N-Glycosylation of extracellular matrix protein 1 (ECM1) regulates its secretion, which is unrelated to lipoid proteinosis

Extracellular matrix protein 1 (ECM1) is expressed in a wide variety of tissues and plays important roles in extracellular matrix formation. Additionally, ECM1 gene mutations cause lipoid proteinosis (LP), a rare skin condition of genetic origin. However, an effective therapeutic approach of LP is not established. Here, we showed that ECM1 gene mutation observed in LP patients significantly suppresses its secretion. As ECM1 has three putative N-glycosylation sites and most of mutated ECM1 observed in LP patients are defective in these N-glycosylation sites, we investigated the correlation between LP and N-glycosylation of ECM1. We identified that the Asn³⁵⁴ and Asn⁴⁴⁴ residues in ECM1 were N-glycosylated by mass spectrometry analysis. In addition, an N-linked glycan at Asn³⁵⁴ negatively regulated secretion of ECM1, contrary to LP patient-derived mutants. These results indicate that the defect of N-glycosylation in ECM1 is not involved in the aberration of secretion of LP-derived mutated ECM1.