MOLECULAR GENETICS OF FACTOR IX AND OTHER BLOOD PROTEINS

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Serine proteases play essential roles in many physiologicl reactions such as blood coagulation, fibrinolysis, and complement activation. We will focus our research efforts on several serine proteases in order to better understand their molecular genetics and biology. Firstly, we propose to extend our study on human abonormal factor IX (christmas factor) genes. Human factor IX is a precursor to a serine protease which is a single chain glycoprotein (Mr=56,000). Factor IX participates in the middle phase of blood coagulation and its deficiency (hemophilia B) is a hereditary disease caused by an abnormal factor IX gene. In order to understand the heterogenous mechanisms of this hereditary disease, we plan to clone and analyze several abnormal factor IX genes as to their DNA sequences. In order to define the regulatory mechanism for factor IX gene, we also propose to anlayze in detail one of the abnormal factor IX genes whose expression is developmentally regulated. We have already determined the complete nucleotide sequence of the normal factor IX gene and this will greatly facilitate our proposed studies. Furthermore, we plan to continue our search for an improved expression system for the factor IX cDNA (or gene). These studies will enable us to establish better methods of diagnosis and therapy for factor IX deficiency. Clr is a precursor to serine protease and is composed of a single- chain glycoprotein (each Mr about 86,000). Clr is a subcomponent of the first component (Cl) of complement and plays a central role in the activation of the classical pathway of complement. Its deficiency is a hereditary disorder caused by an abnormal Clr gene. Individuals with Clr deficiencies often develop auto- immune disease and are highly predisposed to various microbial infections. In order to understand the mechanism of this hereditary disease, we propose to study the structure and organization of the gene for normal and abnormal individuals. A full length cDNA for human Clr has already been isolated and sequenced. A set of human genomic clones for the normal Clr will be isolated and the organization and complete nucleotide sequence for this gene will be elucidated. We also plan to isolate a cDNA and genomic clone for the subcomponent Cls in order to study the mechnaism of its hereditary disorder on the DNA level. Cls is clearly related to Clr and is a precursor to serine protease. Thirdly we propose to study a new serine protease, protease UW in order to define its physiological function and to analyze its gene organization. Protease UW was identified as a member of the serine protease family based on its amino acid sequence derived from a cDNA isolated. Studies on these serine proteases will provide valuable information about the evolutional process and biology of these important proteins. These findings may enable us to establish a fast and reliable prenatal diagnoses and a better therapy for the hereditary disorders of these proteins.