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The cilium, the sensing centre for the cell, displays an extensive repertoire of receptors for various cell signalling processes. The dynamic nature of ciliary signalling indicates that the ciliary entry of receptors and associated proteins must be regulated and conditional. To understand this process, we studied the ciliary localisation of the odour-receptor coreceptor (Orco), a seven-pass transmembrane protein essential for insect olfaction. Little is known about when and how Orco gets into the cilia. Here, using Drosophila melanogaster, we show that the bulk of Orco selectively enters the cilia on adult olfactory sensory neurons in two discrete, one-hour intervals after eclosion. A conditional loss of heterotrimeric kinesin-2 during this period reduces the electrophysiological response to odours and affects olfactory behaviour. We further show that Orco binds to the C-terminal tail fragments of the heterotrimeric kinesin-2 motor, which is required to transfer Orco from the ciliary base to the outer segment and maintain within an approximately four-micron stretch at the distal portion of the ciliary outer-segment. The Orco transport was not affected by the loss of critical intraflagellar transport components, IFT172/Oseg2 and IFT88/NompB, respectively, during the adult stage. These results highlight a novel developmental regulation of seven-pass transmembrane receptor transport into the cilia and indicate that ciliary signalling is both developmentally and temporally regulated. Jana, Dutta, Jain et al., show that the odour-receptor coreceptor only enters the cilia expressed on olfactory sensory neurons at specified developmental stages requiring heterotrimeric kinesin-2. The motor binds to the coreceptor and plays a crucial role in localising them to a compact, environment-exposed domain at the ciliary outer-segment. Author summary: Cilia are antenna-like organelles of eukaryotic cells, which mediate cellular signalling. Dysregulation of cilia assembly and the functionalisation process leads to numerous human diseases, including ciliopathies and cancer. In sensory cilia, specific sub-compartments are established to support multiple signal transduction processes, such as photoreception, olfaction, and mechanosensation. In the last two decades, several reports described how a cilium is built and functions. However, a detailed understanding of the timing and modulation of receptor cargo transport to the cilium remains unclear. Here, we show that Orco, a signalling coreceptor for a family of insect olfactory receptors, specifically enters the cilia expressed on olfactory sensory neurons, and the process is restricted to a narrow developmental window in the fruit fly, Drosophila. The coreceptor is kept out of the cilia until it reaches its structural maturity shortly before Drosophila completes its metamorphosis and emerges from the pupal casing. This time-gated Orco entry would enable the adult fly to smell the environment as it emerged from the pupal case. We also find that the heterotrimeric kinesin-2, a core evolutionarily conserved anterograde motor essential for assembling the ciliary structure, is critical for functionalising the olfactory cilia. It interacts with Orco and transports the receptor into the cilium in an IFT-independent fashion. In addition, the motor appeared to deliver and maintain Orco at its designated slot in the ciliary outer-segment. Altogether, our results describe how activation of the olfactory cilia in a multicellular organism is tightly regulated. This system also provides an excellent tool and platform to understand the complex regulation of signalling components in cilia functionalisation, maintenance, and plasticity. [ABSTRACT FROM AUTHOR]

This document is a correction notice for an article titled "Kinesin-2 transports Orco into the olfactory cilium of Drosophila melanogaster at specific developmental stages." The correction addresses an incomplete funding statement and acknowledgments section. The correct funding statement acknowledges support from the Department of Atomic Energy, Government of India, and the Fundação Portuguesa para a Ciência e Tecnologia (FCT). The correct acknowledgments section thanks various individuals and institutions for their contributions to the study. The authors of the article are Swadhin Chandra Jana, Priya Dutta, Akanksha Jain, Anjusha Singh, Lavanya Adusumilli, Mukul Girotra, Diksha Kumari, Seema Shirolikar, and Krishanu Ray. [Extracted from the article]

The assembly of microtubule-based cytoskeleton propels the cilia and flagella growth. Previous studies have indicated that the kinesin-2 family motors transport tubulin into the cilia through intraflagellar transport. Here, we report a direct interaction between the C-terminal tail fragments of heterotrimeric kinesin-2 and α-tubulin1 isoforms in vitro. Blot overlay screen, affinity purification from tissue extracts, cosedimentation with subtilisin-treated microtubule and LC-ESI-MS/ MS characterization of the tail-fragment-associated tubulin identified an association between the tail domains and α- tubulin1A/D isotype. The interaction was confirmed by Forster's resonance energy transfer assay in tissue-cultured cells. The overexpression of the recombinant tails in NIH3T3 cells affected the primary cilia growth, which was rescued by coexpression of a α-tubulin1 transgene. Furthermore, fluorescent recovery after photobleach analysis in the olfactory cilia of Drosophila indicated that tubulin is transported in a non-particulate form requiring kinesin-2. These results provide additional new insight into the mechanisms underlying selective tubulin isoform enrichment in the cilia. [ABSTRACT FROM AUTHOR]