVE-CENT C terminus (1807–2539) and siRNA against FYVE-CENT (A), or myc- FYVE-CENT C terminus (1807–2539) R1945Q mutant and siRNA against...

Positive hits from yeast two-hybrid screening with the C-terminus of FYVE-CENT. A list of the interacting proteins with the C-terminus (residues 2120–2539) of ZFYVE26 (FYVE-CENT) were identified in a two-hybrid screen of a human T cells RP1 (CEMC7) cell library. The data are from Hybrigenics S.A, Paris, France. (XLS)

A FYVE-CENT R1945Q mutant breast cancer cell line exhibits an increased number of cells arrested in cytokinesis as well as bi- and multinuclear cells. (A–B) Confocal micrographs of HCC-1395 and HCC-1954 breast cancer cells stained with the Aurora B and Hoechst (A), and HCC-1954 breast cancer cells stained with the α-tubulin, Alexa Fluor® 594 phallo...

The tumor suppressor activity of Beclin 1 (BECN1), a subunit of class III phosphatidylinositol 3-kinase complex, has been attributed to its regulation of apoptosis and autophagy. Here, we identify FYVE-CENT (ZFYVE26), a phosphatidylinositol 3-phosphate binding protein important for cytokinesis, as a novel interacting protein of Beclin 1. A mutation...

Cytokinesis, the final step of cell division, normally proceeds to completion in living organisms, so that daughter cells physically separate by abscission. In certain tissues and developmental stages, on the other hand, the cytokinesis process is incomplete, giving rise to cells interconnected in syncytia by stable intercellular bridges. This evol...

Autophagy has been reported to contribute to cell death, but the underlying mechanisms remain largely unknown and controversial. We have: been studying oogenesis in Drosophila melanogaster as a model system to understand the interplay between autophagy and cell death. Using a novel autophagy reporter we found that autophagy occurs during developmen...

Cytokinesis is the final step of cell division whereby the dividing cells separate physically. Failure of this process has been proposed to cause tumourigenesis. Several specific lipids are essential for cytokinesis, and recent evidence has revealed that phosphatidylinositol 3-phosphate (PtdIns3P) - a well-known regulator of endosomal trafficking,...

Autophagy is an evolutionarily conserved pathway responsible for degradation of cytoplasmic material via the lysosome. Although autophagy has been reported to contribute to cell death, the underlying mechanisms remain largely unknown. In this study, we show that autophagy controls DNA fragmentation during late oogenesis in Drosophila melanogaster....

Despite extensive investigations of Cbl-interacting protein of 85 kDa (CIN85) in receptor trafficking and cytoskeletal dynamics, little is known about its functions in vivo. Here, we report the study of a mouse deficient of the two CIN85 isoforms expressed in the central nervous system, exposing a function of CIN85 in dopamine receptor endocytosis....

Autophagic process is one of the best examples of a conserved mechanism of survival in eukaryotes. At the molecular level there are impressive similarities between unicellular and multicellular organisms, but there is increasing evidence that the same process may be used for different ends, i.e., survival or death, at least at cellular levels. Arth...

Cytokinesis, the final step of cell division, conventionally proceeds to cell separation by abscission, or complete cytokinesis [1 • Eggert U.S. • Mitchison T.J. • Field C.M. Animal cytokinesis: From parts list to mechanisms.Annu. Rev. Biochem. 2006; 75: 543-566 • Crossref • PubMed • Scopus (322) • Google Scholar , 2 • Barr F.A. • Gruneberg U. C...

Several subunits of the class III phosphatidylinositol-3-OH kinase (PI(3)K-III) complex are known as tumour suppressors. Here we uncover a function for this complex and its catalytic product phosphatidylinositol-3-phosphate (PtdIns(3)P) in cytokinesis. We show that PtdIns(3)P localizes to the midbody during cytokinesis and recruits a centrosomal pr...

ESCRT proteins were initially isolated in yeast as a single functional set of conserved components controlling endosomal cargo sorting and multivesicular body (MVB) biogenesis. Recent work has suggested that metazoan ESCRT proteins might have more functionally diverse roles, but the limited availability of ESCRT mutants in species other than yeast...

Autophagy is a physiological and evolutionarily conserved process maintaining homeostatic functions, such as protein degradation and organelle turnover. Accumulating data provide evidence that autophagy also contributes to cell death under certain circumstances, but how this is achieved is not well known. Herein, we report that autophagy occurs dur...

P62 has been proposed to mark ubiquitinated protein bodies for autophagic degradation. We report that the Drosophila melanogaster p62 orthologue, Ref(2)P, is a regulator of protein aggregation in the adult brain. We demonstrate that Ref(2)P localizes to age-induced protein aggregates as well as to aggregates caused by reduced autophagic or proteaso...

Oogenesis is a fundamental physiological process in insects. Successful oogenesis is critical for evolutionary success by transferring genetic information to the next generation. This is achieved by the normal maturation of the egg chamber (egg), which is accomplished through cell death of the cells that accompany the oocyte. Recent studies demonst...

It is increasingly recognized that programmed cell death includes not only apoptosis and autophagy, but also other types of nonapoptotic cell death, such as paraptosis, which are all characterized by distinct morphological features. Our findings indicate that all three types of programmed cell death occur in the ovarian nurse cell cluster during la...

Eukaryotes use autophagy to turn over organelles, protein aggregates, and cytoplasmic constituents. The impairment of autophagy causes developmental defects, starvation sensitivity, the accumulation of protein aggregates, neuronal degradation, and cell death [1, 2]. Double-membraned autophagosomes sequester cytoplasm and fuse with endosomes or lyso...

Programmed cell death consists of two major types, apoptotic and autophagic, both of which are mainly defined by morphological criteria. Our findings indicate that both types of programmed cell death occur in the ovarian nurse cells during middle- and late-oogenesis of Drosophila virilis. During mid-oogenesis, the spontaneously degenerated egg cham...