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Super-resolution microscopy unveils the nanoscale organization and self-limiting clustering of CD47 in human erythrocytes
Jianyu Yang1,† , Fulin Xing1,† , Fen Hu1 , Mengdi Hou1 , Hao Dong1 , Jiayu Cheng1 , Wan Li2 , Rui Yan2 , Jingjun Xu1,3 , Ke Xu2,* , Leiting Pan1,3,4,*
1The Key Laboratory of Weak-Light Nonlinear Photonics of Education Ministry, School of Physics and TEDA Institute of Applied Physics, Nankai University, Tianjin 300071, China
2Department of Chemistry, University of California, Berkeley, CA 94720, USA
3Shenzhen Research Institute of Nankai University, Shenzhen 518083, China
4State Key Laboratory of Medicinal Chemical Biology, Frontiers Science Center for Cell Responses, College of Life Sciences, Nankai University, Tianjin 300071, China
These authors contributed equally to this work
*Correspondence to:Leiting Pan , Email:plt@nankai.edu.cn Ke Xu , Email:xuk@berkeley.edu
J Mol Cell Biol, Volume 16, Issue 9, September 2024, mjae041,  https://doi.org/10.1093/jmcb/mjae041
Keyword: super-resolution microscopy, human erythrocytes, CD47, self-limiting clustering

The transmembrane protein CD47, an innate immune checkpoint protein, plays a pivotal role in preventing healthy erythrocytes from immune clearance. Our study utilized stochastic optical reconstruction microscopy (STORM) and single-molecule analysis to investigate the distribution of CD47 on the human erythrocyte membrane. Contrary to previous findings in mouse erythrocytes, we discovered that CD47 exists in randomly distributed monomers rather than in clusters across the human erythrocyte membrane. Using secondary antibody-induced crosslinking, we found that CD47 aggregates into stable clusters within minutes. By comparing these STORM results with those of the fully mobile protein CD59 and the cytoskeleton-bound membrane protein glycophorin C under similar conditions, as well as devising two-color STORM co-labeling and co-clustering experiments, we further quantitatively revealed an intermediate, self-limiting clustering behavior of CD47, elucidating its fractional (∼14%) attachment to the cytoskeleton. Moreover, we report reductions in both the amount of CD47 and its clustering capability in aged erythrocytes, providing new insight into erythrocyte senescence. Together, the combination of STORM and secondary antibody-based crosslinking unveils the unique self-limiting clustering behavior of CD47 due to its fractional cytoskeleton attachment.