Year-end Sale % OFF 
Abstract
Tau is a multiply phosphorylated protein that is essential for the development and maintenance of the nervous system. Errors in Tau action are associated with Alzheimer disease and related dementias. A huge literature has led to the widely held notion that aberrant Tau hyperphosphorylation is central to these disorders. Unfortunately, our mechanistic understanding of the functional effects of combinatorial Tau phosphorylation remains minimal. Here, we generated four singly pseudophosphorylated Tau proteins (at Thr(231), Ser(262), Ser(396), and Ser(404)) and four doubly pseudophosphorylated Tau proteins using the same sites. Each Tau preparation was assayed for its abilities to promote microtubule assembly and to regulate microtubule dynamic instability in vitro. All four singly pseudophosphorylated Tau proteins exhibited loss-of-function effects. In marked contrast to the expectation that doubly pseudophosphorylated Tau would be less functional than either of its corresponding singly pseudophosphorylated forms, all of the doubly pseudophosphorylated Tau proteins possessed enhanced microtubule assembly activity and were more potent at regulating dynamic instability than their compromised singly pseudophosphorylated counterparts. Thus, the effects of multiple pseudophosphorylations were not simply the sum of the effects of the constituent single pseudophosphorylations; rather, they were generally opposite to the effects of singly pseudophosphorylated Tau. Further, despite being pseudophosphorylated at different sites, the four singly pseduophosphorylated Tau proteins often functioned similarly, as did the four doubly pseudophosphorylated proteins. These data lead us to reassess the conventional view of combinatorial phosphorylation in normal and pathological Tau action. They may also be relevant to the issue of combinatorial phosphorylation as a general regulatory mechanism.
Highlights
From the ‡Neuroscience Research Institute and Department of Molecular and Cellular and Developmental Biology, the §Center for Bio-Image Informatics, and the ‡‡Electrical and Computer Engineering Department, University of California, Santa Barbara, California 93106, the ¶TRUE Research Foundation, San Antonio, Texas 78217, ʈNCI-Frederick, National Institutes of Health, Frederick, Maryland 21702, **Rockefeller University, New York, New York 10065, ¶¶California Institute of Technology, Pasadena, California 91125, and §§University of California San Diego, La Jolla, California 92093
In an attempt to better understand the regulatory and mechanistic effects of multiple versus single phosphorylation events upon protein action, focusing on Tau, we have methodically examined the effects of pseudophosphorylation of Tau at four key phosphorylation sites (Thr[231], Ser[262], Ser[396], and Ser404), individually and combinatorially, upon the abilities of Tau (i) to bind and assemble microtubules and (ii) to regulate microtubule dynamic instability
The specificity of the reaction is demonstrated by the lack of any increase in microtubule assembly when Tau was replaced by the nonspecific protein BSA
Summary
MARKEDLY DIFFERENT REGULATORY EFFECTS ON MICROTUBULE ASSEMBLY AND DYNAMIC INSTABILITY THAN THE SUM OF THE INDIVIDUAL PARTS*. In an attempt to better understand the regulatory and mechanistic effects of multiple versus single phosphorylation events upon protein action, focusing on Tau, we have methodically examined the effects of pseudophosphorylation of Tau at four key phosphorylation sites (Thr[231], Ser[262], Ser[396], and Ser404), individually and combinatorially, upon the abilities of Tau (i) to bind and assemble microtubules and (ii) to regulate microtubule dynamic instability These analyses provide novel insights into phosphorylation-mediated regulation of Tau action upon microtubules, functional relationships between singly and multiply phosphorylated proteins, and the plausibility of integrating aberrant phosphorylation into the misregulation of microtubule dynamic instability model for Tau-mediated neuronal cell death
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
