Biochemistry, Biophysics and Molecular Biology, Roy J. Carver Department of
Journal or Book Title
Precise regulation of the kinetics and magnitude of Ca2+ signaling enables this signal to mediate diverse responses, such as cell migration, differentiation, vesicular trafficking, and cell death. Here, we showed that the Ca2+-binding protein calmodulin (CaM) acted in a positive feedback loop to potentiate Ca2+ signaling downstream of the Tec kinase family member Itk. Using NMR (nuclear magnetic resonance), we mapped CaM binding to two loops adjacent to the lipid-binding pocket within the Itk pleckstrin homology (PH) domain. The Itk PH domain bound synergistically to Ca2+/CaM and the lipid phosphatidylinositol-3,4,5-trisphosphate [PI(3,4,5)P3], such that binding to Ca2+/CaM enhanced the binding to PI(3,4,5)P3 and vice versa. Disruption of CaM binding attenuated Itk recruitment to the membrane and diminished release of Ca2+ from the endoplasmic reticulum. Moreover, disruption of this feedback loop abrogated Itk-dependent production of the proinflammatory cytokine IL-17A (interleukin-17A) by CD4+ T cells. Additionally, we found that CaM associated with PH domains from other proteins, indicating that CaM may regulate other PH domain–containing proteins.
American Association for the Advancement of Science
Wang, Xinxin; Boyken, Scott E.; Hu, Jiancheng; Xu, Xiaolu; Rimer, Ryan P.; Shea, Madeline A.; Shaw, Andrey S.; Andreotti, Amy H.; and Huang, Yina H., "Calmodulin and PI(3,4,5)P3 cooperatively bind to the Itk pleckstrin homology domain to promote efficient calcium signaling and IL-17A production" (2014). Biochemistry, Biophysics and Molecular Biology Publications. 188.