Title : The human
CD10 lacking
an N-glycan at
Asn(628) is deficient in surface expression and
neutral endopeptidase activity
Abstract :
- BACKGROUND: CD10 , also known as neprilysin or enkephalinase exhibiting neutral endopeptidase ( NEP ) activity, is expressed by B-lineage hematopoietic cells as well as a variety of cells from normal tissues
- It cleaves peptides such as cytokines to act for terminating inflammatory responses
- Although CD10 molecules of the human pre-B-cell line NALM-6 have 6 consensus N-glycosylation sites , three of them are known to be N-glycosylated by X-ray crystallography
- METHODS: In order to investigate the role of N-glycans in the full expression of NEP activity, we modified N-glycans by treatment of NALM6 cells with various glycosidases or alter each of the consensus N-glycosylation sites by generating site-directed mutagenesis and compared the NEP activities of the sugar-altered CD10 with those of intact CD10
- RESULTS: CD10 of the human B-cell line NALM-6 was dominantly localized in raft microdomains and heterogeneously N-glycosylated
- Although neither desialylation nor further degalactosylation caused defective NEP activity, removal of only a small part of N-glycans by treatment with glycopeptidase F under non-denaturing conditions decreased NEP activity completely
- All of the three consensus sites of CD10 in HEK293 cells introduced with wild type- CD10 were confirmed to be N-glycosylated
- Surface expression of N-glycan at Asn(628)-deleted CD10 by HEK293 cells was greatly decreased as well as it lost entire NEP activities
- CONCLUSIONS: N-glycosylation at Asn(628) is essential not only for NEP activities, but also for surface expression
- GENERAL SIGNIFICANCE: Quality control system does not allow dysfunctional ecto-type proteases to express on plasma membrane