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Abstract
Primary cilium is an organelle that plays significant roles in a number of cellular functions ranging from cell mechanosensation, proliferation, and differentiation to apoptosis. Autophagy is an evolutionarily conserved cellular function in biology and indispensable for cellular homeostasis. Both cilia and autophagy have been linked to different types of genetic and acquired human diseases. Their interaction has been suggested very recently, but the underlying mechanisms are still not fully understood. We examined autophagy in cells with suppressed cilia and measured cilium length in autophagy-activated or -suppressed cells. It was found that autophagy was repressed in cells with short cilia. Further investigation showed that MTOR activation was enhanced in cilia-suppressed cells and the MTOR inhibitor rapamycin could largely reverse autophagy suppression. In human kidney proximal tubular cells (HK2), autophagy induction was associated with cilium elongation. Conversely, autophagy inhibition by 3-methyladenine (3-MA) and chloroquine (CQ) as well as bafilomycin A1 (Baf) led to short cilia. Cilia were also shorter in cultured atg5-knockout (KO) cells and in atg7-KO kidney proximal tubular cells in mice. MG132, an inhibitor of the proteasome, could significantly restore cilium length in atg5-KO cells, being concomitant with the proteasome activity. Together, the results suggest that cilia and autophagy regulate reciprocally through the MTOR signaling pathway and ubiquitin-proteasome system.
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Key Words
- 3-MA, 3-methyladenine
- 70kDa, polypeptide 1
- ANKS6, ankyrin repeat and sterile α motif domain containing 6
- ATG/atg, autophagy-related
- Ac-TUBA, acetylated-tubulin α
- Baf, bafilomycin A1
- CF, confluence
- CQ, chloroquine
- DAPI, 4′-6-diamidino-2-phenylindole
- FBS, fetal bovine serum
- HK2, human kidney proximal tubular cells
- IFT, intraflagellar transport
- KAP3, kinesin family-associated protein 3
- KD, knockdown
- KIF3A/3B, kinesin family member 3A/3B
- KO, knockout
- LTA, lotus tetragonolobus agglutinin
- MAP1LC3B/LC3B, microtubule-associated protein 1 light chain 3 β
- MEF, mouse embryonic fibroblast
- MTOR
- MTOR, mechanistic target of rapamycin
- OFD1, oral-ficial-digital syndrome 1
- PBS, phosphate-buffered saline
- PKD, polycystic kidney disease
- RKRB, Krebs-Henseleit saline containing 25 mM NaHCO3
- RPS6KB1, ribosomal protein S6 kinase
- Rapa, rapamycin
- SD, standard deviation
- autophagy
- cilia
- polycystic kidney disease
- proteasome
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Affiliation(s)
- Shixuan Wang
- a Department of Cellular Biology and Anatomy ; Medical College of Georgia; Georgia Reagents University and Charlie Norwood VA Medical Center ; Augusta , GA USA
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Cabrera S, Maciel M, Herrera I, Nava T, Vergara F, Gaxiola M, López-Otín C, Selman M, Pardo A. Essential role for the ATG4B protease and autophagy in bleomycin-induced pulmonary fibrosis. Autophagy 2016; 11:670-84. [PMID: 25906080 DOI: 10.1080/15548627.2015.1034409] [Citation(s) in RCA: 115] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Autophagy is a critical cellular homeostatic process that controls the turnover of damaged organelles and proteins. Impaired autophagic activity is involved in a number of diseases, including idiopathic pulmonary fibrosis suggesting that altered autophagy may contribute to fibrogenesis. However, the specific role of autophagy in lung fibrosis is still undefined. In this study, we show for the first time, how autophagy disruption contributes to bleomycin-induced lung fibrosis in vivo using an Atg4b-deficient mouse as a model. Atg4b-deficient mice displayed a significantly higher inflammatory response at 7 d after bleomycin treatment associated with increased neutrophilic infiltration and significant alterations in proinflammatory cytokines. Likewise, we found that Atg4b disruption resulted in augmented apoptosis affecting predominantly alveolar and bronchiolar epithelial cells. At 28 d post-bleomycin instillation Atg4b-deficient mice exhibited more extensive and severe fibrosis with increased collagen accumulation and deregulated extracellular matrix-related gene expression. Together, our findings indicate that the ATG4B protease and autophagy play a crucial role protecting epithelial cells against bleomycin-induced stress and apoptosis, and in the regulation of the inflammatory and fibrotic responses.
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Key Words
- ACTA2, actin, α 2, smooth muscle, aorta
- ATG3, autophagy-related 3
- ATG4B
- ATG4B, autophagy-related 4B
- ATG5, autophagy-related 5
- ATG7, autophagy-related 7
- ATG9B, autophagy-related 9B
- BAX, BCL2-associated X protein
- CASP3, caspase 3, apoptosis-related cysteine peptidase
- CAV1, caveolin 1, caveolae protein, 22kDa
- CCL3, chemokine (C-C motif) ligand 3
- CXCL1, chemokine (C-X-C motif) ligand 1 (melanoma growth stimulating activity α)
- CXCR2, chemokine (C-X-C motif) receptor 2
- DRAM2, DNA-damage regulated autophagy modulator 2
- GFP-LC3B, green fluorescent protein-LC3B
- IFNG, interferon, gamma
- IL12B, interleukin 12B
- IL13, interleukin 13
- IPF, idiopathic pulmonary fibrosis
- MAP1LC3B/LC3B, microtubule-associated protein 1 light chain 3 β
- RELA, v-rel reticuloendotheliosis viral oncogene homolog A
- SQSTM1, sequestosome 1
- TGFB1, transforming growth factor, β 1
- TGFBR2, transforming growth factor, β receptor II (70/80kDa)
- TNF, tumor necrosis factor
- TUBB4, tubulin, β 4, class IV
- WT, wild type
- autophagin-1
- autophagy
- cysteine peptidase
- epithelial cell
- idiopathic pulmonary fibrosis
- lung fibrosis
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Affiliation(s)
- Sandra Cabrera
- a Facultad de Ciencias; Universidad Nacional Autónoma de México ; Mexico DF , Mexico
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Eriksen AB, Torgersen ML, Holm KL, Abrahamsen G, Spurkland A, Moskaug JØ, Simonsen A, Blomhoff HK. Retinoic acid-induced IgG production in TLR-activated human primary B cells involves ULK1-mediated autophagy. Autophagy 2016; 11:460-71. [PMID: 25749095 DOI: 10.1080/15548627.2015.1009797] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
In the present study we have established a vital role of autophagy in retinoic acid (RA)-induced differentiation of toll-like receptor (TLR)-stimulated human B cells into Ig-secreting cells. Thus, RA enhanced autophagy in TLR9- and CD180-stimulated peripheral blood B cells, as revealed by increased levels of the autophagosomal marker LC3B-II, enhanced colocalization between LC3B and the lysosomal marker Lyso-ID, by a larger percentage of cells with more than 5 characteristic LC3B puncta, and by the concomitant reduction in the level of SQSTM1/p62. Furthermore, RA induced expression of the autophagy-inducing protein ULK1 at the transcriptional level, in a process that required the retinoic acid receptor RAR. By inhibiting autophagy with specific inhibitors or by knocking down ULK1 by siRNA, the RA-stimulated IgG production in TLR9- and CD180-mediated cells was markedly reduced. We propose that the identified prominent role of autophagy in RA-mediated IgG-production in normal human B cells provides a novel mechanism whereby vitamin A exerts its important functions in the immune system.
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Key Words
- ATG, autophagy-related
- B lymphocytes
- BDS, bright detail similarity
- CD180
- CD180, CD180 molecule
- CVID, common variable immune deficiency
- ELISA, enzyme-linked immunosorbent assay
- IL, interleukin
- Ig, immunoglobulin
- MAP1LC3B/LC3B, microtubule-associated protein 1 light chain 3 β
- MTOR, mechanistic target of rapamycin (serine/threonine kinase)
- PAMP, pathogen-associated molecular pattern, PML/RARA, promyelocytic leukemia/ retinoic acid receptor α
- RA, all-trans retinoic acid
- RAR, retinoic acid receptor
- RP105
- SQSTM1, sequestosome 1
- TLR, toll-like receptor
- TLR9
- ULK1
- ULK1, unc-51 like autophagy activating kinase 1
- antibody secretion
- autophagy
- plasma cell differentiation
- retinoic acid
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Affiliation(s)
- Agnete Bratsberg Eriksen
- a Department of Biochemistry ; Institute of Basic Medical Sciences; University of Oslo ; Oslo , Norway
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Namkoong S, Lee KI, Lee JI, Park R, Lee EJ, Jang IS, Park J. The integral membrane protein ITM2A, a transcriptional target of PKA-CREB, regulates autophagic flux via interaction with the vacuolar ATPase. Autophagy 2016; 11:756-68. [PMID: 25951193 PMCID: PMC4509440 DOI: 10.1080/15548627.2015.1034412] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The PKA-CREB signaling pathway is involved in many cellular processes including autophagy. Recent studies demonstrated that PKA-CREB inhibits autophagy in yeast; however, the role of PKA-CREB signaling in mammalian cell autophagy has not been fully characterized. Here, we report that the integral membrane protein ITM2A expression is positively regulated by PKA-CREB signaling and ITM2A expression interferes with autophagic flux by interacting with vacuolar ATPase (v-ATPase). The ITM2A promoter contains a CRE element, and mutation at the CRE consensus site decreases the promoter activity. Forskolin treatment and PKA expression activate the ITM2A promoter confirming that ITM2A expression is dependent on the PKA-CREB pathway. ITM2A expression results in the accumulation of autophagosomes and interferes with autolysosome formation by blocking autophagic flux. We demonstrated that ITM2A physically interacts with v-ATPase and inhibits lysosomal function. These results support the notion that PKA-CREB signaling pathway regulates ITM2A expression, which negatively regulates autophagic flux by interfering with the function of v-ATPase.
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Key Words
- BafA1, bafilomycin A1
- CRE, cAMP response element
- CREB
- CREB, cAMP responsive element binding protein
- ChIP, chromatin immunoprecipitation
- EBSS, Earle's balanced salt solution
- ITM2A
- ITM2A, integral membrane protein 2A
- LAMP1, lysosomal-associated membrane protein 1
- MAP1LC3B/LC3B, microtubule-associated protein 1 light chain 3 β
- MAPK, mitogen-activated protein kinase
- MTOR, mechanistic target of rapamycin
- PKA
- PKA, protein kinase A
- SQSTM1, sequestosome 1
- TPA, 12-O-tetradecanoylphorbol-13-acetate
- autophagy
- cAMP, cyclic adenosine monophosphate
- tfLC3, tandem fluorescent-tagged LC3
- v-ATPase
- v-ATPase, vacuolar ATPase.
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Affiliation(s)
- Sim Namkoong
- a Division of Biological Science and Technology; Yonsei University ; Wonju , Korea
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Abstract
BECN1/Beclin 1 is regarded as a critical component in the class III phosphatidylinositol 3-kinase (PtdIns3K) complex to trigger autophagy in mammalian cells. Despite its significant role in a number of cellular and physiological processes, the exact function of BECN1 in autophagy remains controversial. Here we created a BECN1 knockout human cell line using the TALEN technique. Surprisingly, the complete loss of BECN1 had little effect on LC3 (MAP1LC3B/LC3B) lipidation, and LC3B puncta resembling autophagosomes by fluorescence microscopy were still evident albeit significantly smaller than those in the wild-type cells. Electron microscopy (EM) analysis revealed that BECN1 deficiency led to malformed autophagosome-like structures containing multiple layers of membranes under amino acid starvation. We further confirmed that the PtdIns3K complex activity and autophagy flux were disrupted in BECN1−/− cells. Our results demonstrate the essential role of BECN1 in the functional formation of autophagosomes, but not in LC3B lipidation.
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Key Words
- ATG, autophagy related
- BCL2L1/Bcl-xL, BCL2-like 1
- BECN1
- BECN1, Beclin 1, autophagy related
- BECN1P1/BECN2, Beclin 1, autophagy related, pseudogene 1
- BafA1, bafilomycin A1
- EM, electron microscopy
- GAPDH, glyceraldehyde-3-phosphate dehydrogenase
- GFP, green fluorescent protein
- KO, knockout
- LC3
- MAP1LC3-I/LC3-I, soluble, proteolytically processed microtubule-associated protein 1 light chain 3
- MAP1LC3-II/LC3-II, proteolytically processed and lipid-modified microtubule-associated protein 1 light chain 3
- MAP1LC3/LC3, microtubule-associated protein 1 light chain 3
- MAP1LC3B/LC3B, microtubule-associated protein 1 light chain 3 β
- PIK3C3/VPS34, phosphatidylinositol 3-kinase, catalytic subunit type 3
- PIK3R4/VPS15, phosphoinositide-3-kinase, regulatory subunit 4
- PtdIns3K
- PtdIns3K, phosphatidylinositol 3-kinase
- SQSTM1/p62, sequestosome 1
- TALEN, transcription activator-like effector nuclease
- TUBB, tubulin, β class I
- UVRAG, UV radiation resistance associated
- ZFYVE1/DFCP1, zinc finger, FYVE domain containing 1.
- autophagosome
- autophagy
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Affiliation(s)
- Ruina He
- a Biodynamic Optical Imaging Center (BIOPIC); Peking-Tsinghua Center for Life Sciences; State Key Laboratory of Protein and Plant Gene Research; School of Life Sciences; Peking University ; Beijing , China
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Zhang SF, Wang XY, Fu ZQ, Peng QH, Zhang JY, Ye F, Fu YF, Zhou CY, Lu WG, Cheng XD, Xie X. TXNDC17 promotes paclitaxel resistance via inducing autophagy in ovarian cancer. Autophagy 2016; 11:225-38. [PMID: 25607466 DOI: 10.1080/15548627.2014.998931] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Paclitaxel is recommended as a first-line chemotherapeutic agent against ovarian cancer, but drug resistance becomes a major limitation of its success clinically. The key molecule or mechanism associated with paclitaxel resistance in ovarian cancer still remains unclear. Here, we showed that TXNDC17 screened from 356 differentially expressed proteins by LC-MS/MS label-free quantitative proteomics was more highly expressed in paclitaxel-resistant ovarian cancer cells and tissues, and the high expression of TXNDC17 was associated with poorer prognostic factors and exhibited shortened survival in 157 ovarian cancer patients. Moreover, paclitaxel exposure induced upregulation of TXNDC17 and BECN1 expression, increase of autophagosome formation, and autophagic flux that conferred cytoprotection for ovarian cancer cells from paclitaxel. TXNDC17 inhibition by siRNA or enforced overexpression by a pcDNA3.1(+)-TXNDC17 plasmid correspondingly decreased or increased the autophagy response and paclitaxel resistance. Additionally, the downregulation of BECN1 by siRNA attenuated the activation of autophagy and cytoprotection from paclitaxel induced by TXNDC17 overexpression in ovarian cancer cells. Thus, our findings suggest that TXNDC17, through participation of BECN1, induces autophagy and consequently results in paclitaxel resistance in ovarian cancer. TXNDC17 may be a potential predictor or target in ovarian cancer therapeutics.
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Key Words
- 95% CI, 95% confidence interval
- ALDOC, aldolase C, fructose-bisphosphate
- ATG5, autophagy-related 5
- BECN1
- BECN1, Beclin 1, autophagy-related
- BafA1, bafilomycin A1
- CNN3, calponin 3, acidic
- DAPI, 4', 6-diamidino-2-phenylindole
- FLNA, filamin A, α
- GO, gene ontology
- GenMAPP, gene microarray pathway profiler
- HBSS, Hank's balanced salt solution
- HR, hazard ratio
- KEGG, Kyoto encyclopedia of genes and genome
- LC-MS/MS, liquid chromatography-mass spectrometry/ mass spectrometry
- MAP1LC3B/LC3B, microtubule-associated protein 1 light chain 3 β
- OS, overall survival
- PFS, progression-free survival
- PGAM1, phosphoglycerate mutase 1 (brain)
- SQSTM1, sequestosome 1
- TNF, tumor necrosis factor
- TXN, thioredoxin
- TXNDC17
- TXNDC17, thioredoxin domain containing 17
- UTP23, small subunit (SSU) processome component, homolog (yeast)
- autophagy
- ovarian cancer
- paclitaxel resistance
- siRNA, short interfering RNA
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Affiliation(s)
- Song-Fa Zhang
- a Women's Reproductive Health Laboratory of Zhejiang Province; Women's Hospital; School of Medicine ; Zhejiang University ; Hangzhou , China
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Rah B, ur Rasool R, Nayak D, Yousuf SK, Mukherjee D, Kumar LD, Goswami A. PAWR-mediated suppression of BCL2 promotes switching of 3-azido withaferin A (3-AWA)-induced autophagy to apoptosis in prostate cancer cells. Autophagy 2016; 11:314-31. [PMID: 25803782 DOI: 10.1080/15548627.2015.1017182] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
An active medicinal component of plant origin with an ability to overcome autophagy by inducing apoptosis should be considered a therapeutically active lead pharmacophore to control malignancies. In this report, we studied the effect of concentration-dependent 3-AWA (3-azido withaferin A) sensitization to androgen-independent prostate cancer (CaP) cells which resulted in a distinct switching of 2 interrelated conserved biological processes, i.e. autophagy and apoptosis. We have observed 3 distinct parameters which are hallmarks of autophagy in our studies. First, a subtoxic concentration of 3-AWA resulted in an autophagic phenotype with an elevation of autophagy markers in prostate cancer cells. This led to a massive accumulation of MAP1LC3B and EGFP-LC3B puncta coupled with gradual degradation of SQSTM1. Second, higher toxic concentrations of 3-AWA stimulated ER stress in CaP cells to turn on apoptosis within 12 h by elevating the expression of the proapoptotic protein PAWR, which in turn suppressed the autophagy-related proteins BCL2 and BECN1. This inhibition of BECN1 in CaP cells, leading to the disruption of the BCL2-BECN1 interaction by overexpressed PAWR has not been reported so far. Third, we provide evidence that pawr-KO MEFs exhibited abundant autophagy signs even at toxic concentrations of 3-AWA underscoring the relevance of PAWR in switching of autophagy to apoptosis. Last but not least, overexpression of EGFP-LC3B and DS-Red-BECN1 revealed a delayed apoptosis turnover at a higher concentration of 3-AWA in CaP cells. In summary, this study provides evidence that 3-AWA is a strong anticancer candidate to abrogate protective autophagy. It also enhanced chemosensitivity by sensitizing prostate cancer cells to apoptosis through induction of PAWR endorsing its therapeutic potential.
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Key Words
- 3-AWA, 3-azido withaferin A
- 3-azido withaferin A
- AO, acridine orange
- ATG, autophagy-related
- AVOs, acidic vesicular organelles
- BAD, BCL2-associated agonist of cell death
- BAF A1, bafilomycin A1
- BCL2
- BCL2, B-cell CLL/lymphoma 2
- BECN1
- BECN1, Beclin 1, autophagy-related
- CASP3, caspase 3
- CASP9, caspase 9
- CQ, chloroquine
- CYCS, cytochrome c, somatic
- CaP, prostate cancer cells
- DAPI, 4’6-diamidino-2-phenylindole
- DCF, dichlorofluorescein
- DDIT3/CHOP, DNA-damage-inducible transcript 3
- EIF2AK3/PERK, eukaryotic initiation translation factor 2-α kinase 3
- ER, endoplasmic reticulum
- HSPA5/GRP78, heat shock 70kDa protein 5 (glucose-regulated protein, 78kDa)
- MAP1LC3B/LC3B, microtubule-associated protein 1 light chain 3 β
- MDC, monodansylcadaverine
- MEFs, mouse embryonic fibroblasts
- MMPψ, mitochondrial membrane potential
- MTOR, mechanistic target of rapamycin
- NAC, N-acetyl-L-cysteine
- PARP1, poly (ADP-ribose) polymerase 1
- PAWR
- PAWR/Par-4, PRKC, apoptosis, WT1, regulator
- PRKCZ/PKCζ, protein kinase C, zeta
- SQSTM1/p62, sequestosome 1
- WT1, Wilms tumor 1
- apoptosis
- autophagy
- myrAKT1, myristoylated v-akt murine thymoma viral oncogene homolog 1
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Affiliation(s)
- Bilal Rah
- a Academy of Scientific & Innovative Research (AcSIR) ; New Delhi , India
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