| First Author | Moulakakis C | Year | 2016 |
| Journal | Am J Respir Cell Mol Biol | Volume | 55 |
| Issue | 1 | Pages | 92-104 |
| PubMed ID | 26771574 | Mgi Jnum | J:250619 |
| Mgi Id | MGI:6101351 | Doi | 10.1165/rcmb.2015-0219OC |
| Citation | Moulakakis C, et al. (2016) Surfactant Protein A Enhances Constitutive Immune Functions of Clathrin Heavy Chain and Clathrin Adaptor Protein 2. Am J Respir Cell Mol Biol 55(1):92-104 |
| abstractText | NF-kappaB transcription factors are key regulators of pulmonary inflammatory disorders and repair. Constitutive lung cell type- and microenvironment-specific NF-kappaB/inhibitor kappaBalpha (IkappaB-alpha) regulation, however, is poorly understood. Surfactant protein (SP)-A provides both a critical homeostatic and lung defense control, in part by immune instruction of alveolar macrophages (AMs) via clathrin-mediated endocytosis. The central endocytic proteins, clathrin heavy chain (CHC) and the clathrin adaptor protein (AP) complex AP2, have pivotal alternative roles in cellular homeostasis that are endocytosis independent. Here, we dissect endocytic from alternative functions of CHC, the alpha-subunit of AP2, and dynamin in basal and SP-A-modified LPS signaling of macrophages. As revealed by pharmacological inhibition and RNA interference in primary AMs and RAW264.7 macrophages, respectively, CHC and alpha-adaptin, but not dynamin, prevent IkappaB-alpha degradation and TNF-alpha release, independent of their canonical role in membrane trafficking. Kinetics studies employing confocal microscopy, Western analysis, and immunomagnetic sorting revealed that SP-A transiently enhances the basal protein expression of CHC and alpha-adaptin, depending on early activation of protein kinase CK2 (former casein kinase II) and Akt1 in primary AMs from rats, SP-A(+/+), and SP-A(-/-) mice, as well as in vivo when intratracheally administered to SP-A(+/+) mice. Constitutive immunomodulation by SP-A, but not SP-A-mediated inhibition of LPS-induced NF-kappaB activity and TNF-alpha release, requires CHC, alpha-adaptin, and dynamin. Our data demonstrate that endocytic proteins constitutively restrict NF-kappaB activity in macrophages and provide evidence that SP-A enhances the immune regulatory capacity of these proteins, revealing a previously unknown pathway of microenvironment-specific NF-kappaB regulation in the lung. |
