PLoS ONE (Jan 2013)

The cytoskeletal protein RHAMM and ERK1/2 activity maintain the pluripotency of murine embryonic stem cells.

  • Jihong Jiang,
  • Pooja Mohan,
  • Christopher A Maxwell

DOI
https://doi.org/10.1371/journal.pone.0073548
Journal volume & issue
Vol. 8, no. 9
p. e73548

Abstract

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Receptor for hyaluronan mediated motility (RHAMM, encoded by HMMR) may be a cell-surface receptor for hyaluronan that regulates embryonic stem cell pluripotency and differentiation, however, a precise mechanism for its action is not known. We examined murine embryonic stem cells with and without hemizygous genomic mutation of Hmmr/RHAMM, but we were not able to find RHAMM on the cell-surface. Rather, RHAMM localized to the microtubule cytoskeleton and along mitotic spindles. Genomic loss of Hmmr/RHAMM did not alter cell cycle progression but augmented differentiation and attenuated pluripotency in murine embryonic stem cells. Through a candidate screen of small-molecule kinase inhibitors, we identified ERK1/2 and aurora kinase A as barrier kinases whose inhibition was sufficient to rescue pluripotency in RHAMM(+/-) murine embryonic stem cells. Thus, RHAMM is not found on the cell-surface of embryonic stem cells, but it is required to maintain pluripotency and its dominant mechanism of action is through the modulation of signal transduction pathways at microtubules.