Bio

Hannah Vicars (she/her) is a Propel Postdoctoral Scholar in Dr. Margaret Fuller’s lab in the Department of Developmental Biology. Hannah is fascinated by how cells make "decisions", particularly the molecular circuitry that controls how cells transition from a dividing state to becoming specialized cell types. She earned her B.S. and Ph.D. in Molecular, Cell, and Developmental Biology at the University of California, Santa Cruz, under the mentorship of Dr. William Sullivan. Hannah emphasized equitable and inclusive teaching when she served as the instructor-of-record for multiple upper- and lower-division biology courses at UC Santa Cruz and Foothill Community College. Throughout her academic career, she has mentored underrepresented students across undergraduate and graduate mentorship programs. When she is not conducting research or teaching, Hannah can be found tending to her vegetable garden, going on runs with her dogs, or playing Dungeons & Dragons.

Stanford Advisors

Contact

  • Academic
    hvicars@stanford.edu
    University - Scholar Department: Department of Developmental Biology Position: Postdoctoral Scholar

Additional Info

All Publications

  • An RNA-binding regulatory cascade controls the switch from proliferation to differentiation in the Drosophila male germ cell lineage. Proceedings of the National Academy of Sciences of the United States of America Harris, D. E., Kim, J. J., Stern, S. R., Vicars, H. M., Matias, N. R., Gallicchio, L., Baker, C. C., Fuller, M. T. 2025; 122 (20): e2418279122

    Abstract

    The switch from precursor cell proliferation to onset of differentiation in adult stem cell lineages must be carefully regulated to produce sufficient progeny to maintain and repair tissues, yet prevent overproliferation that may enable oncogenesis. In the Drosophila male germ cell lineage, spermatogonia produced by germ line stem cells undergo a limited number of transit amplifying mitotic divisions before switching to the spermatocyte program that sets up meiosis and eventual spermatid differentiation. The number of transit amplifying divisions is set by accumulation of the bag-of-marbles (Bam) protein to a critical threshold. In bam mutants, spermatogonia proliferate through several extra rounds of mitosis and then die without becoming spermatocytes. Here, we show that a key role of Bam for the mitosis to differentiation switch is repressing expression of Held Out Wings (how), homolog of mammalian Quaking. Knockdown of how in germ cells was sufficient to allow spermatogonia mutant for bam or its partner benign gonial cell neoplasm to differentiate, while forced expression of nuclear-targeted How protein in spermatogonia wild-type for bam resulted in continued proliferation at the expense of differentiation. Our findings suggest that Bam targets how RNA for degradation by acting as an adapter to recruit the CCR4-NOT deadenylation complex via binding its subunit, Caf40. As How is itself an RNA-binding protein with roles in RNA processing, our findings reveal that the switch from proliferation to meiosis and differentiation in the Drosophila male germ line adult stem cell lineage is regulated by a cascade of RNA-binding proteins.

    View details for DOI 10.1073/pnas.2418279122

    View details for PubMedID 40377994

  • An RNA binding regulatory cascade controls the switch from proliferation to differentiation in the Drosophila male germ line stem cell lineage. bioRxiv : the preprint server for biology Harris, D. E., Kim, J. J., Stern, S. R., Vicars, H. M., Matias, N. R., Gallicchio, L., Baker, C. C., Fuller, M. T. 2024

    Abstract

    The switch from precursor cell proliferation to onset of differentiation in adult stem cell lineages must be carefully regulated to produce sufficient progeny to maintain and repair tissues, yet prevent overproliferation that may enable oncogenesis. In the Drosophila male germ cell lineage, spermatogonia produced by germ line stem cells undergo a limited number of transit amplifying mitotic divisions before switching to the spermatocyte program that sets up meiosis and eventual spermatid differentiation. The number of transit amplifying divisions is set by accumulation of the bag-of-marbles (Bam) protein to a critical threshold. In bam mutants, spermatogonia proliferate through several extra rounds of mitosis then die without becoming spermatocytes. Here we show that the key role of Bam for the mitosis to differentiation switch is repressing expression of Held Out Wings (how), homolog of mammalian Quaking. Knock down of how in germ cells was sufficient to allow spermatogonia mutant for bam or its partner benign gonial cell neoplasm (bgcn) to differentiate, while forced expression of nuclear-targeted How protein in spermatogonia wild-type for bam resulted in continued proliferation at the expense of differentiation. Our findings suggest that Bam targets how RNA for degradation by acting as an adapter to recruit the CCR4-NOT deadenylation complex via binding its subunit, Caf40. As How is itself an RNA binding protein with roles in RNA processing, our findings reveal that the switch from proliferation to meiosis and differentiation in the Drosophila male germ line adult stem cell lineage is regulated by a cascade of RNA-binding proteins.

    View details for DOI 10.1101/2024.09.06.611673

    View details for PubMedID 39282418

    View details for PubMedCentralID PMC11398533

https://orcid.org/0000-0002-3085-0669