Functional implications of O-GlcNAcylation-dependent phosphorylation at a proximal site on keratin 18

Kakade, Poonam S., Budnar, Srikanth, Kalraiya, Rajiv D. and Vaidya, Milind M. (2016) Functional implications of O-GlcNAcylation-dependent phosphorylation at a proximal site on keratin 18. Journal of Biological Chemistry, 291 23: 12003-12013. doi:10.1074/jbc.M116.728717

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Author Kakade, Poonam S.
Budnar, Srikanth
Kalraiya, Rajiv D.
Vaidya, Milind M.
Title Functional implications of O-GlcNAcylation-dependent phosphorylation at a proximal site on keratin 18
Formatted title
Functional implications of O-GlcNAcylation-dependent phosphorylation at a proximal site on keratin 18
Journal name Journal of Biological Chemistry   Check publisher's open access policy
ISSN 0021-9258
1083-351X
Publication date 2016-06-03
Year available 2016
Sub-type Article (original research)
DOI 10.1074/jbc.M116.728717
Open Access Status File (Publisher version)
Volume 291
Issue 23
Start page 12003
End page 12013
Total pages 11
Place of publication American Society for Biochemistry and Molecular Biology
Publisher Bethesda, MD, United States
Collection year 2017
Language eng
Formatted abstract
Keratins 8/18 (K8/18) are phosphoglycoproteins and form the major intermediate filament network of simple epithelia. The three O-GlcNAcylation (Ser29 , Ser30 , and Ser48 ) and two phosphorylation (Ser33 and Ser52 ) serine sites on K18 are well characterized. Both of these modifications have been reported to increase K18 solubility and regulate its filament organization. In this report, we investigated the site-specific interplay between these two modifications in regulating the functional properties of K18, like solubility, stability, and filament organization. An immortalized hepatocyte cell line (HHL-17) stably expressing site-specific single, double, and triple O-GlcNAc and phosphomutants of K18 were used to identify the site(s) critical for regulating these functions. Keratin 18 mutants where O-GlcNAcylation at Ser30 was abolished (K18-S30A) exhibited reduced phosphorylation induced solubility, increased stability, defective filament architecture, and slower migration. Interestingly, K18-S30A mutants also showed loss of phosphorylation at Ser33 , a modification known to regulate the solubility of K18. Further to this, the K18 phosphomutant (K18-S33A) mimicked K18-S30A in its stability, filament organization, and cell migration. These results indicate that O-GlcNAcylation at Ser30 promotes phosphorylation at Ser33 to regulate the functional properties of K18 and also impact cellular processes like migration. O-GlcNAcylation and phosphorylation on the same or adjacent sites on most proteins antagonize each other in regulating protein functions. Here we report a novel, positive interplay between O-GlcNAcylation and phosphorylation at adjacent sites on K18 to regulate its fundamental properties.
Keyword Cytoskeleton
Intermediate filament
Keratin
Migration
O-GlcNAcylation
Phosphorylation
Protein degradation
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: HERDC Pre-Audit
Institute for Molecular Bioscience - Publications
 
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