Wang Hong-Yin, Rumin Alissa, Doktorova Milka, Sputay Daryna, Chan Sze Ham, Wehman Ann M, Levental Kandice R, Levental Ilya
Department of Molecular Physiology and Biological Physics, Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22903.
Molecular and Cellular Biophysics Program, Department of Biological Sciences, University of Denver, Denver, CO 80210.
Proc Natl Acad Sci U S A. 2025 May 13;122(19):e2417145122. doi: 10.1073/pnas.2417145122. Epub 2025 May 5.
Membrane blebs have important roles in cell migration, apoptosis, and intercellular communication through extracellular vesicles (EVs). While plasma membranes (PM) typically maintain phosphatidylserine (PS) on their cytoplasmic leaflet, most blebs have PS exposed on their outer leaflet, revealing that loss of steady-state lipid asymmetry often accompanies PM blebbing. How these changes in PM lipid organization regulate membrane properties and affect bleb formation remains unknown. We confirmed that lipid scrambling through the scramblase TMEM16F is essential for chemically induced membrane blebbing across cell types, with the kinetics of PS exposure being tightly coupled to the kinetics of bleb formation. Measurement of lipid packing with environment-sensitive probes revealed that lipid scrambling changes the physical properties of the PM, reducing lipid packing and facilitating the bilayer bending required for bleb formation. Accordingly, reducing lipid packing of the PM through cholesterol extraction, elevated temperature, or treatment with biological amphiphiles promoted blebbing in the absence of TMEM16F. Consistent with these cellular observations, blebbing in embryos measured via EV production was significantly reduced by depleting the TMEM16-homolog ANOH-2. Our findings suggest that changing membrane biophysical properties by lipid scrambling is an important contributor to the formation of blebs and EVs and potentially other cellular processes involving PM deformation.
膜泡在细胞迁移、凋亡以及通过细胞外囊泡（EVs）进行的细胞间通讯中发挥着重要作用。虽然质膜（PM）通常在其细胞质小叶上维持磷脂酰丝氨酸（PS），但大多数膜泡在其外小叶上暴露有PS，这表明稳态脂质不对称性的丧失通常伴随着质膜起泡。质膜脂质组织的这些变化如何调节膜特性并影响膜泡形成仍然未知。我们证实，通过磷脂翻转酶TMEM16F进行的脂质翻转对于跨细胞类型的化学诱导膜泡形成至关重要，PS暴露的动力学与膜泡形成的动力学紧密相关。用环境敏感探针测量脂质堆积表明，脂质翻转改变了质膜的物理性质，减少了脂质堆积并促进了膜泡形成所需的双层弯曲。因此，通过胆固醇提取、升高温度或用生物两亲物处理来降低质膜的脂质堆积，在没有TMEM16F的情况下促进了膜泡形成。与这些细胞观察结果一致，通过耗尽TMEM16同源物ANOH-2，经EV产生测量的胚胎中的膜泡形成显著减少。我们的研究结果表明，通过脂质翻转改变膜生物物理性质是膜泡和EV形成以及潜在的其他涉及质膜变形的细胞过程的重要促成因素。
