We argue that the field of extracellular vesicle (EV) biology needs more transparent reporting to facilitate interpretation and replication of experiments. To achieve this, we describe EV-TRACK, a crowdsourcing knowledgebase (http://evtrack.org) that centralizes EV biology and methodology with the goal of stimulating authors, reviewers, editors and funders to put experimental guidelines into practice.

Deregulation of signaling pathways that control differentiation, expansion and migration of neural crest-derived melanoblasts during normal development contributes also to melanoma progression and metastasis. Although several epithelial-tomesenchymal (EMT) transcription factors, such as zinc finger E-box binding protein 1 (ZEB1) and ZEB2, have been implicated in neural crest cell biology, little is known about their role in melanocyte homeostasis and melanoma. Here we show that mice lacking Zeb2 in the melanocyte lineage exhibit a melanoblast migration defect and, unexpectedly, a severe melanocyte differentiation defect. Loss of Zeb2 in the melanocyte lineage results in a downregulation of the Microphthalmia-associated transcription factor (Mitf) and melanocyte differentiation markers concomitant with an upregulation of Zeb1. We identify a transcriptional signaling network in which the EMT transcription factor ZEB2 regulates MITF levels to control melanocyte differentiation. Moreover, our data are also relevant for human melanomagenesis as loss of ZEB2 expression is associated with reduced patient survival. Melanocytes are specialized cells in the skin that produce melanin, a pigment that is responsible for skin and hair color and that provides protection against ultraviolet (UV) radiation. During mouse embryogenesis, melanoblasts originate from the neural crest and migrate along a dorsolateral pathway from the neural tube to the developing dermis.1 Around embryonic day (E) E11 they move into the epidermis and eventually populate the developing hair follicle.2 Here they separate into two distinct populations: the differentiated pigmented melanocytes, which reside in the hair matrix, and the non-pigmented melanocyte stem cells (MSC) in the bulge. The latter cells are responsible for replenishing the hair follicle with new melanocytes during each hair cycle. Genetic studies in mice demonstrated the importance of several key players (such as sex-determining region Y (SRY)-box 10 (Sox10), paired-box 3 (Pax3), microphthalmia-associated transcription factor (Mitf), endothelin 3/endothelin receptor B (Edn3/ Ednrb), Kitl/Kit, Slug, cellular myelocytomatosis oncogene cellular homolog (cMyc) and b-Catenin (b-Cat)) for melanoblast cell fate specification, proliferation, migration and survival.2-4 The master regulator of the melanocyte development is MITF, which is spatio-temporally controlled by several key transcription factors such as SOX10, PAX3 and b-catenin.5-7 Fundamentally, MITF induces gene expression patterns that prompt a melanocyte to differentiate and initiate pigment production by activating genes important for melanin biosynthesis (such as Tyrosinase (Tyr), Dopachrome tautomerase (Dct), Tyrosinase-related protein 1 (Tyrp1) and

Epithelial-to-mesenchymal transition (EMT)-inducing transcription factors (TF) are well known for their ability to induce mesenchymal states associated with increased migratory and invasive properties. Unexpectedly, nuclear expression of the EMT-TF ZEB2 in human primary melanoma has been shown to correlate with reduced invasion. We report here that ZEB2 is required for outgrowth for primary melanomas and metastases at secondary sites. Ablation of Zeb2 hampered outgrowth of primary melanomas in vivo, whereas ectopic expression enhanced proliferation and growth at both primary and secondary sites. Gain of Zeb2 expression in pulmonary-residing melanoma cells promoted the development of macroscopic lesions. In vivo fate mapping made clear that melanoma cells undergo a conversion in state where ZEB2 expression is replaced by ZEB1 expression associated with gain of an invasive phenotype. These findings suggest that reversible switching of the ZEB2/ZEB1 ratio enhances melanoma metastatic dissemination.Significance: ZEB2 function exerts opposing behaviors in melanoma by promoting proliferation and expansion and conversely inhibiting invasiveness, which could be of future clinical relevance.

<p>Supplementary Figure legends for Figures 1-5.</p>

<p>Supplementary Figure legends for Figures 1-5.</p>