27 research outputs found
The Cell Adhesion Molecules Roughest, Hibris, Kin of Irre and Sticks and Stones Are Required for Long Range Spacing of the Drosophila Wing Disc Sensory Sensilla.
No full textMost animal tissues and organ systems are comprised of highly ordered arrays of varying cell types. The development of external sensory organs requires complex cell-cell communication in order to give each cell a specific identity and to ensure a regular distributed pattern of the sensory bristles. This involves both long and short range signaling mediated by either diffusible or cell anchored factors. In a variety of processes the heterophilic Irre Cell Recognition Module, consisting of the Neph-like proteins: Roughest, Kin of irre and of the Nephrin-like proteins: Sticks and Stones, Hibris, plays key roles in the recognition events of different cell types throughout development. In the present study these proteins are apically expressed in the adhesive belt of epithelial cells participating in sense organ development in a partially exclusive and asymmetric manner. Using mutant analysis the GAL4/UAS system, RNAi and gain of function we found an involvement of all four Irre Cell Recognition Module-proteins in the development of a highly structured array of sensory organs in the wing disc. The proteins secure the regular spacing of sensory organs showing partial redundancy and may function in early lateral inhibition events as well as in cell sorting processes. Comparisons with other systems suggest that the Irre Cell Recognition module is a key organizer of highly repetitive structures
Reduced Lateral Inhibition Impairs Olfactory Computations and Behaviors in a Drosophila Model of Fragile X Syndrome
No full textInternational audienceFragile X syndrome (FXS) patients present neuronal alterations that lead to severe intellectual disability, but the underlying neuronal circuit mechanisms are poorly understood. An emerging hypothesis postulates that reduced GABAergic inhibition of excitatory neurons is a key component in the pathophysiology of FXS. Here, we directly test this idea in a FXS Drosophila model. We show that FXS flies exhibit strongly impaired olfactory behaviors. In line with this, olfactory representations are less odor specific due to broader response tuning of excitatory projection neurons. We find that impaired inhibitory interactions underlie reduced specificity in olfactory computations. Finally, we show that defective lateral inhibition across projection neurons is caused by weaker inhibition from GABAergic interneurons. We provide direct evidence that deficient inhibition impairs sensory computations and behavior in an in vivo model of FXS. Together with evidence of impaired inhibition in autism and Rett syndrome, these findings suggest a potentially general mechanism for intellectual disability
The irre cell recognition module (IRM) proteins
No full textOne of the most challenging problems in developmental neurosciences is to understand the establishment and maintenance of specific membrane contacts between axonal, dendritic, and glial processes in the neuropils, which eventually secure neuronal connectivity. However, underlying cell recognition events are pivotal in other tissues as well. This brief review focuses on the pleiotropic functions of a small, evolutionarily conserved group of proteins of the immunoglobulin superfamily involved in cell recognition. In Drosophila, this protein family comprises Irregular chiasm C/Roughest (IrreC/Rst), Kin of irre (Kirre), and their interacting protein partners, Sticks and stones (SNS) and Hibris (Hbs). For simplicity, we propose to name this ensemble of proteins the irre cell recognition module (IRM) after the first identified member of this family. Here, we summarize evidence that the IRM proteins function together in various cellular interactions, including myoblast fusion, cell sorting, axonal pathfinding, and target recognition in the optic neuropils of Drosophila. Understanding IRM protein function will help to unravel the epigenetic rules by which the intricate neurite networks in sensory neuropils are formed.sponsorship: The authors thank Margit Bohler and Weronika Brinkmann for their expert technical assistance. Mary Baylies and Susan Abmayr provided batches of their antibodies against Hbs and SNS that were of great help until substituted by our own. The authors also thank Kei Ito and the NP consortium for providing NP-lines. This work was supported by SFB 505 and the Deutsche Forschungsgemeinschaft. Drs. Sujin Bao, Randy Cassada, Gert H. de Couet, Martin Hohne, and Tobias Huber read the manuscript and gave valuable advice. (Deutsche Forschungsgemeinschaft, SFB 505)status: Publishe
Remote control of renal physiology by the intestinal neuropeptide pigment-dispersing factor in Drosophila.
No full textThe role of the central neuropeptide pigment-dispersing factor (PDF) in circadian timekeeping in Drosophila is remarkably similar to that of vasoactive intestinal peptide (VIP) in mammals. Like VIP, PDF is expressed outside the circadian network by neurons innervating the gut, but the function and mode of action of this PDF have not been characterized. Here we investigate the visceral roles of PDF by adapting cellular and physiological methods to the study of visceral responses to PDF signaling in wild-type and mutant genetic backgrounds. We find that intestinal PDF acts at a distance on the renal system, where it regulates ureter contractions. We show that PdfR, PDFs established receptor, is expressed by the muscles of the excretory system, and present evidence that PdfR-induced cAMP increases underlie the myotropic effects of PDF. These findings extend the similarities between PDF and VIP beyond their shared central role as circadian regulators, and uncover an unexpected endocrine mode of myotropic action for an intestinal neuropeptide on the renal system
A simple computer vision pipeline reveals the effects of isolation on social interaction dynamics in <i>Drosophila</i>
No full textIsolation profoundly influences social behavior in all animals. In humans, isolation has serious effects on health. Drosophila melanogaster is a powerful model to study small-scale, temporally-transient social behavior. However, longer-term analysis of large groups of flies is hampered by the lack of effective and reliable tools. We built a new imaging arena and improved the existing tracking algorithm to reliably follow a large number of flies simultaneously. Next, based on the automatic classification of touch and graph-based social network analysis, we designed an algorithm to quantify changes in the social network in response to prior social isolation. We observed that isolation significantly and swiftly enhanced individual and local social network parameters depicting near-neighbor relationships. We explored the genome-wide molecular correlates of these behavioral changes and found that whereas behavior changed throughout the six days of isolation, gene expression alterations occurred largely on day one. These changes occurred mostly in metabolic genes, and we verified the metabolic changes by showing an increase of lipid content in isolated flies. In summary, we describe a highly reliable tracking and analysis pipeline for large groups of flies that we use to unravel the behavioral, molecular and physiological impact of isolation on social network dynamics in Drosophila.</div
The Neph-like proteins Rst and Kirre affect the localization of other IRM members in <i>cis</i> and <i>trans</i>.
No full text<p>(A-M, O, Q-X) Projection views of IRM immunoreactivity in third instar larvae. Rst is shown in red (A, E, I, M-Q and U-V), Hbs in green (B, F, J, M-P, R and U-V), Kirre in blue (C, G, K, S and W-Z) and SNS in yellow (D, H, L, T and W-Z). (A-D) Misexpression of <i>rst</i> using <i>MZ1369-GAL4</i> leads to ubiquitous Rst staining (A) in the entire wing disc. Hbs (B) and Kirre (C) are significantly reduced. SNS (D) staining is unaffected in strength, but the localization is not limited to the apical contact zone of the SOPs. Instead it is found in the entire cell. Additionally, the order of the SOPs is severely disturbed. (E-H) Misexpression of <i>kirre</i> via <i>MZ1369-GAL4</i> leads to wider stripes of Rst (E) and Hbs (F) staining. Kirre (G) can be ubiquitously detected in the entire wing disc. SNS (H) staining is strong on all membranes in contact with Kirre positive membranes. Spacing of SOPs is already disrupted at this developmental stage. (I-L) Misexpression of <i>rst</i> using <i>neur-GAL4</i> leads to strongly stained Rst (I) positive SOPs. Hbs (J) is found only around the SOPs and staining of membranes not in contact to the SOPs is reduced. (K) Kirre staining is further enriched around the SOPs. (L) SNS is relocated and it is not specifically located at the adherens junction any more. (M) Magnification of three SOPs of a wild type control stained for Rst and Hbs. The dashed line shows the approximate area of cut for the Z-projection in (N). Hbs can be detected inside the SOPs (arrowhead) and also in the basal appendix (arrow). (O) Magnification of three SOPs in <i>neur-GAL4</i>><i>UAS-rst</i>. The approximate area of cut for the Z-projection in (P) is given with a dashed line. Arrowheads mark the immunopositive interior of the SOPs showing strong Rst staining. Arrows marks the basal appendix of the SOPs. Asterisk mark the co-localization of Rst and Hbs immunoreactivity at the Border of SOPs. (Q-T) Misexpression of <i>kirre</i> using <i>neur-GAL4</i> leads to strong Rst staining around the SOPs. Hbs (R) is found much stronger around or in the SOPs and is strongly reduced on the membranes not in contact with any SOPs. (S) Kirre staining is strongly found in all membranes of the SOPs, showing no apical-basal polarity. (T) SNS localization inside the SOPs is disrupted and a possible degradation product can be found in vesicles basal of the adherens junction. (U) Magnification of three SOPs of a wild type control stained for Rst and Hbs. (V) Magnification of three SOPs in <i>neur-GAL4</i>><i>UAS-kirre</i>. Strong accumulation of Hbs immunoreactivity is evident around the SOPs. (W) Magnification of three SOPs of a wild type control stained for Kirre and SNS. (X) The magnification of three SOPs of <i>neur-GAL4</i>><i>UAS-kirre</i> shows the strong Kirre staining in the entire SOP and the mislocalization of SNS. A dotted line in (W and X) shows the approximate area of a Z-cut that is shown in (Y and Z). In wild type (Y) both proteins interact with each other only in a defined apical contact zone. The distribution of the proteins is clearly visible. SNS is inside the SOPs and Kirre in the surrounding cells. In (Z) the distribution of Kirre and SNS is shown in the mutant situation. Mislocalization and vesicular degradation products of SNS can be seen basal of the adherens junction in this z-axis view. Scale bars correspond to 10μm in all images.</p
Hbs acts cooperatively with SNS to secure the bristle pattern in the anterior wing margin.
No full text<p>(A-L) Projection views of IRM-protein immunoreactivity in late third instar larvae. Rst is shown in red (A, E and I), Hbs in green (B, F and N), Kirre in blue (C, G and K) and SNS in yellow (D, H and L). (A-D) Global <i>hbs-RNAi</i> using <i>MZ1369-GAL4</i> reduces the staining for Rst (A) and Kirre (C) in all membranes that are not in contact to the SOPs (B) Hbs immunoreactivity is reduced and no clear membrane localization is detectable. (D) SNS immunoreactivity is only mildly affected, but SOPs stand significantly nearer to each other. (E-H) <i>MZ1369-GAL4</i>><i>UAS-sns-RNAi</i> shows mildly reduced Rst staining (E). Hbs (F) and Kirre (K) immunoreactivity is unchanged. SNS (H) is not detectable. (I-L) In the double RNAi <i>MZ1369>hbs-RNAi</i>, <i>SNS-RNAi</i> only the two adhesive belts with Rst (I) and Kirre (K) are visible, but no obvious SOPs are marked. Hbs (J) and SNS (L) are not detectable. (M) In the adult <i>MZ1369-GAL4</i> driven <i>hbs-RNAi</i> shows only a mild spacing phenotype with 0 to 7 intervening cells. (N) The global <i>sns-RNAi</i> in the entire wing disc shows a very mild spacing phenotype with spacing ranging from 1 to 5. (O) <i>MZ1369>hbs-RNAi</i>, <i>sns-RNAi</i> shows a significant disturbance of the spacing of recurved bristles with spacing ranging from 0 to 8. (P) <i>MZ1369-GAL4</i> driven misexpression of <i>hbs</i> has a strong impact on the spacing of recurved bristles with spacing ranging from 0 to 12. Additionally, clustered recurved bristles are frequently observed. (Q) Quantitative analysis of the recurved bristle spacing, as measured by the number of slender bristles between the recurved bristles. The distribution of <i>MZ1369>GFP</i> differs significantly from <i>MZ1369>hbs-RNAi</i> in the following spacing value: 3: p-value = 0.009. <i>MZ1369>SNS-RNAi</i> differs significantly in the following spacing value: < = 1: p-value = 0.035. The double RNAi for <i>hbs</i> and <i>SNS</i> is significantly different for: < = 1: p-value = 0.0002, 3: p-value = 0.014. <i>hbs</i> overexpression differs for: < = 1: p-value = 0.0011, 3: p-value = 0.0013, > = 6: p-value = <0.001. Scale bars correspond to 10μm in all images.</p
Rst acts cooperatively with Kirre to secure the bristle pattern in the anterior wing margin.
No full text<p>(A-L) Projection views of IRM-protein immunoreactivity in late third instar larvae. Rst is shown in red (A, E, and I), Hbs in green (B, F and J), Kirre in blue (C, G and K) and SNS in yellow (D, H and L). (A-D) The <i>rst</i> allele <i>rst</i><sup><i>1R34</i></sup> shows no detectable Rst staining (A). (B) Hbs staining is reduced in the membranes surrounding the SOPs and is mainly detected in SOP membranes. Kirre (C) and SNS (D) show no significant pattern change. (E-H) <i>MZ1369-GAL4</i>><i>UAS-kirre-RNAi</i> shows no significant changes of the Rst (E) and Hbs pattern (F). Kirre immunoreactivity is hardly detectable (G) while SNS (H) is mildly reduced. (I-L) In the <i>rst</i>, <i>kirre</i> double RNAi hardly any Rst (I) and Kirre (K) can be detected. Enrichment of Hbs (J) around SOPs is reduced and the SOP arrangement as seen with SNS (L) is severely disrupted. (M) In the adult <i>MZ1369>rst-RNAi</i> shows a mild spacing phenotype with spacing ranging from 2 to 5 intervening bristles. (N) <i>MZ1369>kirre-RNAi</i> shows a mild spacing phenotype with spacing ranging from 1 to 7 (similar data was obtained for the mutant <i>rst</i><sup><i>1R34</i></sup>, data not shown). (O) <i>MZ1369>rst-RNAi</i>, <i>kirre-RNAi</i> shows a significant disturbance of the spacing of recurved bristles with 0 to 8 intervening cells. (P) <i>MZ1369-GAL4</i> misexpression of <i>rst</i> has a strong impact on the spacing of recurved bristles with spacing ranging from 0 to 13 intervening cells. Clustered recurved bristles are frequently observed and similarly long areas without any chemosensory bristles are seen. (Q) shows the quantitative analysis of the recurved bristle spacing as measured by the number of slender bristles between the recurved bristles. The distribution of <i>MZ1369>GFP</i> differs significantly from <i>MZ1369>rst-RNAi</i>, <i>kirre-RNAi</i> in the following spacing values: < = 1: p-value = 0.034, 5: p-value = 0.041. <i>MZ1369>rst</i> differs significantly in the following spacing values: < = 1: p-value = 0.0002, 3: p-value = 0.0002, > = 6: p-value = 0.0001. Scale bars correspond to 10μm in all images.</p
Model of IRM-protein interactions in the <i>Drosophila</i> anterior wing margin.
No full text<p>(A-E) Illustration of IRM-protein functions in the anterior wing margin. In black are epithelial cells shown, while SOPs are shown in orange. Protein interactions are shown in different sizes according to the strength of the interaction. Red represents Rst, green Hbs, blue Kirre and SNS is shown in yellow. In the wild type (A) preferred adhesion was observed between the SOPs and the surrounding epithelial cells. Epithelial cells are additionally stable connected through the Hbs, Rst and Hbs, Kirre interaction. In <i>rst</i><sup><i>1R34</i></sup> (B), as an example for Neph-like loss of function, preferential adhesion can still be observed between the SOPs and epithelial cells through the SNS, Kirre and Hbs Kirre interaction. Only in the case of Rst and Kirre loss, the adhesive properties of the wing margin is changed leading to bristle clusters (C). Loss of Hbs prevents heterophilic interaction between the non-SOP cells resulting in mild disturbances of the SOP pattern (D). Loss of Hbs and SNS results in total loss of heterophilic interaction between all cell types in the presumptive anterior wing margin (E). This results in strong disturbances of the SOP and later the bristle pattern (F) Summary of the inductive and competitive interactions between the IRM-proteins <i>in trans</i> and <i>in cis</i>. In the interaction between two cells <i>in trans</i> several inductive events were observed, if these events represent inductions of gene expression or stabilization of proteins in the adhesive belt by heterophilic interactions is currently unknown. Inside cells <i>in cis</i> several competitive interactions were observed, resulting in degradation of proteins in vesicles. Altogether, these interactions allow a precise regulation of IRM-protein abundance and function. (G) Chain model of preferential adhesion of IRM-proteins in the wing disc. The IRM-proteins in the wing disc secure a strong adhesive chain in the distal growing wing. Preferential adhesion around the SOPs secures a constant high number of cells between the SOPs. Growth in distal directions explains the lower number of cells between precursors compared to the adult sensory organs.</p
The Nephrin-like proteins Hbs and SNS affect other IRM-proteins asymmetrically and induce filopodial extensions.
No full text<p>(A-L) Projection view of IRM immunoreactivity in late third instar larvae. Rst is shown in red (A, E, I and M), Hbs in green (B, F, J and N), Kirre in blue (C, G, K and O) and SNS in yellow (D, H, L and P). (A-D) Misexpression of <i>hbs</i> using <i>MZ1369-GAL4</i> leads to a significant enlargement of Rst (A) and Kirre (B) immunoreactivity positive areas. Specific enrichment of immunoreactivity around the SOPs is lost. Hbs (C) is ubiquitously located in all membranes. SNS (D) staining shows that the SOPs have lost their regular pattern already in this developmental stage. (E-H) Ubiquitous misexpression of <i>sns</i> via <i>MZ1369-GAL4</i> leads to reduced staining of Rst (E), Hbs (F) and Kirre (G). SNS (H) staining shows patched expression. (I-L) Overexpression of <i>hbs</i> via <i>neur-GAL4</i> leads to strongly Rst stained membranes in contact with the SOPs (I). Membranes not in contact to the SOPs show reduced staining. This is also evident in an enlargement of the Rst staining (I’). (J) Hbs staining can be found in the entire SOPs without profound apical basal polarity. (K) Kirre is similar to Rst enriched at the membranes in contact to the SOPs. Hardly any staining can be found in other membranes of the adhesive belt. (L) Cellular localization of SNS is only mildly affected by the <i>hbs</i> misexpression as the protein is mainly, but not exclusively localized at the SOP membrane. Additionally, filopodial outgrowths are frequently observed in this genotype as marked with arrowheads in (I), (K) and (L) and in the enlargements (K’) and (L’). (M-P) Overexpression of <i>sns</i> using <i>neur-GAL4</i> leads to strongly enriched staining of Rst (M), Hbs (N) and Kirre (O) around the SOPs. (P) SNS can be found along all membranes of the SOPs due to the overexpression. Similar to hbs overexpression are filopodial outgrowth frequently observed. Scale bars correspond to 10μm in all images.</p
