Control of adipogenesis by ezrin, radixin and moesin-dependent biomechanics remodeling.

We have recently shown that altered stem cell biomechanics can regulate the lineage commitment through a family of the membrane-cytoskeleton linker proteins (ERM; ezrin, radixin, moesin). The ERM proteins not only modulate the cell stiffness and actin cytoskeleton organization, but also rearrange focal adhesions and therefore influence the biochemically-directed stem cell differentiation. Combining silencing RNA, atomic force microscopy, and fluorescence microscopy, the role of the ERM proteins involved in the regulation of stem cell biomechanics and adipogenic differentiation was quantitatively determined. Transient ERM knockdown by RNAi caused disassembly of actin stress fibers and focal adhesions and a decrease in the cell stiffness. The silencing RNA treatment not only induced mechanical changes in stem cells but impaired adipogenesis in a time-dependent manner. While siRNA ERM treatment at day 0 substantially interfered with adipogenesis, the same treatment at day 3 of adipogenic differentiation significantly facilitated adipogenesis, as assessed by the expression of adipocyte-specific markers. The intact biomechanics homeostasis appears to be critical for the adipogenic induction. These findings may lead to potential biomechanical intervention techniques and methodologies to control the fate and extent of adipogenesis that would likely be involved in stem cell-based therapeutics for soft tissue repair and regeneration.