Expression of human cathepsin L or human cathepsin V in mouse thymus mediates positive selection of T helper cells in cathepsin L knock-out mice

Sevenich, Lisa; Hagemann, Sascha; Stoeckle, Christina; Tolosa, Eva; Peters, Christoph; Reinheckel, Thomas (2010). Expression of human cathepsin L or human cathepsin V in mouse thymus mediates positive selection of T helper cells in cathepsin L knock-out mice. Biochimie, 92(11), pp. 1674-80. Paris: Elsevier Masson SAS 10.1016/j.biochi.2010.03.014

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A genetic deficiency of the cysteine protease cathepsin L (Ctsl) in mice results in impaired positive selection of conventional CD4+ T helper cells as a result of an incomplete processing of the MHC class II associated invariant chain or incomplete proteolytic generation of positively selecting peptide ligands. The human genome encodes, in contrast to the mouse genome, for two cathepsin L proteases, namely cathepsin L (CTSL) and cathepsin V (CTSV; alternatively cathepsin L2). In the human thymic cortex, CTSV is the predominately expressed protease as compared to CTSL or other cysteine cathepsins. In order to analyze the functions of CTSL and CTSV in the positive selection of CD4+ T cells we employed Ctsl knock-out mice crossed either with transgenic mice expressing CTSL under the control of its genuine human promoter or with transgenic mice expressing CTSV under the control of the keratin 14 (K14) promoter, which drives expression to the cortical epithelium. Both human proteases are expressed in the thymus of the transgenic mice, and independent expression of both CTSL and CTSV rescues the reduced frequency of CD4+ T cells in Ctsl-deficient mice. Moreover, the expression of the human cathepsins does not change the number of CD4+CD25+Foxp3+ regulatory T cells, but the normalization of the frequency of conventional CD4+ T cell in the transgenic mice results in a rebalancing of conventional T cells and regulatory T cells. We conclude that the functional differences of CTSL and CTSV in vivo are not mainly determined by their inherent biochemical properties, but rather by their tissue specific expression pattern.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Pre-clinic Human Medicine > Institute of Pharmacology

UniBE Contributor:

Merz, Christina

ISSN:

0300-9084

Publisher:

Elsevier Masson SAS

Language:

English

Submitter:

Factscience Import

Date Deposited:

04 Oct 2013 14:09

Last Modified:

04 May 2014 23:04

Publisher DOI:

10.1016/j.biochi.2010.03.014

PubMed ID:

20347002

Web of Science ID:

000284717300019

URI:

https://boris.unibe.ch/id/eprint/889 (FactScience: 201182)

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