Human plasminogen activator inhibitor type 1 (PAI-1) is a serine protease inhibitor with a metastable active conformation. Under physiological conditions, half of the inhibitor transitions to a latent state within 1-2 h. The interaction between PAI-1 and the plasma protein vitronectin prolongs this active lifespan by~50%. Previously, our group demonstrated that PAI-1 binds to resins using immobilized metal affinity chromatography (Day, U.S. Pat. 7,015,021 B2, March 21, 2006). In this study, the effect of these metals on function and stability was investigated by measuring the rate of the transition from the active to latent conformation. All metals tested showed effects on stability, with the majority falling into one of two types depending on their effects. The first type of metal, which includes magnesium, calcium and manganese, invoked a slight stabilization of the active conformation of PAI-1. A second category of metals, including cobalt, nickel and copper, showed the opposite effects and a unique vitronectin-dependent modulation of PAI-1 stability. This second group of metals significantly destabilized PAI-1, although the addition of vitronectin in conjunction with these metals resulted in a marked stabilization and slower conversion to the latent conformation. In the presence of copper and vitronectin, the halflife of active PAI-1 was extended to 3 h, compared to a half-life of only~30 min with copper alone. Nickel had the largest effect, reducing the half-life to~5 min. Together, these data demonstrate a heretofore-unknown role for metals in modulating PAI-1 stability.
CRISPR/Cas9 has become a powerful genome editing tool in recent years. CRISPR/Cas9 can be utilized to not only efficiently generate knock out models in various organisms, but also to precisely model human disease or variants to study gene function and develop therapies.However, the latter remains challenging because of low knock-in (KI) efficiency. In this study, precise gene editing modeling plasminogen activator inhibitor-1 (PAI-1) -tissue plasminogen activator (tPA) binding deficiency and PAI-1-vitronectin binding deficiency were generated respectively in mice. Optimization of single guide RNAs (sgRNA) and repair templates, and utilization of restriction fragment length polymorphism (RFLP) to detect KI events are described. Injection of sgRNA/Cas9/single-stranded oligodeoxynucleotide (ssODN) into mouse zygotes resulted in homozygous changes of two silent mutations and changed Arg369>Ala, which abolishes PAI-1 inhibitory activity against tPA. Targeting Arg124 and Gln146 simultaneously involved in vitronectin binding proved to be challenging. However, we successfully generated these relatively distant mutations (23 amino acids apart) seamlessly.Generation of the Arg124 mutation alone was achieved with over 60% efficiency along with the integration of a restriction site, compared to the relatively low double mutation frequency. In summary, our data indicates that the distance between desired mutations and CRISPR-induced double-stranded break (DSB) site is the most critical factor for achieving high efficiency in precise gene modification.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.