Biology subjects

Jensen, R. A.

Publications and source records attributed to Jensen, R. A..

4 recordsLinked to original sources

bioRxiv2024

Differential Remodeling of the BRCA1 Interactome by a Unique Minimal Clinical Truncation Mutation

BRCA1, a critical tumor suppressor gene, plays an essential role in maintaining genomic stability through its involvement in DNA double-strand break repair, particularly via homologous recombination. Loss or impairment of BRCA1 function disrupts this repair pathway, resulting in genomic instability and significantly increased susceptibility to breast and ovarian cancers. To elucidate the molecular mechanisms by which BRCA1 mutations contribute to tumorigenesis, we employed quantitative mass spectrometry-based proximity labeling and affinity purification to identify cancer-specific protein-protein interactions (PPIs). Our integrated omics and visualization analysis of interactors revealed that the BRCA1-Y1853ter mutant, through its interaction with BARD1, perturbs the interactome and impacts cellular processes within the cytoplasm and nucleoplasm. Structural data further corroborated these findings, showing enhanced binding between the mutant BRCA1 and specific interactors, suggesting an altered functional profile. Together, these observations raise the hypothesis that the BRCA1-Y1853ter mutant may exhibit gain-of-function characteristics, providing new insights into the molecular and cellular effects of mutations in the BRCA1 C-Terminal (BRCT) domain and their implications for the pathogenesis of breast and ovarian cancers.

cancer biology↗

bioRxiv2023

IRAK1 is a critical mediator of low molecular weight hyaluronic acid-induced stemness in high-grade serous ovarian cancer

Advanced epithelial ovarian cancer (EOC) survival rates are dishearteningly low, with [~]25% surviving beyond 5 years. Evidence suggests that cancer stem cells (CSCs) contribute to acquired chemoresistance and tumor recurrence. Here, we show that IRAK1 is upregulated in EOC tissues, and enhanced expression correlates with poorer overall survival. IRAK1 and BRCA1/2 mutation status are mutually exclusive. Moreover, low molecular weight hyaluronic acid (LMW HA), which is abundant in malignant ascites from patients with advanced EOC, induced IRAK1 phosphorylation leading to STAT3 activation and enhanced spheroid formation. Knockdown of IRAK1 impaired tumor growth in peritoneal disease models, and impaired HA-induced spheroid growth and STAT3 phosphorylation. Finally, we determined that TCS2210, a known inducer of neuronal differentiation in mesenchymal stem cells, is a selective inhibitor of IRAK1. TCS2210 significantly inhibited EOC growth in vitro and in vivo both as monotherapy, and in combination with cisplatin. Collectively, these data demonstrate IRAK1 as a druggable target for EOC.

cancer biology↗

bioRxiv2022

Single-molecule tracking reveals two low-mobility states for chromatin and transcriptional regulators within the nucleus

How transcription factors (TFs) navigate the complex nuclear environment to assemble the transcriptional machinery at specific genomic loci remains elusive. Using single-molecule tracking, coupled with machine learning, we examined the mobility of multiple transcriptional regulators. We show that H2B and ten different transcriptional regulators display two distinct low-mobility states. Our results indicate that both states represent dynamic interactions with chromatin. Ligand activation results in a dramatic increase in the proportion of steroid receptors in the lowest mobility state. Mutational analysis revealed that only chromatin interactions in the lowest mobility state require an intact DNA-binding domain as well as oligomerization domains. Importantly, these states are not spatially separated as previously believed but in fact, individual H2B and TF molecules can dynamically switch between them. Together, our results identify two unique and distinct low-mobility states of transcriptional regulators that appear to represent common pathways for transcription activation in mammalian cells.

biophysics↗

bioRxiv2021

RNA binding protein RBM3 augments kissing loop formation with lncRNAs to enhance translational control

It is becoming apparent that translational regulation involves the coordinated actions of RNA binding proteins (RBPs) and non-coding RNAs. For efficient translation, mRNA needs to be circularized, which is catalyzed by RNA binding proteins and translation factors. However, the role of lncRNAs in the process is not yet defined. We first performed RNA-seq and RNA- immunoprecipitation coupled-Seq and identified LSAMP-3 and Flii-1. Moreover, modeling studies suggest enhanced kissing loop interactions including of transcripts that encode angiogenesis and epithelial mesenchymal transition. While intestinal epithelial cell specific RBM3 transgenic mice showed increased LSAMP-3 and Flii-1, this was reduced in knockout mice. Also, RBM3 overexpression increased tumor xenograft growth, this was suppressed by knockdown of the lncRNAs. Also, knockdown of endogenous RBM3 reduced lncRNA levels and tumor xenograft growth. In addition, it reduced colitis-associated cancers. We propose that RBPs such as RBM3 mediate their function through regulatory lncRNAs that enable circularization to control translation.

cancer biology↗