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Autophagy Stimulus-Dependent Role of the Small GTPase Ras2 in Peroxisome Degradation. Biomolecules 2020; 10:biom10111553. [PMID: 33202661 PMCID: PMC7696409 DOI: 10.3390/biom10111553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Revised: 11/07/2020] [Accepted: 11/12/2020] [Indexed: 11/17/2022] Open
Abstract
The changing accessibility of nutrient resources induces the reprogramming of cellular metabolism in order to adapt the cell to the altered growth conditions. The nutrient-depending signaling depends on the kinases mTOR (mechanistic target of rapamycin), which is mainly activated by nitrogen-resources, and PKA (protein kinase A), which is mainly activated by glucose, as well as both of their associated factors. These systems promote protein synthesis and cell proliferation, while they inhibit degradation of cellular content by unselective bulk autophagy. Much less is known about their role in selective autophagy pathways, which have a more regulated cellular function. Especially, we were interested to analyse the central Ras2-module of the PKA-pathway in the context of peroxisome degradation. Yeast Ras2 is homologous to the mammalian Ras proteins, whose mutant forms are responsible for 33% of human cancers. In the present study, we were able to demonstrate a context-dependent role of Ras2 activity depending on the type of mTOR-inhibition and glucose-sensing situation. When mTOR was inhibited directly via the macrolide rapamycin, peroxisome degradation was still partially suppressed by Ras2, while inactivation of Ras2 resulted in an enhanced degradation of peroxisomes, suggesting a role of Ras2 in the inhibition of peroxisome degradation in glucose-grown cells. In contrast, the inhibition of mTOR by shifting cells from oleate-medium, which lacks glucose, to pexophagy-medium, which contains glucose and is limited in nitrogen, required Ras2-activity for efficient pexophagy, strongly suggesting that the role of Ras2 in glucose sensing-associated signaling is more important in this context than its co-function in mTOR-related autophagy-inhibition.
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Transcriptional regulatory proteins in central carbon metabolism of Pichia pastoris and Saccharomyces cerevisiae. Appl Microbiol Biotechnol 2020; 104:7273-7311. [PMID: 32651601 DOI: 10.1007/s00253-020-10680-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 05/04/2020] [Accepted: 05/10/2020] [Indexed: 01/21/2023]
Abstract
System-wide interactions in living cells and discovery of the diverse roles of transcriptional regulatory proteins that are mediator proteins with catalytic domains and regulatory subunits and transcription factors in the cellular pathways have become crucial for understanding the cellular response to environmental conditions. This review provides information for future metabolic engineering strategies through analyses on the highly interconnected regulatory networks in Saccharomyces cerevisiae and Pichia pastoris and identifying their components. We discuss the current knowledge on the carbon catabolite repression (CCR) mechanism, interconnecting regulatory system of the central metabolic pathways that regulate cell metabolism based on nutrient availability in the industrial yeasts. The regulatory proteins and their functions in the CCR signalling pathways in both yeasts are presented and discussed. We highlight the importance of metabolic signalling networks by signifying ways on how effective engineering strategies can be designed for generating novel regulatory circuits, furthermore to activate pathways that reconfigure the network architecture. We summarize the evidence that engineering of multilayer regulation is needed for directed evolution of the cellular network by putting the transcriptional control into a new perspective for the regulation of central carbon metabolism of the industrial yeasts; furthermore, we suggest research directions that may help to enhance production of recombinant products in the widely used, creatively engineered, but relatively less studied P. pastoris through de novo metabolic engineering strategies based on the discovery of components of signalling pathways in CCR metabolism. KEY POINTS: • Transcriptional regulation and control is the key phenomenon in the cellular processes. • Designing de novo metabolic engineering strategies depends on the discovery of signalling pathways in CCR metabolism. • Crosstalk between pathways occurs through essential parts of transcriptional machinery connected to specific catalytic domains. • In S. cerevisiae, a major part of CCR metabolism is controlled through Snf1 kinase, Glc7 phosphatase, and Srb10 kinase. • In P. pastoris, signalling pathways in CCR metabolism have not yet been clearly known yet. • Cellular regulations on the transcription of promoters are controlled with carbon sources.
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Germain K, Kim PK. Pexophagy: A Model for Selective Autophagy. Int J Mol Sci 2020; 21:ijms21020578. [PMID: 31963200 PMCID: PMC7013971 DOI: 10.3390/ijms21020578] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 01/09/2020] [Accepted: 01/13/2020] [Indexed: 01/03/2023] Open
Abstract
The removal of damaged or superfluous organelles from the cytosol by selective autophagy is required to maintain organelle function, quality control and overall cellular homeostasis. Precisely how substrate selectivity is achieved, and how individual substrates are degraded during selective autophagy in response to both extracellular and intracellular cues is not well understood. The aim of this review is to highlight pexophagy, the autophagic degradation of peroxisomes, as a model for selective autophagy. Peroxisomes are dynamic organelles whose abundance is rapidly modulated in response to metabolic demands. Peroxisomes are routinely turned over by pexophagy for organelle quality control yet can also be degraded by pexophagy in response to external stimuli such as amino acid starvation or hypoxia. This review discusses the molecular machinery and regulatory mechanisms governing substrate selectivity during both quality-control pexophagy and pexophagy in response to external stimuli, in yeast and mammalian systems. We draw lessons from pexophagy to infer how the cell may coordinate the degradation of individual substrates by selective autophagy across different cellular cues.
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Affiliation(s)
- Kyla Germain
- Cell Biology Program, Hospital for Sick Children, Toronto, ON M5G 0A4, Canada;
- Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Peter K. Kim
- Cell Biology Program, Hospital for Sick Children, Toronto, ON M5G 0A4, Canada;
- Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
- Correspondence: ; Tel.: +1-416-813-5983
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Huang S, Benben A, Green R, Cheranda N, Lee G, Joseph B, Keaveney S, Wang Y. Phosphorylation of the Gα protein Gpa2 promotes protein kinase A signaling in yeast. J Biol Chem 2019; 294:18836-18845. [PMID: 31690628 DOI: 10.1074/jbc.ra119.009609] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 10/31/2019] [Indexed: 01/10/2023] Open
Abstract
Heterotrimeric G proteins are important molecular switches that facilitate transmission of a variety of signals from the outside to the inside of cells. G proteins are highly conserved, enabling study of their regulatory mechanisms in model organisms such as the budding yeast Saccharomyces cerevisiae Gpa2 is a yeast Gα protein that functions in the nutrient signaling pathway. Using Phos-tag, a highly specific phosphate binding tag for separating phosphorylated proteins, we found that Gpa2 undergoes phosphorylation and that its level of phosphorylation is markedly increased upon nitrogen starvation. We also observed that phosphorylation of Gpa2 depends on glycogen synthase kinase (GSK). Disrupting GSK activity diminishes Gpa2 phosphorylation levels in vivo, and the purified GSK isoforms Mck1 and Ygk3 are capable of phosphorylating Gpa2 in vitro Functionally, phosphorylation enhanced plasma membrane localization of Gpa2 and promoted nitrogen starvation-induced activation of protein kinase A. Together, the findings of our study reveal a mechanism by which GSK- and nutrient-dependent phosphorylation regulates subcellular localization of Gpa2 and its ability to activate downstream signaling.
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Affiliation(s)
- Shan Huang
- Department of Biology, Saint Louis University, St. Louis, Missouri 63103
| | - Alex Benben
- Department of Biology, Saint Louis University, St. Louis, Missouri 63103
| | - Robert Green
- Department of Biology, Saint Louis University, St. Louis, Missouri 63103
| | - Nina Cheranda
- Department of Biology, Saint Louis University, St. Louis, Missouri 63103
| | - Grace Lee
- Department of Biology, Saint Louis University, St. Louis, Missouri 63103
| | - Benita Joseph
- Department of Biology, Saint Louis University, St. Louis, Missouri 63103
| | - Shannon Keaveney
- Department of Biology, Saint Louis University, St. Louis, Missouri 63103
| | - Yuqi Wang
- Department of Biology, Saint Louis University, St. Louis, Missouri 63103.
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The Small Yeast GTPase Rho5 and Its Dimeric GEF Dck1/Lmo1 Respond to Glucose Starvation. Int J Mol Sci 2018; 19:ijms19082186. [PMID: 30049968 PMCID: PMC6121567 DOI: 10.3390/ijms19082186] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2018] [Revised: 07/21/2018] [Accepted: 07/23/2018] [Indexed: 12/25/2022] Open
Abstract
Rho5 is a small GTPase of Saccharomyces cerevisiae and a homolog of mammalian Rac1. The latter regulates glucose metabolism and actin cytoskeleton dynamics, and its misregulation causes cancer and a variety of other diseases. In yeast, Rho5 has been implicated in different signal transduction pathways, governing cell wall integrity and the responses to high medium osmolarity and oxidative stress. It has also been proposed to affect mitophagy and apoptosis. Here, we demonstrate that Rho5 rapidly relocates from the plasma membrane to mitochondria upon glucose starvation, mediated by its dimeric GDP/GTP exchange factor (GEF) Dck1/Lmo1. A function in response to glucose availability is also suggested by synthetic genetic phenotypes of a rho5 deletion with gpr1, gpa2, and sch9 null mutants. On the other hand, the role of mammalian Rac1 in regulating the action cytoskeleton does not seem to be strongly conserved in S. cerevisiae Rho5. We propose that Rho5 serves as a central hub in integrating various stress conditions, including a crosstalk with the cAMP/PKA (cyclic AMP activating protein kinase A) and Sch9 branches of glucose signaling pathways.
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Deprez MA, Eskes E, Wilms T, Ludovico P, Winderickx J. pH homeostasis links the nutrient sensing PKA/TORC1/Sch9 ménage-à-trois to stress tolerance and longevity. MICROBIAL CELL 2018; 5:119-136. [PMID: 29487859 PMCID: PMC5826700 DOI: 10.15698/mic2018.03.618] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The plasma membrane H+-ATPase Pma1 and the vacuolar V-ATPase act in close harmony to tightly control pH homeostasis, which is essential for a vast number of physiological processes. As these main two regulators of pH are responsive to the nutritional status of the cell, it seems evident that pH homeostasis acts in conjunction with nutrient-induced signalling pathways. Indeed, both PKA and the TORC1-Sch9 axis influence the proton pumping activity of the V-ATPase and possibly also of Pma1. In addition, it recently became clear that the proton acts as a second messenger to signal glucose availability via the V-ATPase to PKA and TORC1-Sch9. Given the prominent role of nutrient signalling in longevity, it is not surprising that pH homeostasis has been linked to ageing and longevity as well. A first indication is provided by acetic acid, whose uptake by the cell induces toxicity and affects longevity. Secondly, vacuolar acidity has been linked to autophagic processes, including mitophagy. In agreement with this, a decline in vacuolar acidity was shown to induce mitochondrial dysfunction and shorten lifespan. In addition, the asymmetric inheritance of Pma1 has been associated with replicative ageing and this again links to repercussions on vacuolar pH. Taken together, accumulating evidence indicates that pH homeostasis plays a prominent role in the determination of ageing and longevity, thereby providing new perspectives and avenues to explore the underlying molecular mechanisms.
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Affiliation(s)
| | - Elja Eskes
- Functional Biology, KU Leuven, Leuven, Belgium
| | | | - Paula Ludovico
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
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Mellouk N, Ramé C, Barbe A, Grandhaye J, Froment P, Dupont J. Chicken Is a Useful Model to Investigate the Role of Adipokines in Metabolic and Reproductive Diseases. Int J Endocrinol 2018; 2018:4579734. [PMID: 30018639 PMCID: PMC6029501 DOI: 10.1155/2018/4579734] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 05/16/2018] [Indexed: 01/04/2023] Open
Abstract
Reproduction is a complex and essential physiological process required by all species to produce a new generation. This process involves strict hormonal regulation, depending on a connection between the hypothalamus-pituitary-gonadal axis and peripheral organs. Metabolic homeostasis influences the reproductive functions, and its alteration leads to disturbances in the reproductive functions of humans as well as animals. For a long time, adipose tissue has been recognised as an endocrine organ but its ability to secrete and release hormones called adipokines is now emerging. Adipokines have been found to play a major role in the regulation of metabolic and reproductive processes at both central and peripheral levels. Leptin was initially the first adipokine that has been described to be the most involved in the metabolism/reproduction interrelation in mammals. In avian species, the role of leptin is still under debate. Recently, three novel adipokines have been discovered: adiponectin (ADIPOQ, ACRP30), visfatin (NAMPT, PBEF), and chemerin (RARRES2, TIG2). However, their mode of action between mammalian and nonmammalian species is different due to the different reproductive and metabolic systems. Herein, we will provide an overview of the structure and function related to metabolic and reproductive mechanisms of the latter three adipokines with emphasis on avian species.
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Affiliation(s)
- Namya Mellouk
- INRA, UMR 85 Physiologie de la Reproduction et des Comportements, 37380 Nouzilly, France
| | - Christelle Ramé
- INRA, UMR 85 Physiologie de la Reproduction et des Comportements, 37380 Nouzilly, France
| | - Alix Barbe
- INRA, UMR 85 Physiologie de la Reproduction et des Comportements, 37380 Nouzilly, France
| | - Jérémy Grandhaye
- INRA, UMR 85 Physiologie de la Reproduction et des Comportements, 37380 Nouzilly, France
| | - Pascal Froment
- INRA, UMR 85 Physiologie de la Reproduction et des Comportements, 37380 Nouzilly, France
| | - Joëlle Dupont
- INRA, UMR 85 Physiologie de la Reproduction et des Comportements, 37380 Nouzilly, France
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Li J, Xiang L, Jiang X, Teng B, Sun Y, Chen G, Chen J, Zhang JV, Ren PG. Investigation of bioeffects of G protein-coupled receptor 1 on bone turnover in male mice. J Orthop Translat 2017; 10:42-51. [PMID: 29662759 PMCID: PMC5822970 DOI: 10.1016/j.jot.2017.05.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2017] [Revised: 04/30/2017] [Accepted: 05/02/2017] [Indexed: 12/12/2022] Open
Abstract
Maintenance of healthy bone quality and quantity requires a well-coordinated balance between bone formation by osteoblasts and bone resorption by osteoclasts. Chemerin is a novel adipokine with known functions such as regulating immunity and energy homeostasis through activation of chemokine-like receptor 1 (CMKLR1). G protein-coupled receptor 1 (GPR1) is the second mammalian chemerin receptor with similar binding affinity as CMKLR1. In male GPR1-/- mice, a phenotype with significantly low bone mineral density was observed. We hypothesise that GPR1 might participate the process of bone remodelling. In this study, we investigated the role of GPR1 in regulating bone mass maintenance in male mice, and for the first time, revealed that GPR1-/- male mice manifested seriously trabecular bone loss and lower serum testosterone levels compared to the wild type animals. Accordingly, the mRNA expression of biomarkers related to both osteoblast [collagen type I alpha 2 (Col1A2), osteocalcin (OCN)] and osteoclast [tartrate-resistant acid phosphatase (TRAP), Cathepsin K, NFATc1] were significantly decreased or increased in GPR1-/- mice relative to the wild type, respectively. However, other osteogenic markers, Osterix and ALP levels, were increased. Microcomputed tomography scanning and histological analyses proved that there was a myriad of trabecular bone loss in GPR1-/- mice. In the meantime, GPR1-/- mice presented a significant decrease in serum testosterone level. Taken together, these findings suggested that chemerin-GPR1 signalling might be directly or indirectly communicated with testosterone synthesis on bone turnover regulation. Further detailed studies are required to unveil how chemerin-GPR1 participates in bone metabolism. The translational potential of this article: More studies and knowledge about GPR1 regulating function in bone turnover might supply a novel therapeutic target for osteoporosis in the future.
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Affiliation(s)
- Jian Li
- Center for Translational Medicine Research and Development, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, Guangdong, China
| | - Liang Xiang
- Laboratory for Reproductive Health, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, Guangdong, China
| | - Xiaotong Jiang
- College of Animal Science and Technology, Shandong Agricultural University, Tai'an 271018, Shandong, China
| | - Bin Teng
- Center for Translational Medicine Research and Development, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, Guangdong, China.,Shenzhen College of Advanced Technology, University of Chinese Academy of Sciences, Shenzhen 518055, Guangdong, China
| | - Yutao Sun
- Center for Translational Medicine Research and Development, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, Guangdong, China
| | - Guanlian Chen
- Center for Translational Medicine Research and Development, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, Guangdong, China
| | - Jie Chen
- Laboratory for Reproductive Health, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, Guangdong, China
| | - Jian V Zhang
- Laboratory for Reproductive Health, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, Guangdong, China
| | - Pei-Gen Ren
- Center for Translational Medicine Research and Development, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, Guangdong, China
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9
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Yang YL, Ren LR, Sun LF, Huang C, Xiao TX, Wang BB, Chen J, Zabel BA, Ren P, Zhang JV. The role of GPR1 signaling in mice corpus luteum. J Endocrinol 2016; 230:55-65. [PMID: 27149986 PMCID: PMC5064765 DOI: 10.1530/joe-15-0521] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 05/04/2016] [Indexed: 01/17/2023]
Abstract
Chemerin, a chemokine, plays important roles in immune responses, inflammation, adipogenesis, and carbohydrate metabolism. Our recent research has shown that chemerin has an inhibitory effect on hormone secretion from the testis and ovary. However, whether G protein-coupled receptor 1 (GPR1), the active receptor for chemerin, regulates steroidogenesis and luteolysis in the corpus luteum is still unknown. In this study, we established a pregnant mare serum gonadotropin-human chorionic gonadotropin (PMSG-hCG) superovulation model, a prostaglandin F2α (PGF2α) luteolysis model, and follicle and corpus luteum culture models to analyze the role of chemerin signaling through GPR1 in the synthesis and secretion of gonadal hormones during follicular/luteal development and luteolysis. Our results, for the first time, show that chemerin and GPR1 are both differentially expressed in the ovary over the course of the estrous cycle, with highest levels in estrus and metestrus. GPR1 has been localized to granulosa cells, cumulus cells, and the corpus luteum by immunohistochemistry (IHC). In vitro, we found that chemerin suppresses hCG-induced progesterone production in cultured follicle and corpus luteum and that this effect is attenuated significantly by anti-GPR1 MAB treatment. Furthermore, when the phosphoinositide 3-kinase (PI3K) pathway was blocked, the attenuating effect of GPR1 MAB was abrogated. Interestingly, PGF2α induces luteolysis through activation of caspase-3, leading to a reduction in progesterone secretion. Treatment with GPR1 MAB blocked the PGF2α effect on caspase-3 expression and progesterone secretion. This study indicates that chemerin/GPR1 signaling directly or indirectly regulates progesterone synthesis and secretion during the processes of follicular development, corpus luteum formation, and PGF2α-induced luteolysis.
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Affiliation(s)
- Ya-Li Yang
- Research Laboratory for Reproductive HealthShenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Li-Rong Ren
- Shenzhen Key Laboratory of Birth DefectsShenzhen Baoan Maternal and Child Health Hospital, Shenzhen, Guangdong, China
| | - Li-Feng Sun
- Research Laboratory for Reproductive HealthShenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Chen Huang
- Research Laboratory for Reproductive HealthShenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China University of Chinese Academy of SciencesShenzhen, China
| | - Tian-Xia Xiao
- Research Laboratory for Reproductive HealthShenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Bao-Bei Wang
- Research Laboratory for Reproductive HealthShenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Jie Chen
- Research Laboratory for Reproductive HealthShenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Brian A Zabel
- Laboratory of Immunology and Vascular BiologyDepartment of Pathology, Stanford University School of Medicine, Stanford, California, USA, and Center for Molecular Biology and Medicine, Veterans Affairs Palo Alto Health Care System, Palo Alto, California, USA
| | - Peigen Ren
- Research Laboratory for Reproductive HealthShenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Jian V Zhang
- Research Laboratory for Reproductive HealthShenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
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Pexophagy in yeasts. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:992-8. [DOI: 10.1016/j.bbamcr.2015.09.023] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 09/16/2015] [Accepted: 09/21/2015] [Indexed: 01/07/2023]
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Sibirny AA. Yeast peroxisomes: structure, functions and biotechnological opportunities. FEMS Yeast Res 2016; 16:fow038. [DOI: 10.1093/femsyr/fow038] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/07/2016] [Indexed: 01/02/2023] Open
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Polupanov AS, Sibirny AA. Cytoplasmic extension peptide of
Pichia pastoris
glucose sensor Gss1 is not compulsory for glucose signalling. Cell Biol Int 2013; 38:172-8. [DOI: 10.1002/cbin.10189] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 08/30/2013] [Indexed: 11/10/2022]
Affiliation(s)
- Andriy S. Polupanov
- Department of Molecular Genetics and BiotechnologyInstitute of Cell BiologyNational Academy of Sciences of Ukraine79005LvivUkraine
- Key State Laboratory of Molecular and Cellular BiologyLvivUkraine
| | - Andriy A. Sibirny
- Department of Molecular Genetics and BiotechnologyInstitute of Cell BiologyNational Academy of Sciences of Ukraine79005LvivUkraine
- Key State Laboratory of Molecular and Cellular BiologyLvivUkraine
- Department of Biotechnology and MicrobiologyRzeszow UniversityZelwerowicza 4Rzeszow35‐601Poland
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Polupanov AS, Nazarko VY, Sibirny AA. Gss1 protein of the methylotrophic yeast Pichia pastoris is involved in glucose sensing, pexophagy and catabolite repression. Int J Biochem Cell Biol 2012; 44:1906-18. [DOI: 10.1016/j.biocel.2012.07.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Revised: 06/29/2012] [Accepted: 07/17/2012] [Indexed: 10/28/2022]
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Regulation of autophagy by glucose in Mammalian cells. Cells 2012; 1:372-95. [PMID: 24710481 PMCID: PMC3901114 DOI: 10.3390/cells1030372] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2012] [Revised: 06/22/2012] [Accepted: 07/13/2012] [Indexed: 02/07/2023] Open
Abstract
Autophagy is an evolutionarily conserved process that contributes to maintain cell homeostasis. Although it is strongly regulated by many extracellular factors, induction of autophagy is mainly produced by starvation of nutrients. In mammalian cells, the regulation of autophagy by amino acids, and also by the hormone insulin, has been extensively investigated, but knowledge about the effects of other autophagy regulators, including another nutrient, glucose, is more limited. Here we will focus on the signalling pathways by which environmental glucose directly, i.e., independently of insulin and glucagon, regulates autophagy in mammalian cells, but we will also briefly mention some data in yeast. Although glucose deprivation mainly induces autophagy via AMPK activation and the subsequent inhibition of mTORC1, we will also comment other signalling pathways, as well as evidences indicating that, under certain conditions, autophagy can be activated by glucose. A better understanding on how glucose regulates autophagy not only will expand our basic knowledge of this important cell process, but it will be also relevant to understand common human disorders, such as cancer and diabetes, in which glucose levels play an important role.
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Pexophagy: the selective degradation of peroxisomes. Int J Cell Biol 2012; 2012:512721. [PMID: 22536249 PMCID: PMC3320016 DOI: 10.1155/2012/512721] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2011] [Accepted: 11/23/2011] [Indexed: 12/18/2022] Open
Abstract
Peroxisomes are single-membrane-bounded organelles present in the majority of eukaryotic cells. Despite the existence of great diversity among different species, cell types, and under different environmental conditions, peroxisomes contain enzymes involved in β-oxidation of fatty acids and the generation, as well as detoxification, of hydrogen peroxide. The exigency of all eukaryotic cells to quickly adapt to different environmental factors requires the ability to precisely and efficiently control peroxisome number and functionality. Peroxisome homeostasis is achieved by the counterbalance between organelle biogenesis and degradation. The selective degradation of superfluous or damaged peroxisomes is facilitated by several tightly regulated pathways. The most prominent peroxisome degradation system uses components of the general autophagy core machinery and is therefore referred to as “pexophagy.” In this paper we focus on recent developments in pexophagy and provide an overview of current knowledge and future challenges in the field. We compare different modes of pexophagy and mention shared and distinct features of pexophagy in yeast model systems, mammalian cells, and other organisms.
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Sibirny AA. Mechanisms of autophagy and pexophagy in yeasts. BIOCHEMISTRY (MOSCOW) 2011; 76:1279-90. [DOI: 10.1134/s0006297911120017] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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17
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Kim HS, Park SY, Lee S, Adams EL, Czymmek K, Kang S. Loss of cAMP-dependent protein kinase A affects multiple traits important for root pathogenesis by Fusarium oxysporum. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2011; 24:719-732. [PMID: 21261464 DOI: 10.1094/mpmi-11-10-0267] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The soilborne fungal pathogen Fusarium oxysporum causes vascular wilt and root rot diseases in many plant species. We investigated the role of cyclic AMP-dependent protein kinase A of F. oxysporum (FoCPKA) in growth, morphology, and root attachment, penetration, and pathogenesis in Arabidopsis thaliana. Affinity of spore attachment to root surfaces of A. thaliana, observed microscopically and measured by atomic force microscopy, was reduced by a loss-of-function mutation in the gene encoding the catalytic subunit of FoCPKA. The resulting mutants also failed to penetrate into the vascular system of A. thaliana roots and lost virulence. Even when the mutants managed to enter the vascular system via physically wounded roots, the degree of vascular colonization was significantly lower than that of the corresponding wild-type strain O-685 and no noticeable disease symptoms were observed. The mutants also had reduced vegetative growth and spore production, and their hyphal growth patterns were distinct from those of O-685. Coinoculation of O-685 with an focpkA mutant or a strain nonpathogenic to A. thaliana significantly reduced disease severity and the degree of root colonization by O-685. Several experimental tools useful for studying mechanisms of fungal root pathogenesis are also introduced.
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Affiliation(s)
- Hye-Seon Kim
- Department of Plant Pathology, The Pennsylvania State University, University Park, PA, USA
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Reumann S, Voitsekhovskaja O, Lillo C. From signal transduction to autophagy of plant cell organelles: lessons from yeast and mammals and plant-specific features. PROTOPLASMA 2010; 247:233-56. [PMID: 20734094 DOI: 10.1007/s00709-010-0190-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2010] [Accepted: 07/28/2010] [Indexed: 05/08/2023]
Abstract
Autophagy is an evolutionarily conserved intracellular process for the vacuolar degradation of cytoplasmic constituents. The central structures of this pathway are newly formed double-membrane vesicles (autophagosomes) that deliver excess or damaged cell components into the vacuole or lysosome for proteolytic degradation and monomer recycling. Cellular remodeling by autophagy allows organisms to survive extensive phases of nutrient starvation and exposure to abiotic and biotic stress. Autophagy was initially studied by electron microscopy in diverse organisms, followed by molecular and genetic analyses first in yeast and subsequently in mammals and plants. Experimental data demonstrate that the basic principles, mechanisms, and components characterized in yeast are conserved in mammals and plants to a large extent. However, distinct autophagy pathways appear to differ between kingdoms. Even though direct information remains scarce particularly for plants, the picture is emerging that the signal transduction cascades triggering autophagy and the mechanisms of organelle turnover evolved further in higher eukaryotes for optimization of nutrient recycling. Here, we summarize new research data on nitrogen starvation-induced signal transduction and organelle autophagy and integrate this knowledge into plant physiology.
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Affiliation(s)
- Sigrun Reumann
- Centre for Organelle Research, University of Stavanger, 4021 Stavanger, Norway.
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Manjithaya R, Jain S, Farré JC, Subramani S. A yeast MAPK cascade regulates pexophagy but not other autophagy pathways. ACTA ACUST UNITED AC 2010; 189:303-10. [PMID: 20385774 PMCID: PMC2856896 DOI: 10.1083/jcb.200909154] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Autophagy is important for many cellular processes such as innate immunity, neurodegeneration, aging, and cancer. Although the signaling events triggering autophagy have been studied, little is known regarding the signaling mechanisms by which autophagy is redirected to achieve selective removal of cellular components. We have used the degradation of a peroxisomal marker to investigate the role of protein kinases in selective autophagy of peroxisomes (pexophagy) in Saccharomyces cerevisiae. We show that the Slt2p mitogen-activated protein kinase (MAPK) and several upstream components of its signal transduction pathway are necessary for pexophagy but not for pexophagosome formation or other nonselective and selective forms of autophagy. Other extracellular signals that activate this pathway do not trigger pexophagy on their own, suggesting that this MAPK cascade is necessary but not sufficient to trigger pexophagy. We propose that pexophagy requires the simultaneous activation of this MAPK pathway and a hexose-sensing mechanism acting through protein kinase A and cyclic adenosine monophosphate.
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Affiliation(s)
- Ravi Manjithaya
- Section of Molecular Biology, University of California, San Diego, La Jolla, CA 92093, USA
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Manjithaya R, Nazarko TY, Farré JC, Subramani S. Molecular mechanism and physiological role of pexophagy. FEBS Lett 2010; 584:1367-73. [PMID: 20083110 DOI: 10.1016/j.febslet.2010.01.019] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2009] [Revised: 01/12/2010] [Accepted: 01/12/2010] [Indexed: 12/26/2022]
Abstract
Pexophagy is a selective autophagy process wherein damaged and/or superfluous peroxisomes undergo vacuolar degradation. In methylotropic yeasts, where pexophagy has been studied most extensively, this process occurs by either micro- or macropexophagy: processes analogous to micro- and macroautophagy. Recent studies have identified specific factors and illustrated mechanisms involved in pexophagy. Although mechanistically pexophagy relies heavily on the core autophagic machinery, the latest findings about the role of auxiliary pexophagy factors have highlighted specialized membrane structures required for micropexophagy, and shown how cargo selectivity is achieved and how cargo size dictates the requirement for these factors during pexophagy. These insights and additional observations in the literature provide a framework for an understanding of the physiological role(s) of pexophagy.
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Affiliation(s)
- Ravi Manjithaya
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093-0322, USA
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21
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Cebollero E, Reggiori F. Regulation of autophagy in yeast Saccharomyces cerevisiae. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2009; 1793:1413-21. [DOI: 10.1016/j.bbamcr.2009.01.008] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2008] [Revised: 01/04/2009] [Accepted: 01/07/2009] [Indexed: 10/21/2022]
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Abstract
In the presence of glucose, yeast undergoes an important remodelling of its metabolism. There are changes in the concentration of intracellular metabolites and in the stability of proteins and mRNAs; modifications occur in the activity of enzymes as well as in the rate of transcription of a large number of genes, some of the genes being induced while others are repressed. Diverse combinations of input signals are required for glucose regulation of gene expression and of other cellular processes. This review focuses on the early elements in glucose signalling and discusses their relevance for the regulation of specific processes. Glucose sensing involves the plasma membrane proteins Snf3, Rgt2 and Gpr1 and the glucose-phosphorylating enzyme Hxk2, as well as other regulatory elements whose functions are still incompletely understood. The similarities and differences in the way in which yeasts and mammalian cells respond to glucose are also examined. It is shown that in Saccharomyces cerevisiae, sensing systems for other nutrients share some of the characteristics of the glucose-sensing pathways.
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Affiliation(s)
- Juana M Gancedo
- Department of Metabolism and Cell Signalling, Instituto de Investigaciones Biomédicas Alberto Sols, CSIC-UAM, Madrid, Spain.
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Identification of hexose transporter-like sensor HXS1 and functional hexose transporter HXT1 in the methylotrophic yeast Hansenula polymorpha. EUKARYOTIC CELL 2008; 7:735-46. [PMID: 18310355 DOI: 10.1128/ec.00028-08] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
We identified in the methylotrophic yeast Hansenula polymorpha (syn. Pichia angusta) a novel hexose transporter homologue gene, HXS1 (hexose sensor), involved in transcriptional regulation in response to hexoses, and a regular hexose carrier gene, HXT1 (hexose transporter). The Hxs1 protein exhibits the highest degree of primary sequence similarity to the Saccharomyces cerevisiae transporter-like glucose sensors, Snf3 and Rgt2. When heterologously overexpressed in an S. cerevisiae hexose transporter-less mutant, Hxt1, but not Hxs1, restores growth on glucose or fructose, suggesting that Hxs1 is nonfunctional as a carrier. In its native host, HXS1 is expressed at moderately low level and is required for glucose induction of the H. polymorpha functional low-affinity glucose transporter Hxt1. Similarly to other yeast sensors, one conserved amino acid substitution in the Hxs1 sequence (R203K) converts the protein into a constitutively signaling form and the C-terminal region of Hxs1 is essential for its function in hexose sensing. Hxs1 is not required for glucose repression or catabolite inactivation that involves autophagic degradation of peroxisomes. However, HXS1 deficiency leads to significantly impaired transient transcriptional repression in response to fructose, probably due to the stronger defect in transport of this hexose in the hxs1Delta deletion strain. Our combined results suggest that in the Crabtree-negative yeast H. polymorpha, the single transporter-like sensor Hxs1 mediates signaling in the hexose induction pathway, whereas the rate of hexose uptake affects the strength of catabolite repression.
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