A cationic motif upstream Engrailed2 homeodomain controls cell internalization through selective interaction with heparan sulfates

• Published in: Nature communications 2023-04, Vol.14 (1), p.1998-1998, Article 1998
• Main Authors: Cardon, Sébastien, Hervis, Yadira P., Bolbach, Gérard, Lopin-Bon, Chrystel, Jacquinet, Jean-Claude, Illien, Françoise, Walrant, Astrid, Ravault, Delphine, He, Bingwei, Molina, Laura, Burlina, Fabienne, Lequin, Olivier, Joliot, Alain, Carlier, Ludovic, Sagan, Sandrine
• Format: Article
• Language: English
• Subjects: 38/61; 631/1647/2196/2197; 631/45/221; 631/45/612/822; 631/57/2283; 631/80/86/820; 82/58; 82/6; Amino acid sequence; Amino acids; Binding; Biochemistry, Molecular Biology; Cations; Cell surface; Chondroitin Sulfates - metabolism; Dynamic structural analysis; Genomics; Glycosaminoglycans; Glycosaminoglycans - metabolism; Heparan sulfate; Heparitin Sulfate - metabolism; Homeobox; Homeodomain Proteins - genetics; Humanities and Social Sciences; Internalization; Life Sciences; multidisciplinary; Science; Science (multidisciplinary); Sulfates; Transcription Factors; Upstream
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-023-37757-6

Engrailed2 (En2) is a transcription factor that transfers from cell to cell through unconventional pathways. The poorly understood internalization mechanism of this cationic protein is proposed to require an initial interaction with cell-surface glycosaminoglycans (GAGs). To decipher the role of GAGs in En2 internalization, we have quantified the entry of its homeodomain region in model cells that differ in their content in cell-surface GAGs. The binding specificity to GAGs and the influence of this interaction on the structure and dynamics of En2 was also investigated at the amino acid level. Our results show that a high-affinity GAG-binding sequence (RKPKKKNPNKEDKRPR), upstream of the homeodomain, controls En2 internalization through selective interactions with highly-sulfated heparan sulfate GAGs. Our data underline the functional importance of the intrinsically disordered basic region upstream of En2 internalization domain, and demonstrate the critical role of GAGs as an entry gate, finely tuning homeoprotein capacity to internalize into cells. Here, the authors show that cell internalization of Engrailed2 not only relies on its homeodomain, but also involves a cationic region which interacts selectively with cell surface heparan sulfates.