Increased Proteolytic Processing of Protein Tyrosine Phosphatase in Confluent Vascular Endothelial Cells: The Role of PC5, a Member o
详细信息 查看全文
- 作者：Michel Campan ; Masao Yoshizumi ; Nabil G. Seidah ; Mu-En Lee ; Cesario Bianchi ; and Edgar Haber
- 刊名：Biochemistry
- 出版年：1996
- 出版时间：March 26, 1996
- 年：1996
- 卷：35
- 期：12
- 页码：3797 - 3802
- 全文大小：383K
- 年卷期：v.35,no.12(March 26, 1996)
- ISSN：1520-4995
文摘
Cleavage and subsequent release of the extracellulardomains of receptor protein tyrosinephosphatases (RPTP) occur at high cell density and may have animportant role in regulating their activity.Because cleavage of RPTP occurs at a target motif (RXK/RR)recognized by a family of subtilisin/kexin-like endoproteases, we postulated that members of the subtilisin familymay have an important role inthis cleavage. We show in this report that the membrane-associatedRPTP
-both in its full 200-kDaform and as a 100-kDa cleavage product-is upregulated 4- and 7-fold,respectively, as human umbilicalvein endothelial cells (HUVEC) approach confluence. To determinewhether RPTP cleavage dependedon PC5 (a subtilisin/kexin-like endoprotease present in endothelialcells), we transfected COS cells withexpression plasmids coding for RPTP and PC5 or the closely relatedprotease PACE4. PC5, but notPACE4, cleaved RPTP, and RPTP cleavage was absent in COS cellstransfected with an expressionplasmid encoding a mutant PC5 whose active-site serine had been mutatedto alanine. We also performedRNA blot analysis to determine whether PC5 expression was affected byconfluence in HUVEC. PC5mRNA levels were upregulated by more than 30-fold when confluence inHUVEC increased from 25%to 100%. These results indicate that PC5 may have an importantrole in mediating the cleavage of RPTPin response to contact inhibition in HUVEC.
-both in its full 200-kDaform and as a 100-kDa cleavage product-is upregulated 4- and 7-fold,respectively, as human umbilicalvein endothelial cells (HUVEC) approach confluence. To determinewhether RPTP cleavage dependedon PC5 (a subtilisin/kexin-like endoprotease present in endothelialcells), we transfected COS cells withexpression plasmids coding for RPTP and PC5 or the closely relatedprotease PACE4. PC5, but notPACE4, cleaved RPTP, and RPTP cleavage was absent in COS cellstransfected with an expressionplasmid encoding a mutant PC5 whose active-site serine had been mutatedto alanine. We also performedRNA blot analysis to determine whether PC5 expression was affected byconfluence in HUVEC. PC5mRNA levels were upregulated by more than 30-fold when confluence inHUVEC increased from 25%to 100%. These results indicate that PC5 may have an importantrole in mediating the cleavage of RPTPin response to contact inhibition in HUVEC.