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Impaired development of the Harderian gland in mutant protein phosphatase 2A transgenic mice


Schild, A; Isenmann, S; Tanimoto, N; Tonagel, F; Seeliger, M W; Ittner, L M; Kretz, A; Ogris, E; Götz, J (2006). Impaired development of the Harderian gland in mutant protein phosphatase 2A transgenic mice. Mechanisms of Development, 123(5):362-371.

Abstract

Although Harderian glands are especially large in rodents, many features of this retroocular gland, including its development and function, are not well established. Protein phosphatase 2A (PP2A) is a family of heterotrimeric enzymes expressed in this gland. PP2A substrate specificity is determined by regulatory subunits with leucine 309 of the catalytic subunit playing a crucial role in the recruitment of regulatory subunits into the complex in vitro. Here we expressed an L309A mutant catalytic subunit in Harderian gland of transgenic mice. We found a delayed postnatal development and hypoplasia of the gland, causing enophthalmos. To determine why expression of the L309A mutant caused this phenotype, we determined the PP2A subunit composition. We found an altered subunit composition in the transgenic gland that was accompanied by pronounced changes of proteins regulating cell adhesion. Specifically, cadherin and beta-catenin were dramatically reduced and shifted to the cytosol. Furthermore, we found an inactivating phosphorylation of the cadherin-directed glycogen synthase kinase-3beta. In conclusion, the carboxy-terminal leucine L309 of the PP2A catalytic subunit determines PP2A heterotrimer composition in vivo. Moreover, our data demonstrate that PP2A subunit composition plays a crucial role in regulating cell adhesion and as a consequence in the development of the Harderian gland.

Although Harderian glands are especially large in rodents, many features of this retroocular gland, including its development and function, are not well established. Protein phosphatase 2A (PP2A) is a family of heterotrimeric enzymes expressed in this gland. PP2A substrate specificity is determined by regulatory subunits with leucine 309 of the catalytic subunit playing a crucial role in the recruitment of regulatory subunits into the complex in vitro. Here we expressed an L309A mutant catalytic subunit in Harderian gland of transgenic mice. We found a delayed postnatal development and hypoplasia of the gland, causing enophthalmos. To determine why expression of the L309A mutant caused this phenotype, we determined the PP2A subunit composition. We found an altered subunit composition in the transgenic gland that was accompanied by pronounced changes of proteins regulating cell adhesion. Specifically, cadherin and beta-catenin were dramatically reduced and shifted to the cytosol. Furthermore, we found an inactivating phosphorylation of the cadherin-directed glycogen synthase kinase-3beta. In conclusion, the carboxy-terminal leucine L309 of the PP2A catalytic subunit determines PP2A heterotrimer composition in vivo. Moreover, our data demonstrate that PP2A subunit composition plays a crucial role in regulating cell adhesion and as a consequence in the development of the Harderian gland.

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13 citations in Web of Science®
14 citations in Scopus®
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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Institute for Regenerative Medicine (IREM)
Dewey Decimal Classification:610 Medicine & health
Date:2006
Deposited On:12 Oct 2011 12:56
Last Modified:16 Aug 2016 10:14
Publisher:Elsevier
ISSN:0925-4773
Publisher DOI:10.1016/j.mod.2006.03.003
PubMed ID:16679006

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