Role of the ubiquitin-like modifier FAT10 in protein degradation and ...

More documents

Recommendations

Info

Introduction The 26S proteasome plays a pivotal role in many cellular processes and its sub- strates come from a variety of sources and are targeted for a number of different reasons. These reasons can be grouped into two categories: recycling and regula- tion. The former is perhaps the more obvious: proteins which are defective or no longer needed are disassembled into single amino acids which can then be used for neosynthesis. The latter utilizes degradation as a fast, efficient and irreversible means to the inactivation of regulatory proteins such as cell-cycle regulators or components of signaling cascades. Of course, these two functions are not entirely unrelated, as even those proteins which are primarily targeted for degradation to ensure their inactivation are ultimately reduced to their building blocks and subsequently recycled. Conversely, even peptides derived from defective proteins which were targeted in the course of waste disposal might end up being presented on MHC class I molecules (Yewdell et al., 1996; Schubert et al., 2000). One prominent example for the regulatory function of the proteasome is the targeted distruction of cyclins and Cdk inhibitors – which, through their periodic degradation and neosynthesis, ultimately drive the cell-cycle (Nigg, 1995; Obaya and Sedivy, 2002). Another is that of the tumor suppressor p53, which, when stabilized by stress stimuli such as DNA-damage, is responsible for the transcrip- tional activation of a broad array of proteins involved in cell-cycle control, apoptosis and senescence (Lavin and Gueven, 2006). A third example is that of the enzyme ornithine-decarboxylase (ODC), which catalyzes the first and rate-limiting step in the synthesis of cellular polyamines. Interestingly, ODC also doubles as the most prominent example of ubiquitin-independent proteasomal degradation (Kahana et al., 2005). The non-functional proteins which are targeted for proteasomal degradation as a means of waste-disposal originate from several sources: Aging, previously fully functional proteins can become become damaged, primarily through oxidation, over the course of their lifetime (Grune et al., 1997). Alternatively, proteins can be targeted to the proteasome right after synthesis due to failure to pass the stringent cellular quality control mechanisms. As many as 30% of all newly synthesized proteins are ubiquitylated and degraded by the proteasome. Most of these proteins, which are called defective ribosomal products (DRiPs), result from errors in the process of protein synthesis, such as misincorporation of amino acids, premature termination or deletion of residues. Post-translational mistakes which can occur during folding, oligomer assembly or intracellular sorting can also lead to the generation of DRiPs. Importantly, even though they are targeted for degradation through the action of quality control mechanisms, DRiPs 13
Introduction are the major source of antigenic peptides for MHC class I restricted presentation (Yewdell et al., 1996, 2001). Ubiquitin and Ubiquitin-Like Proteins Ubiquitin Ubiquitin is a small, highly conserved protein of 76 amino acids and of compact, globular structure. It exerts its function mainly through covalent attachment to other proteins and is coded for by a number of different genes, which are scattered throughout the genome. In all cases, ubiquitin is expressed as a proprotein with a C-terminal extension and needs to be proteolytically processed before yielding functional, monomeric ubiquitin (Jentsch et al., 1991). The conjugation of ubiquitin to its target proteins, which is termed ubiquitination, ubiquitinylation or ubiquitylation, is dependent on the presence of two consecutive glycine residues at its very C-terminus and requires the sequential action of three enzymes. In a first step, the C-terminal glycine residue of ubiquitin is activated in an ATP-dependent step by a specific ubiquitin activating enzyme, or E1. This step consists of an in- termediate formation of ubiquitin adenylate, with the release of pyrophosphate (PPi), followed by the binding of ubiquitin to a cysteine residue of the E1 enzyme in a thiolester linkage, with the release of AMP. In a second step, ubiquitin is transferred to the active site cysteine residue of a ubiquitin-conjugation enzyme, or E2. The third enzyme in this cascade, the ubiquitin-protein ligase, or E3, catalyzes the isopeptide linkage of the ubiquitin C-terminus to an ε-amino group in of one of the substrate protein’s lysine residues (Hershko and Ciechanover, 1998 and Fig. 2). In most cases, modification of the substrate protein is not limited to the attachment of a single ubiquitin moiety. Instead, the newly attached ubiquitin now serves as the acceptor for a new round of ubiquitylation, which eventually results in the formation of ubiquitin chains. In some cases, the action of an additional enzyme – a multiubiquitin-chain assembly factor, termed E4 – is required for extension of the polyubiquitin chain (Hoppe, 2005). Ubiquitin possesses seven lysine residues, all of which are potentially involved in chain formation. However, only linkages through K48, K63 and sometimes also K29 are readily observed in nature (Haglund and Dikic, 2005). Ubiquitin was first identified as the tag which targets proteins for ATP-dependent degradation (Ciechanover et al., 1978), which 14
Page 1 and 2: Role of the ubiquitin-like modifier
Page 3 and 4: Acknowledgements . . . . . . . . .
Page 5 and 6: Summary / Zusammenfassung English F
Page 7 and 8: Summary In conclusion, these result
Page 9 and 10: Summary nicht von der katalytischen
Page 11 and 12: The Ubiquitin-Proteasome-System The
Page 13: Introduction Figure 1: The 26S prot
Page 17 and 18: Introduction majority of ubiquitin-
Page 19 and 20: Introduction example contained in t
Page 21 and 22: Introduction two modifiers apart fr
Page 23 and 24: Introduction Figure 4: Comparison o
Page 25 and 26: Introduction dependent apoptosis in
Page 27 and 28: Introduction Interestingly, a recen
Page 29 and 30: The Autophagy-Lysosome System Intro
Page 31 and 32: Introduction Figure 5: Molecular ma
Page 33 and 34: Introduction The transport of misfo
Page 35 and 36: Introduction where the proteasome i
Page 37 and 38: Chapter 1 The UBA domains of NUB1L
Page 39 and 40: Introduction Chapter 1 Ubiquitin, a
Page 41 and 42: Chapter 1 no correlation between th
Page 43 and 44: Chapter 1 covered proteins were sep
Page 45 and 46: Chapter 1 Figure 8: Accelerated deg
Page 47 and 48: Chapter 1 Treatment with IFN-γ and
Page 49 and 50: Chapter 1 ing SUMO-1-GFP or the C-t
Page 51 and 52: Chapter 1 Figure 12: Accelerated de
Page 53 and 54: Chapter 1 Figure 13: Co-immunopreci
Page 55 and 56: Chapter 1 domains of NUB1L is requi
Page 57 and 58: Chapter 1 Rad23 (Verma et al., 2004
Page 59 and 60: Chapter 1 FAT10-GFP expressing vect
Page 61 and 62: Chapter 2 Degradation of FAT10 by t
Page 63 and 64: Introduction Chapter 2 The proteaso
Page 65 and 66:
Chapter 2 From our previous data it
Page 67 and 68:
Chapter 2 Figure 14: Purified compo
Page 69 and 70:
Chapter 2 evaluation of the NUB1L b
Page 71 and 72:
Chapter 2 teins which contain intri
Page 73 and 74:
Chapter 2 Combined with our studies
Page 75 and 76:
Chapter 2 Recombinant expression of
Page 77 and 78:
Chapter 2 et al., 2003), both at a
Page 79 and 80:
Abstract Chapter 3 During misfolded
Page 81 and 82:
Chapter 3 tion between the UPS and
Page 83 and 84:
Chapter 3 Figure 18: HDAC6 interact
Page 85 and 86:
Chapter 3 Figure 19: Both the BUZ d
Page 87 and 88:
Chapter 3 of HDAC6 was required for
Page 89 and 90:
Chapter 3 precipitates with HDAC6 (
Page 91 and 92:
90 Chapter 3
Page 93 and 94:
Chapter 3 Figure 23: The model conj
Page 95 and 96:
Chapter 3 HDAC6 is required for the
Page 97 and 98:
Chapter 3 Figure 26: Both ubiquitin
Page 99 and 100:
Chapter 3 also revealed endogenous,
Page 101 and 102:
Chapter 3 and/or its conjugates is
Page 103 and 104:
Chapter 3 (Hipp et al., 2005), pEGF
Page 105 and 106:
Chapter 4 FAT10-deficient mice disp
Page 107 and 108:
Chapter 4 Once the infection is cle
Page 109 and 110:
Chapter 4 As both wild-type as well
Page 111 and 112:
Chapter 4 Peptides. The synthetic p
Page 113 and 114:
Introduction Chapter 5 Antibodies a
Page 115 and 116:
Chapter 5 binant human and mouse GS
Page 117 and 118:
Chapter 5 Figure 34: The antibodies
Page 119 and 120:
Chapter 5 Figure 36: The antibody s
Page 121 and 122:
Discussion 30 years ago, ubiquitin
Page 123 and 124:
Discussion monomeric ubiquitin as w
Page 125 and 126:
Discussion Alternatively, FAT10 cou
Page 127 and 128:
References D. T. Akey, X. Zhu, M. D
Page 129 and 130:
References Y.-H. Chiu, Q. Sun, and
Page 131 and 132:
References S. Gunawardena, L.-S. He
Page 133 and 134:
References J. A. Johnston, M. E. Il
Page 135 and 136:
References F. Lévy, N. Johnsson, T
Page 137 and 138:
References J.-H. Park, H.-S. Jong,
Page 139 and 140:
References P. Schreiner, X. Chen, K
Page 141 and 142:
References S. Vijay-Kumar, C. E. Bu
Page 143 and 144:
Abbreviations aa amino acid AAA ATP
Page 145 and 146:
Amino Acids Alanine Ala A Arginine
show all

Role of the ubiquitin-like modifier FAT10 in protein degradation and ...

Create successful ePaper yourself

Delete template?

Save as template?