A novel proteolytic processing of prolysyl oxidase

Area of Science:

• Biochemistry
• Molecular Biology
• Connective Tissue Research

Background:

• Lysyl oxidase (LOX) is essential for connective tissue stability.
• The secreted proLOX precursor is activated by bone morphogenetic protein (BMP)-1 cleavage.
• The precise mechanisms of LOX activation and processing are not fully understood.

Purpose of the Study:

• To identify and characterize novel processing pathways of proLOX.
• To investigate the mechanisms regulating the activation of lysyl oxidase.
• To determine if alternative activation pathways exist for proLOX.

Main Methods:

• In vitro and in vivo proLOX processing studies.
• Characterization of mature LOX forms using immunoreactivity, amine oxidase activity assays, and mass spectrometry.
• Pro-LOX gene deletion and mutation experiments.

Main Results:

• Two distinct forms of mature LOX were identified.
• One form resulted from the known BMP-1 cleavage, while the second was a novel truncated form.
• The truncated LOX form retained amine oxidase activity.
• This novel processing pathway is independent of BMP-1 and requires the LOX propeptide.

Conclusions:

• Pro-LOX can be processed via at least two distinct mechanisms.
• These mechanisms generate two different active forms of lysyl oxidase.
• This discovery expands our understanding of LOX regulation and connective tissue biology.