New insight into the role of MMP14 in metabolic balance

Abstract

Membrane-anchored matrix metalloproteinase 14 (MMP14) is involved broadly in organ development through both its proteolytic and signal-transducing functions. Knockout of Mmp14 (KO) in mice results in a dramatic reduction of body size and wasting followed by premature death, the mechanism of which is poorly understood. Since the mammary gland develops after birth and is thus dependent for its functional progression on systemic and local cues, we chose it as an organ model for understanding why KO mice fail to thrive. A global analysis of the mammary glands’ proteome in the wild type (WT) and KO mice provided insight into an unexpected role of MMP14 in maintaining metabolism and homeostasis. We performed mass spectrometry and quantitative proteomics to determine the protein signatures of mammary glands from 7 to 11 days old WT and KO mice and found that KO rudiments had a significantly higher level of rate-limiting enzymes involved in catabolic pathways. Glycogen and lipid levels in KO rudiments were reduced, and the circulating levels of triglycerides and glucose were lower. Analysis of the ultrastructure of mammary glands imaged by electron microscopy revealed a significant increase in autophagy signatures in KO mice. Finally, Mmp14 silenced mammary epithelial cells displayed enhanced autophagy. Applied to a systemic level, these findings indicate that MMP14 is a crucial regulator of tissue homeostasis. If operative on a systemic level, these findings could explain how Mmp14KO litter fail to thrive due to disorder in metabolism.

Lysosomal trafficking mediated by Arl8b and BORC promotes invasion of cancer cells that survive radiation

“…Several proteins have been found to affect lysosomal size. For example, the overexpression of TPC 56 or the silencing of MT1-MMP 57 was found to enlarge lysosomes in cells, while the knockdown of Diaskedin 58 or the overexpression of the transcription factor EB 59 reduced lysosomal size. The mechanisms of how these proteins affect lysosomal size are not fully realized.…”

Dual functions of ARP101 in targeting membrane type‐1 matrix metalloproteinase: Impact on U87 glioblastoma cell invasion and autophagy signaling

“…ARP101 has also been documented as a potent inducer of autophagy, although the exact mechanism involved remains poorly understood. Given the above‐described ARP101 capacity to interact with MT1‐MMP extracellular functions, we next assessed the involvement of MT1‐MMP‐mediated intracellular signaling of autophagy . Serum‐starved U87 glioblastoma cells were transiently transfected with a control siRNA (siScrambled) or a siRNA directed against MT1‐MMP (siMT1‐MMP), then treated with or without 10 μM ARP101 for 24 hr.…”

“…Such functional dual targeting properties of ARP101 make this molecule a privileged drug in future selective targeting modalities. Among specific brain cancer biomarkers characterized by both MMP catalytic functions and autophagy inducing properties, membrane type‐1 (MT1) MMP, a key membrane bound MMP involved in tumor invasion, was classically ascribed an active role in extracellular matrix (ECM) degradation and, more recently, signal‐transducing functions leading to angiogenesis, autophagy, inflammation, immune response, and cell death processes . Since autophagy plays a dual role in oncogenesis, where low autophagy promotes cancer cell survival in response to constant stress, but when strongly induced can also trigger cell death of type 3 and lead to complete cellular self‐digestion, any pharmacological approach that would disrupt the homeostatic balance of autophagy may therefore be exploited within antitumor modalities.…”

Pathobiology of the 129:Stat1 −/− mouse model of human age-related ER-positive breast cancer with an immune infiltrate-excluded phenotype

“…To observe RAW264.7/GFP-H2B cell migration, cells were plated at 2 × 10 4 cells/well of an eight-well Lab-Tek II chambered coverglass (Thermo Fisher Scientific, Waltham, MA, USA) in growth medium for 2 days before stimulating cell migration with CM. Fluorescence was visualized with an LSM710 confocal microscope equipped with a temperature- and CO 2 -controlled chamber [ 29 , 30 ]. Before cell migration was analyzed, cells were rinsed twice and maintained in 400 μl of serum-free DMEM for 2 h. The action of RAW264.7/GFP-H2B cells was monitored at 5-minute intervals for more than 8 h. Cell migration was evaluated using time-lapse images with Imaris software (Bitplane, South Windsor, CT, USA).…”