| 1. |
- Lanke, E., et al.
(författare)
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Co-segregation of the PROS1 locus and protein S deficiency in families having no detectable mutations in PROS1
- 2004
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Ingår i: Journal of Thrombosis and Haemostasis. - : Wiley-Blackwell. - 1538-7933 .- 1538-7836. ; 2:11, s. 1918-1923
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Tidskriftsartikel (refereegranskat)abstract
- Inherited deficiency of protein S constitutes an important risk factor of venous thrombosis. Many reports have demonstrated that causative mutations in the protein S gene are found only in approximately 50% of the cases with protein S deficiency. It is uncertain whether the protein S gene is causative in all cases of protein S deficiency or if other genes are involved in cases where no mutation is identified. The aim of the current study was to determine whether haplotypes of the protein S gene cosegregate with the disease phenotype in cases where no mutations have been found. Eight protein S-deficient families comprising 115 individuals where previous DNA sequencing had failed to detect any causative mutations were analyzed using four microsatellite markers in the protein S gene region. Co-segregation between microsatellite haplotypes and protein S deficiency was found in seven of the investigated families, one family being uninformative. This suggests that the causative genetic defects are located in or close to the protein S gene in a majority of such cases where no mutations have been found.
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| 2. |
- Kunz, G, et al.
(författare)
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Naturally occurring mutations in the thrombomodulin gene leading to impaired expression and function
- 2002
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Ingår i: Blood. - 1528-0020. ; 99:10, s. 3646-3653
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Tidskriftsartikel (refereegranskat)abstract
- Sporadic mutations in the thrombomodulin (TM) gene occur in patients with both arterial and venous thrombosis, but the effects of these mutations on expression and function are largely unexplored. Full-length wild-type TM complementary DNA (cDNA) was incorporated into vector pcDNA6 for transfection into COS-7 cells for transient expression. Mutagenesis was performed to create 7 TM mutants with natural mutations either previously identified (Ala25Thr, Gly6lAla, Asp468Tyr, Pro477Ser, Pro483Leu) or reported here (an 11-base pair [bp] deletion, del791-801, leading to STOP306, and a missense mutation, Arg385Ser). Four mutations were found to detrimentally affect the level of expression of the TM protein. Of the missense mutations, 3 had reduced expression compared to wild-type TM (100%), Arg385Ser (50.2% +/- 5%, P < .001), Pro477Ser (76.8% +/-11%, P <.001), Pro483Leu (82.1% +/- 8%, P < .007). No TM protein expression could be detected on the cell surface for mutation del791-801. The cofactor activity of TM in protein C activation was also evaluated. The Michaelis constant (K,) for wild-type thrombin-TM complex was 634 +/- 6 nmol/L. Two mutants, with Arg385Ser and Pro477Ser, had Increased (P < .0001) K, 2967 +/- 283 nM, and 2342 +/- 219 nM, respectively, demonstrating impaired function of the thrombin-TM complex. This work presents biochemical evidence that certain (but not all) natural mutations In the TM gene reduce expression and impair function of the protein on the cell surface, and helps clarify the suggested contribution that these mutations might make to the risk of thromboembolic disease.
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| 3. |
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| 4. |
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| 5. |
- Rezende, SM, et al.
(författare)
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Genetic and phenotypic variability between families with hereditary protein S deficiency
- 2002
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Ingår i: Thrombosis and Haemostasis. - 0340-6245. ; 87:2, s. 258-265
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Tidskriftsartikel (refereegranskat)abstract
- While many mutations thought to result in protein S (PS) deficiency are known. there have been few attempts to relate genotype expression with plasma phenotype. We have investigated the nature and consequence of PS gene (PROS 1) mutations in 17 PS-deficient families who presented with mixed type I and type III phenotypes. Seven different mutations were found in nine families: delG-34 (STOP codon at -24), Val-24Glu, Arg49Cys. Asn217Ser, Gly295Val, +5 G to A intron j and His623Pro. PS wild type (PSWT) and the five missense mutants were transiently expressed in COS-1 cells. All mutants expressed lower (p<0.05) PS antigen compared to PSWT (100%). The mutants Val-24Glu, Gly295Val and His623Pro expressed very low/undetectable PS levels. The Mutant Asn217Ser produced around 30% of PSWT, while the mutant Arg49Cys had the highest PS levels (around 50%). Metabolic labelling and pulse-chase experiments showed that all of the mutants had impaired secretion, but this was of variable severity. Also, enhanced intracellular degradation of unsecreted material was found for all mutants. There was a strong correspondence between plasma free PS levels in carriers of the mutations. secreted PS from transfected COS-1 cells and labelled PS from 24 h conditioned medium in pulse-chase experiment. We conclude that the magnitude of secretion defect depends on the nature of the PROS1 mutation and influences the level of free PS in plasma. It is likely that the severity of the secretion defect will determine the risk for venous thrombosis.
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