Protein misfolding diseases (Alzheimer’s)

1. In the name of God Protein misfolding diseases(Alzheimer’s) Introduction ZeinabMokhtari Protein misfolding diseases Alzheimer’s disease Preventing amyloid aggregate formation References Monday, July-5-2010

2. Protein folding Protein folding refers to the process by which a protein assumes its characteristic structure, known as the native state. The most fundamental question of how an aminoacid sequence specifies both a native structure and the pathwayto attain that state has defined the protein folding field.

3. Protein folding Fig. 1. Growth of the Protein Folding Field. The average number of publications per year in protein folding field and the average number of publications per year that are dedicated to application two predominant phases the first phase Understanding the mechanisms of protein folding and uncovering the fundamental principles that govern the folding transition the second phase What are the mechanisms of protein folding in a context, such as under the influence of other biological molecules in the cellular environment?

4. Protein folding Studying protein folding • Anfinsen • showing that proteins can fold spontaneously • in vitro studies • a milliseconds-to-seconds time scale • Levinthal • a random conformation search does not occur in folding • proteins fold by specific ‘folding pathways’ • well-defined partially-structured intermediate states A small number of residues (folding nucleus) need to form their native contacts in order for the folding reaction to proceed fast into the native state. nucleation theory

5. Protein folding Studying protein folding Experimental methods Protein engineering, nuclear magnetic resonance (NMR), mass spectrometry, hydrogen exchange, fluorescence resonance energy transfer (FRET), and atomic force microscopy (AFM) Computational methods • The Fold-Rate server • (http://psfs.cbrc.jp/fold-rate/) • The Parasol folding server • (http://parasol.tamu.edu/groups/amatogroup/foldingserver) • … The close interplay of computational and experimental efforts has advanced our knowledge of protein folding kinetics, including predicting the protein folding rate, identifying the kinetically-important residues, and characterizing the multiple pathways.

6. Protein folding Two major differences between protein folding in vivo and in vitro : protein folding in vivo is usually assisted by molecular machinery, such as chaperones (in an ATP-dependent manner), and often involves small molecule cofactors. the concentrations of macromolecular solutes in cells can reach hundreds of grams per liter , but most in vitro studies are performed in buffered solution with <1% of the cellular macromolecule concentration.

7. Unfolded, many conformations Native State, one conformation Protein folding The thermodynamic stability of a protein is measured by the free-energy difference between the folded state and the unfolded state: ∆G = Gunfold-Gfold Experimentally, ∆G values can be obtained from denaturing experiments where the protein unfolds by increasing temperature or by adding denaturing agents such as urea and guanidiniumHCl (GdHCl).

8. Protein folding While all the information needed for proteins to fold is encoded in their amino-acid sequence, there are many more elements that play a part in vivo. In a crowded cellular environment, surrounded by interacting proteins, nascent polypeptides face a formidable challenge in finding the correct interactions that result in a folded and functional protein.

9. Protein folding Molecular chaperones, recognize misfolded proteins and provide an environment conducive to the formation of the appropriate native contacts.

10. Protein misfolding diseases(Alzheimer’s) Introduction Protein misfolding diseases Alzheimer’s disease Preventing amyloid aggregate formation References

11. Protein misfolding Many diseases are now associated with protein aggregation and particularly with a form of ordered aggregate called the amyloidfibrils.

12. Protein folding diseases: • excessive quantities of wrongly folded proteins collect in the form of uncontrolled piles of molecular rubbish (amyloidoses). • a small error in the genetic blueprint leads to incomplete folding of a protein, which affects its function. • (P53 : the malfunctioning of central tumour suppressor could cause cancer. )

13. Disease Pick’s Alzheimer’s Parkinson’s Prion disease (e.g. Mad Cow) Amyloid Lateral Sclerosis ( Lou Gehrig’s) Huntington’s Disease Protein tau APP alpha synuclein prion protein TDP-43 Huntingtin Protein misfolding Protein misfolding diseases amyloidoses

14. Protein misfolding diseases(Alzheimer’s) Introduction ZeinabMokhtari Protein misfolding diseases Alzheimer’s disease Preventing amyloid aggregate formation References Monday, July-5-2010

15. Alzheimer Alois Alzheimer and family,1910 Auguste D

16. Alzheimer

17. Alzheimer • Alzheimer’s is a progressive disease. • Age is the biggest risk factor. • We don’t know what causes it. • We can temporarily slow it’s progression. • We can’t cure it. • Caregivers and support groups are very important. • There is always hope for the future. No one knows what causes AD to begin, but we do know a lot about what happens in the brain once AD takes hold. Normal AD

18. Alzheimer 1. Recent memory loss affecting job 2. Difficulty performing familiar tasks 3. Problems with language 4. Disorientation to time or place 5. Poor or decreased judgment 6. Problems with abstract thinking 7. Misplacing things 8. Changes in mood or behavior 9. Changes in personality 10. Loss of initiative Alzheimer’s disease is an irreversible, progressive brain disease that slowly destroys memory and thinking skills.

19. Protein misfolding diseases(Alzheimer’s) Introduction ZeinabMokhtari Protein misfolding diseases Alzheimer’s disease Preventing amyloid aggregate formation References Monday, July-5-2010

20. Alzheimer The aggregation of β-amyloid (Aβ) peptide → Alzheimer’s disease (AD) Aβ-42 peptide is the key target in the finding of inhibitors of AD-related amyloid formation. low molecular weight drugs Aβ-42 monomer–monomer interactions preventing amyloid aggregate formation High temperature, low pH, and salt conditions

21. Alzheimer the effect of α-D-mannosylglycerate (MG) and its structural analogs on the inhibition of Alzheimer’s Aβ aggregate formation and neurotoxicity • Thermal stress • Freezing • Thawing • Drying MG MG strongly inhibits amyloid formation of Aβ-42 and its neurotoxicity in vitro.

22. Alzheimer amyloid aggregates → new emission maximum ThT-induced fluorescence assay and AFM image analysis no inhibition effect • inhibition effect

23. Alzheimer AFM images of Aβ42 (25 mM) samples incubated with control, α-D-mannosylglycerate, α-D-mannosylglyceramide, mannose, glycerol and methylmannoside at 100 mM concentration. • inhibition effect

24. Alzheimer • carboxyl group

25. Alzheimer Sequence (Three-Letter Code) H - Asp - Ala - Glu - Phe - Arg - His - Asp - Ser - Gly - Tyr - Glu - Val - His - His - Gln - Lys - Leu - Val - Phe - Phe - Ala - Glu - Asp - Val - Gly - Ser - Asn - Lys - Gly - Ala - Ile - Ile - Gly - Leu - Met - Val - Gly - Gly - Val - Val - Ile - Ala - Thr - Val - Ile - Val - Ile - OH Sequence (One-Letter Code) DAEFRHDSGYEVHHQKLVFFAEDVGSNKGAIIGLMVGGVVIATVIVI • hydrophobic interactions between highly apolar residues covering the ‘‘hot spots’’ responsible for Ab fibrillation penta peptides such as KLVFF • electrostatic interactions between residues

26. Some References Nanomedicine: Nanotechnology, Biology, and Medicine 1 (2005) 300– 305 Journal of Molecular Biology (2006) 362, 347–354 Archives of Biochemistry and Biophysics 469 (2008) 4–19 peptides 29 (2008) 578 –584 Biochimica et BiophysicaActa 1764 (2006) 443–451

27. Everything is okay in the end. If it's not okay, then it's not the end.