Rapid translocation of pluripotency-related transcription factors by external uniaxial forces

Abstract

Human embryonic stem cells subjected to a one-time uniaxial stretch for as short as 30-min on a flexible substrate coated with Matrigel experienced rapid and irreversible nuclear-to-cytoplasmic translocation of NANOG and OCT4, but not Sox2. Translocations were directed by intracellular transmission of biophysical signals from cell surface integrins to nuclear CRM1 and were independent of exogenous soluble factors. On E-CADHERIN-coated substrates, presumably with minimal integrin engagement, mechanical strain-induced rapid nuclear-to-cytoplasmic translocation of the three transcription factors. These findings might provide fundamental insights into early developmental processes and may facilitate mechanotransductionmediated bioengineering approaches to influencing stem cell fate determination. Insight, innovation, integration How do mechanical stimuli, sensed through different types of cell adhesions, alter embryonic stem cell fate? This paper employs a stretchable device coated with different cell adhesion molecules to apply stretch to human embryonic stem cells in a manner that might mimic differentiation of cell lineages present at the blastocyst stage of development. The work reveals that stretch induces an unexpectedly rapid export of a subset of pluripotent transcription factors from the nucleus to the cytoplasm before significant decreases in overall levels. Interestingly, the subset of transcription factors exported differs between cells stretched on Matrigel-versus E-CADHERIN-coated devices. These results have physiological relevance to embryonic development where some cells experience mechanical forces predominantly through cell-cell contact while other cells also experience cell-ECM interactions leading to different cell-fate specification. These insights might enhance our understanding of early development and may also guide bioengineering approaches where stretching is used to accelerate or regulate the direction of differentiation.

In vitro characterization of 3D culture-based differentiation of human liver stem cells

“…Following 3D differentiation, we observed a shift in the subcellular localization of Nanog and OCT3/4. Consistent with previous reports, Nanog, a mechanosensitive factor, undergoes translocation during the transition from cell renewal to differentiation ( Gu et al, 2012 ; Topal et al, 2019 ). Given the continuous movement inherent in our 3D model, we speculate that a similar phenomenon may be occurring in our system.…”

Mitochondrial ROS Induce Partial Dedifferentiation of Human Mesothelioma via Upregulation of NANOG

“…The subcellular localization analysis of pluripotency factor protein expression showed that NANOG and SOX2 were expressed in the nucleus and cytosol of human mesothelioma and Mero-14 cells. Topal et al showed that increased flux of OCT4 and NANOG, but not SOX2, from the nucleus into cytosol is associated with their degradation and differentiation of stem cells [ 34 ]. Thus, our observation that NANOG is present in the nucleus of mesothelioma, further corroborates that differentiation processes are inhibited in mesothelioma, rendering mesothelioma a highly undifferentiated cancer.…”

“…The advantage over the time-consuming western blot [ 40 ], is that immunocytochemical quantification is not prone to error due to protein crosslinking [ 41 ], it allows cell visualization and analysis of cell subpopulations, protein quantification in subcellular compartments and high-throughput experimentation when working with cell culture. This is important when studying SOX2 and NANOG expression, because their subcellular localization can determine the cell fate [ 34 ]. However, such quantification of protein expression in tissue slides does not always allow such approach due to the existence of multiple cell layers.…”