Ming-Yang Deng1, Zi-Xian Liu1, Hai-Fan Huang1, Yong-Heng Chen2, Yu-Jiao Luo1, Nan-Nan Sun1, Zhao Cheng1, Wen-Zhe Yan1, Guang-Sen Zhang3. 1. Division of Hematology, Institute of Molecular Hematology, the Second Xiang-Ya Hospital, Central South University, Changsha, Hunan 410011, PR China. 2. Laboratory of Structural Biology, Key Laboratory of Cancer Proteomics of Chinese Ministry of Health, Xiang-Ya Hospital & State Key Laboratory of Medical Genetics, Central South University, Changsha, Hunan, PR China. 3. Division of Hematology, Institute of Molecular Hematology, the Second Xiang-Ya Hospital, Central South University, Changsha, Hunan 410011, PR China. Electronic address: zgsllzy@163.com.
Abstract
INTRODUCTION: We diagnosed two Chinese hereditary PC deficiency families and identified two novel compound heterozygous mutations (p.Arg194Cys/Gly324Ser and p.Glu274X/Asp297His) in the protein C (PROC) gene. The probands were classified as types I and II PC deficiency. The aim of this article is to access the influence of the mutations on PC activity, antigen and protein structure, and to evaluate whether there is abnormal PC localization. MATERIALS AND METHODS: Genomic DNA of all family members was extracted, PCR amplified, and sequenced. The mutant PC expression plasmids were constructed. Expression assays, intracellular localization, and molecular modeling were performed. RESULTS: Proband 1, a type II PC defect, harbored a compound heterozygous mutation, p.Arg194Cys/Gly324Ser in the PROC gene, underwent two thromboembolic events. Expression assays indicated that the p.Arg194Cys mutant lead to decreased PC activity and normal PC Ag levels. Intracellular localization showed that both p.Arg194Cys and p.Gly324Ser co-localized with the endoplasmic reticuli and the Golgi apparatus. Molecular modeling suggested that the p.Gly324Ser mutation disturbed the interaction between the heavy and light chains of the PC protein. Proband 2, a type I PC defect, harbored a compound heterozygous PROC gene mutation, p.Glu274X/Asp297His, presented with recurrent spontaneous abortion and right popliteal vein thrombosis. Expression results were in accordance with the PC changes of the patient, and existed in defective PC transport. Structural model suggested p.Glu274X lead to disulfide bond between heavy and light chain cannot form. CONCLUSIONS: Our results confirm that two novel compound heterozygous PROC gene mutations are causative on the two PC deficiency families.
INTRODUCTION: We diagnosed two Chinese hereditary PC deficiency families and identified two novel compound heterozygous mutations (p.Arg194Cys/Gly324Ser and p.Glu274X/Asp297His) in the protein C (PROC) gene. The probands were classified as types I and II PC deficiency. The aim of this article is to access the influence of the mutations on PC activity, antigen and protein structure, and to evaluate whether there is abnormal PC localization. MATERIALS AND METHODS: Genomic DNA of all family members was extracted, PCR amplified, and sequenced. The mutant PC expression plasmids were constructed. Expression assays, intracellular localization, and molecular modeling were performed. RESULTS: Proband 1, a type II PC defect, harbored a compound heterozygous mutation, p.Arg194Cys/Gly324Ser in the PROC gene, underwent two thromboembolic events. Expression assays indicated that the p.Arg194Cys mutant lead to decreased PC activity and normal PC Ag levels. Intracellular localization showed that both p.Arg194Cys and p.Gly324Ser co-localized with the endoplasmic reticuli and the Golgi apparatus. Molecular modeling suggested that the p.Gly324Ser mutation disturbed the interaction between the heavy and light chains of the PC protein. Proband 2, a type I PC defect, harbored a compound heterozygous PROC gene mutation, p.Glu274X/Asp297His, presented with recurrent spontaneous abortion and right popliteal vein thrombosis. Expression results were in accordance with the PC changes of the patient, and existed in defective PC transport. Structural model suggested p.Glu274X lead to disulfide bond between heavy and light chain cannot form. CONCLUSIONS: Our results confirm that two novel compound heterozygous PROC gene mutations are causative on the two PC deficiency families.