Calsenilin/DREAM/KChIP3, a neuronal Ca 2+-binding protein, has multifunctions in nucleus and cytosol. Here, we identified CLN3 as a calsenilin-binding partner whose mutation or deletion is observed in Batten disease. In vitro binding and immunoprecipitation assays show that calsenilin interacts with the C-terminal region of CLN3 and the increase of Ca 2+ concentration in vitro and in cells causes significant dissociation of calsenilin from CLN3. Ectopic expression of CLN3 or its deletion mutant containing only the C-terminus (153-438) and capable of binding to calsenilin suppresses thapsigargin or A23187-induced death of neuronal cells. In contrast, CLN3 deletion mutant containing the N-terminus (1-153) or (1-263), which is frequently found in Batten disease, induces the perturbation of Ca 2+ transient and fails to inhibit the cell death. In addition, the expression of calsenilin is increased in the brain tissues of CLN3 knock-out mice and SH-SY5Y/CLN3 knock-down cells. Down-regulation of CLN3 expression sensitizes SH-SY5Y cells to thapsigargin or A23187. However, additional decrease of calsenilin expression rescues the sensitivity of SH-SY5Y/CLN3 knock-down cells to Ca 2+ -mediated cell death. These results suggest that the vulnerability of CLN3 knock-out or CLN3 deletion (1-153)-expressing neuronal cells to Ca 2+-induced cell death may be mediated by calsenilin.
Bibliographical noteFunding Information:
The authors thank D. Pearce (University of Rochester, USA) for providing whole brains of CLN3 knock-out and wild-type mice, and M. Bennett (University of Iowa, USA) for CLN3 antibody. This work was supported by the Brain Research Center of 21C Frontier and Research Center for Functional Cellulomics and Ubiquitomics of the Korea Science and Engineering Foundation and by the Korean Research Foundation (KRF-2005-201-C00039).