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Dissertation Defense: Internally Translated Cx43 Isoform GJA1-20k Affects Epithelial to Mesenchymal Transition and Metastatic Breast Cancer Cell Behavior

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Kenneth Young

Dissertation Defense: Internally Translated Cx43 Isoform GJA1-20k Affects Epithelial to Mesenchymal Transition and Metastatic Breast Cancer Cell Behavior

Kenneth Young II

Graduate Student, Translational Biology, Medicine, and Health
Graduate Research Assistant, Lamouille and Smyth labs, Fralin Biomedical Research Institute at VTC
Medical Student, Virginia Tech Carilion School of Medicine
Aug. 8, 2024, at 2 p.m.
In person: Room R3012, 2 Riverside Circle
Virtual: Join via Zoom

About this Dissertation

Epithelial-mesenchymal transition (EMT) is a trans-differentiation program essential for development and wound healing that is pathologically activated during cancer progression. During this process, cells undergo complex changes at the transcriptional and translational levels leading to dissolution of cell-cell junctions, loss of apical-basal polarity, and cytoskeleton reorganization. Transforming Growth Factor-β (TGF- β) is well-established in driving cancer progression through EMT induction. Remodeling of cellular junctions, including gap junctions, is critical to acquiring migratory and invasive characteristics during EMT. The gene GJA1 encodes for Connexin43 (Cx43), the most ubiquitously expressed gap junction protein where altered regulation of Cx43 is associated with cancer progression. Intriguingly, Cx43 mRNA undergoes alternative ‘internal’ translation initiation, generating N-terminally truncated isoforms, including GJA1-20k, which regulates Cx43 gap junction formation. Young and the Lamouille and Smyth labs have previously demonstrated GJA1-20k expression is inhibited during TGF-β-induced EMT, limiting gap junction formation; however, the relationship between GJA1-20k modulation of gap junction localization and cellular invasion and migration remains unknown. Given the role GJA1-20k has in regulating gap junctions, Young hypothesizes that suppression of GJA1-20k expression promotes metastatic trait acquisition through limiting gap junction formation. Utilizing lentivirally transduced stable mouse mammary gland epithelial (NMuMG) and triple-negative human breast epithelial (MDA-MB-231) cells expressing GJA1-20k, or Lac Z as control, Young tested effects on TGF-β-induced EMT induction and metastatic trait induction. Boyden chambers, would/scratch assays were employed to analyze cell invasion and migration respectively. The researchers found GJA1-20k overexpression during EMT results in decreased cell invasion and migration to LacZ controls. Future directions include evaluation of GJA1-20k restoration in a metastatic breast cancer model in vivo. Investigating the underlying role of GJA1-20k in EMT-induced cell junction remodeling could be promising as a potential pharmacological target process independent of transcriptional or post-translational pathways. Ultimately, by adding novel information in the expanding and compelling field of translational control, this work could aid in developing the future of precision medicine as new therapeutic solutions to treat cancer will require limiting cancer cell’s ability to metastasize.

More About the Candidate and Project

Education

Virginia Tech, Translational Biology, Medicine, and Health, Ph.D. Candidate

Virginia Tech Carilion School of Medicine, Medical Student

Georgetown University, M.Sc., Physiology and Biophysics

Colorado State University, B.S., Biochemistry

Training

Graduate Research Assistant, Lamouille and Smyth labs, Fralin Biomedical Research Institute at VTC

Mentors

Samy Lamouille, Ph.D., Assistant Professor, Fralin Biomedical Research Institute at VTC

James Smyth, Ph.D., Associate Professor, Fralin Biomedical Research Institute at VTC

Committee Members

  • Shanon Farris, Ph.D., Assistant Professor, Fralin Biomedical Research Institute at VTC
  • Michael Fox, Ph.D., Dean, College of Natural Sciences, University of Massachusetts, Amherst
  • Leslie LaConte, Ph.D., Research Associate Professor, Fralin Biomedical Research Institute at VTC; Associate Dean for Research and Associate Professor, Virginia Tech Carilion School of Medicine

Young II KL. (2021) The Final slide. ARTiculation: Creativity in Medicine Issue II.

Young II KL, Kassouf C, Dolinksa MB, Anderson DE, Sergeev YV. (2020) Human Tyrosinase: Temperature Dependent Kinetics of Oxidase Activity. Int. J. Mol. Sci. 21(13), 895. doi.org/10.3390/ijms21030895

Dolinksa MB, Young II KL, Kassouf C, Dimitriadis EK, Wingfield PT, Sergeev YV. (2020) Protein Stability and Functional Characterization of Intra-Melanosomal Domain of Human Recombinant Tyrosinase-Related Protein 1. Int. J. Mol. Sci. 21(1), 331. doi.org/10.3390/ijms21010331

Dolinska MB, Wingfield PT, Young II KL, Sergeev, YV (2019). The TYRP1‐mediated protection of human tyrosinase activity does not involve stable interactions of tyrosinase domains. Pigment Cell & Melanoma Research. doi.org/10.1111/pcmr.12791

Young II KL, Dolinska MB, Kus NJ, Poliakov E, Sergeev YV. (2018) Protein Purification of Recombinant Human Tyrosinase Full Length and Intra-Melanosomal Domain. Protocols.io doi.org/10.17504/protocols.io.np7ddrn

Kus NJ, Dolinska MB, Young II KL, Dimitriadis EK, Wingfield PT, Sergeev YV. (2018) Membrane-associated human tyrosinase is an enzymatically active monomeric glycoprotein. PLOS ONE 13(6): e0198247. doi.org/10.1371/journal.pone.0198247

  • American Heart Association Predoctoral Fellowship, 2023
  • National Institutes of Health Diversity Supplement, 2021