CRISPR/Cas9-Mediated Gene Editing of ARG1 in Cell Lines and Primary Cells

Arginase 1 deficiency, a urea cycle disorder resulting from an inability of the body to convert arginine into urea, results in hyperargininemia and sporadic episodes of hyperammonemia. Arginase 1 deficiency can lead to a range of developmental disorders and progressive spastic diplegia in children, and current therapeutic options are limited. Clustered regularly interspaced short palindromic repeat (CRISPR) /CRISPR associated protein (Cas) 9 gene editing systems serve as a novel means of treating genetic disorders such as Arginase 1 (ARG1) deficiency, and must be thoroughly examined to determine their curative capabilities. In these experiments numerous guide RNAs and CRISPR/Cas9 systems targeting the ARG1 gene were designed and observed by heteroduplex assay for their targeting capabilities and cleavage efficiencies in multiple cell lines. The CRISPR/Cas9 system utilized in these experiments, along with a panel of guide RNAs targeting various locations in the arginase 1 gene, successfully produced targeted cleavage in HEK293, MCF7, A549, K562, HeLa, and HepG2 cells; however, targeted cleavage in human dermal fibroblasts, blood outgrowth endothelial cells, and induced pluripotent stem cells was not observed. Additionally, a CRISPR/Cas system involving partially inactivated Cas9 was capable of producing targeted DNA cleavage in intron 1 of ARG1, while a Cas protein termed Cpf1 was incapable of producing targeted cleavage. These results indicate a complex set of variables determining the CRISPR/Cas9 systems’ capabilities in the cell lines and primary cells tested. By examining epigenetic factors and alternative CRISPR/Cas9 gene targeting systems, the CRISPR/Cas9 system can be more thoroughly considered in its ability to act as a means towards editing the genome of arginase 1-deficient individuals.

Identification and Development of Enzymes Associated With the Sperm Inner Acrosomal Membrane and Their Function during Fertilization

In order for mammalian fertilization to transpire, spermatozoa must transit through the female reproductive tract and penetrate the outer investments of the oocyte: the cumulus oophorus and the zona pellucida. In order to penetrate the oocyte, spermatozoa must undergo the acrosome reaction. The acrosome reaction results in the exposure of the inner acrosomal membrane (IAM) and proteins that coat it to the extracellular environment. After the acrosome reaction, the IAM becomes the leading edge of spermatozoa undergoing progressive movement. Thus the enzymes which effect lysis of the oocyte investments ought to be located on the IAM. An objective of this study was to identify and characterize enzymatic activity detected on the IAM and provide evidence that they play a role in fertilization. This study also describes procedures for fractionating spermatozoa and isolating the IAM and proteins on its intra- and extra-vesicular surfaces, and describes their development during male gametogenesis. Since the IAM is exposed to the extracellular environment and oviductal milieu after the acrosome reaction, this study also sought to characterize interactions and relationships between factors in the oviductal environment and the enzymes identified on the IAM. The data presented provide evidence that MMP2 and acrosin are co-localized on the IAM, originate from the Golgi apparatus in gametogenesis, and suggest they cooperate in their function. Their localization and results of in vitro fertilization suggests they have a function in zona pellucida penetration. The data also provide evidence that plasminogen, originating from the oviductal epithelium and/or cumulus-oocyte complex, is present in the immediate environment of sperm-egg initial contact and penetration. Additionally, plasminogen interacts with MMP2 and enhances its enzymatic action on the IAM. The data also provide evidence that MMP2 has an important function in penetration of the cumulus oophorus. Holistically, this thesis provides evidence that enzymes on the IAM, originating from the Golgi apparatus in development, have an important function in penetration of the outer investments of the oocyte, and are aided in penetration by plasminogen in the female reproductive tract.