PIEZO1 activation delays erythroid differentiation of normal and Hereditary Xerocytosis-derived human progenitors

Hereditary xerocytosis is a dominant red cell membrane disorder caused in most cases by gain-of-function mutations in PIEZO1, encoding a mechanosensitive ion channel that translates a mechanic stimulus into calcium influx. We found that PIEZO1 was expressed early in erythroid progenitors, and investigated whether it could be involved in erythropoiesis, besides its role in mature red cell hydration homeostasis. In UT7 cells, chemical PIEZO1 activation using YODA1 repressed by 75% glycophorin A expression. This effect was PIEZO1-dependant since reverted using a specific shRNA knockdown. Effect of PIEZO1 activation was confirmed in human primary progenitors, maintaining cells longer at an immature stage and modifying the transcriptional balance in favor of genes associated with early erythropoiesis, as shown by a high GATA2/GATA1 ratio and a decreased α/β-globin expression. Proliferation rate was also reduced, with accumulation of cells in G0/G1 of cell cycle. PIEZO1-mediated effect on UT7 cells required calcium-dependent activation of NFAT and ERK1/2 pathway. In primary erythroid cells, PIEZO1 activation synergized with EPO to activate STAT5 and ERK, indicating that it may modulate signaling pathways downstream EPO-R activation. Finally, we studied the in-vitro erythroid differentiation of primary cells obtained from 14 PIEZO1-mutated patients, from 11 families, carrying 10 different mutations. We observed a delay in erythroid differentiation in all cases, ranging from mild (n=3) to high (n=8). Overall, these data demonstrate a role for PIEZO1 during erythropoiesis, since activation of PIEZO1 - both chemical and through activating mutations- delays erythroid maturation, revealing new insights in the pathophysiology of hereditary xerocytosis.