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Kari Lenhart, PhD

Kari Lenhart, PhD

Assistant Professor
Department of Biology
Office: PISB 420
Phone: 215.895.6772


  • BS, Ursinus College
  • PhD, Princeton University
  • Post-Doc, University of Pennsylvania

Research Interests:

Stem cells are critical for maintenance of adult tissues, with defects in stem cell behavior leading to cancer and tissue degeneration. Yet many aspects of stem cell regulation are still poorly understood. In particular, how the stem cell specialized environment, or niche, is capable of controlling and coordinating multiple different types of stem cells within the same tissue remains largely unknown. In my lab, we study the simplified, easily accessible stem cell system of the Drosophila fruit fly testis to better understand niche-stem cell and stem cell-stem cell interactions. We have identified a crucial cell biological process, cytokinesis (the physical separation of daughter cell membranes following cell division) as a means by which the testis niche controls stem cell behavior and production of daughter cells that will contribute to the tissue.  Control of germline stem cell (GSC) cytokinesis is regulated both by the niche and by the second population of stem cells in the testis, the somatic cyst stem cells (CySCs). This makes the fly testis an ideal system to study the coordination of stem cell behavior across multiple different populations within the niche.

Using a combination of genetic, molecular and live imaging approaches, my lab is focused on addressing four main questions:

  1. How do CySCs control GSC cytokinesis?
    • What are the signaling pathways involved in their communication?
    • How do these signals influence GSC behavior?
  2. What targets of the JAK/Stat pathway (a main niche signal) are activated in GSCs to control cytokinesis timing?
    • How do these signals regulate the cytoskeleton of the stem cells?
  3. How does niche and stem cell control of GSC cytokinesis become disrupted with age?
  4. Is regulation of cytokinesis a conserved mechanism for niche control of stem cell behavior?
    • Is modified cytokinesis a common feature of stem cells in other fly tissues?
    • In stem cells in other organisms?

Studying each of these questions will provide critical insight into how the niche controls stem cell behavior which may have important implications for stem cell therapies, cancer treatments and ameliorating the effects of aging.

Selected Publications:

  • Lenhart KF and DiNardo S. Somatic cell encystment promotes abscission in germline stem cells following a regulated block in cytokinesis. Developmental Cell. 2015.
  • Lenhart KF, Capozzoli B and DiNardo S. Failure of stem cell cytokinesis with age due to diminished JAK/Stat activity. In preparation.