Limits...
The Drosophila homologue of Rootletin is required for mechanosensory function and ciliary rootlet formation in chordotonal sensory neurons.

Styczynska-Soczka K, Jarman AP - Cilia (2015)

Bottom Line: Knock-down of Rootletin results in loss of ciliary rootlet in these neurons and severe disruption of their sensory function.No evidence was found for a defect in cell division.Although our evidence is consistent with an anchoring role for the rootlet, severe loss of mechanosensory function of chordotonal (Ch) neurons upon Rootletin knock-down may suggest a direct role for the rootlet in the mechanotransduction mechanism itself.

View Article: PubMed Central - PubMed

Affiliation: Centre for Integrative Physiology, University of Edinburgh, Edinburgh, EH8 9XD UK.

ABSTRACT

Background: In vertebrates, rootletin is the major structural component of the ciliary rootlet and is also part of the tether linking the centrioles of the centrosome. Various functions have been ascribed to the rootlet, including maintenance of ciliary integrity through anchoring and facilitation of transport to the cilium or at the base of the cilium. In Drosophila, Rootletin function has not been explored.

Results: In the Drosophila embryo, Rootletin is expressed exclusively in cell lineages of type I sensory neurons, the only somatic cells bearing a cilium. Expression is strongest in mechanosensory chordotonal neurons. Knock-down of Rootletin results in loss of ciliary rootlet in these neurons and severe disruption of their sensory function. However, the sensory cilium appears largely normal in structure and in localisation of proteins suggesting no strong defect in ciliogenesis. No evidence was found for a defect in cell division.

Conclusions: The role of Rootletin as a component of the ciliary rootlet is conserved in Drosophila. In contrast, lack of a general role in cell division is consistent with lack of centriole tethering during the centrosome cycle in Drosophila. Although our evidence is consistent with an anchoring role for the rootlet, severe loss of mechanosensory function of chordotonal (Ch) neurons upon Rootletin knock-down may suggest a direct role for the rootlet in the mechanotransduction mechanism itself.

No MeSH data available.


Related in: MedlinePlus

Transport of proteins in Rootletin knock-down Ch cilia. a, b Anti-HRP immunoreactivity (green) in Ch neurons of mature larvae, counterstained with anti-Futsch (magenta). a Wild type, two bands of anti-HRP staining are visible at the cilium base and surrounding a medial point in the cilium (white lines). Yellow line indicates approximate extent of the cilium (ci) at the tip of the dendrite inner segment (is). b The same bands are visible in Rootletin knock-down. c, d NompC localisation (green) in pupal Ch neuron cilia of Johnston’s organ; counterstained with anti-HRP (magenta). c Wild type. dRootletin knock-down. e, f NompC localisation (green) in mature larval Ch neurons (lch5), counterstained with anti-HRP (magenta) (HRP bands indicated by white lines). e Wild type, the NompC is localised distally to the HRP immunoreactivity. fRootletin knock-down, NompC is grossly normal, but shows some mislocalisation to the proximal cilium in one of the neurons. g, h RempA-YFP localisation (green) in mature larval Ch neurons (lch5), counterstained with anti-EYS (magenta) (HRP bands indicated by white lines). g Wild type, showing puncta of localisation at the ciliary dilation (white arrow). hRootletin knock-down, showing no change in RempA-YFP localisation. All scale bars = 5 μm
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC4489026&req=5

Fig6: Transport of proteins in Rootletin knock-down Ch cilia. a, b Anti-HRP immunoreactivity (green) in Ch neurons of mature larvae, counterstained with anti-Futsch (magenta). a Wild type, two bands of anti-HRP staining are visible at the cilium base and surrounding a medial point in the cilium (white lines). Yellow line indicates approximate extent of the cilium (ci) at the tip of the dendrite inner segment (is). b The same bands are visible in Rootletin knock-down. c, d NompC localisation (green) in pupal Ch neuron cilia of Johnston’s organ; counterstained with anti-HRP (magenta). c Wild type. dRootletin knock-down. e, f NompC localisation (green) in mature larval Ch neurons (lch5), counterstained with anti-HRP (magenta) (HRP bands indicated by white lines). e Wild type, the NompC is localised distally to the HRP immunoreactivity. fRootletin knock-down, NompC is grossly normal, but shows some mislocalisation to the proximal cilium in one of the neurons. g, h RempA-YFP localisation (green) in mature larval Ch neurons (lch5), counterstained with anti-EYS (magenta) (HRP bands indicated by white lines). g Wild type, showing puncta of localisation at the ciliary dilation (white arrow). hRootletin knock-down, showing no change in RempA-YFP localisation. All scale bars = 5 μm

Mentions: Although no gross defect in cilium structure was detected above, Ch neurons appear to be severely defective in function when Rootletin is reduced. One possibility is that mechanotransduction proteins are defectively transported and/or localised in the cilium. To test this, we initially examined localisation of the epitope detected by anti-HRP. As stated above, this is initially transported along the embryonic Ch neuron cilium, then at late embryonic stages, it appears to be secreted into the luminal space surrounding the cilium and becomes refined to two bands, one at the cilium base and the other at a medial location along the cilium. These are visible in Ch neurons of mature larvae (Fig. 6a). In Rootletin knock-down larvae, there appeared to be no alteration to this banding pattern (Fig. 6b).Fig. 6


The Drosophila homologue of Rootletin is required for mechanosensory function and ciliary rootlet formation in chordotonal sensory neurons.

Styczynska-Soczka K, Jarman AP - Cilia (2015)

Transport of proteins in Rootletin knock-down Ch cilia. a, b Anti-HRP immunoreactivity (green) in Ch neurons of mature larvae, counterstained with anti-Futsch (magenta). a Wild type, two bands of anti-HRP staining are visible at the cilium base and surrounding a medial point in the cilium (white lines). Yellow line indicates approximate extent of the cilium (ci) at the tip of the dendrite inner segment (is). b The same bands are visible in Rootletin knock-down. c, d NompC localisation (green) in pupal Ch neuron cilia of Johnston’s organ; counterstained with anti-HRP (magenta). c Wild type. dRootletin knock-down. e, f NompC localisation (green) in mature larval Ch neurons (lch5), counterstained with anti-HRP (magenta) (HRP bands indicated by white lines). e Wild type, the NompC is localised distally to the HRP immunoreactivity. fRootletin knock-down, NompC is grossly normal, but shows some mislocalisation to the proximal cilium in one of the neurons. g, h RempA-YFP localisation (green) in mature larval Ch neurons (lch5), counterstained with anti-EYS (magenta) (HRP bands indicated by white lines). g Wild type, showing puncta of localisation at the ciliary dilation (white arrow). hRootletin knock-down, showing no change in RempA-YFP localisation. All scale bars = 5 μm
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4489026&req=5

Fig6: Transport of proteins in Rootletin knock-down Ch cilia. a, b Anti-HRP immunoreactivity (green) in Ch neurons of mature larvae, counterstained with anti-Futsch (magenta). a Wild type, two bands of anti-HRP staining are visible at the cilium base and surrounding a medial point in the cilium (white lines). Yellow line indicates approximate extent of the cilium (ci) at the tip of the dendrite inner segment (is). b The same bands are visible in Rootletin knock-down. c, d NompC localisation (green) in pupal Ch neuron cilia of Johnston’s organ; counterstained with anti-HRP (magenta). c Wild type. dRootletin knock-down. e, f NompC localisation (green) in mature larval Ch neurons (lch5), counterstained with anti-HRP (magenta) (HRP bands indicated by white lines). e Wild type, the NompC is localised distally to the HRP immunoreactivity. fRootletin knock-down, NompC is grossly normal, but shows some mislocalisation to the proximal cilium in one of the neurons. g, h RempA-YFP localisation (green) in mature larval Ch neurons (lch5), counterstained with anti-EYS (magenta) (HRP bands indicated by white lines). g Wild type, showing puncta of localisation at the ciliary dilation (white arrow). hRootletin knock-down, showing no change in RempA-YFP localisation. All scale bars = 5 μm
Mentions: Although no gross defect in cilium structure was detected above, Ch neurons appear to be severely defective in function when Rootletin is reduced. One possibility is that mechanotransduction proteins are defectively transported and/or localised in the cilium. To test this, we initially examined localisation of the epitope detected by anti-HRP. As stated above, this is initially transported along the embryonic Ch neuron cilium, then at late embryonic stages, it appears to be secreted into the luminal space surrounding the cilium and becomes refined to two bands, one at the cilium base and the other at a medial location along the cilium. These are visible in Ch neurons of mature larvae (Fig. 6a). In Rootletin knock-down larvae, there appeared to be no alteration to this banding pattern (Fig. 6b).Fig. 6

Bottom Line: Knock-down of Rootletin results in loss of ciliary rootlet in these neurons and severe disruption of their sensory function.No evidence was found for a defect in cell division.Although our evidence is consistent with an anchoring role for the rootlet, severe loss of mechanosensory function of chordotonal (Ch) neurons upon Rootletin knock-down may suggest a direct role for the rootlet in the mechanotransduction mechanism itself.

View Article: PubMed Central - PubMed

Affiliation: Centre for Integrative Physiology, University of Edinburgh, Edinburgh, EH8 9XD UK.

ABSTRACT

Background: In vertebrates, rootletin is the major structural component of the ciliary rootlet and is also part of the tether linking the centrioles of the centrosome. Various functions have been ascribed to the rootlet, including maintenance of ciliary integrity through anchoring and facilitation of transport to the cilium or at the base of the cilium. In Drosophila, Rootletin function has not been explored.

Results: In the Drosophila embryo, Rootletin is expressed exclusively in cell lineages of type I sensory neurons, the only somatic cells bearing a cilium. Expression is strongest in mechanosensory chordotonal neurons. Knock-down of Rootletin results in loss of ciliary rootlet in these neurons and severe disruption of their sensory function. However, the sensory cilium appears largely normal in structure and in localisation of proteins suggesting no strong defect in ciliogenesis. No evidence was found for a defect in cell division.

Conclusions: The role of Rootletin as a component of the ciliary rootlet is conserved in Drosophila. In contrast, lack of a general role in cell division is consistent with lack of centriole tethering during the centrosome cycle in Drosophila. Although our evidence is consistent with an anchoring role for the rootlet, severe loss of mechanosensory function of chordotonal (Ch) neurons upon Rootletin knock-down may suggest a direct role for the rootlet in the mechanotransduction mechanism itself.

No MeSH data available.


Related in: MedlinePlus