scholarly journals The kinesin motor Klp98A mediates apical to basal Wg transport

Development ◽  
2020 ◽  
Vol 147 (15) ◽  
pp. dev186833 ◽  
Author(s):  
Leonie Witte ◽  
Karen Linnemannstöns ◽  
Kevin Schmidt ◽  
Mona Honemann-Capito ◽  
Ferdinand Grawe ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Family Member ◽  
Long Range ◽  
Basal Cell ◽  
Imaginal Disc ◽  
Tissue Homeostasis ◽  
Recycling Endosomes ◽  
Endosomal Transport ◽  
Functional Relevance ◽  
Endosomal System

ABSTRACTDevelopment and tissue homeostasis rely on the tight regulation of morphogen secretion. In the Drosophila wing imaginal disc epithelium, Wg secretion for long-range signal transduction occurs after apical Wg entry into the endosomal system, followed by secretory endosomal transport. Although Wg release appears to occur from the apical and basal cell sides, its exact post-endocytic fate and the functional relevance of polarized endosomal Wg trafficking are poorly understood. Here, we identify the kinesin-3 family member Klp98A as the master regulator of intracellular Wg transport after apical endocytosis. In the absence of Klp98A, functional mature endosomes accumulate in the apical cytosol, and endosome transport to the basal cytosol is perturbed. Despite the resulting Wg mislocalization, Wg signal transduction occurs normally. We conclude that transcytosis-independent routes for Wg trafficking exist and demonstrate that Wg can be recycled apically via Rab4-recycling endosomes in the absence of Klp98A.

The Humanized Anti-CD40 Monoclonal Antibody, SGN-40, Potentiates Chemotherapy Regimens in NHL Xenograft Models Via Pro-Apoptotic Signaling.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 2342-2342 ◽  
Author(s):  
Timothy S. Lewis ◽  
Renee S. McCormick ◽  
Kim Kissler ◽  
Ivan J. Stone ◽  
Mechthild Jonas ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Monoclonal Antibody ◽  
Antitumor Activity ◽  
Family Member ◽  
Cytotoxic Agents ◽  
P53 Family ◽  
Signaling Mechanism ◽  
Xenograft Models

Abstract SGN-40 is a humanized antibody targeting CD40, a TNF receptor family member expressed on normal B cells, non-Hodgkin’s lymphoma (NHL), multiple myeloma, and a variety of carcinomas. Previous studies have shown that SGN-40 triggers proapoptotic signal transduction, mediates effector function (ADCC), and has in vivo antitumor activity in CD40+ lymphoma xenograft models. We now report in vivo efficacy data for SGN-40 in combination with the anti-CD20 monoclonal antibody, rituximab, and approved chemotherapy regimens for the treatment of NHL. The growth of subcutaneous Ramos tumors in SCID mice was delayed following SGN-40 or rituximab treatment. However, the combination of SGN-40 + rituximab (S-R) significantly improved efficacy over either antibody alone. SGN-40 was then tested with ICE (ifosfamide, carboplatin, etoposide) chemotherapy with or without rituximab (S-R-ICE and S-ICE). These studies demonstrated that both S-R-ICE and S-ICE treated mice had lower tumor burden than R-ICE or SGN-40 treated animals. Additionally, the effect of SGN-40 in combination with CHOP (cyclophosphamide, doxorubicin, vincristine, prednisone) chemotherapy with or without rituximab (S-R-CHOP and S-CHOP) was examined. S-R-CHOP and S-CHOP therapies showed a significant delay in tumor growth compared with R-CHOP or SGN-40 alone. Furthermore, the efficacy observed in S-R-ICE and S-R-CHOP treatments exceeded the S-R combination, suggesting that SGN-40 chemosensitizes lymphoma cells by a signaling mechanism in addition to augmenting ADCC when combined with rituximab. To better understand the chemosensitization effect of SGN-40 in xenograft models, signal transduction events triggered by SGN-40 were examined in vitro. SGN-40 treatment caused the sustained degradation of the BCL-6 protooncogene in several lymphoma cell lines, following prolonged MAP Kinase pathway activation. BCL-6 is implicated in lymphomagenesis of germinal center derived lymphomas, and is proteasomally degraded after phosphorylation by ERK1/2 MAPK. Immunohistochemical analyses of Ramos tumors harvested from mice following treatment with SGN-40 or S-CHOP revealed elevated numbers of apoptotic cells versus untreated tumors. A distinct downregulation of BCL-6 staining in Ramos tumor cells was also observed in SGN-40 and S-CHOP treated animals, correlating with increased cell death. Finally, in some NHL lines SGN-40 upregulated the p53 family member TAp63alpha, a chemo-sensitizing transcription factor capable of inducing apoptosis when overexpressed. When combined with cytotoxic agents, SGN-40 caused a greater induction of TAp63alpha compared with chemotherapy alone, a potential mechanism underlying the improved antitumor activity seen in combination studies. Collectively, these data suggest that SGN-40 signaling occurs at the tumor site, likely contributing directly to tumor cell killing and chemosensitization. These preclinical studies support our earlier work suggesting that addition of SGN-40 to standard therapeutic regimens may improve the outcome for patients with NHL.

Preclinical Analysis of the Combined Activity of SGN-40, Anti-CD40 Monoclonal Antibody, with Rituximab in Non-Hodgkin Lymphoma.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1583-1583 ◽  
Author(s):  
Timothy S. Lewis ◽  
Renee S. McCormick ◽  
Julie A. McEarchern ◽  
Kim Kissler ◽  
Ivan J. Stone ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Monoclonal Antibody ◽  
Family Member ◽  
Cell Lines ◽  
Tumor Response ◽  
Effector Function ◽  
Signal Transduction Pathways ◽  
Non Hodgkin Lymphoma ◽  
Function Activity

Abstract SGN-40 is a humanized monoclonal antibody against CD40, a TNF receptor family member expressed in non-Hodgkin lymphoma (NHL), multiple myeloma, and several carcinomas. SGN-40 is cytotoxic to NHL cell lines via activation of proapoptotic signal transduction pathways and mediates antibody dependent cellular cytotoxicity (ADCC) effector function activity. In this study we examined the anti-tumor activity of SGN-40 in combination with the anti-CD20 antibody, rituximab, in lymphoma cell line models. Cell proliferation data (3H-thymidine incorporation assay) was generated for SGN-40 and rituximab alone and in combination for three NHL cell lines (Ramos, RL, and SU-DHL-4) and combination index (CI) analyses performed. SGN-40 was reproducibly synergistic with rituximab in Ramos cells and additive in the RL and SU-DHL-4 cell lines in this assay. This suggested that different anti-proliferative signaling events are activated by these antibodies, which produce a greater anti-tumor effect when combined. To better understand the combined activity of SGN-40 and rituximab, the signal transduction pathways activated by each antibody were examined. In Ramos cells SGN-40 signaling caused the degradation of pro-survival BCL-6 oncoprotein and upregulation of TAp63α, a proapoptic p53 family member, while only BCL-6 degradation was triggered in the RL and SU-DHL-4 cell lines. In contrast, rituximab signaling degraded BCL-6 protein in only one cell line (SU-DHL-4), and did not upregulate TAp63α expression in any of the cell lines examined. To further define the combined activity of SGN-40 with rituximab the effector function activity of both antibodies were examined in vitro. ADCC assays in the WIL2-S and Raji cell lines both showed a greater percent cell lysis in the presence of both SGN-40 and rituximab compared to either drug alone. Next, the SGN-40 and rituximab were tested in subcutaneous mouse models of NHL to evaluate this combination in vivo. In a Ramos model, SGN-40 and rituximab (dosed at 4.0mg/kg, q4dx4, ip) had significantly greater anti-tumor response when combined compared to the equivalent dose of either antibody alone. The anti-tumor response achieved with dual dosing of SGN-40 and rituximab was greater than the response expected if the combination was additive. Our data suggests that the improved efficacy of SGN-40, rituximab combination therapy in vivo is due to distinct apoptotic signaling pathways activated by these two antibodies in addition to augmented effector function activity. The combination of SGN-40 and rituximab is currently being studied in clinical trials of NHL.

scholarly journals Muscle-derived Myoglianin regulates Drosophila imaginal disc growth

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Ambuj Upadhyay ◽  
Aidan J Peterson ◽  
Myung-Jun Kim ◽  
Michael B O'Connor
Keyword(s):  
Family Member ◽  
Imaginal Disc ◽  
Growth Control ◽  
Wing Size ◽  
Extrinsic Factor ◽  
Allometric Relationship ◽  
Organ Growth ◽  
Disc Cells ◽  
Close Homolog

Organ growth and size are finely tuned by intrinsic and extrinsic signaling molecules. In Drosophila, the BMP family member Dpp is produced in a limited set of imaginal disc cells and functions as a classic morphogen to regulate pattern and growth by diffusing throughout imaginal discs. However, the role of TGFβ/Activin-like ligands in disc growth control remains ill-defined. Here, we demonstrate that Myoglianin (Myo), an Activin family member, and a close homolog of mammalian Myostatin (Mstn), is a muscle-derived extrinsic factor that uses canonical dSmad2-mediated signaling to regulate wing size. We propose that Myo is a myokine that helps mediate an allometric relationship between muscles and their associated appendages.

scholarly journals Muscle-derived Myoglianin regulates Drosophila imaginal disc growth

2019 ◽  
Author(s):  
Ambuj Upadhyay ◽  
Aidan J. Peterson ◽  
Myung-Jun Kim ◽  
Michael B. O’Connor
Keyword(s):  
Family Member ◽  
Imaginal Disc ◽  
Growth Control ◽  
Wing Size ◽  
Extrinsic Factor ◽  
Allometric Relationship ◽  
Organ Growth ◽  
Disc Cells ◽  
Close Homolog

ABSTRACTOrgan growth and size are finely tuned by intrinsic and extrinsic signaling molecules. In Drosophila, the BMP family member Dpp is produced in a limited set of imaginal disc cells and functions as a classic morphogen to regulate pattern and growth by diffusing throughout imaginal discs. However, the role of TGFβ/Activin-like ligands in disc growth control remains ill-defined. Here we demonstrate that Myoglianin (Myo), an Activin family member, and a close homolog of mammalian Myostatin (Mstn), is a muscle-derived extrinsic factor that uses canonical dSmad2 mediated signaling to regulate wing size. We propose that Myo is a myokine that helps mediate an allometric relationship between muscles and their associated appendages.

scholarly journals Sonic hedgehog is basolaterally sorted from the TGN and transcytosed to the apical domain involving Dispatched-1 at Rab11-ARE

2021 ◽  
Author(s):  
Lisett Sandoval ◽  
Mariana Labarca ◽  
Claudio Retamal ◽  
Juan Larrain ◽  
Alfonso Gonzalez
Keyword(s):  
Steady State ◽  
Epithelial Cells ◽  
Cell Surface ◽  
Sonic Hedgehog ◽  
Mdck Cells ◽  
Tissue Homeostasis ◽  
Recycling Endosomes ◽  
Lipid Modifications ◽  
Apical Domain ◽  
Endocytic Pathways

Hedgehog (Hh) secretion from apical and/or basolateral domains occurs in different epithelial cells impacting development and tissue homeostasis. Palmitoylation and cholestyrolation attach Hh proteins to membranes and Dispatched-1 (Disp-1) promotes their release. How these lipidated proteins are handled by the complex secretory and endocytic pathways of polarized epithelial cells remains unknown. We show that MDCK cells address newly synthesized sonic hedgehog (Shh) from the TGN to the basolateral cell surface and then to the apical domain through a transcytosis pathway that includes Rab11-apical recycling endosomes (Rab11-ARE). Both palmitoylation and cholestyrolation contribute to this sorting behavior, otherwise Shh lacking these lipid modifications is unpolarized. Disp-1 mediates first basolateral secretion from the TGN and then transcytosis from the Rab11-ARE. At steady state, Shh predominates apically and can be basolaterally transcytosed. This complex Shh trafficking provides several steps for regulation and variation in different epithelia, subordinating the apical to the basolateral secretion.

scholarly journals A Dopamine-Responsive Signal Transduction Controls Transcription ofSalmonella entericaSerovar Typhimurium Virulence Genes

mBio ◽  
2019 ◽  
Vol 10 (2) ◽  
Author(s):  
Dezhi Yang ◽  
Ying Kong ◽  
Wei Sun ◽  
Wei Kong ◽  
Yixin Shi
Keyword(s):  
Gene Expression ◽  
Signal Transduction ◽  
Family Member ◽  
Virulence Genes ◽  
Enteric Bacteria ◽  
Virulence Determinants ◽  
Transcription Activator ◽  
Content Type ◽  
Serovar Typhimurium ◽  
Target Promoters

ABSTRACTWe have shown that the ligand-responsive MarR family member SlyA plays an important role in transcription activation of multiple virulence genes inSalmonella entericaserovar Typhimurium by responding to guanosine tetraphosphate (ppGpp). Here, we demonstrate that another MarR family member, EmrR, is required for virulence ofS.Typhimurium and another enteric bacterium,Yersinia pestis. EmrR is found to activate transcription of an array of virulence determinants, includingSalmonellapathogenicity island 2 (SPI-2) genes and several divergent operons, which have been shown to be activated by SlyA and the PhoP/PhoQ two-component system. We studied the regulatory effect of EmrR on one of these genetic loci, i.e., thepagC-pagDdivergent operon, and characterized a catecholamine neurotransmitter, dopamine, as an EmrR-sensed signal. Dopamine acts on EmrR to reduce its ability to bind to the target promoters, thus functioning as a negative signal to downregulate this EmrR-activated transcription. EmrR can bind to AT-rich sequences, which particularly overlap the SlyA and PhoP binding sites in thepagC-pagDdivergent promoter. EmrR is a priming transcription regulator that binds its target promoters prior to successive transcription activators, by which it displaces universal silencer H-NS from these promoters and facilitates successive regulators to bind these regions. Regulation of theSalmonella-specific gene inEscherichia coliandY. pestisreveals that EmrR-dependent regulation is conserved in enteric bacteria. These observations suggest that EmrR is a transcription activator to control the expression of virulence genes, including the SPI-2 genes. Dopamine can act on the EmrR-mediated signal transduction, thus downregulating expression of these virulence factors.IMPORTANCEIn this study, MarR family regulator EmrR is identified as a novel virulence factor of enteric bacteria, here exemplified bySalmonella entericaserovar Typhimurium andYersinia pestis. EmrR exerts an essential effect as a transcription activator for expression of virulence determinants, includingSalmonellapathogenicity island 2 genes and a set of horizontally acquired genetic loci that formed divergent operons. EmrR senses the neurotransmitter dopamine and is subsequently released from target promoters, resulting in downregulation of the virulence gene expression. Through this action on EmrR, dopamine can weakenSalmonellaresistance against host defense mechanisms. This provides an explanation for the previous observation that dopamine inhibits bacterial infection in animal gastrointestinal tracts. Our findings provide evidence that this neurotransmitter can modulate bacterial gene expression through interaction with virulence regulator EmrR.

Cross regulation of decapentaplegic and Ultrabithorax transcription in the embryonic visceral mesoderm of Drosophila

Development ◽  
1993 ◽  
Vol 117 (4) ◽  
pp. 1211-1222 ◽  
Author(s):  
D.A. Hursh ◽  
R.W. Padgett ◽  
W.M. Gelbart
Keyword(s):  
Gene Expression ◽  
Signal Transduction ◽  
Family Member ◽  
Reporter Gene ◽  
Expression Patterns ◽  
Reporter Genes ◽  
Regulatory Elements ◽  
Wild Type ◽  
Visceral Mesoderm ◽  
Normal Expression

The Drosophila decapentaplegic gene (dpp) encodes a TGF-beta family member involved in signal transduction during embryonic midgut formation. The shortvein (shv) class of cis-regulatory dpp mutants disrupt expression in parasegments 4 and 7 (ps4 and ps7) of the embryonic visceral mesoderm (VM) surrounding the gut and cause abnormalities in gut morphogenesis. We demonstrate that cis-regulatory elements directing expression in ps4 and ps7 are separable and identify DNA fragments that generate ps4 and ps7 expression patterns using reporter gene constructs. dpp reporter gene expression in both ps4 and ps7 is autoregulated as it requires endogenous dpp+ activity. Reporter gene ps7 expression requires the wild-type action of Ultra-bithorax (Ubx), and abdominal-A. Furthermore, the expression of certain Ubx reporter genes is coincident with dpp in the VM. Both the mis-expression of Ubx reporter genes in the developing gastric caecae at ps4 and its normal expression in ps7 are dependent upon endogenous dpp+ activity. We conclude that dpp both responds to and regulates Ubx in ps7 of the visceral mesoderm and that Ubx autoregulation within this tissue may be indirect as it requires more components than have previously been thought.

Adapting brain metabolism to myelination and long-range signal transduction

Glia ◽  
2014 ◽  
Vol 62 (11) ◽  
pp. 1749-1761 ◽  
Author(s):  
Johannes Hirrlinger ◽  
Klaus-Armin Nave
Keyword(s):  
Signal Transduction ◽  
Long Range ◽  
Brain Metabolism

scholarly journals The AP-1A and AP-1B clathrin adaptor complexes define biochemically and functionally distinct membrane domains

2003 ◽  
Vol 163 (2) ◽  
pp. 351-362 ◽  
Author(s):  
Heike Fölsch ◽  
Marc Pypaert ◽  
Sandra Maday ◽  
Laurence Pelletier ◽  
Ira Mellman
Keyword(s):  
Cell Polarity ◽  
Transferrin Receptor ◽  
Cell Fractionation ◽  
Membrane Domains ◽  
Perinuclear Region ◽  
Recycling Endosomes ◽  
Great Specificity ◽  
Endosomal Transport ◽  
Clathrin Adaptor ◽  
Distinct Membrane

Most epithelial cells contain two AP-1 clathrin adaptor complexes. AP-1A is ubiquitously expressed and involved in transport between the TGN and endosomes. AP-1B is expressed only in epithelia and mediates the polarized targeting of membrane proteins to the basolateral surface. Both AP-1 complexes are heterotetramers and differ only in their 50-kD μ1A or μ1B subunits. Here, we show that AP-1A and AP-1B, together with their respective cargoes, define physically and functionally distinct membrane domains in the perinuclear region. Expression of AP-1B (but not AP-1A) enhanced the recruitment of at least two subunits of the exocyst complex (Sec8 and Exo70) required for basolateral transport. By immunofluorescence and cell fractionation, the exocyst subunits were found to selectively associate with AP-1B–containing membranes that were both distinct from AP-1A–positive TGN elements and more closely apposed to transferrin receptor–positive recycling endosomes. Thus, despite the similarity of the two AP-1 complexes, AP-1A and AP-1B exhibit great specificity for endosomal transport versus cell polarity.

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