Functional characterization of the protein C A267T mutation: evidence for impaired secretion due to defective intracellular transport

BMC Cell Biology

Research Article

Jonas Bergan¹  Kirsten Sandvig¹  Grethe Skretting²  Lena Tjeldhorn³  Per Morten Sandset³  Nina Iversen⁴ 

[1] Department of Biochemistry, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway;Centre for Cancer Biomedicine, University of Oslo, Oslo, Norway;Department of Hematology, Oslo University Hospital, Oslo, Norway;Department of Hematology, Oslo University Hospital, Oslo, Norway;Institute of Clinical Medicine, University of Oslo, Oslo, Norway;Department of Medical Genetics, Oslo University Hospital, Oslo, Norway;

关键词: Endoplasmic Reticulum;    Endoplasmic Reticulum Stress;    Proteasomal Degradation;    Huh7 Cell;    Lactacystin;   

DOI  :  10.1186/1471-2121-11-67

 received in 2010-02-28, accepted in 2010-09-06,  发布年份 2010

来源: Springer

【 摘 要 】

BackgroundActivated protein C (PC) is a serine protease that regulates blood coagulation by inactivating coagulation factors Va and VIIIa. PC deficiency is an autosomally inherited disorder associated with a high risk of recurrent venous thrombosis. The aim of the study was to explore the mechanisms responsible for severe PC deficiency in a patient with the protein C A267T mutation by in-vitro expression studies.ResultsHuh7 and CHO-K1 cells were transiently transfected with expression vectors containing wild-type (WT PC) and mutated PC (A267T PC) cDNAs. PC mRNA levels were assessed by qRT-PCR and the PC protein levels were measured by ELISA. The mRNA levels of WT PC and A267T PC were similar, while the intracellular protein level of A267T PC was moderately decreased compared to WT PC. The secretion of A267T PC into the medium was severely impaired. No differences in molecular weights were observed between WT and A267T PC before and after treatment with endo-β-N-acetylglucosaminidase. Proteasomal and lysosomal degradations were examined using lactacystin and bafilomycin, respectively, and revealed that A267T PC was slightly more susceptible for proteasomal degradation than WT PC. Intracellular co-localization analysis indicated that A267T PC was mainly located in the endoplasmic reticulum (ER), whereas WT PC was observed in both ER and Golgi.ConclusionsIn contrast to what has been reported for other PC mutants, intracellular degradation of A267T PC was not the main/dominant mechanism underlying the reduced intracellular and secretion levels of PC. Our results indicate that the A267T mutation most likely caused misfolding of PC, which might lead to increased retention of the mutated PC in ER.

【 授权许可】

Unknown   
© Tjeldhorn et al; licensee BioMed Central Ltd. 2010. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.