Human DNA Sequences Research Articles

Disentangling Race from Skin Color in Modern Biology and Medicine

In this review, we examine the taxonomies used to classify people, which influenced the development of the modern disciplines of biology and medicine, including dermatology, throughout the world. Early European scientists and physicians were intertwined with the social environment that created classifications and hierarchies of skin-color-based races, which were reinforced by prevailing political systems that supported colonial economic structures and, in many cases, chattel slavery. Even after genomic analysis of diverse human DNA sequences have revealed that systems of skin color-based racial and ethnic classification lacked biological meaning and were socially constructed, these classifications persist and are reinforced by census classifications and frameworks for comparisons in biomedicine in many parts of the world. The bodies of knowledge and practices that were built on these classifications did not reflect the observable biological diversity of people but the dominant cultural institutions and economic systems of their times. We provide actions for our modern institutions to reduce the underpinnings and ramifications of racial and ethnic classifications ultimately to improve biomedical research and medical care for all patients.

Correction: Fractal Properties in Electronic Spectra of GA Sequences of Human DNA

Correction: Fractal Properties in Electronic Spectra of GA Sequences of Human DNA

C16ORF70/MYTHO promotes healthy aging in C.elegans and prevents cellular senescence in mammals.

The identification of genes that confer either extension of life span or accelerate age-related decline was a step forward in understanding the mechanisms of aging and revealed that it is partially controlled by genetics and transcriptional programs. Here, we discovered that the human DNA sequence C16ORF70 encodes a protein, named MYTHO (macroautophagy and youth optimizer), which controls life span and health span. MYTHO protein is conserved from Caenorhabditis elegans to humans and its mRNA was upregulated in aged mice and elderly people. Deletion of the orthologous myt-1 gene in C. elegans dramatically shortened life span and decreased animal survival upon exposure to oxidative stress. Mechanistically, MYTHO is required for autophagy likely because it acts as a scaffold that binds WIPI2 and BCAS3 to recruit and assemble the conjugation system at the phagophore, the nascent autophagosome. We conclude that MYTHO is a transcriptionally regulated initiator of autophagy that is central in promoting stress resistance and healthy aging.

Fractal Properties in Electronic Spectra of GA Sequences of Human DNA

Fractal Properties in Electronic Spectra of GA Sequences of Human DNA

Ancient DNA speaks

Many human DNA sequences have been obtained from ancient remains dating back from several millennia. However, these have low coverage and may contain many errors; this has limited their usefulness for many analyses, in particular the search for Identical By Descent (IBD) segments that is very powerful for detection of kinship. A new method, using imputation from database data and sophisticated statistical analysis, proves able to detect IBD segments (and thus parenthood) in low-quality DNA sequences from individuals linked only by sixth degree parenthood, opening a whole new field of investigation using ancient DNA.

Multifractal Properties of Human Chromosome Sequences

The intricacy and fractal properties of human DNA sequences are examined in this work. The core of this study is to discern whether complete DNA sequences present distinct complexity and fractal attributes compared with sequences containing exclusively exon regions. In this regard, the entire base pair sequences of DNA are extracted from the NCBI (National Center for Biotechnology Information) database. In order to create a time series representation for the base pair sequence {G,C,T,A}, we use the Chaos Game Representation (CGR) approach and a mapping rule f, which enables us to apply the metric known as the Complexity–Entropy Plane (CEP) and multifractal detrended fluctuation analysis (MF-DFA). To carry out our investigation, we divided human DNA into two groups: the first is composed of the 24 chromosomes, which comprises all the base pairs that form the DNA sequence, and another group that also includes the 24 chromosomes, but the DNA sequences rely only on the exons’ presence. The results show that both sets provide fractal patterns in their structure, as obtained by the CGR approach. Complete DNA sequences show a sharper visual fractal pattern than sequences composed only of exons. Moreover, the sequences occupy distinct areas of the complexity–entropy plane, and the complete DNA sequences lead to greater statistical complexity and lower entropy than the exon sequences. Also, we observed that different fractal parameters between chromosomes indicate diversity in genomic sequences. All these results occur in different scales for all chromosomes.

MutLα suppresses error-prone DNA mismatch repair and preferentially protects noncoding DNA from mutations

The DNA mismatch repair (MMR) system promotes genome stability and protects humans from certain types of cancer. Its primary function is the correction of DNA polymerase errors. MutLα is an important eukaryotic MMR factor. We have examined the contributions of MutLα to maintaining genome stability. We show here that loss of MutLα in yeast increases the genome-wide mutation rate by ∼130-fold and generates a genome-wide mutation spectrum that consists of small indels and base substitutions. We also show that loss of yeast MutLα leads to error-prone MMR that produces T > C base substitutions in 5'-ATA-3' sequences. In agreement with this finding, our examination of human whole-genome DNA sequencing data has revealed that loss of MutLα in induced pluripotent stem cells triggers error-prone MMR that leads to the formation of T > C mutations in 5'-NTN-3' sequences. Our further analysis has shown that MutLα-independent MMR plays a role in suppressing base substitutions in N3 homopolymeric runs. In addition, we describe that MutLα preferentially protects noncoding DNA from mutations. Our study defines the contributions of MutLα-dependent and independent mechanisms to genome-wide MMR.

Mitochondria-Selective Dicationic Small-Molecule Ligand Targeting G-Quadruplex Structures for Human Colorectal Cancer Therapy.

Mitochondria are important drug targets for anticancer and other disease therapies. Certain human mitochondrial DNA sequences capable of forming G-quadruplex structures (G4s) are emerging drug targets of small molecules. Despite some mitochondria-selective ligands being reported for drug delivery against cancers, the ligand design is mostly limited to the triphenylphosphonium scaffold. The ligand designed with lipophilic small-sized scaffolds bearing multipositive charges targeting the unique feature of high mitochondrial membrane potential (MMP) is lacking and most mitochondria-selective ligands are not G4-targeting. Herein, we report a new small-sized dicationic lipophilic ligand to target MMP and mitochondrial DNA G4s to enhance drug delivery for anticancer. The ligand showed marked alteration of mitochondrial gene expression and substantial induction of ROS production, mitochondrial dysfunction, DNA damage, cellular senescence, and apoptosis. The ligand also exhibited high anticancer activity against HCT116 cancer cells (IC50, 3.4 μM) and high antitumor efficacy in the HCT116 tumor xenograft mouse model (∼70% tumor weight reduction).

Clustering molecular energy landscapes by adaptive network embedding

In order to efficiently explore the chemical space of all possible small molecules, a common approach is to compress the dimension of the system to facilitate downstream machine learning tasks. Towards this end, we present a data-driven approach for clustering potential energy landscapes of molecular structures by applying recently developed Network Embedding techniques to obtain latent variables defined through the embedding function. To scale up the method, we also incorporate an entropy sensitive adaptive scheme for hierarchical sampling of the energy landscape, based on Metadynamics and Transition Path Theory. Taking into account the kinetic information implied by the energy landscape of a system, we can interpret dynamical node-node relationships in reduced dimensions. We demonstrate the framework through Lennard-Jones clusters and a human DNA sequence.

Mismatch repair enzymes regulate telomere recombination in Saccharomycescerevisiae

DNA mismatch repair (MMR) is a crucial mechanism that ensures chromosome stability and prevents the development of various human cancers. Apart from its role in correcting mismatches during DNA replication, MMR also plays a significant role in regulating recombination between non-identical sequences, a process known as homeologous recombination. Telomeres, the protective ends of eukaryotic chromosomes, possess sequences that are not perfectly homologous. While telomerase primarily maintains telomere length in the yeast Saccharomyces cerevisiae, recombination between telomeres becomes a major pathway for length maintenance in cells lacking telomerase. This study investigates the participation of MMR in telomere recombination. Our findings reveal that mutations in MMR genes activate type I recombination. Notably, among the MMR proteins, MutSα (Msh2 and Msh6) and MutLα (Mlh1 and Pms1) exerted the most pronounced effects on telomere recombination. We also found that yeast cells containing simple human telomeric TTAGGG DNA sequences preferentially utilize type II recombination to maintain their telomeres, highlighting the influence of the heterogeneous nature of yeast telomeric sequences on type II recombination. Furthermore, our observations indicate that MMR activity is indispensable for its impact on telomere recombination. Collectively, these results contribute to a more comprehensive understanding of the role of MMR in telomere recombination.

Quantitation of human mitochondrial DNA and whole mtGenomes sequencing of fingernail/hair shaft samples

Abstract The analysis of mitochondrial DNA (mtDNA) is suitable for fingernail/hair shaft samples in forensic science. A successful mtDNA forensic analysis depends on the quantity and quality of the mtDNA. The application of massively parallel sequence (MPS) techniques to the analysis of mtDNA has the potential to improve the recovery of genetic information from difficult forensic specimens and to increase the discrimination potential of mtDNA by capturing and comparing full mtGenomes. In this study, we constructed mtDNA-specific standard curves using real-time PCR. The 105-base pair target sequence facilitates the amplification of degraded DNA and is minimally homologous to nonhuman mtDNA. The results indicated that the assay enables the absolute quantification of mtDNA down to 10 copies of mtDNA and provides a dynamic range of seven orders of magnitude. Whole mtGenome sequencing experiments demonstrated that as few as 2000 mtDNA copies resulted in a successful full region amplification and sequencing. Moreover, the frequency of point heteroplasmy from one donor showed that hairs from the same donor have been found to differ within and among themselves and from other tissues, which could impact the interpretation of the results obtained in a forensic investigation.

AI will not give us precision medicine.

The completion of human DNA sequencing in the early 2000s initially generated widespread excitement and hope that it would revolutionize medicine. Over time, however, it revealed major limitations due to a lack of understanding of the highly complex genotype-phenotype pathway. Precision medicine has emerged as a response to these biotechnological innovations, tailoring treatments based on an array of new molecular and clinical "omics" data. However, the large volume and heterogeneity of data available today requires the use of dedicated and highly efficient computational analyses. Widely used today are artificial intelligence techniques (such as machine learning) based on artificial neural networks, i.e., a mathematical model of how biological neurons work. Here, we show that artificial neural networks have nothing to do with biology, although their popularity is largely due to their alleged ability to simulate the human brain. Furthermore, we argue that the analysis of large molecular datasets cannot be left to the computational side alone, i.e., to be exclusively data-driven, but on the contrary must meet the challenge of integrating data and expertise, of getting clinicians and data analysts to work together to take into account the absolute and ineradicable uniqueness of each patient's characteristics.

Relationship of MicroRNAs with Transposable Elements in the Type 1 Diabetes Development

The review article describes the involvement of epigenetic factors in type 1 diabetes mellitus (T1DM) etiopathogenesis. The disease is characterized by changes in expression of microRNAs that affect the transcription of genes involved in autoimmune reactions, destruction of beta cells and insulin production. However, the cause of the observed epigenetic changes is still unclear. In evolution, the sources of microRNA genes are transposable elements, which occupy up to 45 % of the entire human DNA sequence and are drivers of epigenetic regulation in ontogenesis. They are sources of transcription factor sequences and binding sites for them. Features of the genome distribution of transposable elements can cause changes in the number of 5’VNTR (variable number of tandem repeats) — repeats of insulin promoter region and HERV insertions into HLA genes, which affects their expression. Therefore, I assume that the cause of the development of type 1 diabetes mellitus may be an imbalance in transcription activation of transposons, which contributes to changes in the expression of specific microRNAs and protein-coding genes, and also contributes to autoimmune response development. Triggers for this may be individual features of genome distribution of transposons, viral infections and stress. An analysis of the scientific literature confirms my proposed mechanisms for T1DM development, since the global role of retroelements in hormonal regulation, the sensitivity of transposable elements to exogenous viral infections and stress, and HERV-W expression of the majority of patients with T1DM with activation of the autoimmune response have been proven. Analysis of the MDTE DB (miRNAs derived from transposable elements database) database showed the transposon origin of 12 T1DM-associated microRNAs (miR-192, miR-224, miR-31, miR-320c, miR-326, miR-340, miR-342, miR-44661, miR-548c, miR-652, miR-95), the use of which can become the basis for targeted therapy for T1DM.

Pangenome databases improve host removal and mycobacteria classification from clinical metagenomic data.

Culture-free real-time sequencing of clinical metagenomic samples promises both rapid pathogen detection and antimicrobial resistance profiling. However, this approach introduces the risk of patient DNA leakage. To mitigate this risk, we need near-comprehensive removal of human DNA sequences at the point of sequencing, typically involving the use of resource-constrained devices. Existing benchmarks have largely focused on the use of standardized databases and largely ignored the computational requirements of depletion pipelines as well as the impact of human genome diversity. We benchmarked host removal pipelines on simulated and artificial real Illumina and Nanopore metagenomic samples. We found that construction of a custom kraken database containing diverse human genomes results in the best balance of accuracy and computational resource usage. In addition, we benchmarked pipelines using kraken and minimap2 for taxonomic classification of Mycobacterium reads using standard and custom databases. With a database representative of the Mycobacterium genus, both tools obtained improved specificity and sensitivity, compared to the standard databases for classification of Mycobacterium tuberculosis. Computational efficiency of these custom databases was superior to most standard approaches, allowing them to be executed on a laptop device. Customized pangenome databases provide the best balance of accuracy and computational efficiency when compared to standard databases for the task of human read removal and M. tuberculosis read classification from metagenomic samples. Such databases allow for execution on a laptop, without sacrificing accuracy, an especially important consideration in low-resource settings. We make all customized databases and pipelines freely available.

Spectroscopy and calorimetry evidence of binding-induced thermal stabilization of human telomeric G-quadruplex DNA by 1,5-disubstituted morpholino-amido anthraquinone: Molecular basis of anticancer action

We report interaction of 1,5-Bis (3-morpholinopropionamido) anthracene-9,10-dione with Human Telomeric G4 DNA sequences, wHTel26 and HTel22 in presence of K+ and Na+ ions, respectively. Surface Plasmon Resonance yields association constant Kb = 1.0–3.8x105 M−1 with HTel22 in K+-rich solution. Significant hypochromism (46–79 %) and fluorescence quenching (83–92 %), no change in absorption and emission maxima, unaltered fluorescence lifetime of ligand, change in conformation of G4 DNA with no overall disruption of G-quartets and absence of induced Circular Dichroism band, suggest external groove binding of ligand. Molecular docking shows short contacts of 9O, 15N, 18O, 11NH, 12CO atoms of ligand with A3, G4, G22, G23 and A1, G3, G14 bases of 3 + 1 hybrid-2 and 2 + 2 anti-parallel conformers, respectively without making any contact with loops, to an energetically more favourable conformation. Ligand-influenced thermal stabilization, up to ΔTm = 37/48 °C, may disrupt access of telomerase enzyme to telomere and promote apoptosis in malignant tissues.

Dynamics and recognition of homeodomain containing protein-DNA complex of IRX4.

Iroquois Homeobox 4 (IRX4) belongs to a family of homeobox TFs having roles in embryogenesis, cell specification, and organ development. Recently, large scale genome-wide association studies and epigenetic studies have highlighted the role of IRX4 and its associated variants in prostate cancer. No studies have investigated and characterized the structural aspect of the IRX4 homeodomain and its potential to bind to DNA. The current study uses sequence analysis, homology modeling, and molecular dynamics simulations to explore IRX4 homeodomain-DNA recognition mechanisms and the role of somatic mutations affecting these interactions. Using publicly available databases, gene expression of IRX4 was found in different tissues, including prostate, heart, skin, vagina, and the protein expression was found in cancer cell lines (HCT166, HEK293), B cells, ascitic fluid, and brain. Sequence conservation of the homeodomain shed light on the importance of N- and C-terminal residues involved in DNA binding. The specificity of IRX4 homodimer bound to consensus human DNA sequence was confirmed by molecular dynamics simulations, representing the role of conserved amino acids including R145, A194, N195, S190, R198, and R199 in binding to DNA. Additional N-terminal residues like T144 and G143 were also found to have specific interactions highlighting the importance of N-terminus of the homeodomain in DNA recognition. Additionally, the effects of somatic mutations, including the conserved Arginine (R145, R198, and R199) residues on DNA binding elucidated the importance of these residues in stabilizing the protein-DNA complex. Secondary structure and hydrogen bonding analysis showed the roles of specific residues (R145, T191, A194, N195, R198, and R199) in maintaining the homogeneity of the structure and its interaction with DNA. The differences in relative binding free energies of all the mutants shed light on the structural modularity of this protein and the dynamics behind protein-DNA interaction. We also have predicted that the C-terminal sequence of the IRX4 homeodomain could act as a potential cell-penetrating peptide, emphasizing the role these small peptides could play in targeting homeobox TFs.

Big Data in Bioinformatics and Computational Biology: Basic Insights.

The human genome was first sequenced in 1994. It took 10years of cooperation between numerous international research organizations to reveal a preliminary human DNA sequence. Genomics labs can now sequence an entire genome in only a few days. Here, we talk about how the advent of high-performance sequencing platforms has paved the way for Big Data in biology and contributed to the development of modern bioinformatics, which in turn has helped to expand the scope of biology and allied sciences. New technologies and methodologies for the storage, management, analysis, and visualization of big data have been shown to be necessary. Not only does modern bioinformatics have to deal with the challenge of processing massive amounts of heterogeneous data, but it also has to deal with different ways of interpreting and presenting those results, as well as the use of different software programs and file formats. Solutions to these problems are tried to present in this chapter. In order to store massive amounts of data and provide a reasonable period for completing search queries, new database management systems other than relational ones will be necessary. Emerging advance programing approaches, such as machine learning, Hadoop, and MapReduce, aim to provide the capacity to easily construct one's own scripts for data processing and address the issue of the diversity of genomic and proteomic data formats in bioinformatics.

Spectroscopy evidence of interaction of 1,5 disubstituted piperidino-amido anthraquinone derivative with human telomeric G-quadruplex DNA: Basis of anticancer action

The binding of ligands to G-quadruplex (G4) structures at the ends of human telomeric DNA induces thermal stabilization, which interferes with telomere maintenance by disrupting the association of telomeres with the telomerase enzyme—an important marker for cancer. Understanding the binding mode of the ligand-G quadruplex DNA complex is imperative for evaluating the relative efficacy and specificity of their interaction. We focused on the interaction of 1,5-Bis(3-piperidino propionamido) anthracene-9,10-dione with human telomeric DNA sequences using surface plasmon resonance, absorbance, fluorescence (steady-state and lifetime), and circular dichroism spectroscopy techniques. The ligand binding with HTel22 (Kb = 8.4 × 105 M−1) induced cell toxicity with an IC50 value of ∼ 8.64 µM in MCF-7 cancer cell lines. Significant hypochromism (59 %), fluorescence quenching (97 %), no change in fluorescence lifetime and absence of induced Circular Dichroism (CD) band upon addition of G4 DNA to ligand, suggest a groove/external binding mode. CD spectral changes reflect rearrangement in parallel and antiparallel strands to accommodate the ligand. Docking results reveal specific short contacts of the ligand's side chain, including 9CO, 13N, 14NH, and 11CO, with the grooves of the G4 DNA, without making any contact with the loops, favoring an energetically more favorable conformation. Thermal denaturation profiles, obtained by Differential Scanning Calorimetry and CD, show the stabilization of wHTel26 and HTel22 G4 DNA in K+ and Na+ rich solutions by 21.2 and 17.6 °C, respectively, which may restrict the access of telomerase to telomeres. The findings indicate the potential of modifying anthraquinone substituent groups for therapeutic applications.

Post- and Pre-Radiolabeling Assays for anti Thymidine Cyclobutane Dimers as Intrinsic Photoprobes of Various Types of G-Quadruplexes, Reverse Hoogsteen Hairpins, and Other Non-B DNA Structures.

G-quadruplexes are thought to play an important role in gene regulation and telomere maintenance, but developing probes for their presence and location is challenging due to their transitory and highly dynamic nature. The majority of probes for G-quadruplexes have relied on antibody or small-molecule binding agents, many of which can also alter the dynamics and relative populations of G-quadruplexes. Recently, it was discovered that ultraviolet B (UVB) irradiation of human telomeric DNA and various G-quadruplex forming sequences found in human promoters, as well as reverse Hoogsteen hairpins, produces a unique class of non-adjacent anti cyclobutane pyrimidine dimers (CPDs). Therefore, one can envision using a pulse of UVB light to irreversibly trap these non-B DNA structures via anti CPD formation without perturbing their dynamics, after which the anti CPDs can be identified and mapped. As a first step toward this goal, we report radioactive post- and pre-labeling assays for the detection of non-adjacent CPDs and illustrate their use in detecting trans,anti T=(T) CPD formation in a human telomeric DNA sequence. Both assays make use of snake venom phosphodiesterase (SVP) to degrade the trans,anti T=(T) CPD-containing DNA to the tetranucleotide pTT=(pTT) corresponding to CPD formation between the underlined T's of two separate dinucleotides while degrading the adjacent syn TT CPDs to the trinucleotide pGT=T. In the post-labeling assay, calf intestinal phosphodiesterase is used to dephosphorylate the tetranucleotides, which are then rephosphorylated with kinase and [32P]-ATP to produce radiolabeled mono- and diphosphorylated tetranucleotides. The tetranucleotides are confirmed to be non-adjacent CPDs by 254 nm photoreversion to the dinucleotide p*TT. In the pre-labeling assay, radiolabeled phosphates are introduced into non-adjacent CPD-forming sites by ligation prior to irradiation, thereby eliminating the dephosphorylation and rephosphorylation steps. The assays are also demonstrated to detect the stereoisomeric cis,anti T=(T) CPD.

Phase II randomized window of opportunity trial evaluating cytotoxic and immunomodulatory effects of intratumoral INT230-6 in early stage breast cancer: The INVINCIBLE trial.

573 Background: Most breast cancers are considered immunological cold and are therefore minimally responsive to immunotherapies. Local cytotoxic therapies can induce cell death, expose tumor antigens, provide adjuvants for anti-tumor immune priming, and potentially increase responsiveness to immunotherapies. We conducted a randomized, double blind, Phase 2 presurgical Window-Of-Opportunity trial for intratumoral (IT) INT230-6 (comprising VINblastine (VIN) Cisplatin (VIN)) evaluating clinical and BioLogical Effects in patients with early-stage operable Breast Cancer (the INVINCIBLE trialNCT04781725. The trial evaluated the immune response within the tumor and microenvironment in vivo after IT INT230-6 injections. Methods: Women with newly diagnosed and awaiting surgery for early-stage intermediate or high-grade ER+ T1-T2 invasive breast cancers were recruited to the trial. Participating patients were allocated (2:1) to IT injections of INT230-6 vs saline placebo, prior to resection. RNA profiling of the pre- (baseline biopsy) and post- treatment (surgical resection) tumours using the Ion AmpliSeq Transcriptome Human Gene Expression (Thermo Fisher Scientific) and DNA sequencing using a large (500 gene) comprehensive genomic profiling panel (OCAPlus,) was performed. Results: Significant tumor necrosis was observed in the majority of subjects injected with INT230-6. In the 60 pre-treatment biopsies profiled with OCAPlus, the genes most frequently mutated included PIK3CA (38%), TP53 (23%), CDH1 (22%) and TBX3 (17%). Frequent copy number changes were identified in CCND1 (23%), FGFR1 (18%), and CDH1 (17%). Gene expression analysis showed significant differential gene expression between the baseline biopsy and surgical specimens in patients treated with the drug. Pathway analysis identified genes associated with TCR signaling, macrophage markers, IL-18 signaling and B cell receptor signaling were significantly up-regulated in the post treatment samples. Conclusions: This is the first study evaluating the potential biologic effects of intratumoral cytotoxicity with INT230-6 and its role as a potential immune priming therapy in traditional immune quiescent ER+ breast cancers.