RESUMEN
Membrane-type-I matrix metalloproteinase (MT1-MMP) is one of six human membrane-bound MMPs and is responsible for extracellular matrix remodelling by degrading several substrates like fibrillar collagens, including types I-III, or fibronectin. Moreover, MT1-MMP was described as a key player in cancer progression and it is involved in various inflammatory processes, as well as in the pathogenesis of Alzheimer's disease (AD). The membrane-tethered metalloprotease meprin ß as well as a disintegrin and metalloproteinase 10 (ADAM10) and ADAM17 are also associated with these diseases. Interestingly, meprin ß, ADAM10/17 and MT1-MMP also have a shared substrate pool including the interleukin-6 receptor and the amyloid precursor protein. We investigated the interaction of these proteases, focusing on a possible connection between MT1-MMP and meprin ß, to elucidate the potential mutual regulations of both enzymes. Herein, we show that besides ADAM10/17, MT1-MMP is also able to shed meprin ß from the plasma membrane, leading to the release of soluble meprin ß. Mass spectrometry-based cleavage site analysis revealed that the cleavage of meprin ß by all three proteases occurs between Pro602 and Ser603 , N-terminal of the EGF-like domain. Furthermore, only inactive human pro-meprin ß is shed by MT1-MMP, which is again in accordance with the shedding capability observed for ADAM10/17. Vice versa, meprin ß also appears to shed MT1-MMP, indicating a complex regulatory network. Further studies will elucidate this well-orchestrated proteolytic web under distinct conditions in health and disease and will possibly show whether the loss of one of the above-mentioned sheddases can be compensated by the other enzymes.
Asunto(s)
Proteína ADAM10 , Proteína ADAM17 , Metaloproteinasa 14 de la Matriz , Proteínas de la Membrana , Humanos , Proteína ADAM10/genética , Proteína ADAM10/metabolismo , Proteína ADAM17/genética , Proteína ADAM17/metabolismo , Secretasas de la Proteína Precursora del Amiloide/genética , Secretasas de la Proteína Precursora del Amiloide/metabolismo , Membrana Celular/metabolismo , Metaloproteinasa 14 de la Matriz/genética , Metaloproteinasa 14 de la Matriz/metabolismo , Proteínas de la Membrana/genética , Proteínas de la Membrana/metabolismoRESUMEN
The metalloproteases meprin α and meprin ß are highly expressed in the healthy gut but significantly decreased in inflammatory bowel disease, implicating a protective role in mucosal homeostasis. In the colon, meprin α and meprin ß form covalently linked heterodimers tethering meprin α to the plasma membrane, therefore presenting dual proteolytic activity in a unique enzyme complex. To unravel its function, we applied N-terminomics and identified galectin-3 as the major intestinal substrate for meprin α/ß heterodimers. Galectin-3-deficient and meprin α/ß double knockout mice show similar alterations in their microbiome in comparison to wild-type mice. We further demonstrate that meprin α/ß heterodimers differentially process galectin-3 upon bacterial infection, in germ-free, conventionally housed (specific pathogen-free), or wildling mice, which in turn regulates the bacterial agglutination properties of galectin-3. Thus, the constitutive cleavage of galectin-3 by meprin α/ß heterodimers may play a key role in colon host-microbiome homeostasis.