Cdc42‐Borg4‐Septin7 axis regulates HSC polarity and function |
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| Authors: | Ravinder Kandi Katharina Senger Ani Grigoryan Karin Soller Vadim Sakk Tanja Schuster Karina Eiwen Manoj B Menon Matthias Gaestel Yi Zheng Maria Carolina Florian Hartmut Geiger |
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| Affiliation: | 1. Institute of Molecular Medicine, Ulm University, Ulm Germany ; 2. Institute of Cell Biochemistry, Hannover Medical School, Hannover Germany ; 3. Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, New Delhi India ; 4. Division of Experimental Hematology and Cancer Biology, Cincinnati Children''s Hospital Medical Center, Cincinnati OH, USA ;5.Present address: Program of Regenerative Medicine, IDIBELL, Barcelona Spain |
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| Abstract: | Aging of hematopoietic stem cells (HSCs) is caused by the elevated activity of the small RhoGTPase Cdc42 and an apolar distribution of proteins. Mechanisms by which Cdc42 activity controls polarity of HSCs are not known. Binder of RhoGTPases proteins (Borgs) are known effector proteins of Cdc42 that are able to regulate the cytoskeletal Septin network. Here, we show that Cdc42 interacts with Borg4, which in turn interacts with Septin7 to regulate the polar distribution of Cdc42, Borg4, and Septin7 within HSCs. Genetic deletion of either Borg4 or Septin7 results in a reduced frequency of HSCs polar for Cdc42 or Borg4 or Septin7, a reduced engraftment potential and decreased lymphoid‐primed multipotent progenitor (LMPP) frequency in the bone marrow. Taken together, our data identify a Cdc42‐Borg4‐Septin7 axis essential for the maintenance of polarity within HSCs and for HSC function and provide a rationale for further investigating the role of Borgs and Septins in the regulation of compartmentalization within stem cells. |
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| Keywords: | Borg4 Cdc42 HSCs polarity Septin7 |
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