Syndecan-4, a transmembrane heparan sulfate proteoglycan, plays a critical role in cell adhesion as adhesion receptor. Both transmembrane and cytoplasmic domain of syndecan-4 are known to be involved in the regulation of syndecan-4 functions. In this study, we further investigated the domain hierarchy of syndecan-4. Fluorescence resonance energy transfer (FRET)-based assays showed that expression of syndecan-4 enhanced RhoA activation. RhoA activation was much lower in rat embryonic fibroblasts (REFs) plated on fibronectin-fragment lacking the heparin binding domain, than that of cells on fibronectin. Syndecan-4 transmembrane domain mutants that were defective in transmembrane domain-induced oligomerization diminished RhoA activation and RhoA-related functions such as cell adhesion and spreading. On the other hand, syndecan-4 phosphorylation-mimicking cytoplasmic domain mutants showed SDS-resistant dimer formation and the similar inhibitory effects as transmembrane domain mutants, but to a less extent, suggesting the existence of domain hierarchy of syndecan-4. Consistently, syndecan-4 transmembrane domain mutant inhibited syndecan-4-mediated protein kinase C activation more efficiently than that of the cytoplasmic domain mutant, and the cytoplasmic domain activation failed to overcome inhibition of transmembrane domain mutants. Taken together, these data suggest that the domain hierarchy of syndecan-4 plays a role in the regulation of syndecan-4 functions.
저자
Youngsil Choi [ Department of Life Sciences, Division of Life and Pharmaceutical Sciences and the Center for Cell Signaling & Drug Discovery Research, Ewha Womans University ]
Mijung Kwon [ Department of Life Sciences, Division of Life and Pharmaceutical Sciences and the Center for Cell Signaling & Drug Discovery Research, Ewha Womans University ]
Eok-Soo Oh [ Department of Life Sciences, Division of Life and Pharmaceutical Sciences and the Center for Cell Signaling & Drug Discovery Research, Ewha Womans University ]
본 학회는 화학, 생화학, 분자생물학, 미생물학, 식품공학, 의학, 약학, 유전공학 및 생물공학, 환경 및 기타 공업 등 전 분야의 탄수화물관련 이론과 기술을 연구 발전시키고 산학협동을 통해 이를 보급하여 국내 관련 산업의 발전 및 국민생활의 과학화에 기여하고자 하며, 이러한 목표와 비젼의 실현을 위해 회원들이 적극적인 참여와 활동을 전개하고자 한다.