Lysyl oxidase-like 2 processing by factor Xa modulates its activity and substrate preference

Abstract

Lysyl oxidase-like 2 (LOXL2) has been identified as an essential mediator of extracellular matrix (ECM) remodeling in several disease processes including cardiovascular disease. Thus, there is growing interest in understanding the mechanisms by which LOXL2 is regulated in cells and tissue. While LOXL2 occurs both in full length and processed forms in cells and tissue, the precise identity of the proteases that process LOXL2 and the consequences of processing on LOXL2’s function remain incompletely understood. Here we show that Factor Xa (FXa) is a protease that processes LOXL2 at Arg-338. Processing by FXa does not affect the enzymatic activity of soluble LOXL2. However, in situ in vascular smooth muscle cells, LOXL2 processing by FXa results in decreased cross-linking activity in the ECM and shifts substrate preference of LOXL2 from type IV collagen to type I collagen. Additionally, processing by FXa increases the interactions between LOXL2 and prototypical LOX, suggesting a potential compensatory mechanism to preserve total LOXs activity in the vascular ECM. FXa expression is prevalent in various organ systems and shares similar roles in fibrotic disease progression as LOXL2. Thus, LOXL2 processing by FXa could have significant implications in pathologies where LOXL2 is involved.

Sex Differences and Role of Lysyl Oxidase Like 2 (LOXL2) in Angiotensin II-Induced Hypertension in Mice

“…Thus, females appear to have a compensatory increase in prototypic LOX activation following induction of experimental hypertension, but not males. Previous studies have shown that LOXL2 processing shifts its substrate preference from Collagen IV to Collagen I in VSMCs 24 and the prototypic active LOX also exhibits preference for Collagen I. Consistent with the increase in active LOX and processed LOXL2, a significant increase in Collagen I abundance and a decrease in Collagen IV abundance was noted in the aortic ECM with Ang II infusion.…”

“…A qualitative increase in collagen content was noted with Ang II infusion by Masson’s trichrome and MOVAT pentachrome staining in both WT and Loxl2 +/- male mice and WT female mice (Figure 5Ai, Aii). However, the stains do not allow us to distinguish the specific subtypes of collagen, particularly Collagen I and IV, that are known substrates of LOXL2 24 . We therefore next evaluated LOX, LOXL2, Collagen I, and Collagen IV protein abundance in the aortic ECM by Western blotting.…”

“…LOX is secreted as a pro-protein (∼50 kDa) and requires processing by BMPs to release the active form (∼25 kDa) 28 . While LOXL2 is active in its full-length form (∼100 kDa), processing shifts its substrate preference from Collagen IV for the full-length form to Collagen I for the processed form (∼65 kDa) 24 . Western blotting revealed elevated full length and processed LOXL2 in WT males with Ang II infusion ( Figure 6Ai-iii ).…”

Exploring the Interplay between Polyphenols and Lysyl Oxidase Enzymes for Maintaining Extracellular Matrix Homeostasis

“…Primarily, LOX enzymes promote the first step in the formation of covalent cross-linking to stabilize collagen fibrils [ 12 , 50 , 51 ]. Specifically, for fibrillar type I collagen, it has been reported that LOX and LOXL2 can form covalent cross-links in the molecule [ 52 ]. It has also been demonstrated that LOX, LOXL2 and LOXL4 cross-link collagen IV, along with indications that LOXL4 cross-links IV via an increase in collagen IV deposition in vascular matrix remodeling [ 47 , 53 , 54 , 55 ].…”

LOXL2 in Cancer: A Two-Decade Perspective

“…Factor Xa cleaves LOXL2 at the beginning of SRCR3 (site R338↓). LOXL2 processing by factor Xa results in reduced cross-linking activity in the ECM and a change in LOXL2 substrate preference from collagen type IV to type I collagen [ 93 ].…”