Carlos M. Luque

Two distinct modes of guidance signalling during collective migration of border cells

Although directed migration is a feature of both individual cells and cell groups, guided migration has been studied most extensively for single cells in simple environments. Collective guidance of cell groups remains poorly understood, despite its relevance for development and metastasis. Neural crest cells and neuronal precursors migrate as loosely organized streams of individual cells, whereas cells of the fish lateral line, Drosophila tracheal tubes and border-cell clusters migrate as more coherent groups. Here we use Drosophila border cells to examine how collective guidance is performed. We report that border cells migrate in two phases using distinct mechanisms. Genetic analysis combined with live imaging shows that polarized cell behaviour is critical for the initial phase of migration, whereas dynamic collective behaviour dominates later. PDGF- and VEGF-related receptor and epidermal growth factor receptor act in both phases, but use different effector pathways in each. The myoblast city (Mbc, also known as DOCK180) and engulfment and cell motility (ELMO, also known as Ced-12) pathway is required for the early phase, in which guidance depends on subcellular localization of signalling within a leading cell. During the later phase, mitogen-activated protein kinase and phospholipase Cγ are used redundantly, and we find that the cluster makes use of the difference in signal levels between cells to guide migration. Thus, information processing at the multicellular level is used to guide collective behaviour of a cell group.

Coenzyme Q10: A novel therapeutic approach for Fibromyalgia? Case series with 5 patients

Coenzyme Q(10) (CoQ(10)) is an essential electron carrier in the mitochondrial respiratory chain and a strong antioxidant. Low CoQ(10) levels have been detected in patients with Fibromyalgia (FM). The purpose of the present work was to assess the effect of CoQ(10) on symptoms of five patients with FM. Patients were evaluated clinically with Visual Analogical Scale of pain (VAS), and Fibromyalgia Impact Questionnaire (FIQ). Patients with CoQ(10) deficiency showed a statistically significant reduction on symptoms after CoQ(10) treatment during 9 months (300 mg/day). Determination of deficiency and consequent supplementation in FM may result in clinical improvement. Further analysis involving more scientifically rigorous methodology will be required to confirm this observation.

GTP exchange factor Vav regulates guided cell migration by coupling guidance receptor signalling to local Rac activation

Summary Guided cell migration is a key mechanism for cell positioning in morphogenesis. The current model suggests that the spatially controlled activation of receptor tyrosine kinases (RTKs) by guidance cues limits Rac activity at the leading edge, which is crucial for establishing and maintaining polarized cell protrusions at the front. However, little is known about the mechanisms by which RTKs control the local activation of Rac. Here, using a multidisciplinary approach, we identify the GTP exchange factor (GEF) Vav as a key regulator of Rac activity downstream of RTKs in a developmentally regulated cell migration event, that of the Drosophila border cells (BCs). We show that elimination of the vav gene impairs BC migration. Live imaging analysis reveals that vav is required for the stabilization and maintenance of protrusions at the front of the BC cluster. In addition, activation of the PDGF/VEGF-related receptor (PVR) by its ligand the PDGF/PVF1 factor brings about activation of Vav protein by direct interaction with the intracellular domain of PVR. Finally, FRET analyses demonstrate that Vav is required in BCs for the asymmetric distribution of Rac activity at the front. Our results unravel an important role for the Vav proteins as signal transducers that couple signalling downstream of RTKs with local Rac activation during morphogenetic movements.

A role for the chaperone Hsp70 in the regulation of border cell migration in the Drosophila ovary

Unravelling the molecular mechanisms that govern cell migration is of great importance towards understanding both normal embryogenesis and physiological and pathological processes occurring in the adult. Migration of border cells (BCs) during Drosophila oogenesis provides a simple and attractive model in which to address this problem. Here, we show that the molecular chaperone Hsp70 is required for BC migration. Thus, BCs lacking all Hsp70 genes present in the fly genome fail to reorganize their actin cytoskeleton, resulting in migration defects. Similar defects are found when the Hsp70 co-chaperone DnaJ-1, the Drosophila homolog of the human Hsp40, is overexpressed specifically in BCs. In addition, we provide biochemical and genetic evidence for an interaction between DnaJ-1 and PDGF/VEGF receptor (PVR), which is also required for actin-mediated BC migration. Furthermore, our results showing that PVR also interacts genetically with Hsp70 suggest that a mechanism by which the DnaJ-1/Hsp70 chaperone complex regulates BC migration is by modulating PVR function.

Of Fat flies and Hippos, or the magic of animal size

A stream of papers exposes the molecular nuts and bolts of a mechanism that prevents cells from becoming immortal.