The GTP- and Phospholipid-Binding Protein TTD14 Regulates Trafficking of the TRPL Ion Channel in Drosophila Photoreceptor Cells.

Recycling of signaling proteins is a common phenomenon in diverse signaling pathways. In photoreceptors of Drosophila, light absorption by rhodopsin triggers a phospholipase Cβ-mediated opening of the ion channels transient receptor potential (TRP) and TRP-like (TRPL) and generates the visual response. The signaling proteins are located in a plasma membrane compartment called rhabdomere.

Mutation of light-dependent phosphorylation sites of the Drosophila transient receptor potential-like (TRPL) ion channel affects its subcellular localization and stability.

The Drosophila phototransduction cascade terminates in the opening of the ion channel transient receptor potential (TRP) and TRP-like (TRPL). Contrary to TRP, TRPL undergoes light-dependent subcellular trafficking between rhabdomeric photoreceptor membranes and an intracellular storage compartment, resulting in long term light adaptation. Here, we identified in vivo phosphorylation sites of TRPL that affect TRPL stability and localization.

A dual role for nanos and pumilio in anterior and posterior blastodermal patterning of the short-germ beetle Tribolium castaneum.

Abdominal patterning in Drosophila requires the function of Nanos (nos) and Pumilio (pum) to repress posterior translation of hunchback mRNA. Here we provide the first functional analysis of nanos and pumilio genes during blastodermal patterning of a short-germ insect. We found that nos and pum in the red flour beetle Tribolium castaneum crucially contribute to posterior segmentation by preventing hunchback translation.

The Drosophila TRPL ion channel shares a Rab-dependent translocation pathway with rhodopsin.

The Drosophila visual transduction cascade is embedded in the rhabdomeres of photoreceptor cells and culminates in the opening of the two ion channels, TRP and TRPL. TRPL translocates from the rhabdomeres to the cell body upon illumination and vice versa when flies are kept in the dark. Here, we studied the mechanisms underlying the light-dependent internalization of TRPL.

Regulation of TRP signalling by ion channel translocation between cell compartments.

The TRP (transient receptor potential) family of ion channels is a heterogeneous family of calcium permeable cation channels that is subdivided into seven subfamilies: TRPC ("Canonical"), TRPV ("Vanilloid"), TRPM ("Melastatin"), TRPA ("Ankyrin"), TRPN ("NOMPC"), TRPP ("Polycystin"), and TRPML ("Mucolipin"). TRP-mediated ion currents across the cell membrane are determined by the single channel conductance, by the fraction of activated channels, and by the total amount of TRP channels present at the plasma membrane. In many cases, the amount of TRP channels at the plasma membrane is altered in response to physiological stimuli by translocation of channels to and from the plasma membrane.

JAK-STAT signalling is required throughout telotrophic oogenesis and short-germ embryogenesis of the beetle Tribolium.

In Drosophila, the JAK-STAT signalling pathway regulates a broad array of developmental functions including segmentation and oogenesis. Here we analysed the functions of Tribolium JAK-STAT signalling factors and of Suppressor Of Cytokine Signalling (SOCS) orthologues, which are known to function as negative regulators of JAK-STAT signalling, during telotrophic oogenesis and short-germ embryogenesis. The beetle Tribolium features telotrophic ovaries, which differ fundamentally from the polytrophic ovary of Drosophila.

The Tribolium ortholog of knirps and knirps-related is crucial for head segmentation but plays a minor role during abdominal patterning.

Segment formation in the long germ insect Drosophila is dominated by overlapping gap gene domains in the syncytial blastoderm. In the short germ beetle Tribolium castaneum abdominal segments arise from a cellular growth zone, implying different patterning mechanisms. We describe here the single Tribolium ortholog of the Drosophila genes knirps and knirps-related (called Tc-knirps).

Breakdown of abdominal patterning in the Tribolium Kruppel mutant jaws.

During Drosophila segmentation, gap genes function as short-range gradients that determine the boundaries of pair-rule stripes. A classical example is Drosophila Krüppel (Dm'Kr) which is expressed in the middle of the syncytial blastoderm embryo. Patterning defects in Dm'Kr mutants are centred symmetrically around its bell-shaped expression profile.