Function of Pias Proteins in Steroid Receptor-dependent Signaling

.................................................................................................................... 5 ORIGINAL PUBLICATIONS........................................................................................ 6 ABBREVIATIONS ......................................................................................................... 7 REVIEW OF THE LITERATURE................................................................................ 8 1. PIAS PROTEIN FAMILY................................................................................................ 8 1.1. Discovery of PIAS proteins................................................................................. 8 1.2. Structure of PIAS proteins .................................................................................. 9 1.3. Expression of PIAS proteins ............................................................................. 11 1.4. PIAS proteins in cytokine-signaling pathway .................................................... 12 1.5. Other interaction partners and functions of PIAS proteins ................................. 13 2. STEROID RECEPTOR-MEDIATED SIGNALING ................................................................ 14 2.1. General transcription machinery........................................................................ 15 2.2. Nuclear receptor superfamily ............................................................................ 16 2.3. Mode of steroid receptor action......................................................................... 17 2.3.1. Coactivators............................................................................................... 19 Complexes with histone acetyltransferase activity..............................................................21 Complexes with ATP-dependent chromatin remodeling activity .......................................21 TRAP/DRIP complexes........................................................................................................22 2.3.2. Corepressors.............................................................................................. 22 2.4. Androgen receptor ............................................................................................ 23 3. COVALENT MODIFICATIONS IN NUCLEAR RECEPTOR FUNCTION ................................... 24 3.1. Modification of structural proteins of chromatin................................................ 24 3.2. Modification of transcription factors ................................................................. 25 3.2.1. Ubiquitination and proteasome-mediated degradation ............................... 26 4. SUMO-1 MODIFICATION........................................................................................... 27 4.1. Enzymes involved in SUMO modification pathway .......................................... 28 4.1.1. E1, E2 and E3 activities ............................................................................. 29 4.1.2. SUMO C-terminal hydrolases and isopeptidases ........................................ 30 4.2. SUMO target proteins and possible functions of sumoylation............................ 31 4.2.1. Regulation of protein targeting and protein–protein interactions ............... 32 4.2.2. Sumoylation of transcription factors........................................................... 33 4.2.3. Regulation of protein stability .................................................................... 34 4.3. Future perspectives ........................................................................................... 34 AIMS OF THE STUDY ................................................................................................ 35 METHODS.....................................................................................................................36 THE SEQUENCES OF PIAS PROTEINS USED IN THIS STUDY................................................36 RESULTS AND DISCUSSION .....................................................................................37 1. PIAS PROTEINS FUNCTION AS STEROID RECEPTOR COREGULATORS (I, II) ....................37 2. DOMAINS IMPORTANT FOR COREGULATOR FUNCTION OF PIAS PROTEINS (I, II, III) .....38 3. PIAS PROTEINS ARE MODIFIED BY SUMO-1 (III) .......................................................40 4. PIAS PROTEINS INTERACT WITH SUMO-1-MODIFIED PROTEINS AND COLOCALIZE WITH SUMO-1 IN NUCLEI (III) ...............................................................................................42 5. PIAS PROTEINS MODULATE TRANSCRIPTION FACTORS BY FUNCTIONING AS SUMO-1 E3 LIGASES (III, IV)...........................................................................................................44 6. SUMO-1 MODIFICATIONS REGULATE THE FUNCTION OF GRIP1 (III, IV) ....................46 7. PIAS PROTEINS COOPERATE WITH GRIP1 IN STEROID RECEPTOR-DEPENDENT TRANSCRIPTION (II, IV).................................................................................................49 CONCLUSIONS ............................................................................................................52 ACKNOWLEDGEMENTS ...........................................................................................53 REFERENCES ..............................................................................................................54