Lnk controls mouse hematopoietic stem cell self-renewal and quiescence through direct interactions with JAK2
Alexey Bersenev, … , Joanna Balcerek, Wei Tong
Alexey Bersenev, … , Joanna Balcerek, Wei Tong
Published July 10, 2008
Citation Information: J Clin Invest. 2008;118(8):2832-2844. https://doi.org/10.1172/JCI35808.
View: Text | PDF
Research Article Hematology

Lnk controls mouse hematopoietic stem cell self-renewal and quiescence through direct interactions with JAK2

Abstract

In addition to its role in megakaryocyte production, signaling initiated by thrombopoietin (TPO) activation of its receptor, myeloproliferative leukemia virus protooncogene (c-Mpl, or Mpl), controls HSC homeostasis and self-renewal. Under steady-state conditions, mice lacking the inhibitory adaptor protein Lnk harbor an expanded HSC pool with enhanced self-renewal. We found that HSCs from Lnk–/– mice have an increased quiescent fraction, decelerated cell cycle kinetics, and enhanced resistance to repeat treatments with cytoablative 5-fluorouracil in vivo compared with WT HSCs. We further provide genetic evidence demonstrating that Lnk controls HSC quiescence and self-renewal, predominantly through Mpl. Consistent with this observation, Lnk–/– HSCs displayed potentiated activation of JAK2 specifically in response to TPO. Biochemical experiments revealed that Lnk directly binds to phosphorylated tyrosine residues in JAK2 following TPO stimulation. Of note, the JAK2 V617F mutant, found at high frequencies in myeloproliferative diseases, retains the ability to bind Lnk. Therefore, we identified Lnk as a physiological negative regulator of JAK2 in stem cells and TPO/Mpl/JAK2/Lnk as a major regulatory pathway in controlling stem cell self-renewal and quiescence.

Authors

Alexey Bersenev, Chao Wu, Joanna Balcerek, Wei Tong

×

Figure 2

Lnk–/– LSK HSCs show decelerated cell cycle kinetics.

Options: View larger image (or click on image) Download as PowerPoint
Lnk–/– LSK HSCs show decelerated cell cycle kinetics. WT, Mpl–/–, L...
WT, Mpl–/–, Lnk–/–, and Mpl–/–Lnk–/– mice were fed with water containing BrdU for 7 days. Left panels show representative FACS plots of Lin–Kithi BM cells gated for LSK and LK HSC progenitors. Numbers indicate percentage of cells within each boxed area. Bold numbers indicate that Lnk–/– and Mpl–/– mice were significantly different from WT mice. BrdU incorporation analysis in purified LSK (middle panels) and LK (right panels) cells were determined by FACS. Representative pseudocolor plots are shown. BrdU– 2N, BrdU+ 2N, and BrdU+ populations with over 2N DNA content were quantified (mean ± SD). n = 4.