Highly Conserved <i>C</i>-Terminal Region of Indian Hedgehog <i>N</i>-Fragment Contributes to Its Auto-Processing and Multimer Formation

• Main Authors: Xiaoqing Wang, Hao Liu, Yanfang Liu, Gefei Han, Yushu Wang, Haifeng Chen, Lin He, Gang Ma
• Format: Article
• Language: English
• Published: MDPI AG 2021-05-01
• Series: Biomolecules
• Subjects: Indian Hedgehog; <i>C</i>-terminal region; autoproteolytic cleavage; protein stability; multimer formation
• Online Access: https://www.mdpi.com/2218-273X/11/6/792

Hedgehog (HH) is a highly conserved secretory signalling protein family mainly involved in embryonic development, homeostasis, and tumorigenesis. HH is generally synthesised as a precursor, which subsequently undergoes autoproteolytic cleavage to generate an amino-terminal fragment (HH-N), mediating signalling, and a carboxyl-terminal fragment (HH-C), catalysing the auto-processing reaction. The <i>N</i>-terminal region of HH-N is required for HH multimer formation to promote signal transduction, whilst the functions of the <i>C</i>-terminal region of HH-N remain ambiguous. This study focused on Indian Hedgehog (IHH), a member of the HH family, to explore the functions of the <i>C</i>-terminal region of the amino-terminal fragment of IHH (IHH-N) via protein truncation, cell-based assays, and 3D structure prediction. The results revealed that three amino acids, including S195, A196, and A197, were crucial for the multimer formation by inserting the mutual binding of IHH-N proteins. K191, S192, E193, and H194 had an extremely remarkable effect on IHH self-cleavage. In addition, A198, K199, and T200 evidently affected the stability of IHH-N. This work suggested that the <i>C</i>-terminus of IHH-N played an important role in the physiological function of IHH at multiple levels, thus deepening the understanding of HH biochemical properties.