A mitotic kinase scaffold depleted in testicular seminomas impacts spindle orientation in germ line stem cells
Heidi Hehnly,
David Canton,
Paula Bucko,
Lorene K Langeberg,
Leah Ogier,
Irwin Gelman,
L Fernando Santana,
Linda Wordeman,
John D Scott
Affiliations
Heidi Hehnly
Department of Pharmacology, Howard Hughes Medical Institute, University of Washington, Seattle, United States; Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, United States
David Canton
Department of Pharmacology, Howard Hughes Medical Institute, University of Washington, Seattle, United States
Paula Bucko
Department of Pharmacology, Howard Hughes Medical Institute, University of Washington, Seattle, United States
Lorene K Langeberg
Department of Pharmacology, Howard Hughes Medical Institute, University of Washington, Seattle, United States
Leah Ogier
Department of Pharmacology, Howard Hughes Medical Institute, University of Washington, Seattle, United States
Irwin Gelman
Department of Cancer Genetics, Roswell Park Cancer Institute, Buffalo, United States
L Fernando Santana
Department of Physiology and Biophysics, University of Washington, Seattle, United States
Linda Wordeman
Department of Physiology and Biophysics, University of Washington, Seattle, United States
John D Scott
Department of Pharmacology, Howard Hughes Medical Institute, University of Washington, Seattle, United States
Correct orientation of the mitotic spindle in stem cells underlies organogenesis. Spindle abnormalities correlate with cancer progression in germ line-derived tumors. We discover a macromolecular complex between the scaffolding protein Gravin/AKAP12 and the mitotic kinases, Aurora A and Plk1, that is down regulated in human seminoma. Depletion of Gravin correlates with an increased mitotic index and disorganization of seminiferous tubules. Biochemical, super-resolution imaging, and enzymology approaches establish that this Gravin scaffold accumulates at the mother spindle pole during metaphase. Manipulating elements of the Gravin-Aurora A-Plk1 axis prompts mitotic delay and prevents appropriate assembly of astral microtubules to promote spindle misorientation. These pathological responses are conserved in seminiferous tubules from Gravin−/− mice where an overabundance of Oct3/4 positive germ line stem cells displays randomized orientation of mitotic spindles. Thus, we propose that Gravin-mediated recruitment of Aurora A and Plk1 to the mother (oldest) spindle pole contributes to the fidelity of symmetric cell division.
