Involvement of exon 6-mediated calpastatin intracellular movements in the modulation of calpain activation |
| |
Authors: | Roberta De Tullio Claudia Cantoni Chiara Broggio Carola Prato Roberto Stifanese Monica Averna Renzo Antolini Sandro Pontremoli Edon Melloni |
| |
Institution: | 1. Department of Experimental Medicine (DIMES), Section of Biochemistry and Center of Excellence for Biomedical Research, University of Genova, Viale Benedetto XV, 1-16132 Genova, Italy;2. Department of Experimental Medicine (DIMES), Section of General Pathology and Center of Excellence for Biomedical Research, University of Genova, Viale Benedetto XV, 1-16132 Genova, Italy;3. Giannina Gaslini Institute, Largo G. Gaslini, Genova, Italy;4. LENS - European Laboratory for Non-Linear Spectroscopy, University of Firenze, Via Nello Carrara 1, I-50019 Sesto Fiorentino, Firenze, Italy;5. Department of Physics and ITC-IRST, University of Trento, Via Mesiano 77, 38050 Povo-Trento, Italy |
| |
Abstract: | BackgroundTo establish the physiological role of calpain, it is necessary to define how the protease can escape from the effect of its natural inhibitor calpastatin, since both proteins co-localize into the cell cytosol.MethodsTo answer this question, we have overexpressed four fluorescent calpastatin constructs, differing in the composition of their XL- and L-domains, and the intracellular trafficking of this protein inhibitor has been followed by single cell fluorescence imaging.Results and conclusionsBy the use of these calpastatin forms differing in the type of exon-derived sequences contained in the XL- and L-domains, we have demonstrated that the sequence coded by exon 6, containing multiple phosphorylation sites, is directly involved in determining the cell localization of calpastatin. In fact, exposure to cAMP promotes the recruitment into aggregates of those calpastatin forms containing the exon 6 sequence. These protein movements are directly related to the level of cytosolic inhibitory capacity and thereby to the extent of intracellular calpain activation.General significanceThe recruitment of calpastatin into aggregates allows the translocation and activation of the protease to the membranes; on the contrary, the presence of large amounts of calpastatin in the cytosol prevents both processes, protecting the cell from undesired proteolysis. |
| |
Keywords: | Calpain Calpastatin cAMP Ca2+ homeostasis Regulation of Ca2+-dependent proteolysis Intracellular protein trafficking |
本文献已被 ScienceDirect 等数据库收录! |
|