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Differentiation-inducing factor-1 and -2 function also as modulators for Dictyostelium chemotaxis.

Kuwayama H, Kubohara Y - PLoS ONE (2009)

Bottom Line: To further elucidate the functions of DIFs, in the present study we investigated their effects on chemotaxis under various conditions.Analyses with various mutants revealed that DIF-1 may inhibit chemotaxis, at least in part, via GbpB (a phosphodiesterase) and a decrease in the intracellular cGMP concentration ([cGMP](i)).To our knowledge, this is the first report in any organism of physiologic modulators (small molecules) for chemotaxis having differentiation-inducing activity.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan.

ABSTRACT

Background: In the early stages of development of the cellular slime mold Dictyostelium discoideum, chemotaxis toward cAMP plays a pivotal role in organizing discrete cells into a multicellular structure. In this process, a series of signaling molecules, such as G-protein-coupled cell surface receptors for cAMP, phosphatidylinositol metabolites, and cyclic nucleotides, function as the signal transducers for controlling dynamics of cytoskeleton. Differentiation-inducing factor-1 and -2 (DIF-1 and DIF-2) were originally identified as the factors (chlorinated alkylphenones) that induce Dictyostelium stalk cell differentiation, but it remained unknown whether the DIFs had any other physiologic functions.

Methodology/principal findings: To further elucidate the functions of DIFs, in the present study we investigated their effects on chemotaxis under various conditions. Quite interestingly, in shallow cAMP gradients, DIF-1 suppressed chemotaxis whereas DIF-2 promoted it greatly. Analyses with various mutants revealed that DIF-1 may inhibit chemotaxis, at least in part, via GbpB (a phosphodiesterase) and a decrease in the intracellular cGMP concentration ([cGMP](i)). DIF-2, by contrast, may enhance chemotaxis, at least in part, via RegA (another phosphodiesterase) and an increase in [cGMP](i). Using mutants for DimA and DimB, the transcription factors that are required for DIF-dependent prestalk differentiation, we also showed that the mechanisms for the modulation of chemotaxis by DIFs differ from those for the induction of cell differentiation by DIFs, at least in part.

Conclusions/significance: Our findings indicate that DIF-1 and DIF-2 function as negative and positive modulators for Dictyostelium chemotaxis, respectively. To our knowledge, this is the first report in any organism of physiologic modulators (small molecules) for chemotaxis having differentiation-inducing activity.

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Effects of DIF-1 and DIF-2 on chemotaxis in Dim mutants.(A) Starved (for 6 h) dimA-, dimB-, and dimA-/B- cells were spotted on PB agar containing 3 mM caffeine (Control) plus 100 nM DIF-1 or DIF-2 and assayed for chemotaxis toward the indicated doses of cAMP. Data are the mean and s.d. (bars) of three independent experiments (n = 3). (B) Starved dimA-, dimB-, and dimA-/B- cells were spotted on PB agar containing 3 mM caffeine plus the indicated concentrations of DIF-1 or DIF-2 and assayed for chemotaxis toward the doses of cAMP indicated above in square brackets. Data are the mean and s.d. (bars) of three independent experiments (n = 3). *P<0.05, as compared with Control. (C) Expression levels of regA and gbpB. Cells were starved for 6 h, and RNAs collected from the cells were used for semi-quantitative RT-PCR to detect regA, gbpB, and rnlA (internal control).
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pone-0006658-g004: Effects of DIF-1 and DIF-2 on chemotaxis in Dim mutants.(A) Starved (for 6 h) dimA-, dimB-, and dimA-/B- cells were spotted on PB agar containing 3 mM caffeine (Control) plus 100 nM DIF-1 or DIF-2 and assayed for chemotaxis toward the indicated doses of cAMP. Data are the mean and s.d. (bars) of three independent experiments (n = 3). (B) Starved dimA-, dimB-, and dimA-/B- cells were spotted on PB agar containing 3 mM caffeine plus the indicated concentrations of DIF-1 or DIF-2 and assayed for chemotaxis toward the doses of cAMP indicated above in square brackets. Data are the mean and s.d. (bars) of three independent experiments (n = 3). *P<0.05, as compared with Control. (C) Expression levels of regA and gbpB. Cells were starved for 6 h, and RNAs collected from the cells were used for semi-quantitative RT-PCR to detect regA, gbpB, and rnlA (internal control).

Mentions: To investigate whether the DIFs modulate chemotaxis via cell differentiation, we examined the effects on chemotaxis in the mutants for DimA and DimB, the transcription factors that are required for DIF-dependent prestalk differentiation [23]–[25]. Quite interestingly, chemotactic cell movement was significantly suppressed by DIF-1 and was well enhanced by DIF-2 in a dose-dependent manner in the dimA- mutant (Fig. 4). By contrast, DIF-1 did not affect chemotaxis in either the dimB- or dimA-/B- mutants, whereas DIF-2 promoted chemotaxis in all the mutants (Fig. 4). These results suggest that DimA is not essential for the actions of DIF-1 and DIF-2, whereas DimB is required for the action of DIF-1 but not of DIF-2. In other words, DIF-1 should suppress chemotaxis via DimB or DimB-inducible gene products, whereas DIF-2 promotes chemotaxis via a DimA/DimB-independent pathway. Thus, the mechanisms for the modulation of chemotaxis by DIFs differ from those for the induction of cell differentiation by DIFs, at least in part.


Differentiation-inducing factor-1 and -2 function also as modulators for Dictyostelium chemotaxis.

Kuwayama H, Kubohara Y - PLoS ONE (2009)

Effects of DIF-1 and DIF-2 on chemotaxis in Dim mutants.(A) Starved (for 6 h) dimA-, dimB-, and dimA-/B- cells were spotted on PB agar containing 3 mM caffeine (Control) plus 100 nM DIF-1 or DIF-2 and assayed for chemotaxis toward the indicated doses of cAMP. Data are the mean and s.d. (bars) of three independent experiments (n = 3). (B) Starved dimA-, dimB-, and dimA-/B- cells were spotted on PB agar containing 3 mM caffeine plus the indicated concentrations of DIF-1 or DIF-2 and assayed for chemotaxis toward the doses of cAMP indicated above in square brackets. Data are the mean and s.d. (bars) of three independent experiments (n = 3). *P<0.05, as compared with Control. (C) Expression levels of regA and gbpB. Cells were starved for 6 h, and RNAs collected from the cells were used for semi-quantitative RT-PCR to detect regA, gbpB, and rnlA (internal control).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2722026&req=5

pone-0006658-g004: Effects of DIF-1 and DIF-2 on chemotaxis in Dim mutants.(A) Starved (for 6 h) dimA-, dimB-, and dimA-/B- cells were spotted on PB agar containing 3 mM caffeine (Control) plus 100 nM DIF-1 or DIF-2 and assayed for chemotaxis toward the indicated doses of cAMP. Data are the mean and s.d. (bars) of three independent experiments (n = 3). (B) Starved dimA-, dimB-, and dimA-/B- cells were spotted on PB agar containing 3 mM caffeine plus the indicated concentrations of DIF-1 or DIF-2 and assayed for chemotaxis toward the doses of cAMP indicated above in square brackets. Data are the mean and s.d. (bars) of three independent experiments (n = 3). *P<0.05, as compared with Control. (C) Expression levels of regA and gbpB. Cells were starved for 6 h, and RNAs collected from the cells were used for semi-quantitative RT-PCR to detect regA, gbpB, and rnlA (internal control).
Mentions: To investigate whether the DIFs modulate chemotaxis via cell differentiation, we examined the effects on chemotaxis in the mutants for DimA and DimB, the transcription factors that are required for DIF-dependent prestalk differentiation [23]–[25]. Quite interestingly, chemotactic cell movement was significantly suppressed by DIF-1 and was well enhanced by DIF-2 in a dose-dependent manner in the dimA- mutant (Fig. 4). By contrast, DIF-1 did not affect chemotaxis in either the dimB- or dimA-/B- mutants, whereas DIF-2 promoted chemotaxis in all the mutants (Fig. 4). These results suggest that DimA is not essential for the actions of DIF-1 and DIF-2, whereas DimB is required for the action of DIF-1 but not of DIF-2. In other words, DIF-1 should suppress chemotaxis via DimB or DimB-inducible gene products, whereas DIF-2 promotes chemotaxis via a DimA/DimB-independent pathway. Thus, the mechanisms for the modulation of chemotaxis by DIFs differ from those for the induction of cell differentiation by DIFs, at least in part.

Bottom Line: To further elucidate the functions of DIFs, in the present study we investigated their effects on chemotaxis under various conditions.Analyses with various mutants revealed that DIF-1 may inhibit chemotaxis, at least in part, via GbpB (a phosphodiesterase) and a decrease in the intracellular cGMP concentration ([cGMP](i)).To our knowledge, this is the first report in any organism of physiologic modulators (small molecules) for chemotaxis having differentiation-inducing activity.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan.

ABSTRACT

Background: In the early stages of development of the cellular slime mold Dictyostelium discoideum, chemotaxis toward cAMP plays a pivotal role in organizing discrete cells into a multicellular structure. In this process, a series of signaling molecules, such as G-protein-coupled cell surface receptors for cAMP, phosphatidylinositol metabolites, and cyclic nucleotides, function as the signal transducers for controlling dynamics of cytoskeleton. Differentiation-inducing factor-1 and -2 (DIF-1 and DIF-2) were originally identified as the factors (chlorinated alkylphenones) that induce Dictyostelium stalk cell differentiation, but it remained unknown whether the DIFs had any other physiologic functions.

Methodology/principal findings: To further elucidate the functions of DIFs, in the present study we investigated their effects on chemotaxis under various conditions. Quite interestingly, in shallow cAMP gradients, DIF-1 suppressed chemotaxis whereas DIF-2 promoted it greatly. Analyses with various mutants revealed that DIF-1 may inhibit chemotaxis, at least in part, via GbpB (a phosphodiesterase) and a decrease in the intracellular cGMP concentration ([cGMP](i)). DIF-2, by contrast, may enhance chemotaxis, at least in part, via RegA (another phosphodiesterase) and an increase in [cGMP](i). Using mutants for DimA and DimB, the transcription factors that are required for DIF-dependent prestalk differentiation, we also showed that the mechanisms for the modulation of chemotaxis by DIFs differ from those for the induction of cell differentiation by DIFs, at least in part.

Conclusions/significance: Our findings indicate that DIF-1 and DIF-2 function as negative and positive modulators for Dictyostelium chemotaxis, respectively. To our knowledge, this is the first report in any organism of physiologic modulators (small molecules) for chemotaxis having differentiation-inducing activity.

Show MeSH