Journal
TRAFFIC
Volume 15, Issue 4, Pages 401-417Publisher
WILEY
DOI: 10.1111/tra.12149
Keywords
brefeldin A; ERGIC; intermediate compartment; intracellular MMP; membrane; proteinase K; surface biotinylation; Triton X-114
Categories
Funding
- Fonds de la Recherche Scientifique Medicale
- Concerted Research Actions
- Communaute Francaise de Belgique
- Region wallonne
- IUAP
- Region bruxelloise
- Loterie nationale
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Matrix metalloproteinase-27 (MMP-27) is poorly characterized. Sequence comparison suggests that a C-terminal extension (CTE) includes a potential transmembrane domain as in some membrane-type (MT)-MMPs. Having noticed that MMP-27 was barely secreted, we investigated its subcellular localization and addressed CTE contribution for MMP-27 retention. Intracellular MMP-27 was sensitive to endoglycosidase H. Subcellular fractionation and confocal microscopy evidenced retention of endogenous MMP-27 or recombinant rMMP-27 in the endoplasmic reticulum (ER) with locked exit across the intermediate compartment (ERGIC). Conversely, truncated rMMP-27 without CTE accessed downstream secretory compartments (ERGIC and Golgi) and was constitutively secreted. CTE addition to rMMP-10 (a secreted MMP) caused ER retention and blocked secretion. Addition of a PKA target sequence to the cytosolic C-terminus of transmembrane MT1-MMP/MMP-14 led to effective phosphorylation upon forskolin stimulation, but not for MMP-27, excluding transmembrane anchorage. Moreover, MMP-27 was protected from digestion by proteinase K. Finally, MT1-MMP/MMP-14 but neither endogenous nor recombinant MMP-27 partitioned in the detergent phase after Triton X-114 extraction, indicating that MMP-27 is not an integral membrane protein. In conclusion, MMP-27 is efficiently retained within the ER due to its unique CTE, which does not lead to stable membrane insertion. This could represent a novel ER retention system.
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