ABSTRACT
Formation and resolution of multicellular rosettes can drive convergent extension (CE) type cell rearrangements during tissue morphogenesis. Rosette dynamics are regulated by both planar cell polarity (PCP)-dependent and -independent pathways. Here we show that CE is involved in ventral nerve cord (VNC) assembly in Caenorhabditis elegans. We show that a VANG-1/Van Gogh and PRKL-1/Prickle containing PCP pathway and a Slit-independent SAX-3/Robo pathway cooperate to regulate, via rosette intermediaries, the intercalation of post-mitotic neuronal cell bodies during VNC formation. We show that VANG-1 and SAX-3 are localized to contracting edges and rosette foci and act to specify edge contraction during rosette formation and to mediate timely rosette resolution. Simultaneous loss of both pathways severely curtails CE resulting in a shortened, anteriorly displaced distribution of VNC neurons at hatching. Our results establish rosette-based CE as an evolutionarily conserved mechanism of nerve cord morphogenesis and reveal a role for SAX-3/Robo in this process.
Subject(s)
Cell Polarity/physiology , Morphogenesis/physiology , Nerve Tissue Proteins/metabolism , Neurons/metabolism , Receptors, Immunologic/metabolism , Signal Transduction , Animals , Animals, Genetically Modified , Axons/metabolism , Caenorhabditis elegans , Cell Movement/physiology , Roundabout ProteinsABSTRACT
Genetic pathways that regulate nascent neurite formation play a critical role in neuronal morphogenesis. The core planar cell polarity components VANG-1/Van Gogh and PRKL-1/Prickle are involved in blocking inappropriate neurite formation in a subset of motor neurons in C. elegans. A genetic screen for mutants that display supernumerary neurites was performed to identify additional factors involved in this process. This screen identified mutations in fntb-1, the ß subunit of farnesyltransferase. We show that fntb-1 is expressed in neurons and acts cell-autonomously to regulate neurite formation. Prickle proteins are known to be post-translationally modified by farnesylation at their C-terminal CAAX motifs. We show that PRKL-1 can be recruited to the plasma membrane in both a CAAX-dependent and CAAX-independent manner but that PRKL-1 can only inhibit neurite formation in a CAAX-dependent manner.
Subject(s)
Caenorhabditis elegans Proteins/metabolism , Caenorhabditis elegans/physiology , Farnesyltranstransferase/metabolism , Intracellular Signaling Peptides and Proteins/metabolism , Neurites/physiology , Animals , Caenorhabditis elegans Proteins/analysis , Caenorhabditis elegans Proteins/genetics , Farnesyltranstransferase/analysis , Farnesyltranstransferase/genetics , Intracellular Signaling Peptides and Proteins/analysis , Intracellular Signaling Peptides and Proteins/genetics , Models, Molecular , Mutation , Prenylation , Protein Processing, Post-Translational , Protein Subunits/analysis , Protein Subunits/genetics , Protein Subunits/metabolismABSTRACT
Pseudomonas aeruginosa is a key opportunistic pathogen characterized by its biofilm formation ability and high-level multiple antibiotic resistance. By screening a library of random transposon insertion mutants with an increased biofilm-specifc antibiotic susceptibility, we previously identified 3 genes or operons of P. aeruginosa UCBPP-PA14 (ndvB, PA1875-1877 and tssC1) that do not affect biofilm formation but are involved in biofilm-specific antibiotic resistance. In this study, we demonstrate that PA0756-0757 (encoding a putative two-component regulatory system), PA2070 and PA5033 (encoding hypothetical proteins of unknown function) display increased expression in biofilm cells and also have a role in biofilm-specific antibiotic resistance. Furthermore, deletion of each of PA0756, PA2070 and PA5033 resulted in a significant reduction of lethality in Caenorhabditis elegans, indicating a role for these genes in both biofilm-specific antibiotic resistance and persistence in vivo. Together, these data suggest that these genes are potential targets for antimicrobial agents.
Subject(s)
Anti-Bacterial Agents/pharmacology , Biofilms/drug effects , Drug Resistance, Bacterial/genetics , Genes, Bacterial , Pseudomonas aeruginosa/drug effects , Pseudomonas aeruginosa/genetics , Animals , Caenorhabditis elegans/microbiology , Gene Expression , Microbial Sensitivity Tests , Mutation , Pseudomonas aeruginosa/growth & developmentABSTRACT
Type 1 diabetes (T1D) is an autoimmune disorder that results from the destruction of insulin-producing beta-cells in the islets of Langerhans. To date, autoimmune T-cell response and antibody reactivity to more than 20 autoantigens have been linked to this disease. Some studies have described the intermediate filament protein peripherin (PRPH) as an autoantigen associated with T1D in non-obese diabetic (NOD) mice. We evaluated immune reactivity of mouse and rabbit sera and human plasma to a 58 kDa protein expressed in RIN-m5F rat insulinoma cells. The protein was isolated using 2-DE and identified by mass spectrometry as PRPH. Antibodies from healthy humans and T1D patients, CD-1 mice, C57BL/6 mice, NOR (non-obese diabetes resistant) mice, and NOD mice reacted with PRPH on Western blots. However, antibody response to PRPH was stronger in NOD than non-autoimmune prone C57BL/6 mice. We conclude that immune reactivity to PRPH is not exclusively associated with NOD mice or human patients with T1D. Furthermore, the frequent occurrence of PRPH-reactive antibodies in mouse and human blood suggests that binding may be non-specific or could reflect the presence of natural autoantibodies against PRPH. These findings point to the need for a re-evaluation of PRPH as a T1D autoantigen in NOD mice and raise the question of the physiological relevance of such widespread immune reactivity against this peripheral nervous system protein.
