Matriptase activation of Gq drives epithelial disruption and inflammation via RSK and DUOX

Abstract

Epithelial tissues are primed to respond to insults by activating epithelial cell motility and rapid inflammation. Such responses are also elicited upon overexpression of the membrane bound protease, Matriptase, or mutation of its inhibitor, Hai1. Unrestricted Matriptase activity also predisposes to carcinoma. How Matriptase leads to these cellular outcomes is unknown. We demonstrate that zebrafish hai1a mutants show increased H2O2, NfkB signalling, and IP3R -mediated calcium flashes, and that these promote inflammation, but do not generate epithelial cell motility. In contrast, inhibition of the Gq subunit in hai1a mutants rescues both the inflammation and epithelial phenotypes, with the latter recapitulated by the DAG analogue, PMA. We demonstrate that hai1a has elevated MAPK pathway activity, inhibition of which rescues the epidermal defects. Finally, we identify RSK kinases as MAPK targets disrupting adherens junctions in hai1a mutants. Our work maps novel signalling cascades mediating the potent effects of Matriptase on epithelia, with implications for tissue damage response and carcinoma progression.

Matriptase-dependent epidermal pre-neoplasm in zebrafish embryos caused by a combination of hypotonic stress and epithelial polarity defects

“…Yet, even these “lateral-like” domains display a certain epithelial polarity, with highest levels of the cell-cell adhesion molecule E-cadherin levels at the interface of the two cell layers [ 67 ]. However, loss of atp1b1a or lgl2 does not affect this E-cadherin polarity [ 67 ] or even causes decreased E-cadherin levels [ 23 ]. Therefore, the aberrant accumulation of Matriptase-1 in atp1b1a mutants on the basal side of peridermal cells most likely is not mediated via E-cadherin [ 68 , 69 ] but might be directly influenced by the disrupted cell polarity.…”

“…Mild hypotonicity (small blue star), most likely due to compromised epidermal integrity, further enhances Matriptase activity levels. Note that additional pathways downstream of Par2b have been described, which lead to additional pre-neoplastic events, like sterile inflammation; however, they do not include PI3K [ 23 ]. (C) More extreme hypotonicity in the pericellular space (due to loss of ATP1b1a or Pax2a; large blue star) causes (moderate) Matriptase activation even in the presence of Hai1a.…”

“…One of them, an EGFR—Phospholipase D (PLD) pathway, branches off at the level of the PLD product phosphatidic acid and promotes 1) mTORC1 signaling and thereby epidermal cell proliferation and mmp9 expression, and 2) sphingosine kinase activity and thereby S1P production and apical cell extrusion of epidermal cells [ 20 ]. Additionally, Matriptase-activated Par2b in hai1a mutants can activate PLC, leading to sterile inflammation via PLC-induced IP3 signaling as well as interference with cell adhesion via PLC-induced DAG-MAPK-RSK signaling [ 23 ].…”

“…Several zebrafish mutants have been identified that display early stages of carcinogenesis in the bi-layered embryonic epidermis, characterized by keratinocyte hyper-proliferation and aggregate formation, as well as partial or complete epithelial-mesenchymal transitions (EMTs) of keratinocytes. Among them are loss-of-function mutants in hai1a [ 20 , 21 , 22 , 23 , 24 , 25 ], in which epidermal pre-neoplasm but also concomitant tumor-suppressive processes occur as direct consequences of increased Matriptase-1 activity, mediated by the Protease-activated receptor 2b (Par2b) and a linear EGFR (Epidermal growth factor receptor)–PLD (Phospholipase D) signal transduction pathway [ 20 ].…”

Matriptase drives dissemination of ovarian cancer spheroids by a PAR-2/PI3K/Akt/MMP9 signaling axis

“…PAR-2 is a G-protein-coupled receptor that is activated by proteolytic cleavage of an extracellular N-terminal activation site that reveals a “tethered ligand,” which binds to an intramolecular docking domain to trigger intracellular signaling pathways. PAR-2 is implicated in the inflammatory effects of matriptase overactivity in zebrafish and the potentiation of matriptase-driven Ras-mediated squamous cell carcinogenesis in mice ( Ma et al, 2021 ; Sales et al, 2015 ; Schepis et al, 2018 ). Both matriptase and PAR-2 exhibit substantially elevated expression in OvCa compared with normal ovary tissues ( Pawar et al, 2019 ), which suggests a potentially important function for activation of this substrate in OvCa progression.…”