VARP and Rab9 Are Dispensable for the Rab32/BLOC-3 Dependent Salmonella Killing

ACKNOWLEDGMENTS: We are grateful to Juan S. Bonifacino for his generous gift pCI-neoHA-HPS1 and pCI-neo-Myc-HPS4 plasmids.We also thank to Leigh Knodler for her generous gift of P22 phage.We thank members of SS laboratory for their continuous help for technical advice. FUNDING: This work was supported by the Wellcome Trust (Seed Award 109680/Z/15/Z), the European Union’s Horizon 2020 ERC consolidator award (2016-726152-TYPHI), the BBSRC (BB/N017854/1), the Royal Society (RG150386), and Tenovus Scotland (G14/19) to SS.Peer reviewedPublisher PD

VARP and Rab9 are dispensable for the Rab32/BLOC-3 dependent salmonella killing in mouse macrophages

Salmonella enterica serovar Typhi (S. Typhi) is the causative agent of typhoid fever, a disease that kills an estimated 200,000 people annually. Previously, we discovered an antimicrobial pathway dependent on Rab32 and BLOC-3 (BRAM) that is critical to kill S. Typhi in murine macrophages. The BLOC-3 complex is comprised of the two sub-units HPS1 and HPS4 and exhibits guanine-nucleotide exchange factor (GEF) activity to Rab32. In melanocytes, Rab9 has been shown to interact with HPS4 and RUTBC1, a Rab32 GTPase activating (GAP) protein, and regulate the Rab32-mediated melanosome biogenesis. Intriguingly, Rab9-deficient melanocytes exhibit hypopigmentation, a similar phenotype to Rab32 or BLOC-3 deficient melanocytes. Additionally, VPS9-ankyrin-repeat-protein (VARP) has been shown to regulate melanocytic enzyme trafficking into the melanosomes through interaction with Rab32. Although Rab32, Rab9 and VARP are a part of melanogenesis in melanocytes, whether Rab9 and VARP are required for the BRAM mediated killing in macrophages is currently unknown. Here we showed that HPS4 is recruited to the Salmonella-containing vacuoles (SCV) and over-expression of BLOC-3 significantly increased Rab32-positive bacteria vacuoles. We found that SCV acquire Rab9, however over-expressing Rab9 did not change HPS4 localisation on bacteria vacuoles. Importantly, we used shRNA to knock-down Rab9 and VARP in macrophages and showed that these proteins are dispensable for Rab32 recruitment to the SCV. Furthermore, we assessed the survival of S. Typhimurium in macrophages deficient for Rab9 or VARP and demonstrated that these proteins are not essential for BRAM pathway-dependent killing

Bscl2 Deficiency Does Not Directly Impair the Innate Immune Response in a Murine Model of Generalized Lipodystrophy

Funding: Work was supported by Diabetes UK (JJR;18/0005884, MD;17/0005621) the Medical Research Council (JJR; MR/L002620/1, MC/PC/15077), the British Heart Foundation (MD; PG/14/43/30889), The Agency for Science, Technology and Research, Singapore (A*STAR) (WH), The Wellcome Trust (ISSF Funding to GDM) and the European Union’s Horizon 2020 ERC consolidator award (MB:2016-726152-TYPHI).Peer reviewedPublisher PD

Recurrent hydatidiform moles: detection of a new mutation in the NLRP7 gene in the family

Hydatidiform moles are the most common type of gestational trophoblastic neoplasia. Hyperproliferative vesicular trophoblasts and imperfect fetal development are abnormal pregnancies, and recurrent hydatidiform moles are rare. Mutations in NLRP7 are responsible for recurrent hydatidiform mole. Genetic heterogeneity has been demonstrated in patients with the NLRP7 mutation. This study presents our case with gravida 11, parity 0, histopathologically diagnosed with six hydatidiform moles and five missed abortion histories at age 35. Karyotype analyses of the unrelated couple were normal. A genetic examination revealed a novel mutation of the NLRP7 gene in the patient, his brother, and his parents. Detecting a new NLRP7 mutation in recurrent hydatidiform moles cases provides further evidence for the predetermined role of NLRP7 mutations in the pathophysiology of recurrent moles hydatidiform. Based on our findings, we hope to contribute to the literature by expanding the spectrum of recurrent pregnancy loss associated with NLRP7 mutations in patients

The Rab32/BLOC-3-dependent pathway mediates host defense against different pathogens in human macrophages.

Macrophages provide a first line of defense against microorganisms, and while some mechanisms to kill pathogens such as the oxidative burst are well described, others are still undefined or unknown. Here, we report that the Rab32 guanosine triphosphatase and its guanine nucleotide exchange factor BLOC-3 (biogenesis of lysosome-related organelles complex-3) are central components of a trafficking pathway that controls both bacterial and fungal intracellular pathogens. This host-defense mechanism is active in both human and murine macrophages and is independent of well-known antimicrobial mechanisms such as the NADPH (reduced form of nicotinamide adenine dinucleotide phosphate)-dependent oxidative burst, production of nitric oxide, and antimicrobial peptides. To survive in human macrophages, Salmonella Typhi actively counteracts the Rab32/BLOC-3 pathway through its Salmonella pathogenicity island-1-encoded type III secretion system. These findings demonstrate that the Rab32/BLOC-3 pathway is a novel and universal host-defense pathway and protects mammalian species from various pathogens