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1.
Nat Commun ; 13(1): 4628, 2022 08 08.
Article in English | MEDLINE | ID: mdl-35941116

ABSTRACT

The presence of distinct stem cells that maintain the interfollicular epidermis is highly debated. Here, we report a population of keratinocytes, marked by Thy1, in the basal layer of the interfollicular epidermis. We find that epidermal cells expressing differential levels of Thy1 display distinct transcriptional signatures. Thy1+ keratinocytes do not express T cell markers, express a unique transcriptional profile, cycle significantly slower than basal epidermal progenitors and display significant expansion potential in vitro. Multicolor lineage tracing analyses and mathematical modeling reveal that Thy1+ basal keratinocytes do not compete neutrally alike interfollicular progenitors and contribute long-term to both epidermal replenishment and wound repair. Importantly, ablation of Thy1+ cells strongly impairs these processes, thus indicating the non-redundant function of Thy1+ stem cells in the epidermis. Collectively, these results reveal a distinct stem cell population that plays a critical role in epidermal homeostasis and repair.


Subject(s)
Epidermal Cells , Stem Cells , Animals , Cell Differentiation/physiology , Epidermis/metabolism , Keratinocytes/metabolism , Mice , Stem Cells/metabolism
2.
Elife ; 102021 08 12.
Article in English | MEDLINE | ID: mdl-34382936

ABSTRACT

The blood-brain barrier (BBB) of Drosophila comprises a thin epithelial layer of subperineural glia (SPG), which ensheath the nerve cord and insulate it against the potassium-rich hemolymph by forming intercellular septate junctions (SJs). Previously, we identified a novel Gi/Go protein-coupled receptor (GPCR), Moody, as a key factor in BBB formation at the embryonic stage. However, the molecular and cellular mechanisms of Moody signaling in BBB formation and maturation remain unclear. Here, we identify cAMP-dependent protein kinase A (PKA) as a crucial antagonistic Moody effector that is required for the formation, as well as for the continued SPG growth and BBB maintenance in the larva and adult stage. We show that PKA is enriched at the basal side of the SPG cell and that this polarized activity of the Moody/PKA pathway finely tunes the enormous cell growth and BBB integrity. Moody/PKA signaling precisely regulates the actomyosin contractility, vesicle trafficking, and the proper SJ organization in a highly coordinated spatiotemporal manner. These effects are mediated in part by PKA's molecular targets MLCK and Rho1. Moreover, 3D reconstruction of SJ ultrastructure demonstrates that the continuity of individual SJ segments, and not their total length, is crucial for generating a proper paracellular seal. Based on these findings, we propose that polarized Moody/PKA signaling plays a central role in controlling the cell growth and maintaining BBB integrity during the continuous morphogenesis of the SPG secondary epithelium, which is critical to maintain tissue size and brain homeostasis during organogenesis.


Subject(s)
Drosophila Proteins/genetics , Drosophila melanogaster/physiology , Receptors, G-Protein-Coupled/genetics , Signal Transduction , Animals , Blood-Brain Barrier/physiology , Drosophila Proteins/metabolism , Drosophila melanogaster/genetics , Receptors, G-Protein-Coupled/metabolism
3.
Proc Natl Acad Sci U S A ; 116(49): 24639-24650, 2019 12 03.
Article in English | MEDLINE | ID: mdl-31754024

ABSTRACT

Proteasome-mediated degradation of intracellular proteins is essential for cell function and survival. The proteasome-binding protein PI31 (Proteasomal Inhibitor of 31kD) promotes 26S assembly and functions as an adapter for proteasome transport in axons. As localized protein synthesis and degradation is especially critical in neurons, we generated a conditional loss of PI31 in spinal motor neurons (MNs) and cerebellar Purkinje cells (PCs). A cKO of PI31 in these neurons caused axon degeneration, neuronal loss, and progressive spinal and cerebellar neurological dysfunction. For both MNs and PCs, markers of proteotoxic stress preceded axonal degeneration and motor dysfunction, indicating a critical role for PI31 in neuronal homeostasis. The time course of the loss of MN and PC function in developing mouse central nervous system suggests a key role for PI31 in human neurodegenerative diseases.


Subject(s)
Carrier Proteins/metabolism , Motor Neurons/physiology , Neurodegenerative Diseases/genetics , Proteostasis/physiology , Purkinje Cells/physiology , Synapses/physiology , Animals , Axons/pathology , Axons/physiology , Behavior Observation Techniques , Carrier Proteins/genetics , Cell Survival/physiology , Disease Models, Animal , Female , Humans , Mice , Mice, Knockout , Motor Neurons/pathology , Mutation , Neurodegenerative Diseases/diagnosis , Neurodegenerative Diseases/pathology , Proteasome Endopeptidase Complex/metabolism , Proteolysis , Purkinje Cells/pathology , Synapses/pathology
4.
Mech Dev ; 160: 103583, 2019 12.
Article in English | MEDLINE | ID: mdl-31678471

ABSTRACT

The establishment of planar cell polarity (PCP) in the Drosophila eye requires correct specification of the R3/R4 pair of photoreceptor cells, determined by a Frizzled mediated signaling event that specifies R3 and induces Delta to activate Notch signaling in the neighboring cell, specifying it as R4. Here, we investigated the role of the Notch signaling negative regulator Numb in the specification of R3/R4 fates and PCP establishment in the Drosophila eye. We observed that Numb is transiently upregulated in R3 at the time of R3/R4 specification. This regulation of Numb levels in developing photoreceptors occurs at the post-transcriptional level and is dependent on Dishevelled, an effector of Frizzled signaling, and Lethal Giant Larva. We detected PCP defects in cells homozygous for numb15, but these defects were due to a loss of function mutation in fat (fatQ805⁎) being present in the numb15 chromosome. However, mosaic overexpression of Numb in R4 precursors (only) caused PCP defects and numb loss-of-function alleles had a modifying effect on the defects found in a hypomorphic dishevelled mutation. Our results suggest that Numb levels are upregulated to reinforce the bias of Notch signaling activation in the R3/R4 pair, two post-mitotic cells that are not specified by asymmetric cell division.


Subject(s)
Cell Polarity , Drosophila Proteins/metabolism , Drosophila melanogaster/cytology , Drosophila melanogaster/metabolism , Eye/cytology , Eye/metabolism , Juvenile Hormones/metabolism , Animals , Chromosomes/genetics , Drosophila Proteins/genetics , Drosophila melanogaster/genetics , Gene Expression Regulation, Developmental , Male , Mutation/genetics , Phenotype , Up-Regulation/genetics
5.
Dev Cell ; 50(4): 509-524.e10, 2019 08 19.
Article in English | MEDLINE | ID: mdl-31327739

ABSTRACT

Protein degradation by the ubiquitin-proteasome system is critical for neuronal function. Neurons utilize microtubule-dependent molecular motors to allocate proteasomes to synapses, but how proteasomes are coupled to motors and how this is regulated to meet changing demand for protein breakdown remain largely unknown. We show that the conserved proteasome-binding protein PI31 serves as an adaptor to couple proteasomes with dynein light chain proteins (DYNLL1/2). The inactivation of PI31 inhibited proteasome motility in axons and disrupted synaptic proteostasis, structure, and function. Moreover, phosphorylation of PI31 by p38 MAPK enhanced binding to DYNLL1/2 and promoted the directional movement of proteasomes in axons, suggesting a mechanism to regulate loading of proteasomes onto motors. Inactivation of PI31 in mouse neurons attenuated proteasome movement in axons, indicating this process is conserved. Because mutations affecting PI31 activity are associated with human neurodegenerative diseases, impairment of PI31-mediated axonal transport of proteasomes may contribute to these disorders.


Subject(s)
Neurons/metabolism , Proteins/genetics , Proteolysis , Synapses/genetics , Adaptor Proteins, Signal Transducing/genetics , Animals , Axonal Transport/genetics , Axons/metabolism , Cytoplasm/genetics , Cytoplasm/metabolism , Cytoplasmic Dyneins/genetics , Humans , Mice , Microtubules/genetics , Proteasome Endopeptidase Complex/genetics , Proteostasis/genetics , Synapses/metabolism , p38 Mitogen-Activated Protein Kinases/genetics
6.
Development ; 146(6)2019 03 15.
Article in English | MEDLINE | ID: mdl-30796047

ABSTRACT

Self-renewal of intestinal stem cells is controlled by Wingless/Wnt-ß catenin signaling in both Drosophila and mammals. As Axin is a rate-limiting factor in Wingless signaling, its regulation is essential. Iduna is an evolutionarily conserved ubiquitin E3 ligase that has been identified as a crucial regulator for degradation of ADP-ribosylated Axin and, thus, of Wnt/ß-catenin signaling. However, its physiological significance remains to be demonstrated. Here, we generated loss-of-function mutants of Iduna to investigate its physiological role in Drosophila Genetic depletion of Iduna causes the accumulation of both Tankyrase and Axin. Increase of Axin protein in enterocytes non-autonomously enhanced stem cell divisions in the Drosophila midgut. Enterocytes secreted Unpaired proteins and thereby stimulated the activity of the JAK-STAT pathway in intestinal stem cells. A decrease in Axin gene expression suppressed the over-proliferation of stem cells and restored their numbers to normal levels in Iduna mutants. These findings suggest that Iduna-mediated regulation of Axin proteolysis is essential for tissue homeostasis in the Drosophila midgut.


Subject(s)
Axin Protein/metabolism , Drosophila Proteins/metabolism , Drosophila melanogaster/metabolism , Intestines/physiology , Poly-ADP-Ribose Binding Proteins/metabolism , Stem Cells/cytology , Ubiquitin-Protein Ligases/metabolism , Wnt1 Protein/metabolism , Animals , CRISPR-Cas Systems , Cell Proliferation , Crosses, Genetic , Female , Gene Expression Regulation, Developmental , Green Fluorescent Proteins/metabolism , Homeostasis , Male , Models, Genetic , Mutation , RNA Interference , Recombinant Proteins/metabolism , Signal Transduction , Tankyrases/metabolism
7.
Cancer Res ; 78(13): 3458-3468, 2018 07 01.
Article in English | MEDLINE | ID: mdl-29716915

ABSTRACT

Protein degradation by the ubiquitin-proteasome system (UPS) is central to protein homeostasis and cell survival. The active 26S proteasome is a large protease complex consisting of a catalytic 20S subunit and 19S regulatory particles. Cancer cells are exposed to considerable protein overload due to high metabolic rates, reprogrammed energy metabolism, and aneuploidy. Here we report a mechanism that facilitates the assembly of active 26S proteasomes in malignant cells. Upon tumorigenic transformation of the gut epithelium, 26S proteasome assembly was significantly enhanced, but levels of individual subunits were not changed. This enhanced assembly of 26S proteasomes increased further with tumor progression and was observed specifically in transformed cells, but not in other rapidly dividing cells. Moreover, expression of PSMD5, an inhibitor of proteasome assembly, was reduced in intestinal tumors and silenced with tumor progression. Reexpression of PSMD5 in tumor cells caused decreased 26S assembly and accumulation of polyubiquitinated proteins. These results suggest that inhibition of cancer-associated proteasome assembly may provide a novel therapeutic strategy to selectively kill cancer cells.Significance: Enhanced cancer-associated proteasome assembly is a major stress response that allows tumors to adapt to and to withstand protein overload.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/78/13/3458/F1.large.jpg Cancer Res; 78(13); 3458-68. ©2018 AACR.


Subject(s)
Cell Transformation, Neoplastic/pathology , Colorectal Neoplasms/pathology , Proteasome Endopeptidase Complex/metabolism , Adenomatous Polyposis Coli Protein/genetics , Animals , Azoxymethane/toxicity , Colorectal Neoplasms/chemically induced , Colorectal Neoplasms/genetics , Dextran Sulfate/toxicity , Disease Progression , Female , Gene Expression Regulation, Neoplastic , HEK293 Cells , HT29 Cells , Humans , Male , Mice, Transgenic , Neoplasms, Experimental/chemically induced , Neoplasms, Experimental/genetics , Neoplasms, Experimental/pathology , Proteasome Endopeptidase Complex/genetics
8.
Cell Rep ; 21(3): 758-772, 2017 Oct 17.
Article in English | MEDLINE | ID: mdl-29045842

ABSTRACT

Non-coding RNA biogenesis in higher eukaryotes has not been fully characterized. Here, we studied the Drosophila melanogaster Rexo5 (CG8368) protein, a metazoan-specific member of the DEDDh 3'-5' single-stranded RNA exonucleases, by genetic, biochemical, and RNA-sequencing approaches. Rexo5 is required for small nucleolar RNA (snoRNA) and rRNA biogenesis and is essential in D. melanogaster. Loss-of-function mutants accumulate improperly 3' end-trimmed 28S rRNA, 5S rRNA, and snoRNA precursors in vivo. Rexo5 is ubiquitously expressed at low levels in somatic metazoan cells but extremely elevated in male and female germ cells. Loss of Rexo5 leads to increased nucleolar size, genomic instability, defective ribosome subunit export, and larval death. Loss of germline expression compromises gonadal growth and meiotic entry during germline development.


Subject(s)
Drosophila Proteins/metabolism , Drosophila melanogaster/metabolism , Exoribonucleases/metabolism , RNA Processing, Post-Transcriptional/genetics , RNA, Ribosomal, 28S/metabolism , RNA, Small Nucleolar/metabolism , Animals , Conserved Sequence , Drosophila Proteins/genetics , Drosophila melanogaster/genetics , Exoribonucleases/genetics , Female , Gonads/embryology , Gonads/metabolism , Homozygote , Male , Mitosis , Mutation , Ribosomes/metabolism
9.
Elife ; 62017 06 28.
Article in English | MEDLINE | ID: mdl-28656888

ABSTRACT

Adenylyl cyclases (ACs) generate cAMP, a second messenger of utmost importance that regulates a vast array of biological processes in all kingdoms of life. However, almost nothing is known about how AC activity is regulated through protein degradation mediated by ubiquitination or other mechanisms. Here, we show that transcriptional regulator interacting with the PHD-bromodomain 1 (TRIP-Br1, Sertad1), a newly identified protein with poorly characterized functions, acts as an adaptor that bridges the interaction of multiple AC isoforms with X-linked inhibitor of apoptosis protein (XIAP), a RING-domain E3 ubiquitin ligase. XIAP ubiquitinates a highly conserved Lys residue in AC isoforms and thereby accelerates the endocytosis and degradation of multiple AC isoforms in human cell lines and mice. XIAP/TRIP-Br1-mediated degradation of ACs forms part of a negative-feedback loop that controls the homeostasis of cAMP signaling in mice. Our findings reveal a previously unrecognized mechanism for degrading multiple AC isoforms and modulating the homeostasis of cAMP signaling.


Subject(s)
Adenylyl Cyclases/metabolism , Nuclear Proteins/metabolism , Proteolysis , Trans-Activators/metabolism , Ubiquitination , X-Linked Inhibitor of Apoptosis Protein/metabolism , Animals , Cell Line , Humans , Mice , Protein Isoforms/metabolism , Transcription Factors
10.
PLoS One ; 12(3): e0174495, 2017.
Article in English | MEDLINE | ID: mdl-28319181

ABSTRACT

[This corrects the article DOI: 10.1371/journal.pone.0169639.].

11.
PLoS One ; 12(1): e0169639, 2017.
Article in English | MEDLINE | ID: mdl-28060904

ABSTRACT

Endocytosis is a multi-step process involving a large number of proteins, both general factors, such as clathrin and adaptor protein complexes, and unique proteins, which modulate specialized endocytic processes, like the EHD proteins. EHDs are a family of Eps15 Homology Domain containing proteins that consists of four mammalian homologs, one C. elegans, one Drosophila melanogaster and two plants orthologs. These membrane-associated proteins are involved in different steps of endocytic trafficking pathways. We have previously shown that the Drosophila EHD ortholog, PAST1, associates predominantly with the plasma membrane. Mutations in Past1 result in defects in endocytosis, male sterility, temperature sensitivity and premature death of the flies. Also, Past1 genetically interacts with Notch. In the present study, we investigated the role of PAST1 in the developing fly eye. In mutant flies lacking PAST1, abnormal differentiation of photoreceptors R1, R6 and R7 was evident, with partial penetrance. Likewise, five cone cells were present instead of four. Expression of transgenic PAST1 resulted in a dominant negative effect, with a phenotype similar to that of the deletion mutant, and appearance of additional inter-ommatidial pigment cells. Our results strongly suggest a role for PAST1 in differentiation of photoreceptors R1/R6/R7 and cone cells of the fly ommatidia.

12.
Hum Mol Genet ; 25(13): 2712-2727, 2016 07 01.
Article in English | MEDLINE | ID: mdl-27162249

ABSTRACT

Gaucher disease (GD) results from mutations in the acid ß-glucocerebrosidase (GCase) encoding gene, GBA, which leads to accumulation of glucosylceramides. GD patients and carriers of GD mutations have a significantly higher propensity to develop Parkinson disease (PD) in comparison to the non-GD population. In this study, we used the fruit fly Drosophila melanogaster to show that development of PD in carriers of GD mutations results from the presence of mutant GBA alleles. Drosophila has two GBA orthologs (CG31148 and CG31414), each of which has a minos insertion, which creates C-terminal deletion in the encoded GCase. Flies double heterozygous for the endogenous mutant GBA orthologs presented Unfolded Protein Response (UPR) and developed parkinsonian signs, manifested by death of dopaminergic cells, defective locomotion and a shorter life span. We also established transgenic flies carrying the mutant human N370S, L444P and the 84GG variants. UPR activation and development of parkinsonian signs could be recapitulated in flies expressing these three mutant variants.UPR and parkinsonian signs could be partially rescued by growing the double heterozygous flies, or flies expressing the N370S or the L444P human mutant GCase variants, in the presence of the pharmacological chaperone ambroxol, which binds and removes mutant GCase from the endoplasmic reticulum (ER). However flies expressing the 84GG mutant, that does not express mature GCase, did not exhibit rescue by ambroxol. Our results strongly suggest that the presence of a mutant GBA allele in dopaminergic cells leads to ER stress and to their death, and contributes to development of PD.


Subject(s)
Glucosylceramidase/genetics , Glucosylceramidase/metabolism , Ambroxol/metabolism , Animals , Disease Models, Animal , Dopaminergic Neurons/metabolism , Drosophila melanogaster/metabolism , Endoplasmic Reticulum/metabolism , Gaucher Disease/genetics , Heterozygote , Humans , Mutation , Parkinson Disease/genetics , Unfolded Protein Response/genetics , Unfolded Protein Response/physiology
13.
J Vis Exp ; (110)2016 04 29.
Article in English | MEDLINE | ID: mdl-27168117

ABSTRACT

The hair follicle (HF) is an ideal system for studying the biology and regulation of adult stem cells (SCs). This dynamic mini organ is replenished by distinct pools of SCs, which are located in the permanent portion of the HF, a region known as the bulge. These multipotent bulge SCs were initially identified as slow cycling label retaining cells; however, their isolation has been made feasible after identification of specific cell markers, such as CD34 and keratin 15 (K15). Here, we describe a robust method for isolating bulge SCs and epidermal keratinocytes from mouse HFs utilizing fluorescence activated cell-sorting (FACS) technology. Isolated hair follicle SCs (HFSCs) can be utilized in various in vivo grafting models and are a valuable in vitro model for studying the mechanisms that govern multipotency, quiescence and activation.


Subject(s)
Hair Follicle/cytology , Keratinocytes/cytology , Stem Cells/cytology , Animals , Epidermal Cells , Mice , Multipotent Stem Cells
14.
Dev Cell ; 37(1): 1-2, 2016 Apr 04.
Article in English | MEDLINE | ID: mdl-27046823

ABSTRACT

In this issue of Developmental Cell, Aram et al. (2016) identify a mechanism that uses a Krebs cycle protein to control local activation of a ubiquitin ligase complex at the mitochondrial outer membrane for temporally and spatially restricted caspase activation during Drosophila sperm differentiation.


Subject(s)
Caspases/metabolism , Citric Acid Cycle/physiology , Cullin Proteins/metabolism , Drosophila Proteins/metabolism , Drosophila/metabolism , Mitochondria/metabolism , Spermatids/metabolism , Animals , Male
15.
Int J Mol Sci ; 17(2): 27, 2016 Feb 05.
Article in English | MEDLINE | ID: mdl-26861293

ABSTRACT

Ferritins are protein nanocages that accumulate inside their cavity thousands of oxidized iron atoms bound to oxygen and phosphates. Both characteristic types of eukaryotic ferritin subunits are present in secreted ferritins from insects, but here dimers between Ferritin 1 Heavy Chain Homolog (Fer1HCH) and Ferritin 2 Light Chain Homolog (Fer2LCH) are further stabilized by disulfide-bridge in the 24-subunit complex. We addressed ferritin assembly and iron loading in vivo using novel transgenic strains of Drosophila melanogaster. We concentrated on the intestine, where the ferritin induction process can be controlled experimentally by dietary iron manipulation. We showed that the expression pattern of Fer2LCH-Gal4 lines recapitulated iron-dependent endogenous expression of the ferritin subunits and used these lines to drive expression from UAS-mCherry-Fer2LCH transgenes. We found that the Gal4-mediated induction of mCherry-Fer2LCH subunits was too slow to effectively introduce them into newly formed ferritin complexes. Endogenous Fer2LCH and Fer1HCH assembled and stored excess dietary iron, instead. In contrast, when flies were genetically manipulated to co-express Fer2LCH and mCherry-Fer2LCH simultaneously, both subunits were incorporated with Fer1HCH in iron-loaded ferritin complexes. Our study provides fresh evidence that, in insects, ferritin assembly and iron loading in vivo are tightly regulated.


Subject(s)
Drosophila melanogaster/metabolism , Enterocytes/metabolism , Ferritins/metabolism , Animals , Animals, Genetically Modified , Drosophila melanogaster/genetics , Ferritins/chemistry , Ferritins/genetics , Gastrointestinal Tract/metabolism , Gene Expression , Genes, Reporter , Genotype , Iron/metabolism , Larva , Models, Biological , Protein Subunits/genetics , Protein Subunits/metabolism , Protein Transport , Recombinant Fusion Proteins
16.
Development ; 142(19): 3253-62, 2015 Oct 01.
Article in English | MEDLINE | ID: mdl-26443630

ABSTRACT

Apoptosis, in contrast to other forms of cell death such as necrosis, was originally regarded as a 'silent' mechanism of cell elimination designed to degrade the contents of doomed cells. However, during the past decade it has become clear that apoptotic cells can produce diverse signals that have a profound impact on neighboring cells and tissues. For example, apoptotic cells can release factors that influence the proliferation and survival of adjacent tissues. Apoptosis can also affect tissue movement and morphogenesis by modifying tissue tension in surrounding cells. As we review here, these findings reveal unexpected roles for apoptosis in tissue remodeling during development, as well as in regeneration and cancer.


Subject(s)
Apoptosis/physiology , Growth and Development/physiology , Morphogenesis/physiology , Neoplasms/physiopathology , Regeneration/physiology , Signal Transduction/physiology , Animals , Autophagy/physiology , Humans , Necrosis/physiopathology
18.
J Cell Mol Med ; 19(9): 2181-92, 2015 Sep.
Article in English | MEDLINE | ID: mdl-26033448

ABSTRACT

Here, we report a novel mechanism of proteasome inhibition mediated by Thiostrepton (Thsp), which interacts covalently with Rpt subunits of the 19S proteasome and proteasome substrates. We identified Thsp in a cell-based high-throughput screen using a fluorescent reporter sensitive to degradation by the ubiquitin-proteasome pathway. Thiostrepton behaves as a proteasome inhibitor in several paradigms, including cell-based reporters, detection of global ubiquitination status, and proteasome-mediated labile protein degradation. In vitro, Thsp does not block the chymotrypsin activity of the 26S proteasome. In a cell-based IκBα degradation assay, Thsp is a slow inhibitor and 4 hrs of treatment achieves the same effects as MG-132 at 30 min. We show that Thsp forms covalent adducts with proteins in human cells and demonstrate their nature by mass spectrometry. Furthermore, the ability of Thsp to interact covalently with the cysteine residues is essential for its proteasome inhibitory function. We further show that a Thsp modified peptide cannot be degraded by proteasomes in vitro. Importantly, we demonstrate that Thsp binds covalently to Rpt subunits of the 19S regulatory particle and forms bridges with a proteasome substrate. Taken together, our results uncover an important role of Thsp in 19S proteasome inhibition.


Subject(s)
Proteasome Endopeptidase Complex/metabolism , Protein Subunits/metabolism , Thiostrepton/pharmacology , Genes, Reporter , HEK293 Cells , Humans , Models, Molecular , Proteasome Inhibitors/pharmacology , Protein Binding/drug effects , Protein Stability/drug effects , Proteolysis/drug effects , Substrate Specificity/drug effects
19.
Nat Rev Mol Cell Biol ; 16(6): 329-44, 2015 Jun.
Article in English | MEDLINE | ID: mdl-25991373

ABSTRACT

All life ends in death, but perhaps one of life's grander ironies is that it also depends on death. Cell-intrinsic suicide pathways, termed programmed cell death (PCD), are crucial for animal development, tissue homeostasis and pathogenesis. Originally, PCD was almost synonymous with apoptosis; recently, however, alternative mechanisms of PCD have been reported. Here, we provide an overview of several distinct PCD mechanisms, namely apoptosis, autophagy and necroptosis. In addition, we discuss the complex signals that emanate from dying cells, which can either trigger regeneration or instruct additional killing. Further advances in understanding the physiological roles of the various mechanisms of cell death and their associated signals will be important to selectively manipulate PCD for therapeutic purposes.


Subject(s)
Apoptosis/physiology , Autophagy/physiology , Signal Transduction/physiology , Animals , Humans
20.
BMC Genomics ; 16: 338, 2015 Apr 23.
Article in English | MEDLINE | ID: mdl-25903460

ABSTRACT

BACKGROUND: Dystonia1 (DYT1) dystonia is caused by a glutamic acid deletion (ΔE) mutation in the gene encoding Torsin A in humans (HTorA). To investigate the unknown molecular and cellular mechanisms underlying DYT1 dystonia, we performed an unbiased proteomic analysis. RESULTS: We found that the amount of proteins and transcripts of an Endoplasmic reticulum (ER) resident chaperone Heat shock protein cognate 3 (HSC3) and a mitochondria chaperone Heat Shock Protein 22 (HSP22) were significantly increased in the HTorA(ΔE)- expressing brains compared to the normal HTorA (HTorA(WT)) expressing brains. The physiological consequences included an increased susceptibility to oxidative and ER stress compared to normal HTorA(WT) flies. The alteration of transcripts of Inositol-requiring enzyme-1 (IRE1)-dependent spliced X box binding protein 1(Xbp1), several ER chaperones, a nucleotide exchange factor, Autophagy related protein 8b (ATG8b) and components of the ER associated degradation (ERAD) pathway and increased expression of the Xbp1-enhanced Green Fluorescence Protein (eGFP) in HTorA(ΔE) brains strongly indicated the activation of the unfolded protein response (UPR). In addition, perturbed expression of the UPR sensors and inducers in the HTorA(ΔE) Drosophila brains resulted in a significantly reduced life span of the flies. Furthermore, the types and quantities of proteins present in the anti-HSC3 positive microsomes in the HTorA(ΔE) brains were different from those of the HTorA(WT) brains. CONCLUSION: Taken together, these data show that HTorA(ΔE) in Drosophila brains may activate the UPR and increase the expression of HSP22 to compensate for the toxic effects caused by HTorA(ΔE) in the brains.


Subject(s)
Drosophila/genetics , Drosophila/metabolism , Molecular Chaperones/metabolism , Oxidative Stress , Unfolded Protein Response , Activating Transcription Factor 4/genetics , Activating Transcription Factor 4/metabolism , Activating Transcription Factor 6/genetics , Activating Transcription Factor 6/metabolism , Androstadienes/pharmacology , Animals , Brain/metabolism , Calreticulin/genetics , Calreticulin/metabolism , Chromones/pharmacology , DNA-Binding Proteins/genetics , DNA-Binding Proteins/metabolism , Down-Regulation/drug effects , Drosophila Proteins/genetics , Drosophila Proteins/metabolism , Electrophoresis, Gel, Two-Dimensional , Endoplasmic Reticulum Stress/drug effects , Glycoproteins/genetics , Glycoproteins/metabolism , HSP70 Heat-Shock Proteins/genetics , HSP70 Heat-Shock Proteins/metabolism , Heat-Shock Proteins/genetics , Heat-Shock Proteins/metabolism , Humans , Molecular Chaperones/genetics , Morpholines/pharmacology , Oxidative Stress/genetics , Tandem Mass Spectrometry , Unfolded Protein Response/drug effects , Wortmannin
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