Jin Wang,Tong Zhao,Xiang-Ling Li,Xi-Liang Luo,Hong-Yuan Chen,Jing-Juan Xu
Hydrogen sulfide (H2S), a gaseous signaling agent, was considered to play an essential role in the regulation of many biological systems. Herein, we design a surface-enhanced Raman scattering (SERS) and plasmon resonance Rayleigh scattering (PRRS) dual-mode nanoprobe for real-time imaging of H2S in living cells. To realize the dual-mode imaging, we fabricated a core–shell nanostructure with built-in electromagnetic hot spots by embedded Raman dyes between a gold nanostar (AuNS) core and a silver shell. When exposed to sulfide, the Ag shell will rapidly transform into Ag2S, resulting in the variation of PRRS caused by the change of the dielectric constant and the reduction of the SERS signal resulted from the blocking effect of Ag2S. There was well-defined linearity between the dual signals and the sulfide concentrations from 1 to 100 nM. The limit of detection (LOD) was 87 pM for the SERS mode and 53 pM for the PRRS mode, respectively. Complementary performances were proclaimed between the two proposed sensing modes, i.e., the PRRS mode sensing based on single nanoprobes can provide local concentration information of H2S in single cells, while the SERS signal can directly provide the average concentration information of H2S in single cells. This nanoprobe has been successfully utilized in real-time monitoring of H2S levels in living cells.
Yangxi Xiang,Yue Shi,Lianlian Sun,Weikang Liang,Kaiyu Chen,Chenghua Li
Pattern recognition receptors (PRRs) mediate the innate immune responses and play a crucial role in host defense against pathogen infections. Apextrin C-terminal (ApeC)-containing proteins (ACPs), a newly discovered class of PRRs specific to invertebrates, recognize pathogens through their ApeC domain as intracellular or extracellular effectors. However, the other immunological functions of ACPs remain unclear. In this study, a membrane-localized ACP receptor was identified in the sea cucumber Apostichopus japonicus (denoted as AjACP1). The ApeC domain of AjACP1, which was located outside of its cell membrane, exhibited the capability to recognize and aggregate Vibrio splendidus . AjACP1 was upregulated upon V. splendidus infection, internalizing into the cytoplasm of coelomocytes. AjACP1 overexpression enhanced the phagocytic activity of coelomocytes against V. splendidus , while knockdown of AjACP1 by RNA interfere inhibited coelomocyte endocytosis. Inhibitor experiments indicated that AjACP1 regulated coelomocyte phagocytosis through the actin-dependent endocytic signaling pathway. Further investigation revealed that AjACP1 interacted with the subunit of the actin-related protein 2/3 complex ARPC2, promoting F-actin polymerization and cytoskeletal rearrangement and thereby affecting the coelomocyte phagocytosis of V. splendidus via the actin-dependent endocytic signaling pathway. As a novel membrane PRR, AjACP1 mediates the recognition and phagocytic activity of coelomocytes against V. splendidus through the AjACP1-ARPC2-F-actin polymerization and cytoskeletal rearrangement pathway.
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