Analysis of the Rab GTPase Interactome in Dendritic Cells Reveals Anti-microbial Functions of the Rab32 Complex in Bacterial Containment.

Dendritic cells (DCs) orchestrate complex membrane trafficking through an interconnected transportation network linked together by Rab GTPases. Through a tandem affinity purification strategy and mass spectrometry, we depicted an interactomic landscape of major members of the mammalian Rab GTPase family. When complemented with imaging tools, this proteomic analysis provided a global view of intracellular membrane organization. Driven by this analysis, we investigated dynamic changes to the Rab32 subnetwork in DCs induced by L. monocytogenes infection and uncovered an essential role of this subnetwork in controlling the intracellular proliferation of L. monocytogenes. Mechanistically, Rab32 formed a persistent complex with two interacting proteins, PHB and PHB2, to encompass bacteria both during early phagosome formation and after L. monocytogenes escaped the original containment vacuole. Collectively, we have provided a functional compartmentalization overview and an organizational framework of intracellular Rab-mediated vesicle trafficking that can serve as a resource for future investigations.

Proteome screening of pleural effusions identifies IL1A as a diagnostic biomarker for non-small cell lung cancer.

Non-small cell lung cancer (NSCLC) is a common malignant disease, and in ~10-20% of patients, pleural effusion is the first symptom. The pleural effusion proteome contains information on pulmonary disease that directly or indirectly reflects pathophysiological status. However, the proteome of pleural effusion in NSCLC patients is not well understood, nor is the variability in protein composition between malignant and benign pleural effusions. Here, we investigated the different proteins in pleural effusions from NSCLC and tuberculosis (TB) patients by using nano-scale liquid chromatography-tandem mass spectrometry (nLC-MS/MS) analysis. In total, 363 proteins were identified in the NSCLC pleural effusion proteome with a low false discovery rate (<1%), and 199 proteins were unique to NSCLC. The proteins in the NSCLC patients' pleural effusion were involved in cell adhesion, proteolysis, and cell migration. Furthermore, interleukin 1 alpha (IL1A), a protein that regulates tumor growth, angiogenesis, and metastasis, was significantly more abundant in the NSCLC group compared to the TB group, a finding that was validated with an ELISA assay.