Abstract
The driving forces for the regulation of cell morphology are the Rho family GTPases that coordinate the assembly of the actin cytoskeleton. This dynamic feature is a result of tight coupling between the cytoskeleton and signal transduction and is facilitated by actin-binding proteins (ABPs). Mutations in the actin bundling and PDZ domain-containing protein harmonin are the causes of Usher syndrome type 1C (USH1C), a syndrome of congenital deafness and progressive blindness, as well as certain forms of non-syndromic deafness. Here, we have used the yeast two-hybrid assay to isolate molecular partners of harmonin and identified DOCK4, an unconventional guanine exchange factor for the Rho family of guanosine triphosphatases (Rho GEF GTPases), as a protein interacting with harmonin. Detailed molecular analysis revealed that a novel DOCK4 isoform (DOCK4-Ex49) is expressed in the brain, eye and inner ear tissues. We have further provided evidence that the DOCK4-Ex49 binds to nucleotide free Rac as effectively as DOCK2 and DOCK4 and it is a potent Rac activator. By immunostaining using a peptide antibody specific to DOCK4-Ex49, we showed its localization in the inner ear within the hair bundles along the stereocilia (SC). Together, our data indicate a possible Rac-DOCK4-ABP harmonin-activated signaling pathway in regulating actin cytoskeleton organization in stereocilia.
| Original language | English |
|---|---|
| Pages (from-to) | 755-764 |
| Number of pages | 10 |
| Journal | Journal of Molecular Biology |
| Volume | 357 |
| Issue number | 3 |
| DOIs | |
| State | Published - Mar 31 2006 |
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Keywords
- Actin bundling protein
- DOCK4
- GTPase regulator
- Harmonin
ASJC Scopus subject areas
- Virology
Cite this
An isoform of GTPase regulator DOCK4 localizes to the stereocilia in the inner ear and binds to harmonin (USH1C). / Yan, Denise; Li, F.; Hall, M. L.; Sage, C.; Hu, W. H.; Giallourakis, Cosmas; Upadhyay, G.; Ouyang, X. M.; Du, L. L.; Bethea, John R.; Chen, Z. Y.; Yajnik, V.; Liu, Xue Z.
In: Journal of Molecular Biology, Vol. 357, No. 3, 31.03.2006, p. 755-764.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - An isoform of GTPase regulator DOCK4 localizes to the stereocilia in the inner ear and binds to harmonin (USH1C)
AU - Yan, Denise
AU - Li, F.
AU - Hall, M. L.
AU - Sage, C.
AU - Hu, W. H.
AU - Giallourakis, Cosmas
AU - Upadhyay, G.
AU - Ouyang, X. M.
AU - Du, L. L.
AU - Bethea, John R.
AU - Chen, Z. Y.
AU - Yajnik, V.
AU - Liu, Xue Z
PY - 2006/3/31
Y1 - 2006/3/31
N2 - The driving forces for the regulation of cell morphology are the Rho family GTPases that coordinate the assembly of the actin cytoskeleton. This dynamic feature is a result of tight coupling between the cytoskeleton and signal transduction and is facilitated by actin-binding proteins (ABPs). Mutations in the actin bundling and PDZ domain-containing protein harmonin are the causes of Usher syndrome type 1C (USH1C), a syndrome of congenital deafness and progressive blindness, as well as certain forms of non-syndromic deafness. Here, we have used the yeast two-hybrid assay to isolate molecular partners of harmonin and identified DOCK4, an unconventional guanine exchange factor for the Rho family of guanosine triphosphatases (Rho GEF GTPases), as a protein interacting with harmonin. Detailed molecular analysis revealed that a novel DOCK4 isoform (DOCK4-Ex49) is expressed in the brain, eye and inner ear tissues. We have further provided evidence that the DOCK4-Ex49 binds to nucleotide free Rac as effectively as DOCK2 and DOCK4 and it is a potent Rac activator. By immunostaining using a peptide antibody specific to DOCK4-Ex49, we showed its localization in the inner ear within the hair bundles along the stereocilia (SC). Together, our data indicate a possible Rac-DOCK4-ABP harmonin-activated signaling pathway in regulating actin cytoskeleton organization in stereocilia.
AB - The driving forces for the regulation of cell morphology are the Rho family GTPases that coordinate the assembly of the actin cytoskeleton. This dynamic feature is a result of tight coupling between the cytoskeleton and signal transduction and is facilitated by actin-binding proteins (ABPs). Mutations in the actin bundling and PDZ domain-containing protein harmonin are the causes of Usher syndrome type 1C (USH1C), a syndrome of congenital deafness and progressive blindness, as well as certain forms of non-syndromic deafness. Here, we have used the yeast two-hybrid assay to isolate molecular partners of harmonin and identified DOCK4, an unconventional guanine exchange factor for the Rho family of guanosine triphosphatases (Rho GEF GTPases), as a protein interacting with harmonin. Detailed molecular analysis revealed that a novel DOCK4 isoform (DOCK4-Ex49) is expressed in the brain, eye and inner ear tissues. We have further provided evidence that the DOCK4-Ex49 binds to nucleotide free Rac as effectively as DOCK2 and DOCK4 and it is a potent Rac activator. By immunostaining using a peptide antibody specific to DOCK4-Ex49, we showed its localization in the inner ear within the hair bundles along the stereocilia (SC). Together, our data indicate a possible Rac-DOCK4-ABP harmonin-activated signaling pathway in regulating actin cytoskeleton organization in stereocilia.
KW - Actin bundling protein
KW - DOCK4
KW - GTPase regulator
KW - Harmonin
UR - http://www.scopus.com/inward/record.url?scp=33644963622&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33644963622&partnerID=8YFLogxK
U2 - 10.1016/j.jmb.2006.01.017
DO - 10.1016/j.jmb.2006.01.017
M3 - Article
C2 - 16464467
AN - SCOPUS:33644963622
VL - 357
SP - 755
EP - 764
JO - Journal of Molecular Biology
JF - Journal of Molecular Biology
SN - 0022-2836
IS - 3
ER -