| Autor: |
Li Xie, Subhankar Dolai, Youhou Kang, Tao Liang, Huanli Xie, Tairan Qin, Lu Yang, Liangyi Chen, Herbert Y Gaisano |
| Jazyk: |
angličtina |
| Rok vydání: |
2016 |
| Předmět: |
|
| Zdroj: |
PLoS ONE, Vol 11, Iss 2, p e0147862 (2016) |
| Druh dokumentu: |
article |
| ISSN: |
1932-6203 |
| DOI: |
10.1371/journal.pone.0147862 |
| Popis: |
Syntaxin (Syn)-1A mediates exocytosis of predocked insulin-containing secretory granules (SGs) during first-phase glucose-stimulated insulin secretion (GSIS) in part via its interaction with plasma membrane (PM)-bound L-type voltage-gated calcium channels (Cav). In contrast, Syn-3 mediates exocytosis of newcomer SGs that accounts for second-phase GSIS. We now hypothesize that the newcomer SG Syn-3 preferentially binds and modulates R-type Cav opening, which was postulated to mediate second-phase GSIS. Indeed, glucose-stimulation of pancreatic islet β-cell line INS-1 induced a predominant increase in interaction between Syn-3 and Cavα1 pore-forming subunits of R-type Cav2.3 and to lesser extent L-type Cavs, while confirming the preferential interactions between Syn-1A with L-type (Cav1.2, Cav1.3) Cavs. Consistently, direct binding studies employing heterologous HEK cells confirmed that Syn-3 preferentially binds Cav2.3, whereas Syn-1A prefers L-type Cavs. We then used siRNA knockdown (KD) of Syn-3 in INS-1 to study the endogenous modulatory actions of Syn-3 on Cav channels. Syn-3 KD enhanced Ca2+ currents by 46% attributed mostly to R- and L-type Cavs. Interestingly, while the transmembrane domain of Syn-1A is the putative functional domain modulating Cav activity, it is the cytoplasmic domain of Syn-3 that appears to modulate Cav activity. We conclude that Syn-3 may mimic Syn-1A in the ability to bind and modulate Cavs, but preferring Cav2.3 to perhaps participate in triggering fusion of newcomer insulin SGs during second-phase GSIS. |
| Databáze: |
Directory of Open Access Journals |
| Externí odkaz: |
|
