Biology subjects

Mita, P.

Publications and source records attributed to Mita, P..

11 recordsLinked to original sources

bioRxiv2025

Pan-cancer analysis reveals context-dependent roles of LINE-1 ORF1p in immune regulation and copy number alterations

L1 comprises 17% of the human genome, with 50-150 full-length sequences capable of retrotransposition. Although largely inactive in normal somatic tissues, tumorigenesis leads to L1 derepression and overexpression of its RNA binding chaperone protein, ORF1p. A potential cancer biomarker, ORF1p expression is a hallmark of multiple cancers and an early event in precursor lesions. Our study provides a comprehensive pan-cancer analysis of ORF1p using CPTAC proteogenomic data, revealing a dichotomous role in modulating immune responses. Integrated analyses and supervised learning models divide ORF1p-high tumors into two groups: (1) high ORF1p associates with immunosuppression, reduced interferon signaling and diminished immune cell infiltration (HNSCC and LSCC), and (2) ORF1p-high tumors associate with immune activation (UCEC). Linear regression models reveal that cancer-specific aneuploidies may underlie this immune dichotomy, highlighting the prognostic significance of ORF1p and informing new strategies to leverage detection of plasma-circulating ORF1p to enhance immunotherapeutic efficacy in different tumor contexts.

genomics↗

bioRxiv2024

Functional high capacity exosome-encapsulating bioinspired hydrogel promotes microvascularbed expansion in diabetic mice

Chronic wounds present a significant clinical challenge due to impaired skin microvasculature, particularly in diabetes. The tissue engineering study introduces therapeutic Exo-Q, a unique thermoresponsive polymer hydrogel created with Q protein nanofibers and cultured human bone marrow multipotent stromal cell exosomes with consistent gene signature. Limited, local and topical application of Exo-Q hydrogel is feasible for maximum neovascularization during murine diabetic wound closure in a xenotransplantation model, as well as compatibility and vascular delivery in human skin in a xenograft model. Exo-Q hydrogel treatment significantly reduces diabetic wound closure time within ranges of non-diabetic wounds. This innovative, non-invasive tissue engineered therapeutic option offers a promising approach to addressing the complex pathologies of non-healing wounds.

bioengineering↗

bioRxiv2020

LINE-1 ORF1p RIP-seq reveals widespread association with p-body enriched mRNAs

BackgroundLong INterspersed Element-1 (LINE-1) is an autonomous retroelement able to "copy-and-paste" itself into new loci of the host genome through a process called retrotransposition. The LINE-1 bicistronic mRNA codes for two proteins, ORF1p, a nucleic acid chaperone, and ORF2p, a protein with endonuclease and reverse transcriptase activity. Both proteins bind LINE-1 mRNA in cis and are necessary for retrotransposition. While LINE-1 transcription is usually repressed in most healthy somatic cells through a plethora of mechanisms, ORF1p expression has been observed in nearly 50% of tumors, and new LINE-1 insertions have been documented in a similar fraction of tumors, including prostate cancer. ResultsHere, we utilized RNA ImmunoPrecipitation (RIP) and the L1EM analysis software to identify ORF1p bound RNA in prostate cancer cells. We identified LINE-1 loci that were expressed in androgen sensitive and androgen independent cells, that we show are representative of LINE-1 copies expressed in prostate cancer before and after treatment. In all androgen independent cells, we found higher levels of LINE-1 RNA, as well as unique expression patterns of LINE-1 loci. Interestingly, we observed that ORF1p bound many non-LINE-1 mRNA in all prostate cancer cell lines evaluated, and polyA RNA, and RNA localized in p-bodies were especially enriched. Furthermore, the expression levels of many of the identified ORF1p bound mRNAs also correlated with expression of LINE-1 RNA in prostate tumors from The Cancer Genome Atlas (TCGA). ConclusionOur results show a significant remodeling of LINE-1 loci expression in androgen independent cell lines when compared to parental androgen dependent cells, suggesting an evolution of LINE-1 expression during prostate cancer progression. Additionally, our finding that ORF1p bound a significant amount of non-LINE-1 mRNA, and that the enriched ORF1p bound mRNAs are also amplified in LINE-1 expressing TCGA prostate tumors, suggest that ORF1p may play a role in non-LINE-1 RNA processing and regulation of specific transcripts in prostate tumors.

cell biology↗

bioRxiv2020

LINE-1 expression in cancer correlates with DNA damage response, copy number variation, and cell cycle progression

ABSTRACTRetrotransposons are genomic DNA sequences that are capable of copying themselves to new genomic locations via RNA intermediates; LINE-1 is the only retrotransposon that remains autonomous and active in the human genome. The mobility of LINE-1 is largely repressed in somatic tissues, but LINE-1 is active in many cancers. Recent studies using LINE-1 constructs indicate that host cells activate a DNA damage response (DDR) to repair retrotransposition intermediates and resolve conflicts between LINE-1 and DNA replication. Using multi-omic data from the CPTAC project, we found correlations between LINE-1 expression and ATM-MRN-SMC DDR signalling in endometrial cancer and between LINE-1 and the ATR-CHEK1 pathway in p53 wild type breast cancer. This provides evidence that conflicts between LINE-1 and DNA replication occur in at least some human cancers. Furthermore, LINE-1 expression in these cancers is correlated with the total amount of copy number variation genome wide, indicating that, when active in cancer, pointing to a direct impact of LINE-1 associated DNA damage on genome structure. We also find that, in endometrial and ovarian cancer, LINE-1 expression is correlated with the expression of genes that drive cycle progression including E2F3, PLK1 and Aurora kinase B. This study provides evidence, supporting recent work in model cell lines, of a LINE-1/DDR connection in human tumors and raises the possibility of additional interactions between LINE-1 and the cell cycle.Competing Interest StatementThe authors have declared no competing interest.View Full Text

cancer biology↗

bioRxiv2020

SHP2 Inhibition Abrogates Adaptive Resistance to KRASG12C-Inhibition and Remodels the Tumor Microenvironment of KRAS-Mutant Tumors

KRAS is the most frequently mutated oncogene in human cancer, and KRAS inhibition has been a longtime therapeutic goal. Recently, inhibitors (G12C-Is) that bind KRASG12C-GDP and react with Cys-12 were developed. Using new affinity reagents to monitor KRASG12C activation and inhibitor engagement, we found that, reflecting its action upstream of SOS1/2, SHP2 inhibitors (SHP2-Is) increased KRAS-GDP occupancy, enhancing G12C-I efficacy. SHP2-Is abrogated feedback signaling by multiple RTKs and blocked adaptive resistance to G12C-Is in vitro, in xenografts, and in syngeneic KRASG12C-mutant pancreatic ductal adenocarcinoma (PDAC) and non-small cell lung cancer (NSCLC) models. Biochemical analysis revealed enhanced suppression of ERK-, MYC-, anti-apoptotic-, and cell-cycle genes, and increased pro-apoptotic gene expression in tumors from combination-treated mice. SHP2-I/G12C-I also evoked favorable changes in the immune microenvironment, decreasing myeloid suppressor cells, increasing CD8+ T cells, and sensitizing tumors to PD-1 blockade. Experiments using cells expressing inhibitor-resistant SHP2 showed that SHP2 inhibition in PDAC cells is required for tumor regression and remodeling of the immune microenvironment, but also revealed direct inhibitory effects on angiogenesis resulting in decreased tumor vascularity. Our results demonstrate that SHP2-I/G12C-I combinations confer a substantial survival benefit in PDAC and NSCLC and identify additional combination strategies for enhancing the efficacy of G12C-Is.

cancer biology↗

bioRxiv2019

Comprehensive scanning mutagenesis of human retrotransposon LINE-1 identifies motifs essential for function

Long Interspersed Nuclear Element-1 (LINE-1, L1) is the only autonomous active transposable element in the human genome. The L1-encoded proteins ORF1p and ORF2p enable the element to jump from one locus to another via a \"copy and paste\" mechanism. ORF1p is an RNA-binding protein and ORF2p has endonuclease and reverse transcriptase activities. The huge number of truncated L1 remnants in the human genome suggests that the host has likely evolved mechanisms to prevent full L1 replication and thereby decrease the proliferation of active elements and reduce the mutagenic potential of L1. In turn, L1 appears to have a minimized length to increase the probability of successful full-length replication. This streamlining would be expected to lead to high information density. Here, we describe the construction and initial characterization of a library of 538 consecutive trialanine substitutions that scan along ORF1p and ORF2p to identify functionally important regions. In accordance with the streamlining hypothesis, retrotransposition was overall very sensitive to mutations in ORF1p and ORF2p, only 16% of trialanine mutants retained near-wild-type activity. All ORF1p mutants formed near-wild-type levels of mRNA transcripts and seventy-five percent formed near-wild-type levels of protein. Two ORF1p mutants present a unique nucleolar-relocalization phenotype. Regions of ORF2p that are sensitive to mutagenesis, but lack phylogenetic conservation were also identified. We provide comprehensive information on the regions most critical to retrotransposition. This resource will guide future studies of intermolecular interactions that form with RNA, proteins and target DNA throughout the L1 life cycle.

genetics↗

bioRxiv2019

BRCA1 Mediated Homologous Recombination and S Phase DNA Repair Pathways Restrict LINE-1 Retrotransposition in Human Cells

Long interspersed element-1 (LINE-1 or L1) is the only autonomous retrotransposon active in human cells. L1s DNA makes about 17% of the human genome and retrotransposition of a few active L1 copies has been detected in various tumors, underscoring the potential role of L1 in mediating or increasing genome instability during tumorigenic development. Different host factors have been shown to influence L1 mobility through several mechanisms. However, systematic analyses of host factors affecting L1 retrotransposition are limited. Here, we developed a high-throughput microscopy-based retrotransposition assay and coupled it to a genome-wide siRNA knockdown screen to study the cellular regulators of L1 retrotransposition in human cells. We showed that L1 insertion frequency was stimulated by knockdown of Double-Stranded Break (DSB) repair factors that are active in the S/G2 phase of the cell cycle including Homologous Recombination (HR), Fanconi Anemia (FA) and, to a less extent, microhomology-mediated end-joining (MMEJ) factors. In particular, we show that BRCA1, an E3 ubiquitin ligase with a key role in several DNA repair pathways, plays multiple roles in regulating L1; BRCA1 knockdown directly affects L1 retrotransposition frequency and structure and also plays a role in controlling L1 ORF2 protein translation through L1 mRNA binding. These results suggest the existence of a \"battle\" between HR factors and L1 retrotransposons, revealing a potential role for L1 in development of tumors characterized by BRCA1 and HR repair deficiencies.

cell biology↗

bioRxiv2017

LINE-1 and the cell cycle: protein localization and functional dynamics

LINE-1/L1 retrotransposon sequences comprise 17% of the human genome. Among the many classes of mobile genetic elements, L1 is the only autonomous retrotransposon that still drives human genomic plasticity today. Through its co-evolution with the human genome, L1 has intertwined itself with host cell biology to aid its proliferation. However, a clear understanding of L1s lifecycle and the processes involved in restricting its insertion and its intragenomic spreading remains elusive. Here we identify modes of L1 proteins entrance into the nucleus, a necessary step for L1 proliferation. Using functional, biochemical, and imaging approaches, we also show a clear cell cycle bias for L1 retrotransposition that peaks during the S phase. Our observations provide a basis for novel interpretations about the nature of nuclear and cytoplasmic L1 ribonucleoproteins (RNPs) and the potential role of DNA replication in L1 retrotransposition.

cell biology↗

bioRxiv2017

Dissection of purified LINE-1 reveals distinct nuclear and cytoplasmic intermediates

1.Long Interspersed Nuclear Element-1 (LINE-1, L1) is a mobile genetic element active in human genomes. L1-encoded ORF1 and ORF2 proteins bind L1 RNAs, forming ribonucleoproteins (RNPs). These RNPs interact with diverse host proteins, some repressive and others required for the L1 lifecycle. Using differential affinity purifications and quantitative mass spectrometry, we have characterized the proteins associated with distinctive L1 macromolecular complexes. Our findings support the presence of multiple L1-derived retrotransposition intermediates in vivo. Among them, we describe a cytoplasmic intermediate that we hypothesize to be the canonical ORF1p/ORF2p/L1-RNA-containing RNP, and we describe a nuclear population containing ORF2p, but lacking ORF1p, which likely contains host factors participating in template-primed reverse transcription.

molecular biology↗

bioRxiv2017

Human to yeast pathway transplantation: cross-species dissection of the adenine de novo pathway regulatory node

Pathway transplantation from one organism to another represents a means to a more complete understanding of a biochemical or regulatory process. The purine biosynthesis pathway, a core metabolic function, was transplanted from human to yeast. We replaced the entire Saccharomyces cerevisiae adenine de novo pathway with the cognate human pathway components. A yeast strain was \"humanized\" for the full pathway by deleting all relevant yeast genes completely and then providing the human pathway in trans using a neochromosome expressing the human protein coding regions under the transcriptional control of their cognate yeast promoters and terminators. The \"humanized\" yeast strain grows in the absence of adenine, indicating complementation of the yeast pathway by the full set of human proteins. While the strain with the neochromosome is indeed prototrophic, it grows slowly in the absence of adenine. Dissection of the phenotype revealed that the human ortholog of ADE4, PPAT, shows only partial complementation. We have used several strategies to understand this phenotype, that point to PPAT/ADE4 as the central regulatory node. Pathway metabolites are responsible for regulating PPATs protein abundance through transcription and proteolysis as well as its enzymatic activity by allosteric regulation in these yeast cells. Extensive phylogenetic analysis of PPATs from diverse organisms hints at adaptations of the enzyme-level regulation to the metabolite levels in the organism. Finally, we isolated specific mutations in PPAT as well as in other genes involved in the purine metabolic network that alleviate incomplete complementation by PPAT and provide further insight into the complex regulation of this critical metabolic pathway.

synthetic biology↗

bioRxiv2017

A toolbox of immunoprecipitation-grade monoclonal antibodies against human transcription factors.

A key component to overcoming the reproducibility crisis in biomedical research is the development of readily available, rigorously validated and renewable protein affinity reagents. As part of the NIH Protein Capture Reagents Program (PCRP), we have generated a collection of 1406 highly validated, immunoprecipitation (IP) and/or immunoblotting (IB) grade, mouse monoclonal antibodies (mAbs) to 736 human transcription factors. We used HuProt human protein microarrays to identify mAbs that recognize their cognate targets with exceptional specificity. Using an integrated production and validation pipeline, we validated these mAbs in multiple experimental applications, and have distributed them to the Developmental Studies Hybridoma Bank (DSHB) and several commercial suppliers. This study allowed us to perform a meta-analysis that identified critical variables that contribute to the generation of high quality mAbs. We find that using full-length antigens for immunization, in combination with HuProt analysis, provides the highest overall success rates. The efficiencies built into this pipeline ensure substantial cost savings compared to current standard practices.

biochemistry↗