Pxmp4, also known as peroxisomal membrane protein 4 or PMP24, is a ubiquitously expressed peroxisomal membrane protein. It is transcriptionally regulated by peroxisome proliferator-activated receptor α (PPARα). Peroxisomes, where Pxmp4 is located, are essential organelles in higher eukaryotes, catalyzing metabolic functions like fatty acid β-oxidation, ether phospholipid biosynthesis, etc. [3,5].

A Pxmp4 knockout (Pxmp4-/-) mouse model was generated to study its physiological function [3]. Under standard chow-fed conditions, Pxmp4-/-mice were viable and fertile, with no change in peroxisome numbers or morphology. Although there were no differences in plasma levels of major peroxisomal pathway products, elevated levels of phytol metabolites in Pxmp4-/-mice indicated an impairment in peroxisomal α-oxidation capacity. Lipidomic analysis showed that loss of Pxmp4 decreased hepatic levels of the alkyldiacylglycerol class of neutral ether lipids, suggesting its role in (ether)lipid metabolism [3].

In conclusion, Pxmp4 may not be critical for overall peroxisome function under normal conditions, but is involved in the metabolism of (ether)lipids as revealed by the Pxmp4-/-mouse model. Additionally, studies have shown its potential roles in various diseases. In gastric cancer, PXMP4 promotes cell epithelial-mesenchymal transition via the PI3K/AKT signaling pathway [1]. In hepatocellular carcinoma, its high expression may promote cancer occurrence and development [2]. In non-small cell lung cancer, it is down-regulated and may be a new marker for diagnosis and prognosis [4].