Biomedical subjects

Iva Pichova

Publications and source records attributed to Iva Pichova.

3 recordsLinked to original sources

PubMed2026

Highly efficient base editing at PCSK9 and normal human embryo development.

Cas9-based tools enable programmable DNA lesions for studying repair outcomes, gene function, and genome correction. In human embryos, Cas9-induced DNA double-strand breaks are genotoxic, causing frequent aneuploidy and large deletions1,2. Here, we evaluate DNA repair outcomes at nicks and mismatches introduced by base editors at the PCSK9 and HBG loci in human embryos. Delivering ABE8e-V106W as a protein at fertilization achieved editing at all PCSK9 alleles, supporting development to the blastocyst stage and the derivation of homozygous edited stem cell lines. No insertions or deletions were detected, although rare on-target chromosome breakage and chromosomal abnormalities occurred. Nevertheless, editing at bystander and off-target sites was mosaic, and the introduction of the editor as mRNA caused frequent embryo arrest due to guide-independent deaminase activity. Thus, unlike Cas9-induced DNA breaks, base editor-induced lesions are efficiently repaired. However, undesirable consequences for the genome and development can occur, currently precluding clinical use in reproduction.

Journal Article↗

PubMed2005

Glycosylphosphatidylinositol-anchored proteases of Candida albicans target proteins necessary for both cellular processes and host-pathogen interactions.

Intracellular and secreted proteases fulfill multiple functions in microorganisms. In pathogenic microorganisms extracellular proteases may be adapted to interactions with host cells. Here we describe two cell surface-associated aspartic proteases, Sap9 and Sap10, which have structural similarities to yapsins of Saccharomyces cerevisiae and are produced by the human pathogenic yeast Candida albicans. Sap9 and Sap10 are glycosylphosphatidylinositol-anchored and located in the cell membrane or the cell wall. Both proteases are glycosylated, cleave at dibasic or basic processing sites similar to yapsins and Kex2-like proteases, and have functions in cell surface integrity and cell separation during budding. Overexpression of SAP9 in mutants lacking KEX2 or SAP10, or of SAP10 in mutants lacking KEX2 or SAP9, only partially restored these phenotypes, suggesting distinct target proteins of fungal origin for each of the three proteases. In addition, deletion of SAP9 and SAP10 modified the adhesion properties of C. albicans to epithelial cells and caused attenuated epithelial cell damage during experimental oral infection suggesting a unique role for these proteases in both cellular processes and host-pathogen interactions.

Animals↗

PubMed2005

Amino acid residues in the cytoplasmic domain of the Mason-Pfizer monkey virus glycoprotein critical for its incorporation into virions.

Assembly of an infectious retrovirus requires the incorporation of the envelope glycoprotein complex during the process of particle budding. We have recently demonstrated that amino acid substitutions of a tyrosine residue in the cytoplasmic domain block glycoprotein incorporation into budding Mason-Pfizer monkey virus (M-PMV) particles and abrogate infectivity (C. Song, S. R. Dubay, and E. Hunter, J. Virol. 77:5192-5200, 2003). To investigate the contribution of other amino acids in the cytoplasmic domain to the process of glycoprotein incorporation, we introduced alanine-scanning mutations into this region of the transmembrane protein. The effects of the mutations on glycoprotein biosynthesis and function, as well as on virus infectivity, have been examined. Mutation of two cytoplasmic residues, valine 20 and histidine 21, inhibits viral protease-mediated cleavage of the cytoplasmic domain that is observed during virion maturation, but the mutant virions show only moderately reduced infectivity. We also demonstrate that the cytoplasmic domain of the M-PMV contains three amino acid residues that are absolutely essential for incorporation of glycoprotein into virions. In addition to the previously identified tyrosine at residue 22, an isoleucine at position 18 and a leucine at position 25 each mediate the process of incorporation and efficient release of virions. While isoleucine 18 may be involved in direct interactions with immature capsids, antibody uptake studies showed that leucine 25 and tyrosine 22 are part of an efficient internalization signal in the cytoplasmic domain of the M-PMV glycoprotein. These results demonstrate that the cytoplasmic domain of M-PMV Env, in part through its YXXL-mediated endocytosis and intracellular trafficking signals, plays a critical role in the incorporation of glycoprotein into virions.

Amino Acid Sequence↗