Open Access Highly Accessed Research article

Cathepsin K deficiency in mice induces structural and metabolic changes in the central nervous system that are associated with learning and memory deficits

Stephanie Dauth1, Ruxandra F Sîrbulescu13, Silvia Jordans14, Maren Rehders1, Linda Avena1, Julia Oswald1, Alexander Lerchl1, Paul Saftig2 and Klaudia Brix1*

Author Affiliations

1 School of Engineering and Science, Research Center MOLIFE - Molecular Life Science, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany

2 Institute of Biochemistry, Christian-Albrechts Universität Kiel, 24118 Kiel, Germany

3 Department of Biology, Northeastern University, 360 Huntington Avenue, Boston, MA 02115, USA

4 Silvia Jordans' current address is Institute of Biochemistry and Molecular Biology, Friedrich-Wilhelms Universität Bonn, 53115 Bonn, Germany

For all author emails, please log on.

BMC Neuroscience 2011, 12:74  doi:10.1186/1471-2202-12-74

Published: 27 July 2011

Additional files

Additional file 1:

Proteolytic network in specific brain regions of Ctsk-/- mice as compared to WT controls. Densitometry analysis of immunoblots and results of cathepsin activity assays performed with brain tissue lysates of WT (open bars) and Ctsk-/- mice (grey bars) (A-D, A'-D') Cathepsin D protein levels were unaltered and its activity as determined by cleavage of MOCAc-Gly-Lys-Pro-Ile-Leu-Phe ~ Phe-Arg-Leu-Lys (Dnp)-D-Arg-NH2 at pH 4.0 was slightly elevated in cerebellum of Ctsk-/- mice, but these changes were not significant (A, Ctsk-/- n = 20, WT n = 19; A', Ctsk-/- n = 5, WT n = 5; B, Ctsk-/- n = 15, WT n = 17; B', Ctsk-/- n = 5, WT n = 5; C, Ctsk-/- n = 16, WT n = 17; C', Ctsk-/- n = 5, WT n = 5; D, Ctsk-/- n = 8, WT n = 12; D', Ctsk-/- n = 5, WT n = 5). (E-H, E'-H') Cathepsin B protein levels were decreased in cerebral cortex of Ctsk-/- mice, while its activity as determined by cleavage of Z-Arg-Arg-AMC at pH 6.0 was reduced only in striatum/mesencephalon of these mice (E, Ctsk-/- n = 18, WT n = 19; E', Ctsk-/- n = 5, WT n = 5; F, Ctsk-/- n = 14, WT n = 15; F', Ctsk-/- n = 8, WT n = 8; G, Ctsk-/- n = 16, WT n = 18; G', Ctsk-/- n = 5, WT n = 5; H, Ctsk-/- n = 13, WT n = 17; H', Ctsk-/- n = 5, WT n = 5). (I-L, I'-L') Cathepsin L protein levels were down-regulated in cerebral cortex, while its Z-Phe-Arg-AMC cleaving activity at pH 5.5 was decreased in striatum/mesencephalon (I, Ctsk-/- n = 19, WT n = 19; I', Ctsk-/- n = 5, WT n = 5; J, Ctsk-/- n = 13, WT n = 15; J', Ctsk-/- n = 8, WT n = 8; K, Ctsk-/- n = 16, WT n = 18; K', Ctsk-/- n = 5, WT n = 5; L, Ctsk-/- n = 13, WT n = 17; L', Ctsk-/- n = 5, WT n = 5). (M-P) Protein levels of the endogenous cysteine peptidase inhibitor, cystatin C, were significantly upregulated in striatum/mesencephalon and hippocampus of Ctsk-/- mice (M, Ctsk-/- n = 15, WT n = 17; N, Ctsk-/- n = 14, WT n = 12; O, Ctsk-/- n = 14, WT n = 17; P, Ctsk-/- n = 17, WT n = 16). The results indicated deregulated cysteine cathepsins B and L and cystatin C levels depending on the particular brain region analyzed in Ctsk-/- mice, whereas the neuroprotective aspartic protease cathepsin D remained unaffected. Levels of significance are denoted as * for p < 0.05; ** for p < 0.01; *** for p < 0.001.

Format: PDF Size: 67KB Download file

This file can be viewed with: Adobe Acrobat Reader

Open Data

Additional file 2:

Cathepsin and cystatin C status in the cerebral cortex, striatum/mesencephalon, cerebellum, and hippocampus. Representative immunoblots for densitometry analysis shown in Additional file 1; lanes represent separate individuals. (A-D) Cathepsin D (heavy chain and light chain) expression. (E-H) Cathepsin B (single chain) expression. (I-L) Cathepsin L (heavy chain) expression. (M-P) Cystatin C expression. Corresponding loading controls (β-tubulin) for each immunoblot are shown in the lower panels.

Format: PDF Size: 1.3MB Download file

This file can be viewed with: Adobe Acrobat Reader

Open Data

Additional file 3:

Locomotor activity analysis by infrared sensor module recordings of activity frequencies. Mice were singly housed over a time period of four weeks and recordings were taken by integrating activity frequencies over time intervals of 10 min, each, as detected by the infrared sensor module throughout weeks 2-4. Ctsk-/- mice (grey dotted line) exhibited no obvious differences in locomotor activity and diurnal rhythm in comparison to WT controls (straight black line) (Ctsk-/- n = 5; WT n = 5).

Format: PDF Size: 365KB Download file

This file can be viewed with: Adobe Acrobat Reader

Open Data

Additional file 4:

Elevated plus maze and hole board test. (A) Ctsk-/- mice (grey bars) spent approximately 36% of the total time in the open arms, a marked increase compared to the WT controls (open bars). In addition, while the WT mice showed a pronounced preference for the closed arms of the maze, this difference was not significant in Ctsk-/- mice. (B) The hole board test revealed a significant increase in the frequency of central area crossing in Ctsk-/- mice compared to WT controls (A and B, Ctsk-/- n = 10; WT n = 12). Levels of significance are denoted as * for p < 0.05; *** for p < 0.001.

Format: PDF Size: 25KB Download file

This file can be viewed with: Adobe Acrobat Reader

Open Data