Trafficking and Regulation of MMPs

Matrix metalloproteinases (MMPs) have emerged as major regulators of proteolytic cell invasion in various cell types. They can be separated into soluble and membrane type (MT) proteases. In particular, the membrane-bound isoform MT1-MMP (MMP14) is a key protease, which acts as a central regulator of proteolytic cell invasion in a variety of settings, including monocyte diapedesis, T-cell homing, and cancer cell metastasis.
A complex regulatory network has evolved around MT1-MMP. Besides the activation of the protease by convertases and its inhibition by endogenous elements (e.g. Tissue Inhibitors of Metalloproteases (TIMPs)), the regulation also depends on multiple intracellular trafficking events. Surface-exposed MT1-MMP, in turn, can be internalized and recycled, a process that is regulated by both clathrin- or caveolae-dependent pathways.
We investigate the role of kinesins and RabGTPases as motor proteins and regulators for the intracellular transport of MT1-MMP in primary human macrophages. We could already show that MT1-MMP positive vesicles travel bidirectionally along microtubules. This process is driven by kinesin-1 and -2 motors, as well as by cytoplasmic dynein, and regulates cell surface exposure of MT1-MMP (Wiesner et al., 2010).

Furthermore, the impact of several specific RabGTPases on MT1-MMP trafficking and function in primary human macrophages could be demonstrated. The GTPases Rab5a, Rab8a and Rab14 critically regulate cell surface exposure of MT1-MMP, contact of MT1-MMP-positive vesicles with podosomes, as well as podosome-localised ECM degradation in 2D and 3D, and also 3D proteolytic invasion (Wiesner et al, 2013).

Furthermore, our lab showed the importance of MT1-MMP islets underneath podosomes for their reemergence, highlighting the relevance of the protease for the main degradative structures of macrophages (El Azzouzi et al, 2016).
Recently, we were able to identify the kinesin family member KIF16B as a main regulator of MT1-MMP fast-recycling in primary human macrophages. We further investigated the impact of KIF16B driven MT1-MMP recycling in macrophages on the invasive capabilities of in vitro lung cancer spheroids in a 3D collagen I environment (Hey et al, 2023).

Our current projects focus on a deeper understanding of the cellular processes MT1-MMP is involved in macrophages and how the proteases regulation is impacting general cellular mechanisms like migration, invasion and adherence. For this reason, we use different state of the art methods including 3D invasion assays, mass spectrometry, FACS analysis and 3D cancer cell co-invasion assays.

Invasion of primary human macrophages into collagen I.
Time lapse video of primary human macrophages embedded in dense collagen I (2.5 mg/ml; dark area on the left), invading into less dense collagen I (2 mg/ml; lighter area on the right), which contains a chemoattractant. White bar scales 41 µm; video starts 9 h after cell seeding. Note mesenchymal morphology of invading cells characterised by numerous elongated protrusions. To see movie, click on the image. (1 image/15 min; frame rate: 10 f/s; sequence: 32 h 15 min; 1.2 MB)

Colocalisation of MT1-MMP-mCherry and GFP-Rab22a in living cells.
Confocal time-lapse video of a primary human macrophage expressing MT1-MMP-mCherry (red) and GFP-Rab22a (green). White bar scales 12 µm; white boxes show simultaneously detailed time lapse, marked within the cell. Note colocalisation of MT1-MMP-mCherry with GFP-Rab22a positive (small or giant) vesicles. To see movie, click on the image. (1 image/2 sec; frame rate: 10 f/s; sequence: 92 s; 397 KB)

Co-invasion of H1299-GFP cancer cells and primary human macrophages.
Co-invasion of H1299-GFP cancer cells and primary human macrophages.
(B) Schematic drawing of tumor spheroid co-invasion assay. (C) Fluorescent image of a cancer cell spheroid (H1299-GFP) co-cultivated with primary human macrophages. The tumor cells can be identified by their GFP signal (D) and all cells are stained for F-actin (E). Detailed images from C (dashed white boxes) showing collective (F) and single cell invasion (G). (Hey et al, 2023)

Model of MT1-MMP trafficking in macrophages.
Model of MT1-MMP trafficking in primary human macrophages. Intracellular trafficking pathways to and from the plasma membrane are depicted, together with known vesicle regulators of the RabGTPase family and known kinesin motors associated with respective pathways. Note the role of KIF16B in the Rab14-dependent fast recycling pathway of the proteinase back to the cell surface. PM, plasma membrane; TGN, trans-Golgi network; EE, early endosome; EV, exocytic vesicle; RE, recycling endosome; LE, late endosome; Lys, lysosome. (Hey et al, 2023)


KIF16B drives MT1-MMP recycling in macrophages and promotes co-invasion of cancer cells.
Hey et al, 2023 (Life Science Alliance)

Metalloproteinase MT1-MMP islets act as memory devices for podosome reemergence.
El Azzouzi et al, 2016 (Journal of Cell Biology)

A specific subset of RabGTPases controls cell surface exposure of MT1-MMP, extracellular matrix degradation and three-dimensional invasion of macrophages.
Wiesner et al, 2013 (Journal of Cell Science)

KIF5B and KIF3A/KIF3B kinesins drive MT1-MMP surface exposure, CD44 shedding, and extracellular matrix degradation in primary macrophages.
Wiesner et al, 2010 (Blood)


Proteolysis of CD44 at the cell surface controls a downstream protease network.
Wöhner et al, 2023 (Frontiers in Molecular Bioscience)

MT1-MMP and ADAM10/17 exhibit a remarkable overlap of shedding properties.
Werny et al, 2022 (FEBS Journal)


There and back again: Intracellular trafficking, release and recycling of matrix metalloproteinases.
Hey et al, 2022 (Biochim Biophys Acta Mol Cell Res)

MT1-MMP: Endosomal delivery drives breast cancer metastasis.
Linder S, 2015 (Journal of Cell Biology)

RABGTPases in MT1-MMP trafficking and cell invasion: Physiology versus pathology.
Linder S and Scita G, 2015 (Small GTPases)

Podosomes in space – Macrophage migration and matrix degradation in 2D and 3D settings.
Wiesner et al, 2014 (Cell Adhesion & Mirgation)

Degrading devices: Invadosomes in proteolytic cell invasion.
Linder et al, 2011 (Annual Review of Cell and Developmental Biology)