1 / 43

A P O P toza

A P O P toza. Broj celija nije regulisan samo kontrolom celijske deobe nego je regulisan i celijskom smrti. Za svaku celiju postoji vreme kada treba da umre. Celije umiru na dva nacina: umiru usled povrede (nekroza) ili

kaye-carrillo
Download Presentation

A P O P toza

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. A P O P toza

  2. Broj celija nije regulisan samo kontrolom celijske deobe • nego je regulisan i celijskom smrti. • Za svaku celiju postoji vreme kada treba da umre. • Celije umiru na dva nacina: • umiru usled povrede (nekroza) ili • ukoliko vise nisu potrebne sprovode program smrti tj izvrse “samoubistvo” = APOPTOZA (programirana celijska smrt). • Nekroza: • mehanicko ostecenje • hemijsko ostecenje • Morfoloske karakteristike nekroze: • celija, kao i njene organele (posebno mitohondrije) “bubre”, zbog nesposobnosti njihove membrane da kontrolise prolaz vode i jona; • sadrzaj celije se izliva i dovodi do • imflamacije okolnog tkiva

  3. “Samoubistvo” celija se morfoloski manifestuje: • celja se “skuplja” zbog cepanja lamina i aktinskih filamenata (A) • degradacijom hromatina – nukleus apoptoticke celije ima izgled potkovice (B) • iz mitohondrija “izlazi” citohrom c • fosfatidilserini, koji su normalno sakriveni u plazma membrani, se okrecu ka spoljasnjoj povrsini membrane – “pojedi me” signali (C) • ovi signali se vezuju za receptore na fagocitima (makrofage ili dendritske celije) - - - fagocitoza • fagociti sekretuju citokine koji inhibisu inflamaciju (npr. IL-10 i TGF-b) • celija se raspada na male membranom okruzene fragmente – apoptoticka tela (D) Apoptoticne celije trofoblasta (u toku 6h)

  4. Zasto celije izvrsavaju samoubistvo? • Programiranacelijskasmrt je neophodnazapravilanrazvojkaoimitoza • Npr: • resorpcijarepakodpunoglavca u tokumetamorfozezabe; • zaformiranjeprstijukodfetusaneophodno je da se uklonitkivoizmedjunjih; • eliminacijaendometrijumauterusanapocetkumenstruacije • u tokurazvoja CNS eliminise se velikibrojneurona • Programiranacelijskasmrt je neophodnazaeliminacijucelijakojesupretnjaintegritetuorganizma • Npr: • CTLpokrecuapoptozu u celijamainficrinamvirusima • eliminacijacelijasaostecenom DNA --- povecanaprodukcijap53 – potentaninduktorapoptoze (celijekanceracestoimajudefektan p53)

  5. Sta “nagovori” celije da se ubiju? Smanjenje signala neophodnih za prezivljavanje primanje negativnih signala Povecan nivo oksidanata u celiji (ultravioletno svetlo x-zraci, hemoterapeutski lekovi) Molekuli koji reaguju sa specificnim receptorima na pov. membrane – signali za apoptozu = signali smrti (TNF-α + TNF receptor; Lymphotoxin (TNF-β ) koji se takodje veze zaTNF receptor; Fas ligand (FasL), molekul koji se veze za Fas receptor (tzv. CD95). Faktori rasta za neurone Interleukin-2 (IL-2), osnovni faktor mitoze za limfocite Bcl-2 proteini anti-apoptoticki vs. proapoptoticki proteini Bcl-2, bcl-XL Bad, Bax, Bid

  6. Apoptoza je posredovana intracelularnom proteolitickom kaskadom CASPASES: Cysteine Aspartate Specific ProteASEs • Generalne karakteristike • visoko specificne proteaze • cepaju proteine iz ostatka aspartata • 3 amino kiseline ispred aspartata odredjuju specificnost prema substratu • funkcija: regulisu proteolizu tokom apoptoticke smrti celije • obicno “sve ili nista” • protezna kaskada je ireverzibilna = kad jednom dostigne kriticnu tacku na putu destrukcije, celija ne moze da se povrati

  7. Sve celije poseduju u sebi “seme” sopstvene destrukcije u obliku neaktivnih prokaspaza, koje cekaju signal za destrukciju celije. 2, 8, 9, 10 3, 6, 7

  8. Kaskada kaspaza ukljucenih u apoptozu Prokaspaze se aktiviraju vezivanjem za adapterne proteine koji povezuju veci broj inicijalnih prokaspaza u kompleks. Inicijalne prokaspaze imaju malu proteaznu aktivnost – agregacija – medjusobna aktivacija. Aktivacija prokaspaza Aktivnakaspaza NH2 Mesto proteolize COOH Aktivnakaspaza prodomen Inaktivna prokaspaza Kaskada kaspaza 1 molekul aktivnekaspaze X Proteoliza citosolnih proteina Mnogomolekulaaktivnekaspaze Y Proteolizanuklearnih Lamina iliproteinekojicuvajuDNAse u neaktivnojformi Jos vise molekulaaktivnekaspaze Z

  9. Degradacija hromatina = je znak apoptoze 1. Inaktivacija enzima DNA obnove 2. Cepanje strukturnih nuklearnih proteina 3. Fragmentacija DNA Caspasa 6 Caspasa 3 Caspasa 3 degradacija lamina PARP (poly ADP-ribose polimerase) enzim obnove DNA CAD + ICAD (Caspase activated DNAse + inhibitor of CAD) CAD ICAD Brza fragmentacija DNA u nukleosomalne jedinice

  10. Mehanizam apoptoze • Spoljasnji put - aktivatori smrti koji se vezu za receptore na povrsini membrane: • TNF-α • Lymphotoxin • Fasligand (FasL) • Signali koji nastaju u celiji - unutrasnji ili mitohondrijalni put

  11. IAP proteins inhibit apoptosis by binding to activated caspases. They inhibit signals generated through both the two major pathways of apoptosis: the Extrinsic (death receptor mediated) and the Intrinsic (mitochondrial mediated) pathways

  12. Spoljasnji put In some cases the apoptotic stimuli comprise extrinsic signals such as the binding of death inducing ligands to cell surface receptors called death receptors. These ligands can either be soluble factors or can be expressed on the surface of cells such as cytotoxic T lymphocytes. Also, when T-cells recognise damaged or virus infected cells and initiate apoptosis in order to prevent damaged cells from becoming neoplastic (cancerous) or virus-infected cells from spreading the infection. Apoptosis can also be induced by cytotoxic T-lymphocytes using the enzyme granzyme.

  13. i. Receptori smrti – prenose apoptoticke signale inicirane ligandima kao sto su FasL, TNF i TRAIL (Tumour necrosis factor-related apoptosis-inducing ligand). Aktiviraju kaspaznu kaskadu u toku 1 sec od vezivanja liganda. Vezivanje za DR: produkcija ceramida na membrani – “lipid raft” – grupisanje velikog broja DR (“clustering”) = vazno za amplifikaciju signalnog puta neophodnog za aktivaciju apoptoze; Konformaciona promena intracelularnog domena R – “death domen” – regrutovanje adapternih i drugih proteina = proteinski kompleks DISC (Death Inducing Signaling Complex) – regrutovanje prokaspaza (obicno prokaspaza 8) i zapocinjanje apoptoze.

  14. Spoljasnji put Signaling preko TNFR1 TNF se produkuje u T limfocitima i aktiviranim makrofagama, kao odgovor na infekciju. Vezivanje za TNFR1 – nekoliko efekata: • Trimerizacija receptora i “clustering” • Vezivanje adapternog molekula TRADD (TNFR-associated death domains) za “death domene” • Regrutacija razlicitih proteina npr- TRAF-2 (TNF-associated factor 2) = aktivacija NFkB i JNK puta • TRADD + FADD = indikcija apoptoze regrutacija – prokaspaze 8 Adapterni molekul aktivacija NFkB i JNK puta Obicno vezivanje liganda za TNFR-1 nije dovoljno da inicira apoptozu (kao npr. vezivanje FasL ) Aktivacija NF-kB i AP-1 – indukcija velikog broja gena

  15. Caspase activated DNAse Spoljasnji put aktivira apoptozu i nema znacajnu ulogu u drugim aspektima signalinga Fas (CD95) signaling • “clustering” receptora • FADD regrutuje direktno za death domen R • (bez prethodne aktivacije TRADD-a) CAD = Caspase activated DNAse ICAD = inhibitor CAD

  16. Spoljasnji put TRAIL (TNF-related apoptosis inducing ligand) signaling Vezivanje za DR4ili DR5 – brza apoptoza u mnogim celijama The death receptors DR4 and/or DR5 can be functionally engaged by recombinant soluble APO2L/TRAIL in its zinc-bound, trimeric form. Antibodies that bind to the extracellular portion of either receptor can also stimulate caspase-mediated apoptosis, with or without a requirement for receptor crosslinking. Nature Reviews Cancer 2, 420-430(June 2002)

  17. Spoljasnji put The Ligand induced trimerisation model. The incoming trimeric ligand recruits three receptors into a complex. This induced juxtaposition of the intracellular domains triggers recruitment of the intracellular signalling components leading to either the caspase cascade and cell death, or activation of NF-B. Cell Research (2004); 14(5):359-372

  18. Again With the Comics Sem DR4/5, TRAIL se vezu i za “decoy” receptore DcR1 I DcR2 (koji kompetituju sa DR4 i DR5 za TRAIL). “decoy” receptori DcR1 - nema citoplazmaticni domen; DcR2 - ima “death domen” kome nedostaje 4 od 6 AA = vaznih za regrutovanje adapternih proteina. Schematic of the five TRAIL Receptors. The extracellular cysteine-rich domains are represented by coloured ovals; yellow, for the first partial CRD1, which has one cystiene bond, and the other full cysteine rich domains in blue. Cell Research (2004); 14(5):359-372

  19. TRAIL receptor signalling. Schematic showing the major signalling pathways initiated following TRAIL ligation of DR4 or DR5. The major pathway is the initiation of apoptosis. However, there is also some NF-kB and c-Jun activation. These transcription factors can have an anti-apoptotic effect via the up-regulation of pro-survival genes, or can amplify the apoptotic signal through transcription of genes that can act via the mitochondria (the intrinsic pathway). Cell Research (2004); 14(5):359-372

  20. unutrasnji ili mitohondrijalni put • Mitohondrije sadrze mnoge pro-apoptoticke proteine: • AIF (Apoptosis Inducing Factor) • Smac/DIABOLO • Citohrom C Koji se oslobadjaju iz mitohondrija nakon formiranja PT pore (Permeability Transition pore), nastalih usled aktivacije pro-apoptotickih proteina iz familije bcl-2. Bcl-2 su aktivirani apoptotickim signalima – stres celije, slobodni radikali, ili nedostatak faktora rasta … Bcl-2 proteini mogu biti aktivirani I angazovanjem kaspaze 8 - amplifikuju apoptoticke signale od death receptora.

  21. unutrasnji ili mitohondrijalni put • Bcl-2 proteini – ukljuceni u apoptozu: pro- i anti-apoptoticki proteini. • Prisustvo bcl-2 proteina na povrsini mitoh – formiranje PT pore PUMA p53-upregulated modulator of apoptosis

  22. Pro-apoptoticki bcl-2 proteini (nprBad) – u citosolu – senzoricelijskogstresa • Moguda se translocirajunapovrsinumitoh, gdesulocirani anti-apoptotickiproteini. • Interakcija pro- i anti-apoptotickihproteina = narusavanjenormalne anti- apoptotickefunkcije bcl-2 proteina = formiranje PT poraioslobadjanjecyt C idruhihproteina. • cyt c u citosolureagujesaApaf-1proteinom (adapterniprot) = formiranjemultiproteinskogkompleksatzvapoptozom = angazovanjeprokaspaze 9 u apoptozom ---- apoptoza.

  23. CTL Granzyme B Granzyme B and perforin, proteins released by an effector cell (cytotoxic T cell), can induce apoptosis in target cells by forming transmembrane pores and through cleavage of effector caspases such as caspase-3. In addition, caspase-independent mechanisms of granzyme B-mediated apoptosis have been suggested. Caspase-activated DNAse (CAD) is activated through the cleavage of its associated inhibitor ICAD by caspase-3. CAD is then able to interact with components such as topoisomerase II (Topo II) to condense chromatin, leading to DNA fragmentation and ultimately apoptosis. Ili 7,8 i 10 SIGMA-ALDRICH

  24. p53 (also known as protein 53 or tumor protein 53), is a transcription factor . p53 is important in multicellular organisms, where it regulates the cell cycle and thus functions as a tumor suppressor that is involved in preventing cancer. As such, p53 has been described as "the guardian of the genome," "the guardian angel gene," and the "master watchman," referring to its role in conserving stability by preventing genome mutation

  25. A model for p53-mediated apoptosis A model for p53-mediated apoptosis. This model depicts the involvement of p53 in the extrinsic and intrinsic apoptotic pathways. p53 target genes are shown in red. The convergence of the two pathways through Bid is shown Haupt, S. et al. J Cell Sci 2003;116:4077-4085

  26. Schematic representation of the p53-dependent apoptotic pathways by transcriptional activation of BAX, PUMA and Apaf-1 One important p53 effector is PUMA (p53-upregulated modulator of apoptosis) (Yee and Vousden, 2005). PUMA is a BH3-only member of the Bcl-2 family that is a potent inducer of apoptosis mediated by p53. It initiates the cell-death cascade by modulating Bax activity to facilitate cytochrome c release from the mitochondria.

  27. Role of PUMA and SLUG in Modulating Apoptosis Mediated by p53 Once activated by DNA damage, p53 induces various target genes, including Puma (which encodes a proapoptotic BH3-only protein) and Slug (which encodes a transcription factor that represses Puma transcription). In most cells, the amount of SLUG may not be sufficient to repress Puma and prevent apoptosis. Importantly, in hematopoietic progenitor cells, the endogenous amount of SLUG protein is sufficient to repress Puma and limit apoptosis induced by DNA damage. Also shown is the role of PUMA and p53 in coordinating cell death in the cytoplasm. Here, PUMA binds Bcl-xL and displaces p53, thereby allowing p53 to directly activate Bax and induce permeabilization of mitochondria and cell death Bcl-Xl = anti-apoptoticki bcl-2 protein

  28. Nitric oxide: NO apoptosis or turning it ON? Zavisno od koncentracije NO moze da ispolji anti- i pro-apoptoticki efekat Antiapoptotickiefekat NO: Nitrosilacijaiinaktivacijamnogihkaspasa (3,1,8) Aktivacija p53 – heat shock proteina 70 = blokiranjeregrutovanja pro-kaspase 9 za Apaf-1 iformiranjeapoptosoma “up”-regulacija Bcl-2 I Bcl-XL – inhibicijaoslobadjanjacyt C izmitoh AktiviranjecGMPsignalinga – cGMPzavisnihkinaza = smanjenjeaktivnostikaspazailifosforilacije TAB-a inemogucnostiaktivacije p38 …

  29. Model of GC-induced apoptosis in leukemic cells. Leukemia (2003) 17, 17–25. Glucocorticoids (GC) enter the cell by passive transport, and bind to the glucocorticoid receptor (GR). The unbound GR forms heterocomplexes consisting of heat-shock chaperone molecules hsp90 and 70, co-chaperone molecules hsp40, Hop (p60), p23 and immunophillins FKBp52 and CyP40, required for optimal configuration of the GR to be able to bind GC. As a homodimer the GC–GR complex translocates to the nucleus. There it interacts with either a GRE (consensus sequence (GGT ACA NNNTGT TCT) of a target gene (transactivation), or it interacts with other transcription factors such as AP-1 and NF-B (transrepression). Both processes may finally result in the induction of cell death (apoptosis). NF-B is kept in the cytoplasm in a complex with IB. Upon dissociation it can translocate to the nucleus.

  30. Simplified model of pro- and anti-apoptotic pathways in hen granulosa cells.

  31. Apoptosis Detection Kits DNA Fragmentation Comet Assay™Cells are immobilized on a slide in a bed of low melting point agarose and gently lysed and treated with alkali to unwind and denature the DNA. The samples are electrophoresed, stained, and visualized by fluorescence or light microscopy. Evidence of a "comet tail" shape and migration pattern indicates DNA Damage. DNA Laddering KitsInternucleosomal cleavage of DNA is a hallmark of apoptosis and can be assessed using Gel Electrophoresis with R&D Systems' colorimetric, ethidium bromide, luminescent, and isotope-based kits. Tissue supplement is also available. TUNEL Labeling KitsApoptotic cells can be detected by terminal deoxynucleotidyltransferase (TdT)-mediated dUTP nick end labeling (TUNEL). . It may also label cells that have suffered severe DNA damage.

  32. anti-active caspase 3 antibody Caspase Activity Caspase Colorimetric Activity AssaysCaspase Fluorometric Activity Assays Microplate-based fluorometric and colorimetric assays for measuring Caspase activity in cell lysates. ApoStat (FITC-VD-FMK) ApoStat is designed to identify and quantitate caspase activity in apoptotic cells by flow cytometry. Cells undergoing apoptosis are labeled with a cell permeable, FITC-conjugated pan caspase inhibitor (ApoStat). Any unbound reagent diffuses out of the cell and is washed away. Cells are then analyzed by flow cytometry for the presence of bound reagent. Increased fluorescence is an indicator of caspase activity within individual cells. Phosphatidylserine in the outer leaflet (Annexin V) Annexin V KitsEarly in the apoptotic process, cell surface phospholipid asymmetry is disrupted leading to the exposure of phosphatidylserine (PS) on the outer leaflet of the cell membrane. Annexin V preferentially binds PS and can be used as an early indicator of apoptosis using either colorimetric orfluorescence-based detection.

  33. PARP Activity/Inhibition PARP Universal Colorimetric AssayThis assay allows for the measurment of Polymerase (PARP) activity can be used to determine whether DNA is damaged, or to test for PARP inhibition. Cleavage of PARP inactivates the enzyme and is an indicator of apoptosis.Format: Scintillation counting; [32P]-NAD Mitochondrial Membrane Potential Disruption DePsipher™Disruption of the mitochondrial transmembrane potential is one of the early intracellular events to occur following induction of apoptosis. DePsipher contains a lipophiliccation that can be used as a mitochondrial activity marker in live cells. The kit can be used to evaluate cellular viability, estimate the effect of drugs or other cytotoxic treatments, or detect early apoptosis in known models using fluorescence microscopy or flow cytometry.

  34. Cell Viability and Proliferation MTT Cell Proliferation/Viability AssayCells undergoing apoptosis demonstrate a decrease in their ability to reduce the tetrazolium salt, MTT. This microplate-based assay allows for the safe, sensitive, measurement of cell proliferation and viability. The rate of tetrazolium reduction is proportional to the rate of proliferation. XTT Cell Proliferation/Viability AssayCells undergoing apoptosis demonstrate a decrease in their ability to reduce XTT, a yellow tetrazolium salt. XTT is cleaved to a soluble orange formazan dye which can be measured by absorbance on a microplate reader. This microplate-based assay allows for the safe, sensitive measurement of cell proliferation and viability and is ideal for high throughput platforms. The rate of tetrazolium reduction is proportional to the rate of proliferation.

  35. The PKC (protein kinase C) family of serine/threonine kinases regulates many cellular functions including proliferation and survival PKCα, β, ε and ζ have been identified as isoforms that can suppress apoptosis, while PKCδ is a critical pro-apoptotic signal in many cell types PKCδ is required for execution of the apoptotic programme PKCδ is activated downstream of cellular damage signals and functions as a proximal regulator of apoptosis. Under normal growth conditions, tight regulation of nuclear import and export of PKCδ is required for cell survival.We propose that in the absence of an apoptotic signal, PKCδ is retained in the cytoplasm by a mechanism that is dependent on the regulatory domain. Apoptotic signals such as etoposide induce post-translational modifications in the PKCδ, such as tyrosine phosphorylation of the regulatory domain, which may allow nuclear accumulation of PKCδ. Active caspase 3 also accumulates in the nucleus in response to etoposide, resulting in cleavage of PKCδ and generation of δCF. In contrast with PKCδ, δCF is constitutively present in the nucleus where it presumably regulates apoptosis through phosphorylation of proteins involved in cell damage as well as other apoptotic mediators. Taken together, our studies suggest that tight regulation of nuclear import and export of PKCδ is critical for cell survival and that caspase cleavage of PKCδ in the nucleus signals an irreversible commitment to PKC - Apoptoza

  36. Caspase-3 activation via tumor necrosis factor (TNF) family receptors (for example, Fas), FADD (Fas-activated death domain protein) and caspase-8 represents the extrinsic pathway (blue), whereas caspase-3 activation via the mitochondrial release of cytochrome c and Apaf-1–mediated processing of caspase-9 represents the intrinsic pathway (red)3. For clarity, not all of the players are shown. Procaspase-3 is shown as a PAC-1–sensitive dormant single-chain precursor with an N-terminal prodomain (Pro). During apoptosis, caspase-3 assembles as an active p17-p12 heterotetramer after proteolytic processing between the p17 and p12 subunits (at Asp175) and removal of the prodomain2. PAC-1 is proposed to regulate the Asp-Asp-Asp (DDD) safety catch at amino acids 179–181 in procaspase-3, consequently inducing a conformational change that leads to proteolytic processing into the active p17 and p12 subunits1. Cys163 is the catalytic cysteine in the active site of caspase-3; the sequence shown illustrates its proximity to the DDD safety catch and DDM motif. Although caspase-7 (not shown) is believed to be a downstream caspase, its position relative to caspase-3 in apoptosis pathways is unclear. Nature Chemical Biology 2, 509 - 510 (2006)

More Related