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The RHO-1 RhoGTPase modulates fertility and multiple behaviors in adult C. elegans.

McMullan R, Nurrish SJ - PLoS ONE (2011)

Bottom Line: Changes in RHO-1 signaling in cholinergic neurons affected locomotion, pharyngeal pumping and fecundity.Changes in RHO-1 signaling outside the cholinergic neurons resulted in defective defecation, ovulation, and changes in C. elegans body morphology.Finally both increased and decreased RHO-1 signaling in adults resulted in death within hours.

View Article: PubMed Central - PubMed

Affiliation: MRC Cell Biology Unit, MRC Laboratory for Molecular Cell Biology and Department of Neuroscience, Physiology and Pharmacology, University College, London, United Kingdom.

ABSTRACT
The Rho family of small GTPases are essential during early embryonic development making it difficult to study their functions in adult animals. Using inducible transgenes expressing either a constitutively active version of the single C. elegans Rho ortholog, RHO-1, or an inhibitor of endogenous Rho (C3 transferase), we demonstrate multiple defects caused by altering Rho signaling in adult C. elegans. Changes in RHO-1 signaling in cholinergic neurons affected locomotion, pharyngeal pumping and fecundity. Changes in RHO-1 signaling outside the cholinergic neurons resulted in defective defecation, ovulation, and changes in C. elegans body morphology. Finally both increased and decreased RHO-1 signaling in adults resulted in death within hours. The multiple post-developmental roles for Rho in C. elegans demonstrate that RhoA signaling pathways continue to be used post-developmentally and the resulting phenotypes provide an opportunity to further study post-developmental Rho signaling pathways using genetic screens.

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RHO-1 regulates pharyngeal pumping.Pumping rate was determined by manually counting contractions of the pharyngeal bulb for 2 min. (A) Following heat shock at 33°C animals were allowed to recover for 30 min before determining pumping rate. Expression of a constitutively activated hsRHO-1(G14V)(nzIs1) in adult animals or inhibition of endogenous RHO-1 using hsC3 transferase (nzEx4) decreased pumping rate. The pumping rate of animals expressing nRHO-1(G14V) (nzIs29) was also decreased when compared to wild type. This decrease was mimicked by increasing the extracellular ACh concentration using a 1 hour exposure to the acetylcholinesterase inhibitor aldicarb. (B) The pumping rate of hsRHO-1(G14V) (nzIs1) expressing animals heat shocked at 27°C was determined 30 min and 24 hours following heat shock. Expression of hsRHO-1(G14V) (nzIs1) resulted in a decrease in pumping rate 30 min after heat shock that was not observed after 24 hours recovery.
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pone-0017265-g002: RHO-1 regulates pharyngeal pumping.Pumping rate was determined by manually counting contractions of the pharyngeal bulb for 2 min. (A) Following heat shock at 33°C animals were allowed to recover for 30 min before determining pumping rate. Expression of a constitutively activated hsRHO-1(G14V)(nzIs1) in adult animals or inhibition of endogenous RHO-1 using hsC3 transferase (nzEx4) decreased pumping rate. The pumping rate of animals expressing nRHO-1(G14V) (nzIs29) was also decreased when compared to wild type. This decrease was mimicked by increasing the extracellular ACh concentration using a 1 hour exposure to the acetylcholinesterase inhibitor aldicarb. (B) The pumping rate of hsRHO-1(G14V) (nzIs1) expressing animals heat shocked at 27°C was determined 30 min and 24 hours following heat shock. Expression of hsRHO-1(G14V) (nzIs1) resulted in a decrease in pumping rate 30 min after heat shock that was not observed after 24 hours recovery.

Mentions: Expression of hsRHO-1(G14V) in adult animals decreased the rate of pharyngeal pumping even in the presence of food (Figure 2A). This decrease was observed when animals were heat shocked using our standard heat shock temperature of 33°C. A smaller, but significant, decrease was also observed when animals were heat shocked at 27°C (Figure 2B). Unlike heat shock at 33°C, a 27°C heat shock did not alter responsiveness to the ACh esterase inhibitor, aldicarb (data not shown). There are a number of possible explanations for this observation; Firstly, the pharyngeal neurons may be more sensitive to either heat shock or RHO-1(G14V) expression. Secondly, the pharyngeal muscle is more sensitive to ACh than the body wall muscle, or finally low levels RHO-1(G14V) may alter the release of something other than ACh.


The RHO-1 RhoGTPase modulates fertility and multiple behaviors in adult C. elegans.

McMullan R, Nurrish SJ - PLoS ONE (2011)

RHO-1 regulates pharyngeal pumping.Pumping rate was determined by manually counting contractions of the pharyngeal bulb for 2 min. (A) Following heat shock at 33°C animals were allowed to recover for 30 min before determining pumping rate. Expression of a constitutively activated hsRHO-1(G14V)(nzIs1) in adult animals or inhibition of endogenous RHO-1 using hsC3 transferase (nzEx4) decreased pumping rate. The pumping rate of animals expressing nRHO-1(G14V) (nzIs29) was also decreased when compared to wild type. This decrease was mimicked by increasing the extracellular ACh concentration using a 1 hour exposure to the acetylcholinesterase inhibitor aldicarb. (B) The pumping rate of hsRHO-1(G14V) (nzIs1) expressing animals heat shocked at 27°C was determined 30 min and 24 hours following heat shock. Expression of hsRHO-1(G14V) (nzIs1) resulted in a decrease in pumping rate 30 min after heat shock that was not observed after 24 hours recovery.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3046162&req=5

pone-0017265-g002: RHO-1 regulates pharyngeal pumping.Pumping rate was determined by manually counting contractions of the pharyngeal bulb for 2 min. (A) Following heat shock at 33°C animals were allowed to recover for 30 min before determining pumping rate. Expression of a constitutively activated hsRHO-1(G14V)(nzIs1) in adult animals or inhibition of endogenous RHO-1 using hsC3 transferase (nzEx4) decreased pumping rate. The pumping rate of animals expressing nRHO-1(G14V) (nzIs29) was also decreased when compared to wild type. This decrease was mimicked by increasing the extracellular ACh concentration using a 1 hour exposure to the acetylcholinesterase inhibitor aldicarb. (B) The pumping rate of hsRHO-1(G14V) (nzIs1) expressing animals heat shocked at 27°C was determined 30 min and 24 hours following heat shock. Expression of hsRHO-1(G14V) (nzIs1) resulted in a decrease in pumping rate 30 min after heat shock that was not observed after 24 hours recovery.
Mentions: Expression of hsRHO-1(G14V) in adult animals decreased the rate of pharyngeal pumping even in the presence of food (Figure 2A). This decrease was observed when animals were heat shocked using our standard heat shock temperature of 33°C. A smaller, but significant, decrease was also observed when animals were heat shocked at 27°C (Figure 2B). Unlike heat shock at 33°C, a 27°C heat shock did not alter responsiveness to the ACh esterase inhibitor, aldicarb (data not shown). There are a number of possible explanations for this observation; Firstly, the pharyngeal neurons may be more sensitive to either heat shock or RHO-1(G14V) expression. Secondly, the pharyngeal muscle is more sensitive to ACh than the body wall muscle, or finally low levels RHO-1(G14V) may alter the release of something other than ACh.

Bottom Line: Changes in RHO-1 signaling in cholinergic neurons affected locomotion, pharyngeal pumping and fecundity.Changes in RHO-1 signaling outside the cholinergic neurons resulted in defective defecation, ovulation, and changes in C. elegans body morphology.Finally both increased and decreased RHO-1 signaling in adults resulted in death within hours.

View Article: PubMed Central - PubMed

Affiliation: MRC Cell Biology Unit, MRC Laboratory for Molecular Cell Biology and Department of Neuroscience, Physiology and Pharmacology, University College, London, United Kingdom.

ABSTRACT
The Rho family of small GTPases are essential during early embryonic development making it difficult to study their functions in adult animals. Using inducible transgenes expressing either a constitutively active version of the single C. elegans Rho ortholog, RHO-1, or an inhibitor of endogenous Rho (C3 transferase), we demonstrate multiple defects caused by altering Rho signaling in adult C. elegans. Changes in RHO-1 signaling in cholinergic neurons affected locomotion, pharyngeal pumping and fecundity. Changes in RHO-1 signaling outside the cholinergic neurons resulted in defective defecation, ovulation, and changes in C. elegans body morphology. Finally both increased and decreased RHO-1 signaling in adults resulted in death within hours. The multiple post-developmental roles for Rho in C. elegans demonstrate that RhoA signaling pathways continue to be used post-developmentally and the resulting phenotypes provide an opportunity to further study post-developmental Rho signaling pathways using genetic screens.

Show MeSH
Related in: MedlinePlus