👤 Hanisha Bhakta

Lipoprotein(a) (Lp(a)) is a genetically determined causal risk factor for cardiovascular disease, with approximately 20% of the population exhibiting elevated levels. While there are promising drugs in development, there are currently no approved therapies specifically designed to lower Lp(a) levels. For high-risk individuals with extreme levels of Lp(a), liver-directed genome editing could be an effective one-time solution. Genome editing approaches such as CRISPR and TALENs can reduce Lp(a) in LPA-transgenic mouse models, but they frequently induce large and potentially harmful genomic deletions. Here, we report the first application of TadA-derived cytosine base editing (CBE), delivered via helper-dependent adenovirus (HDAdV) and adeno-associated virus (AAV) vectors, to introduce premature stop codons into LPA. This strategy produced robust and durable lowering of circulating apolipoprotein(a) (apo(a)) in LPA-transgenic mice. Using SMRT-seq with single-molecule unique molecular identifiers, we quantified deletion events and found that CBE did not induce large deletions when targeting a single LPA site and produced only a small fraction (<4%) of large deletions when editing across multiple sites. In contrast, CRISPR-Cas9 cutting of LPA resulted primarily in large deletions. These findings demonstrate that CBE enables sustained reduction of circulating apolipoprotein(a) in an LPA-transgenic mouse model while largely preserving genomic integrity. Show less

RNA editing is a significant mechanism underlying genetic variation and protein molecule alteration; C-to-U RNA editing, specifically, is important in the regulation of mammalian genetic diversity. The ability to define and limit accesses of enzymatic machinery to avoid the modification of unintended targets is key to the success of RNA editing. Identification of the core component of the apoB RNA editing holoenzyme, APOBEC, and investigation into new candidate genes encoding other elements of the complex could reveal further details regarding APOBEC-mediated mRNA editing. Menkes disease is a recessive X-chromosome-linked hereditary syndrome in humans, caused by defective copper metabolism due to mutations in the Show less

Were Neanderthals and Denisovans (referred here also as extinct hominidae) carrying deleterious variants in genes regulating reproduction? The majority of extinct hominidae analyzed here, presented a considerable number of deleterious variants per individual in proteins regulating different aspects of reproduction, including gonad and uterine function, and gametogenesis. Neanderthals, Denisovans and extant humans were interfertile and hybridized while occupying geographically overlapping areas in Europe and Asia. This is evidenced by the small archaic genome component (average ∼2%) present in non-African extant humans. The genome of eight extinct hominidae, together with five human genome databases, plus 44 mothers and 48 fathers (fertile controls), were screened to look for deleterious variants in 1734 protein-coding genes regulating reproduction. Ancient DNA from six Neanderthals and two Denisovans dated between ∼82 000 and 43 000 calibrated years was retrieved from the public European Nucleotide Archive. The hominins analyzed include Altai, Vindija 33.15, 33.19, 33.25 and 33.26, El Sidron 1253, Denisova 3 and 11. Their DNA was analyzed using the CLC Genomics Workbench 12, by mapping overlapping paired-end reads (Illumina, FASTQ files) to the human genome assembly GRCh37 (hg19) (Vindija 33.19, 33.25, 33.26, Denisova 3 and Denisova 11) or by analyzing BAM files (Altai, El Sidron 1253 and Vindija 33.15) (human genome reference, GRCh37 (hg19)). Non-synonymous reproductive variants were classified as deleterious or tolerated (PolyPhen-2 and SIFT analyses) and were compared to deleterious variants obtained from extant human genome databases (Genome Aggregation Database (GnomAD), 1000 Genomes, the Haplotype Map (HapMap), Single Nucleotide Polymorphism Database (dbSNPs)) across different populations. A genetic intersection between extant or extinct DNA variants and other genetic disorders was evaluated by annotating the obtained variants with the Clinical Variant (ClinVar) database. Among the eight extinct hominidae analyzed, a total of 9650 non-synonymous variants (only coverage ≥20 reads included; frameshift mutations were excluded) in 1734 reproductive protein-coding genes were found, 24% of which were classified as deleterious. The majority (73%) of the deleterious alleles present in extant humans that are shared between extant humans and extinct hominidae were found to be rare (<1%) in extant human populations. A set of 8044 variants were found uniquely in extinct hominidae. At the single-gene level, no extinct individual was found to be homozygous for deleterious variants in genes necessary for gamete recognition and fusion, and no higher chance of embryo-lethality (calculated by Mendelian Genetics) was found upon simulated mating between extant human and extinct hominidae compared to extant human-extant human. However, three of the eight extinct hominidae were found to be homozygous for 48-69 deleterious variants in 55 genes controlling ovarian and uterine functions, or oogenesis (AKAP1, BUB1B, CCDC141, CDC73, DUSP6, ESR1, ESR2, PATL2, PSMC3IP, SEMA3A, WT1 and WNT4). Moreover, we report the distribution of nine Neanderthal variants in genes associated with a human fertility phenotype found in extant human populations, one of which has been associated with polycystic ovarian syndrome and primary congenital glaucoma. While analyzing archaic DNA, stringent filtering criteria were adopted to screen for deleterious variants in Neanderthals and Denisovans, which could result in missing a number of variants. Such restraints preserve the potential for detection of additional deleterious variants in reproductive proteins in extinct hominidae. This study provides a comprehensive overview of putatively deleterious variants in extant human populations and extinct individuals occurring in 1734 protein-coding genes controlling reproduction and provides the fundaments for future functional studies of extinct variants in human reproduction. This study was supported by the Department of Biological Science and by the Office of Research and Sponsored Programs at the University of Tulsa (Faculty Research Grant and Faculty Research Summer Fellowship) to M.A. and the University of Tulsa, Tulsa Undergraduate Research Challenge (TURC) program to E.L.; no conflict of interest to declare. N/A. Show less