This presentation showcases the molecular pathway of beta catenin protein regulation in Huntington's Disease. This work is a part of my PhD Thesis

1. Beta Catenin Regulation in
“HD”
Supratim Ghatak
Research Associate
Crystallography and Molecular Biology Division
Saha Institute of Nuclear Physics
Kolkata
27.05.2016 (CDFD, Hyderabad)

2. Cell-Cell Adhesion
Beta catenin
Wnt
Receptor
Beta catenin
“Destruction Complex”
Cytosol Nucleus
Wnt target genes
Canonical Wnt Signaling
Proteasome

3. HUNTINGTON’S DISEASE
HTT
Normal: CAG repeat 6- 36 HD: CAG repeat >36
HD BrainNormal Brain
HTT
Involuntary Limb Movement Cognitive Decline

4. Beta
Catenin
Carmichael 2002 Gines 2003 Godin 2010 Reis 2011
(Akt activation) (UPS impairment)
Controversies of Beta Catenin status in HD

5. Striatal Cell Models
(Q7)
Normal
WT Htt
(Q111)
HD
Mutant Htt

6. Endogenous Whole cell beta catenin: Wnt/Beta Catenin signaling activity in the cell:
Nuclear Beta Catenin level:
Target gene expressions:

7. Beta Catenin expression
at transcriptional level:Beta catenin
Ctnnb1 mRNA

8. Degraded
Beta catenin
ProteasomePhospho
Beta catenin
Beta catenin

9. Involvement of Proteasomal
degradation: Proteasomal Inhibition

10. Proteasomal impairment high nuclear/ whole cell beta catenin ratio
Proteasomal impairment effect of Translation inhibition

11. Q111 Cell
Phospho
Beta catenin
Degraded
Beta catenin
Proteasome

12. Beta catenin
Phospho
Beta catenin
Gsk3beta

13. Involvement of Gsk3beta : Gsk3beta Inhibition

14. Status of Gsk3beta:
Status of Akt:

15. Phospho
Beta catenin
Degraded
Beta catenin
Proteasome
Beta catenin
Gsk3beta
Q111 Cell
Not Responsible

16. Reason for low beta catenin in Q111 (HD cell): micro RNA involved?
(M. Sinha et al. BBRC 2010)
Strong evidence
(WB, qRT-PCR, Reporter
assay)

17. Effect of miR-214 on beta catenin protein level:
Effect of miR-214 on Wnt/Beta catenin signaling
and beta catenin responsive target gene
expression:
Effect of miR-214 on beta catenin
mRNA level:

18. Beta catenin
Ctnnb1 mRNA
miR-214
Q111 Cell

19. Effect of HTT:
Q111 cell
Loss of function
Of
Wild type Htt?
Gain of function
Of
Mutant Htt?
or
Beta cateninmiR-214
+

20. Effect of HTT knockdown on beta catenin expression and Wnt/beta catenin signaling:
Effect of HTT knockdown on miR-214 level

21. Beta catenin
Proteasome
Ctnnb1 mRNA
miR-214
Q111 Cell
Mutant HttMutant Htt
Proteasome

22. Impact of Aggregation
Effect of Aggregate prone
83Q-Exon1-mHtt-DsRed

23. Beta catenin
Proteasome
Ctnnb1 mRNA
miR-214
Q111 Cell
Aggregate Independent
Mutant HttMutant Htt
Proteasome

24. Phospho
Beta catenin

25. Regulation of Phospho Beta Catenin:
Sub cellular localization of beta catenin
Proteasome
?

26. Q111 Cell
Membrane
Beta catenin
Gsk3beta
Phospho
Beta catenin
Cytosol

27. Quick RECAP

28. Beta catenin
Ctnnb1 mRNA
miR-214
Q111 Cell
Mutant Htt
Membrane
Beta catenin
Degraded
Beta catenin
ProteasomeGsk3beta
Phospho
Beta catenin
Cytosol

29. Study - Significance
Proteasome
status
In HD?
Low protein
In
Impaired UPS?
mHTT
Functionality?
Protein
Localization
&
Phosphorylation?

30. PAPERS:
1. Supratim Ghatak, Sanghamitra Raha, Micro RNA-214 contributes to proteasome independent
downregulation of beta catenin in Huntington’s disease knock-in striatal cell model
STHdhQ111/Q111, Biochem. Biophys. Res. Commun. 459 (2015) 509-514
2. Mahan Ray, Neha Rai, Kuladip Jana, Supratim Ghatak, Arnab Basu, Soumyajit Banerjee Mustafi,
Sanghamitra Raha, Beta catenin is degraded by both caspase-3 and proteasomal activity during
resveratrol-induced apoptosis in HeLa cells in a GSK3beta independent manner, Indian J. Biochem.
Biophys. 52 (2015) 7-13.
3. Supratim Ghatak, Sanghamitra Raha, Positive effect by multiple positive and negative regulators
on beta catenin abundance and activity in A549 non-small cell lung cancer (NSCLC) cell,
(Communicated)
4. Supratim Ghatak, Sanghamitra Raha, Mutant Huntingtin Status and Subcellular Distribution of
Beta Catenin are the Keys to Beta Catenin Regulation in Huntington’s Disease cell STHdhQ111/Q111,
(Manuscript prepared; to be communicated soon)
5. Supratim Ghatak, Sanghamitra Raha, Dietary Phytochemicals and Histone Modifications in Cancer
(Manuscript under preparation)

31. Acknowledgements
Supervisors- Prof. S. Raha & Prof. N.P. Bhattacharyya
DAE Fundings- MMDDA, MSACR
Cell- M.E. McDonalds