Williams Syndrome

Natalie DeCheck

Image from: http://mindbodyshift.wordpress.com/2010/05/18/an-unquenchable-thirst-for-love-the-paradox-of-living-with-williams-syndrome/

What is Williams Syndrome?

Physical characteristics:•“elfin” facial features•narrowing of aorta or pulmonary arteries•musculoskeletal problems•sensitive hearing•short stature and slow weight gain

Behavioral characteristics:

•exceptional music and linguistic abilities•poor numerical abilities•lack of visuospatial abilities •lack of social inhibition•mental retardation•general anxiety

What is Williams Syndrome?

Image from : Bellugi, U.,Wang, P. P., & Jernigan, T. L. (1994).Williams syndrome: An unusual neuropsychological profile. In S. H. Broman & J. Grafman (Eds.), A typical cognitive deficits in developmentaldisorders: Implications for brain function (pp. 23–56). Hillsdale, NJ: Lawrence Erlbaum.

What causes Williams Syndrome?

Image from: Francke U. Williams-Beuren syndrome: genes and mechanisms. Hum Mol Genet. 1999;8:1947–1954.

LIMK1 affects visuospatial cognition

http://neuralmodel.net/library/brain/parietal_cortex.htm

... But how?

Biological ProcessesRho protein signal transduction, actin cytoskeleton organization, axon guidance, negative regulation of ubiquitin protein ligase activity, positive regulation of actin filament bundle assembly, positive regulation of axon extension

Cellular componentcytosol, neuron projection, nucleus

Molecular FunctionATP binding, heat shock protein binding, protein serine/threonine

kinase activity, zinc ion binding

How does the actin cytoskeleton affect nervous

system development?neuron pathfinding!

http://www3.utsouthwestern.edu/psychlab/cowan/

LIMK1 regulates actin cytoskeleton organization in

hippocampus

WT KO LIMK1 Meng, Y., Zhang, Y., Tregoubov, V., Janus, C., Cruz, L., Jackson, M., Lu, W.Y., MacDonald, J.F., Wang, J.Y., Falls, D.L., and Jia, Z. (2002). Neuron 35, this issue, 121–133.

How does LIMK1 interact with other

proteins?

Image from: String Interaction Network 9.0

Proteins expressed in human brain tissue

Image from: String Interaction Network 9.0

LIMK1 - binding domains

Binding domains of interacting proteins

SSH1

CLF1

PAK1

Rac1

PAK4

Images from PFAM

Main hypothesis: Deletion of LIMK1 alters actin cytoskeleton organization of parietal neurons.

Experiment 1: Establish where

LIMK1 and interacting proteins localize in parietal

neurons

Experiment 2: Establish the role of

cofilin in actin cytoskeleton

organization in parietal neurons

Model Organism

http://adasperdown.blogspot.com/2012/02/mouse-remorse.html

Generated using TCoffee

Homologs of LIMK1

Protein interaction in humans

Image from: String Interaction Network 9.0

Protein interactions in mus musculus

Image from: String Interaction Network 9.0

Experiment 1Question: How does LIMK1 and its interacting proteins localize in parietal neurons?

Method:

Immunofluorescence - GFP (determine localization)

2. In LIMK1 WT and KO mice:

1. RNAi to knockout LIMK1 (WS phenotype)

Microarray (determine expression)

http://anthropology.net/2008/02/29/differences-of-gene-expression-between-human-populations/microarray/

http://www.wadsworth.org/cores/alm/gallery.htm

Cofilin - LIMK1 interaction

http://www.ncbi.nlm.nih.gov/pubmed/16230460

Activates

Inactivates1. 2.XLIMK1

CFL1

inhibition of neurite transport and synaptic loss in many cognitive disorders

Previous studies have shown decreased spine area and length of postsynaptic density in hippocampus when LIMK1 is deleted (via effect on actin filament

dynamics through hyperactivation of cofilin)

Samiere PD, Bamburg JR. Head, neck, and spines: a role for LIMK-1 in the hippocampus. Neuron. 2002;35:3-5/

Experiment 2 Question: What is the role of cofilin in actin cytoskeleton organization in parietal neurons?Method:

1. RNAi (generate KO LIMK1 mice)

Microarray (determine expression)

Immunohistochemistry- (determine

phosphorylation (inactivation) of cofilin)

Immunofluorescence - GFP (determine localization)

2. In LIMK1 WT and KO:

http://www.sciencedirect.com/science/article/pii/S0169328X0200445X

http://www.jbc.org/content/282/32/23491/F5.expansion.html

Future research

Can LIMK1 be linked to anxiety in WS patients?

Chemical screen - regulate cofilin activation

http://www.kcl.ac.uk/depsta/biomedical/randall/methods/im-fluo.html

SourcesGungabissoon, R.A., and Bamburg, J.R. (2003). Regulation of growth cone actin dynamics by ADF/Cofilin. J. Histochem. Cytochem. 51, 411–420.

Meng Y, Takahashi H, Meng J, Zhang Y, Lu G, Asrar S, Nakamura T, Jia Z. Regulation of ADF/cofilin phosphorylation and synaptic function by LIM-kinase. Neuropharmacology. 2004;47:746–754.

Samiere PD, Bamburg JR. Head, neck, and spines: a role for LIMK-1 in the hippocampus. Neuron. 2002;35:3-5/

Meng Y, Zhang Y, Tregoubov V, Janus C, Cruz L, Jackson M, Lu WY, MacDonald JF, Wang JY, Falls DL, and Jia Z. Abnormal spine morphology and enhanced LTP in LIMK-1 knockout mice. Neuron 35: 121–133, 2002.

http://www.braincenteramerica.com/visuospa.php

http://www.pdb.org/pdb/explore/explore.do?structureId=3S95

Questions?

http://www.wadsworth.org/cores/alm/gallery.htm