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The eicosanoid Leukotriene B 4 (LTB 4 ) relays chemotactic signals to direct neutrophil interstitial migration through its receptor, BLT1. However, whether the LTB 4 -BLT1 axis relays signals during intravascular neutrophil response has not been addressed. Here, we report that LTB 4 produced by neutrophils acts as an autocrine/paracrine signal to drive neutrophil recruitment, arrest, and extravasation during infection in living mice. Using Intravital Subcellular Microscopy (ISMic), we reveal that LTB 4 elicits sustained cell polarization and adhesion response during neutrophil arrest in vivo . Specifically, LTB 4 signaling coordinates the dynamic redistribution of non-muscle Myosin IIA (NMIIA) and β 2-integrin (Itgb2), whose retention at the cell surface facilitates neutrophil arrest. Notably, we also found that inhibition of the machinery regulating exosomes release from the cell blocks the autocrine/paracrine LTB 4 -dependent extravasation response. Overall, our study reveals a critical function for LTB 4 in promoting neutrophil communication in the vasculature during early inflammation response.

Deficiency in the serine protease inhibitor LEKTI is the etiological origin of Netherton syndrome. The principal morbidities of the disease are stratum corneum detachment and chronic inflammation. We show that the membrane protease, matriptase, initiates Netherton syndrome in a LEKTI-deficient mouse model by premature activation of a pro-kallikrein-related cascade. Auto-activation of pro-inflammatory and stratum corneum detachment-associated pro-kallikrein-related peptidases was either low or undetectable, but they were efficiently activated by matriptase. Ablation of matriptase from LEKTI-deficient mice dampened inflammation, eliminated aberrant protease activity, prevented stratum corneum detachment, and improved epidermal barrier function. The study uncovers a pathogenic matriptase-pro-kallikrein pathway that could be operative in several human skin and inflammatory diseases.

Regulated exocytosis is a fundamental process that every secretory cell uses to deliver molecules to the cell surface and the extracellular space by virtue of membranous carriers. This process has been extensively studied using various approaches such as biochemistry, electro-physiology, and electron microscopy. However, recent developments in time-lapse light microscopy have made possible imaging individual exocytic events hence advancing our understanding of this process at a molecular level. In this review, we focus on intravital microscopy a light microscopy-based approach that enables imaging subcellular structures in live animals, and discuss its recent application to study regulated exocytosis. Intravital microscopy has revealed differences in regulation and modality of regulated exocytosis between in vitro and in vivo model systems, unraveled novel aspects of this process that can be appreciated only in in vivo settings, and provided valuable and novel information on its molecular machinery. In conclusion, we make the case for intravital microscopy being a mature technique that can be used to investigate the molecular machinery of several intracellular events under physiological conditions.

Regulated exocytosis is a fundamental process that every secretory cell uses to deliver molecules to the cell surface and the extracellular space by virtue of membranous carriers. This process has been extensively studied using various approaches such as biochemistry, electro-physiology, and electron microscopy. However, recent developments in time-lapse light microscopy have made possible imaging individual exocytic events hence advancing our understanding of this process at a molecular level. In this review, we focus on intravital microscopy a light microscopy-based approach that enables imaging subcellular structures in live animals, and discuss its recent application to study regulated exocytosis. Intravital microscopy has revealed differences in regulation and modality of regulated exocytosis between in vitro and in vivo model systems, unraveled novel aspects of this process that can be appreciated only in in vivo settings, and provided valuable and novel information on its molecular machinery. In conclusion, we make the case for intravital microscopy being a mature technique that can be used to investigate the molecular machinery of several intracellular events under physiological conditions.

Cyclooxygenases (COX)-1 and -2 are key enzymes required for the conversion of arachidonic acid (AA) to eicosanoids, potent mediators of inflammation. In patients with multiple sclerosis (MS), COX-2 derived prostaglandins (PGs) are elevated in the cerebrospinal fluid and COX-2 is upregulated in demyelinating plaques. However, it is not known whether COX-2 activity contributes to oligodendrocyte death. In cuprizone-induced demyelination, oligodendrocyte apoptosis and a concomitant increase in the gene expression of COX-2 and PGE2-EP2 receptor precede histological demyelination. COX-2 and EP2 receptor were expressed by oligodendrocytes, suggesting a causative role for the COX-2/EP2 pathway in the initiation of oligodendrocyte death and demyelination. COX-2 gene deletion, chronic treatment with the COX-2 selective inhibitor celecoxib, or with the EP2 receptor antagonist AH6809 reduced cuprizone-induced oligodendrocyte apoptosis, the degree of demyelination and motor dysfunction. These data indicate that the PGE2 EP2 receptor contributes to oligodendrocyte apoptosis and open possible new therapeutic approaches for MS.

Membranous tubules are very abundant structures in living cells and form or are part of most intracellular organelles. The Golgi apparatus is mainly formed by tubules, which adopt different geometries and conformations. However, their physiological role has not yet been established and this is mainly due to the almost absolute lack of knowledge about the biochemical mechanisms regulating their formation, maintenance and disruption.\ud \ud The aim of this thesis was to investigate in a systematic way these mechanisms. The first step has been to set up an in vitro morphological assay suitable for the visualisation of Golgi-associated tubules in isolated Golgi stacks. This assay was based on electron microscopy and specifically on negative staining of whole-mount preparations. It allowed both qualitative and quantitative analysis of the morphological changes of Golgiassociated tubules after in vitro incubations.\ud \ud This assay was then used for screening several molecules or experimental conditions for their effect on tubular homeostasis. Among them, the most significant was BARS (BFA-dependent ADP-Ribosylation Substrate), a protein previously implicated in the maintenance of Golgi architecture. BARS has been found to cause the selective breakdown of the tubular part of the Golgi complex promoting fission events which convert the tubular structures into clusters of vesicles. This effect correlated with the enzymatic activity of BARS, which acts as an acyl-CoA dependent lysophosphatidic acid acyl transferase (LPAAT), increasing phosphatidic acid (PA) levels in Golgi membranes. This suggests that local modifications of the composition of the lipid bilayer is a possible mechanism for the fission of membranous tubules.

The present disclosure relates to methods for detecting a prostate cancer. Certain embodiments of the present disclosure provide a method of detecting a prostate cancer in a subject, the method comprising detecting a marker selected from an endosomal associated marker and/or a lysosomal associated marker from the subject.

The present disclosure relates to methods for detecting a prostate cancer. Certain embodiments of the present disclosure provide a method of detecting a prostate cancer in a subject, the method comprising detecting a marker selected from an endosomal associated marker and/or a lysosomal associated marker from the subject.

The present disclosure relates to methods for detecting a prostate cancer. Certain embodiments of the present disclosure provide a method of detecting a prostate cancer in a subject, the method comprising detecting a marker selected from an endosomal associated marker and/or a lysosomal associated marker from the subject.

Prostate cancer is the second most common form of cancer in males, affecting one in eight men by the time they reach the age of 70 years. Current diagnostic tests for prostate cancer have significant problems with both false negatives and false positives, necessitating the search for new molecular markers. A recent investigation of endosomal and lysosomal proteins revealed that the critical process of endosomal biogenesis might be altered in prostate cancer. Here, a panel of endosomal markers was evaluated in prostate cancer and nonmalignant cells and a significant increase in gene and protein expression was found for early, but not late endosomal proteins. There was also a differential distribution of early endosomes, and altered endosomal traffic and signaling of the transferrin receptors (TFRC and TFR2) in prostate cancer cells. These findings support the concept that endosome biogenesis and function are altered in prostate cancer. Microarray analysis of a clinical cohort confirmed the altered endosomal gene expression observed in cultured prostate cancer cells. Furthermore, in prostate cancer patient tissue specimens, the early endosomal marker and adaptor protein APPL1 showed consistently altered basement membrane histology in the vicinity of tumors and concentrated staining within tumor masses. These novel observations on altered early endosome biogenesis provide a new avenue for prostate cancer biomarker investigation and suggest new methods for the early diagnosis and accurate prognosis of prostate cancer. Implications: This discovery of altered endosome biogenesis in prostate cancer may lead to novel biomarkers for more precise cancer detection and patient prognosis. Mol Cancer Res; 12(12); 1851–62. ©2014 AACR.

The present disclosure relates to methods for detecting a prostate cancer. Certain embodiments of the present disclosure provide a method of detecting a prostate cancer in a subject, the method comprising detecting a marker selected from an endosomal associated marker and/or a lysosomal associated marker from the subject.

An effective innate immune response is critical for the protection of an organism against pathogen and environmental challenge. There is emerging evidence that an effective immune response depends heavily on the traffic and function of endosomes and lysosomes. However, there is very little understanding of the dynamics of an innate immune response, especially in vivo. Toward this aim, we have used two-photon microscopy to visualize the response to bacterial infection of the endosome-lysosome system in immune response tissues using intact Drosophila larvae. First, we set up the conditions to image intact larva in vivo and more specifically GFP-labeled endosomes-lysosomes in the fat body, and compared their distribution and size with those in tissue explanted ex vivo. Notably, we observed significant expansion of both Rab5 and Rab7 endosomal compartments upon both tissue isolation and minor aseptic wounding, indicating significant differences between live and explanted tissue. We also observed changes in endosome-lysosome vesicles within internal immune response tissues following in vivo bacterial infection by the oral route (to avoid a wounding response). We conclude that there are significant changes to the architecture of endosomes and lysosomes during an innate immune response, setting the scene for mechanistic studies to identify the signaling pathways that orchestrate this process Refereed/Peer-reviewed