RhoB deficiency in thymic medullary epithelium leads to early thymic atrophy

RhoB, a member of the Rho subfamily of small GTPases, mediates diverse cellular functions, including cytoskeletal organization, cell transformation and vesicle trafficking. The thymus undergoes progressive decline in its structure and function after puberty. We found that RhoB was expressed in thymi...

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Bibliographic Details
Published in:International immunology 2011-10, Vol.23 (10), p.593-600
Main Authors: Bravo-Nuevo, Arturo, O'Donnell, Rebekah, Rosendahl, Alexander, Chung, Jae Hoon, Benjamin, Laura E., Odaka, Chikako
Format: Article
Language:English
Subjects:
Animals
Epithelium - immunology
Epithelium - metabolism
Epithelium - pathology
Female
Male
Mice
Mice, Inbred Strains
Mice, Knockout
Reverse Transcriptase Polymerase Chain Reaction
rhoB GTP-Binding Protein - deficiency
rhoB GTP-Binding Protein - genetics
rhoB GTP-Binding Protein - metabolism
Thymus Gland - immunology
Thymus Gland - metabolism
Thymus Gland - pathology
Transforming Growth Factor beta - metabolism
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Summary:RhoB, a member of the Rho subfamily of small GTPases, mediates diverse cellular functions, including cytoskeletal organization, cell transformation and vesicle trafficking. The thymus undergoes progressive decline in its structure and function after puberty. We found that RhoB was expressed in thymic medullary epithelium. To investigate a role of RhoB in the regulation of thymic epithelial organization or thymocyte development, we analyzed the thymi of RhoB-deficient mice. RhoB-deficient mice were found to display earlier thymic atrophy. RhoB deficiency showed significant reductions in thymus weight and cellularity, beginning as early as 5 weeks of age. The enhanced expression of TGF-β receptor type II (TGFβRII) in thymic medullary epithelium was observed in RhoB-null mice. In addition, the expression of fibronectin, which is shown to be regulated by TGF-β signaling, was accordingly increased in the mutant thymic medulla. Since there is no age-related change of RhoB expression in the thymus, it is unlikely that RhoB in thymic epithelium directly contributes to age-related thymic involution. Nevertheless, our findings strongly support a physiological role of RhoB in regulation of thymus development and maintenance through the inhibition of TGF-β signaling in thymic medullary epithelium.
ISSN:0953-8178
1460-2377
DOI:10.1093/intimm/dxr064