scholarly journals A reverse signaling pathway downstream of Sema4A controls cell migration via Scrib

2016 ◽  
Vol 216 (1) ◽  
pp. 199-215 ◽  
Author(s):  
Tianliang Sun ◽  
Lida Yang ◽  
Harmandeep Kaur ◽  
Jenny Pestel ◽  
Mario Looso ◽  
...  
Keyword(s):  
Cell Migration ◽  
Signaling Pathway ◽  
Large Family ◽  
Mass Spectrometry Analysis ◽  
Cellular Functions ◽  
Spectrometry Analysis ◽  
Reverse Signaling ◽  
Downstream Effector ◽  
Guanosine Triphosphatase ◽  
Interfering Rna

Semaphorins comprise a large family of ligands that regulate key cellular functions through their receptors, plexins. In this study, we show that the transmembrane semaphorin 4A (Sema4A) can also function as a receptor, rather than a ligand, and transduce signals triggered by the binding of Plexin-B1 through reverse signaling. Functionally, reverse Sema4A signaling regulates the migration of various cancer cells as well as dendritic cells. By combining mass spectrometry analysis with small interfering RNA screening, we identify the polarity protein Scrib as a downstream effector of Sema4A. We further show that binding of Plexin-B1 to Sema4A promotes the interaction of Sema4A with Scrib, thereby removing Scrib from its complex with the Rac/Cdc42 exchange factor βPIX and decreasing the activity of the small guanosine triphosphatase Rac1 and Cdc42. Our data unravel a role for Plexin-B1 as a ligand and Sema4A as a receptor and characterize a reverse signaling pathway downstream of Sema4A, which controls cell migration.

scholarly journals Essential and nonredundant roles for Diaphanous formins in cortical microtubule capture and directed cell migration

2014 ◽  
Vol 25 (5) ◽  
pp. 658-668 ◽  
Author(s):  
Pascale Daou ◽  
Salma Hasan ◽  
Dennis Breitsprecher ◽  
Emilie Baudelet ◽  
Luc Camoin ◽  
...  
Keyword(s):  
Cell Migration ◽  
Actin Polymerization ◽  
Affinity Purification ◽  
Cortical Microtubule ◽  
Leading Edge ◽  
Large Family ◽  
Mass Spectrometry Analysis ◽  
Cell Cortex ◽  
Spectrometry Analysis ◽  
Microtubule Capture

Formins constitute a large family of proteins that regulate the dynamics and organization of both the actin and microtubule cytoskeletons. Previously we showed that the formin mDia1 helps tether microtubules at the cell cortex, acting downstream of the ErbB2 receptor tyrosine kinase. Here we further study the contributions of mDia1 and its two most closely related formins, mDia2 and mDia3, to cortical microtubule capture and ErbB2-dependent breast carcinoma cell migration. We find that depletion of each of these three formins strongly disrupts chemotaxis without significantly affecting actin-based structures. Further, all three formins are required for formation of cortical microtubules in a nonredundant manner, and formin proteins defective in actin polymerization remain active for microtubule capture. Using affinity purification and mass spectrometry analysis, we identify differential binding partners of the formin-homology domain 2 (FH2) of mDia1, mDia2, and mDia3, which may explain their nonredundant roles in microtubule capture. The FH2 domain of mDia1 specifically interacts with Rab6-interacting protein 2 (Rab6IP2). Further, mDia1 is required for cortical localization of Rab6IP2, and concomitant depletion of Rab6IP2 and IQGAP1 severely disrupts cortical capture of microtubules, demonstrating the coinvolvement of mDia1, IQGAP1, and Rab6IP2 in microtubule tethering at the leading edge.

scholarly journals Synaptic mutant huntingtin inhibits synapsin-1 phosphorylation and causes neurological symptoms

2013 ◽  
Vol 202 (7) ◽  
pp. 1123-1138 ◽  
Author(s):  
Qiaoqiao Xu ◽  
Shanshan Huang ◽  
Mingke Song ◽  
Chuan-En Wang ◽  
Sen Yan ◽  
...  
Keyword(s):  
Neurotransmitter Release ◽  
Critical Role ◽  
Early Death ◽  
Neurological Symptoms ◽  
Mass Spectrometry Analysis ◽  
Mutant Huntingtin ◽  
Cellular Functions ◽  
Spectrometry Analysis ◽  
Knockin Mouse ◽  
Synapsin 1

Many genetic mouse models of Huntington’s disease (HD) have established that mutant huntingtin (htt) accumulates in various subcellular regions to affect a variety of cellular functions, but whether and how synaptic mutant htt directly mediates HD neuropathology remains to be determined. We generated transgenic mice that selectively express mutant htt in the presynaptic terminals. Although it was not overexpressed, synaptic mutant htt caused age-dependent neurological symptoms and early death in mice as well as defects in synaptic neurotransmitter release. Mass spectrometry analysis of synaptic fractions and immunoprecipitation of synapsin-1 from HD CAG150 knockin mouse brains revealed that mutant htt binds to synapsin-1, a protein whose phosphorylation is critical for neurotransmitter release. We found that polyglutamine-expanded exon1 htt binds to the C-terminal region of synapsin-1 to reduce synapsin-1 phosphorylation. Our findings point to a critical role for synaptic htt in the neurological symptoms of HD, providing a new therapeutic target.

scholarly journals Involvement of Cell Surface HSP90 in Cell Migration Reveals a Novel Role in the Developing Nervous System

2004 ◽  
Vol 279 (44) ◽  
pp. 45379-45388 ◽  
Author(s):  
Katerina Sidera ◽  
Martina Samiotaki ◽  
Eleni Yfanti ◽  
George Panayotou ◽  
Evangelia Patsavoudi
Keyword(s):  
Nervous System ◽  
Cell Migration ◽  
Heat Shock ◽  
Cell Surface ◽  
Antigen Expression ◽  
Mass Spectrometry Analysis ◽  
Rhodamine Phalloidin ◽  
Spectrometry Analysis ◽  
Hsp90 Activity ◽  
Surface Localization

Heat shock protein HSP90 plays important roles in cellular regulation, primarily as a chaperone for a number of key intracellular proteins. We report here that the two HSP90 isoforms, α and β, also localize on the surface of cells in the nervous system and are involved in their migration. A 94-kDa surface antigen, the 4C5 antigen, which was previously shown to be involved in migration processes during development of the nervous system, is shown to be identical to HSP90α using mass spectrometry analysis. This identity is further confirmed by immunoprecipitation experiments and by induction of 4C5 antigen expression in heat shock-treated embryonic rat brain cultures. Moreover, immunocytochemistry on live cerebellar rat cells reveals cell surface localization of both HSP90α and -β. Cell migration from cerebellar and sciatic nerve explants is inhibited by anti-HSP90α and anti-HSP90β antibodies, similarly to the inhibition observed with monoclonal antibody 4C5. Moreover, immunostaining with rhodamine-phalloidin of migrating Schwann cells cultured in the presence of antibodies against both α and β isoforms of HSP90 reveals that HSP90 activity is associated with actin cytoskeletal organization, necessary for lamellipodia formation.

scholarly journals Bone secreted factors induce cellular quiescence in prostate cancer cells

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Li-Yuan Yu-Lee ◽  
Yu-Chen Lee ◽  
Jing Pan ◽  
Song-Chang Lin ◽  
Tianhong Pan ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Signaling Pathway ◽  
Disseminated Tumor Cells ◽  
Dominant Negative ◽  
Mass Spectrometry Analysis ◽  
Pcr Analysis ◽  
Spectrometry Analysis ◽  
Secreted Factors ◽  
Cellular Quiescence ◽  
Inducing Factors

AbstractDisseminated tumor cells (DTCs) undergo a dormant state in the distant metastatic site(s) before becoming overt metastatic diseases. In prostate cancer (PCa), bone metastasis can occur years after prostatectomy, suggesting that bone may provide dormancy-inducing factors. To search for these factors, we prepared conditioned media (CM) from calvariae. Using live-cell imaging, we found that Calvarial-CM treatment increased cellular quiescence in C4-2B4 PCa cells. Mass spectrometry analysis of Calvarial-CM identified 132 secreted factors. Western blot and ELISA analyses confirmed the presence of several factors, including DKK3, BMP1, neogenin and vasorin in the Calvarial-CM. qRT-PCR analysis of total calvariae versus isolated osteoblasts showed that DKK3, BMP1, vasorin and neogenin are mainly expressed by osteoblasts, while MIA, LECT1, NGAL and PEDF are expressed by other calvarial cells. Recombinant human DKK3, BMP1, vasorin, neogenin, MIA and NGAL treatment increased cellular quiescence in both C4-2b and C4-2B4 PCa cells. Mechanistically, DKK3, vasorin and neogenin, but not BMP1, increased dormancy through activating the p38MAPK signaling pathway. Consistently, DKK3, vasorin and neogenin failed to induce dormancy in cells expressing dominant-negative p38αMAPK while BMP1 remained active, suggesting that BMP1 uses an alternative dormancy signaling pathway. Thus, bone secretes multiple dormancy-inducing factors that employ distinct signaling pathways to induce DTC dormancy in bone.

scholarly journals The scaffolding function of the RLTPR protein explains its essential role for CD28 co-stimulation in mouse and human T cells

2016 ◽  
Vol 213 (11) ◽  
pp. 2437-2457 ◽  
Author(s):  
Romain Roncagalli ◽  
Margot Cucchetti ◽  
Nicolas Jarmuzynski ◽  
Claude Grégoire ◽  
Elise Bergot ◽  
...  
Keyword(s):  
T Cells ◽  
Signaling Pathway ◽  
Affinity Purification ◽  
Mass Spectrometry Analysis ◽  
Pleckstrin Homology Domain ◽  
Spectrometry Analysis ◽  
Human T Cells ◽  
Repeat Domain ◽  
Human And Mouse

The RLTPR cytosolic protein, also known as CARMIL2, is essential for CD28 co-stimulation in mice, but its importance in human T cells and mode of action remain elusive. Here, using affinity purification followed by mass spectrometry analysis, we showed that RLTPR acts as a scaffold, bridging CD28 to the CARD11/CARMA1 cytosolic adaptor and to the NF-κB signaling pathway, and identified proteins not found before within the CD28 signaling pathway. We further demonstrated that RLTPR is essential for CD28 co-stimulation in human T cells and that its noncanonical pleckstrin-homology domain, leucine-rich repeat domain, and proline-rich region were mandatory for that task. Although RLTPR is thought to function as an actin-uncapping protein, this property was dispensable for CD28 co-stimulation in both mouse and human. Our findings suggest that the scaffolding role of RLTPR predominates during CD28 co-stimulation and underpins the similar function of RLTPR in human and mouse T cells. Along that line, the lack of functional RLTPR molecules impeded the differentiation toward Th1 and Th17 fates of both human and mouse CD4+ T cells. RLTPR was also expressed in both human and mouse B cells. In the mouse, RLTPR did not play, however, any detectable role in BCR-mediated signaling and T cell-independent B cell responses.

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