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![Building rules of canonical, phosphorylation-, and acetylation-generated KFERQ-like tifs (adapted from [21]). The KFERQ-like motif may contain up to two hydrophobic residues leucine (I), phenylalanine (F), leucine (L), or valine (V)), up to two positive residues (arginine ( lysine (K)), and a single negatively-charged residue (glutamate € or aspartate (D)) flanked at e the N-or C-terminus of the pentapeptide by a single glutamine (Q) residue. KFERQ-like motif also be generated via post-translational modifications, such as phosphorylation or acetylation o amino acid residues along protein regions that do not originally show the mentioned properti](publication/361361986/figure/fig1/AS:1179084474335245@1658127053197/Building-rules-of-canonical-phosphorylation-and-acetylation-generated-KFERQ-like-tifs.png)
Building rules of canonical, phosphorylation-, and acetylation-generated KFERQ-like tifs (adapted from [21]). The KFERQ-like motif may contain up to two hydrophobic residues leucine (I), phenylalanine (F), leucine (L), or valine (V)), up to two positive residues (arginine ( lysine (K)), and a single negatively-charged residue (glutamate € or aspartate (D)) flanked at e the N-or C-terminus of the pentapeptide by a single glutamine (Q) residue. KFERQ-like motif also be generated via post-translational modifications, such as phosphorylation or acetylation o amino acid residues along protein regions that do not originally show the mentioned properti
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Autophagy is a pleiotropic and evolutionarily conserved process in eukaryotes that encompasses different types of mechanisms by which cells deliver cytoplasmic constituents to the lysosome for degradation. Interestingly, in mammals, two different and specialized autophagic pathways, (i) the chaperone-mediated autophagy (CMA) and (ii) the endosomal...
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... the exact sequence, -KFERQ-, is only contained in RNase A. Further studies conducted by the same team also demonstrated that the physical properties of the residues constituting the motif, rather than the specific amino acids per se, determine the ability of the chaperone HSC70 to bind this region [17]. Accordingly, these authors defined that a canonical KFERQ-like motif is always flanked by a glutamine (Q) on either side and must contain (i) one or two of the positive residues K and R, (ii) one or two of the hydrophobic residues F, L, I, or V, and (iii) one of the negatively-charged residues E or D (Figure 2). Recently, other studies have demonstrated that KFERQ-like motifs can be generated via post-translational modifications. ...
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... other studies have demonstrated that KFERQ-like motifs can be generated via post-translational modifications. Thus, phosphorylation or acetylation of the amino acid residues along protein regions that do not originally display the mentioned properties dramatically increases the repertory of putative HSC70 substrates (Figure 2) [18][19][20]. Cells 2022, 11, x FOR PEER REVIEW 4 contained in RNase A. Further studies conducted by the same team also demonstr that the physical properties of the residues constituting the motif, rather than the spe amino acids per se, determine the ability of the chaperone HSC70 to bind this region Accordingly, these authors defined that a canonical KFERQ-like motif is always flan by a glutamine (Q) on either side and must contain (i) one or two of the positive resi K and R, (ii) one or two of the hydrophobic residues F, L, I, or V, and (iii) one of the atively-charged residues E or D (Figure 2). ...
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... phosphorylation or acetylation of the amino acid residues along protein regions that do not originally display the mentioned properties dramatically increases the repertory of putative HSC70 substrates (Figure 2) [18][19][20]. Cells 2022, 11, x FOR PEER REVIEW 4 contained in RNase A. Further studies conducted by the same team also demonstr that the physical properties of the residues constituting the motif, rather than the spe amino acids per se, determine the ability of the chaperone HSC70 to bind this region Accordingly, these authors defined that a canonical KFERQ-like motif is always flan by a glutamine (Q) on either side and must contain (i) one or two of the positive resi K and R, (ii) one or two of the hydrophobic residues F, L, I, or V, and (iii) one of the atively-charged residues E or D (Figure 2). Recently, other studies have demonstrated KFERQ-like motifs can be generated via post-translational modifications. ...
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... other studies have demonstrated KFERQ-like motifs can be generated via post-translational modifications. Thus, p phorylation or acetylation of the amino acid residues along protein regions that do originally display the mentioned properties dramatically increases the repertory of p tive HSC70 substrates (Figure 2) [18][19][20]. According to the above-described definition of the KFERQ-like motif, approxim 46% of proteins in human proteome contain at least one canonical motif, 20% contai canonical motif but a phosphorylation-generated one, and 9% contain only acetyla generated motifs [22]. ...
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... suggests a substantial degr evolution of this motif in different species. Whether the evolution of this region is dep ent on their ability to perform either eMI, CMA, or both remains to be further investig Figure 2. Building rules of canonical, phosphorylation-, and acetylation-generated KFERQ-like motifs (adapted from [21]). ...
Citations
... (B) Endosomal invagination: Also known as endosomal microautophagy, this has been studied in Drosophila melanogaster and dendritic cell lines. This approach recruits ESCRT proteins and accessory proteins like Nbr1 and Hsc70, providing selectivity to the process (Schnebert et al. 2022). Multivesicular bodies or intraluminal vesicles are formed inside endosomes. ...
... In D. melanogaster, which lacks Chaperone-Mediated Autophagy (CMA), Hsc70 protein is recruited via electrostatic interactions with phosphatidylserine, deforming the endosomal membrane, a requirement for autophagy. Nbr1, in conjunction with ESCRT-0, aids cargo targeting and the ubiquitination of cytoplasmic proteins on the endosomal surface for delivery into the vacuole (Schnebert et al. 2022;Tekirdag and Cuervo 2018). ...
Autophagy, a highly regulated cellular process, assumes a dual role in the context of cancer. On the one hand, it functions as a crucial homeostatic pathway, responsible for degrading malfunctioning molecules and organelles, thereby maintaining cellular health. On the other hand, its involvement in cancer development and regression is multifaceted, contingent upon a myriad of factors. This review meticulously examines the intricacies of autophagy, from its molecular machinery orchestrated by Autophagy-Related Genes (ATG) initially discovered in yeast to the various modes of autophagy operative within cells. Beyond its foundational role in cellular maintenance, autophagy reveals context-specific functions in processes like angiogenesis and inflammation. Our analysis delves into how autophagy-related factors directly impact inflammation, underscoring their profound implications for cancer dynamics. Additionally, we extend our inquiry to explore autophagy’s associations with cardiovascular conditions, neurodegenerative disorders, and autoimmune diseases, illuminating the broader medical relevance of this process. Furthermore, this review elucidates how autophagy contributes to sustaining hallmark cancer features, including stem cell maintenance, proliferation, angiogenesis, metastasis, and metabolic reprogramming. Autophagy emerges as a pivotal process that necessitates careful consideration in cancer treatment strategies. To this end, we investigate innovative approaches, ranging from enzyme-based therapies to MTOR inhibitors, lysosomal blockers, and nanoparticle-enabled interventions, all aimed at optimizing cancer treatment outcomes by targeting autophagy pathways. In summary, this comprehensive review provides a nuanced perspective on the intricate and context-dependent role of autophagy in cancer biology. Our exploration not only deepens our understanding of this fundamental process but also highlights its potential as a therapeutic target. By unraveling the complex interplay between autophagy and cancer, we pave the way for more precise and effective cancer treatments, promising better outcomes for patients.
... Chaperone-mediated autophagy (CMA) is a type of autophagy that selectively recognizes cytosolic proteins bearing a pentapeptide sequence sharing biochemical similarities to KFERQ (lysine-phenylalanine-glutamate-arginine-glutamine) [1]. In detail, these KFERQ-like domain containing proteins are first recognized by HSPA8/HSC70 (heat shock protein family A (Hsp70) member 8) and co-chaperones [2,3]. ...
... In addition, unlike the most commonly used model species (i.e., rodents and zebrafish) in biomedical research, the RT has two paralogs of the CMA-limiting factor Lamp2A. These two Lamp2A, which most likely originate from the wholegenome duplication event that occurred in the common ancestor of salmonids about 100 million years ago [20], show divergence in some residues within the cytosolic domain (C-terminal), which is considered as a recognition signal for lysosomal targeting and therefore supposedly critical for protein function [1]. Taken together, RT represents an interesting model to explore the roles of CMA during impaired-glucose homeostasis and to gain new insights into the evolution of this selective autophagic pathway. ...
... Into that direction, among those common upregulated proteins ( Figure S4F) we could identify Eif4a1 (eukaryotic translation initiation factor 4a1), which has been recently confirmed as a CMA substrate [56,57]. Noteworthy, we also found Tsg101 (tumor susceptibility 101), which is a component of the ESCRT-1 machinery involved in the selective targeting of KFERQ-like containing-proteins into late endosome or multivesicular bodies that occurs during endosomal microautophagy (eMI) [1,58]. Although the existence of eMI has not been yet reported in fish, most of the core proteins/components of its machinery are nevertheless conserved amongst eukaryotes [1]. ...
Chaperone-mediated autophagy (CMA) is a major pathway of lysosomal proteolysis critical for cellular homeostasis and metabolism, and whose defects have been associated with several human pathologies. While CMA has been well described in mammals, functional evidence has only recently been documented in fish, opening up new perspectives to tackle this function under a novel angle. Now we propose to explore CMA functions in the rainbow trout (RT, Oncorhynchus mykiss), a fish species recognized as a model organism of glucose intolerance and characterized by the presence of two paralogs of the CMA-limiting factor Lamp2A (lysosomal associated membrane protein 2A). To this end, we validated a fluorescent reporter (KFERQ-PA-mCherry1) previously used to track functional CMA in mammalian cells, in an RT hepatoma-derived cell line (RTH-149). We found that incubation of cells with high-glucose levels (HG, 25 mM) induced translocation of the CMA reporter to lysosomes and/or late endosomes in a KFERQ- and Lamp2A-dependent manner, as well as reduced its half-life compared to the control (5 mM), thus demonstrating increased CMA flux. Furthermore, we observed that activation of CMA upon HG exposure was mediated by generation of mitochondrial reactive oxygen species, and involving the antioxidant transcription factor Nfe2l2/Nrf2 (nfe2 like bZIP transcription factor 2). Finally, we demonstrated that CMA plays an important protective role against HG-induced stress, primarily mediated by one of the two RT Lamp2As. Together, our results provide unequivocal evidence for CMA activity existence in RT and highlight both the role and regulation of CMA during glucose-related metabolic disorders.Abbreviations: AREs: antioxidant response elements; CHC: α-cyano -4-hydroxycinnamic acid; Chr: chromosome; CMA: chaperone-mediated autophagy; CT: control; DMF: dimethyl fumarate; Emi: endosomal microautophagy; HG: high-glucose; HMOX1: heme oxygenase 1; H2O2: hydrogen peroxide; KFERQ: lysine-phenylalanine-glutamate-arginine-glutamine; LAMP1: lysosomal associated membrane protein 1; LAMP2A: lysosomal associated membrane protein 2A; MCC: Manders' correlation coefficient; Manders' correlation coefficient Mo: morpholino oligonucleotide; NAC: N-acetyl cysteine; NFE2L2/NRF2: NFE2 like bZIP transcription factor 2; PA-mCherry: photoactivable mCherry; PCC: Pearson's correlation coefficient; ROS: reactive oxygen species; RT: rainbow trout; siRNAs: small interfering RNAs; SOD: superoxide dismutase; Tsg101: tumor susceptibility 101; TTFA: 2-thenoyltrifluoroacetone; WGD: whole-genome duplication.
... In general, autophagosomes consisting of double membrane-bound structures mature and fuse with lysosomes to achieve their function. Autophagy is classified into three forms: macroautophagy, microautophagy, and chaperone-mediated autophagy (Schnebert et al., 2022). Macroautophagy is performed via the autophagosome-lysosome fusion complex. ...
We investigated the involvement of autophagy with steroidogenesis in testicular Leydig cells. Human chorionic gonadotropin (hCG)-stimulated T production in Leydig cells was not remarkably altered in the presence of an autophagy inhibitor 3-methyladenine (3-MA). Although pretreatment with 3-MA demonstrated a tendency to decrease hCG-induced T production, the differences were significant only at a higher time point of 24 h following hCG. Microtubule associated protein light chain 3 (LC3)-II was detectable in the control cells in all the experiments. The hCG-induced increase in steroidogenic acute regulatory protein (StAR) and cytochrome P450 side chain cleave (P450scc) protein levels were not significantly altered by 3-MA. Leydig cells isolated from immature rat testes 12 h following hCG treatment showed relatively increased levels of LC3-II protein compared to the control group. Furthermore, LC3-II levels shown in these cells reached almost the identical to those from normal adult testes. However, LC3-II protein levels were almost comparable or even slightly lower than the controls at 48 h following hCG. Expression of StAR and P450scc was upregulated at both 12 and 48 h after hCG. We also used MA-10 cells, the mouse Leydig cell line, in this experiment. When dibutyryl cyclic-AMP was treated with MA-10 cells, P4 levels were significantly increased in the cell culture medium. However, P4 levels tended to decrease in the presence of 3-MA, but the difference was not statistically significant. This was consistent with the results of the rat Leydig cell experiments. Together, we believe that although autophagy participates in steroidogenesis and enhances steroidogenic efficacy of Leydig cells, it may not be a decisive cellular process for steroidogenesis, specifically in the mature Leydig cells.
... Other autophagic pathways that have been associated with the lysosomal degradation of proteinopathy proteins are chaperone-mediated autophagy (CMA) and endosomal microautophagy (eMI) (Figure 2). The HSP70 chaperone machinery (with a different cochaperone dependency) also plays a central role in both of these pathways, although distinguishing between these pathways experimentally remains challenging because there is so far no specific marker for eMI [75,76] (Box 1). Although there is no evidence for the direct involvement of CMA in degrading protein aggregates, inhibition of CMA leads to the accumulation of insoluble and ubiquitinylated proteins, including α-synuclein [77,78]. ...
Aggrephagy describes the selective lysosomal transport and turnover of cytoplasmic protein aggregates by macro-autophagy. In this process, protein aggregates and conglomerates are polyubiquitinated and then sequestered by autophagosomes. Soluble selective autophagy receptors (SARs) are central to aggrephagy and physically bind to both ubiquitin and the autophagy machinery, thus linking the cargo to the forming autophagosomal membrane. Because the accumulation of protein aggregates is associated with cytotoxicity in several diseases, a better molecular understanding of aggrephagy might provide a conceptual framework to develop therapeutic strategies aimed at delaying the onset of these pathologies by preventing the buildup of potentially toxic aggregates. We review recent advances in our knowledge about the mechanism of aggrephagy.
... This process is beneficial for cells to renew their organelles and prevent further impairment by damaged organelles. Based on the degraded contents, there are three types of autophagy: macroautophagy [76], microautophagy [77], and chaperone-mediated autophagy (CMA) [78]. Macroautophagy is further divided into mitophagy [37], ER-phagy [79], lipophagy [80], and so on. ...
Diabetic nephropathy (DN), a metabolic disease, is characterized by severe systemic metabolic disorders. A unique dietary pattern, such as intermittent fasting (IF) has shown promising protective effects on various metabolic diseases, such as diabetes and cardiovascular and nervous system diseases. However, its role in regulating kidney disease, especially in DN, is still being investigated. Here, we summarize the current research progress, highlighting the relationship between IF and the risk factors for the progression of DN, and discuss the potential mechanisms by which IF improves renal injury in DN. Finally, we propose IF as a potential strategy to prevent and delay DN progression. Abbreviation: DN: Diabetic nephropathy; IF: Intermittent fasting; CPT1A: Carnitine palmitoyltransferase 1A; L-FABP: Liver-type fatty acid-binding protein; STZ: Streptozotocin; LDL: Low-density lipoproteins; HIIT: High-intensity interval training; CKD: Chronic kidney disease; ACEI: Angiotensin-converting enzyme inhibitors; ARB: Angiotensin receptor blockers; MDA: Malondialdehyde; mtDNA: Mitochondrial DNA; UCP3: Uncoupling protein-3; MAM: Mitochondria-associated endoplasmic reticulum membrane; PBMCs: Peripheral blood mononuclear cells; ERK1/2: Extracellular signal-regulated kinase 1/2; DRP1: Dynamin-related protein 1; β-HB: β-Hydroxybutyrate; AcAc: Acetoacetate; GEO: Gene Expression Omnibus; NCBI: National Center for Biotechnology Information; mTORC1: Mechanistic target of rapamycin complex 1; HMGCS2: 3-Hydroxy-3-methylglutaryl-CoA synthase 2; GSK3β: Glycogen synthase kinase 3β; AKI: Acute kidney injury; CMA: Chaperone-mediated autophagy; FGF21: Fibroblast growth factor 21.
... In this study, we described the copy number as "copy 1" instead of adding the digit at the end to clarify the relationship between orthologues. This annotation strategy was successfully applied to the genome-wide screening of Hsp70s in the rotifer Brachionus plicatilis sensu stricto (Grewal et al. 2022), an annelid Urechis unicinctus (Liu et al. 2022), and D. melanogaster (Kaneko 2022) as well as has been positively cited to describe Hsp70s in various fields (Aksakal and Ekinci 2021;Khieokhajonkhet et al. 2022;Schnebert et al. 2022;Stamperna et al. 2021). The latest update of the FlyBase (FB2022_03 released on June 9, 2022) incorporated the proposed D. melanogaster Hsp70 gene names. ...
Annotation of the 70 kDa heat shock proteins (Hsp70s) has been chaotic especially in invertebrates. In this study, we validated an emerging nomenclature of Hsp70s, which can be potentially applied to all metazoan Hsp70s, by conducting a genome-wide annotation of Caenorhabditis elegans Hsp70s. Using the phylogenetic annotation, the seven canonical C. elegans Hsp70s were successfully classified into four known lineages, cytosolic A, cytosolic B, endoplasmic reticulum, and mitochondria. Motifs specific to each lineage were all conserved in the C. elegans Hsp70s. From these results, we propose new aliases of C. elegans Hsp70s that should help future annotation of this important molecular chaperone.
... There are three known forms of autophagy: Microautophagy, Macroautopha- [9]. Figure 1 shows the types of autophagy and its processes. ...
Hepatocellular carcinoma (HCC) is the most prevalent primary liver cancer in Sub-Saharan African countries, including South Africa (SA). Given the limitations in current HCC therapeutics, there is an increasing need for alternative adjuvant therapeutic options. As such, several cell survival mechanisms, such as autophagy, have been identified as potential adjuvant therapeutic targets in HCC treatment. Of the three most established autophagic pathways, the upregulation of chaperone-mediated autophagy (CMA) has been extensively described in various cancer cells, including HCC cells. CMA promotes tumor growth and chemotherapeutic drug resistance, thus contributing to HCC tumorigenesis. Therefore, the modulation of CMA serves as a promising adjuvant target for current HCC therapeutic strategies. Phytochemical extracts found in the medicinal plant, Moringa oleifera (MO), have been shown to induce apoptosis in numerous cancer cells, including HCC. MO leaves have the greatest abundance of phytochemicals displaying anticancer potential. However, the potential interaction between the pro-apoptotic effects of MO aqueous leaf extract and the survival-promoting role of CMA in an in vitro model of HCC remains unclear. This review aims to summarize the latest findings on the role of CMA, and MO in the progression of HCC.
