Intracellular Role of Adenylyl Cyclase in Regulation of Lateral Pseudopod Formation during<i>Dictyostelium</i>Chemotaxis

Stepanovic, Vesna; Wessels, Deborah; Daniels, Karla J.; Loomis, William F.; Soll, David R.

doi:10.1128/ec.4.4.775-786.2005

Cited by 32 publications

(28 citation statements)

References 56 publications

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“…Together, they are responsible for about one-third of the chemotactic response as indicated by the chemotaxis index of gc-null cells of 0.43 compared with 0.64 of gc-null cells expressing the wild-type sGC protein, or wild-type AX3 cells. The chemotaxis index of gc-null cells is similar to the chemotaxis defects observed in PI3K-null cells (Funamoto et al, 2001;Loovers et al, 2006) but much larger than the minimal defects seen in PLC-null (Drayer et al, 1994) and adenylyl cyclase-null cells (Pitt et al, 1992;Stepanovic et al, 2005). In Dictyostelium, cGMP is involved in the regulation of myosin.…”

Section: Discussionmentioning

confidence: 51%

Guanylyl Cyclase Protein and cGMP Product Independently Control Front and Back of ChemotaxingDictyosteliumCells

Veltman

Haastert

2006

MBoC

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Chemotaxis of amoeboid cells is driven by actin filaments in leading pseudopodia and actin-myosin filaments in the back and at the side of the cell to suppress pseudopodia. In Dictyostelium, cGMP plays an important role during chemotaxis and is produced predominantly by a soluble guanylyl cyclase (sGC). The sGC protein is enriched in extending pseudopodia at the leading edge of the cell during chemotaxis. We show here that the sGC protein and the cGMP product have different functions during chemotaxis, using two mutants that lose either catalytic activity (sGC⌬cat) or localization to the leading edge (sGC⌬N). Cells expressing sGC⌬N exhibit excellent cGMP formation and myosin localization in the back of the cell, but they exhibit poor orientation at the leading edge. Cells expressing the catalytically dead sGC⌬cat mutant show poor myosin localization at the back, but excellent localization of the sGC protein at the leading edge, where it enhances the probability that a new pseudopod is made in proximity to previous pseudopodia, resulting in a decrease of the degree of turning. Thus cGMP suppresses pseudopod formation in the back of the cell, whereas the sGC protein refines pseudopod formation at the leading edge. INTRODUCTIONChemotaxis is a vital process in a variety of organisms, ranging from bacteria to vertebrates. Prokaryotes use chemotaxis to move toward high nutrient concentrations or away from unfavorable conditions, whereas in eukaryotes chemotaxis is also involved in embryogenesis, wound healing, and the immune response. Chemotaxis is achieved by coupling gradient sensing to basic cell movement. Prokaryotes are too small to sense spatial gradients and therefore rely on temporal changes of the chemoattractant concentration to achieve chemotaxis. They do this by adjusting their tumbling frequency in response to temporal changes of the chemoattractant concentration (Szurmant and Ordal, 2004;Wadhams and Armitage, 2004). Eukaryotic cells are typically large enough to be able to measure a spatial gradient. The difference in receptor occupation between each side of the cell leads to an internal polarization. A pseudopod is extended at the side with the highest receptor occupation and at the same time, pseudopod formation at all other sides is repressed, resulting in directional cell migration (Devreotes and Janetopoulos, 2003;Postma et al., 2004).Dictyostelium is a eukaryotic organism that is widely used to study chemotaxis (Williams and Harwood, 2003;Parent, 2004;Affolter and Weijer, 2005). Starved Dictyostelium cells periodically secrete cAMP. Through relay of the cAMP signal by neighboring cells, concentric cAMP waves are generated. Starved Dictyostelium cells are chemotactically sensitive to cAMP and by movement in the direction of the origin of the cAMP waves, the cells are able to aggregate into groups of up to 100,000 cells. The chemotactic response of Dictyostelium is optimized for the dynamic cAMP waves that coordinate both aggregation and multicellular development. Cells show a much stronger chemotact...

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Section: Discussionmentioning

confidence: 51%

Guanylyl Cyclase Protein and cGMP Product Independently Control Front and Back of ChemotaxingDictyosteliumCells

Veltman

Haastert

2006

MBoC

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“…In a spatial or increasing temporal gradient of cAMP, the average frequency of lateral pseudopod formation of wild-type cells is reduced to once every 4-5 minutes (Kumar et al, 2004;Shutt et al, 1995;Stepanovic et al, 2005;Varnum-Finney et al, 1987a;Wessels et al, 2000a;Wessels et al, 2000b;Zhang et al, 2003). In marked contrast, pten -cells challenged with spatial or temporal gradients of cAMP continued to form lateral pseudopods at abnormally high frequency, and continued to extend them in parallel and from the rear of the cell.…”

Section: Pten's Role Is Constitutivementioning

confidence: 99%

“…They included the null mutant of the myosin II heavy chain (MHC), mhcA - (Wessels et al, 1989;Wessels and Soll, 1990;Peters et al, 1988;Sheldon and Knecht, 1996;Heid et al, 2004), the MHC dephosphorylation mutant, 3XASP (Heid et al, 2004), the null mutant of clathrin, chc - (Wessels et al, 2000a), the null mutant for sphingosine-1-phosphate (S-1-P) lyase (Kumar et al, 2004), and null mutants of three class I myosins, myoB -, myoA -and myoF - (Falk et al, 2003;Titus et al, 1993;Wessels et al, 1996). The remaining mutants that were subjected to computer-assisted methods exhibited a variety of behavioral defects quite distinct from those of pten -and this subset (Cox et al, 1992;Cox et al, 1996;Alexander et al, 1992;Shutt et al, 1995;Wessels et al, 2000a;Wessels et al, 2000b;Zhang et al, 2002;Bosgraaf et al, 2002;Bosgraaf et al, 2005;Stepanovic et al, 2005).…”

Section: Pten and The Cortical Localization Of Myosin II And F-actinmentioning

confidence: 99%

PTEN plays a role in the suppression of lateral pseudopod formation duringDictyosteliummotility and chemotaxis

Wessels

Lusche

Kuhl

et al. 2007

Journal of Cell Science

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112

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It has been suggested that the phosphatydylinositol (3,4,5)-trisphosphate [PtdIns(3,4,5)P3] phosphatase and tensin homolog PTEN plays a fundamental role in Dictyostelium discoideum chemotaxis. To identify that role, the behavior of a pten– mutant was quantitatively analyzed using two-dimensional and three-dimensional computer-assisted methods. pten– cells were capable of polarizing and translocating in the absence of attractant, and sensing and responding to spatial gradients, temporal gradients and natural waves of attractant. However, all of these responses were compromised (i.e. less efficient) because of the fundamental incapacity of pten– cells to suppress lateral pseudopod formation and turning. This defect was equally manifested in the absence, as well as presence, of attractant. PTEN, which is constitutively localized in the cortex of polarized cells, was found essential for the attractant-stimulated increase in cortical myosin II and F-actin that is responsible for the increased suppression of pseudopods during chemotaxis. PTEN, therefore, plays a fundamental role in the suppression of lateral pseudopod formation, a process essential for the efficiency of locomotion and chemotaxis, but not in directional sensing.

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“…This prediction is predicated on their normal responses to spatial and temporal gradients of cAMP assayed in vitro. To test this prediction, we analyzed the behavior of vitally stained minority iplA -cells seeded in majority wildtype cell aggregation territories (Wessels et al, 2000a;Wessels et al, 2000b;Wessels et al, 2004;Wessels et al, 2007;Heid et al, 2004;Stepanovic et al, 2005). Under these conditions, minority mutant cells are challenged with natural waves relayed by majority wild-type cells.…”

Section: Chemotaxis Of Ipla -Cells In Natural Ax2 Aggregation Territomentioning

confidence: 99%

“…7A,B). The relayed waves can be deduced from the behavior of majority, unlabeled Ax2 cells, which undergo transient increases in velocity towards the aggregation center in the front of each wave, and decreases at the peak and in the back of each wave (Wessels et al, 1992;Wessels et al, 2000a;Wessels et al, 2000b;Wessels et al, 2007;Heid et al, 2004;Stepanovic et al, 2005;Soll et al, 2002). The behavior of minority iplA -cells in relayed waves could then be assessed through comparison with the behavior of Ax2 cells located within a 30 mm radius, which were responding to the same relayed waves.…”

Section: Chemotaxis Of Ipla -Cells In Natural Ax2 Aggregation Territomentioning

confidence: 99%

The IplA Ca++ Channel OfDictyostelium discoideumIs Necessary For Ca++, But Not cAMP Chemotaxis, And Plays A Fundamental Role In Natural Aggregation

Lusche¹,

Wessels²,

Scherer³

et al. 2012

Journal of Cell Science

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During aggregation of Dictyostelium discoideum, nondissipating, symmetric,outwardly moving waves of cAMP direct cells towards aggregation centers. It has been assumed that the spatial and temporal characteristics of the front and back of each cAMP wave regulate both chemokinesis and chemotaxis. However, during the period preceding aggregation, cells acquire not only the capacity to chemotax in a spatial gradient of cAMP, but also in a spatial gradient of Ca++. The null mutant of the putative iplACa++ channel gene, iplA-, undergoes normal chemotaxis in spatial gradients of cAMP and normal chemokinetic responses to increasing temporal gradients of cAMP, both generated in vitro. However, iplA-cells lose the capacity to undergo chemotaxis in response to a spatial gradient of Ca++, suggesting that IplA is either the Ca++ chemotaxis receptor or an essential component of the Ca++ chemotaxis regulatory pathway. In response to natural chemotactic waves generated by wild type cells, the chemokinetic response of iplA- cells to the temporal dynamics of the cAMP waveis intact, but the capacity to reorient in the direction of the aggregation center at the onset of each waveis lost. These results suggest a model in which transient Ca++ gradients formed between cells at the onset of each natural cAMP wave augment reorientation towards the aggregation center. If this hypothesis proves correct, it will provide a more complex contextual framework for interpreting D. discoideum chemotaxis.

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Intracellular Role of Adenylyl Cyclase in Regulation of Lateral Pseudopod Formation duringDictyosteliumChemotaxis

Cited by 32 publications

References 56 publications

Guanylyl Cyclase Protein and cGMP Product Independently Control Front and Back of ChemotaxingDictyosteliumCells

Guanylyl Cyclase Protein and cGMP Product Independently Control Front and Back of ChemotaxingDictyosteliumCells

PTEN plays a role in the suppression of lateral pseudopod formation duringDictyosteliummotility and chemotaxis

The IplA Ca++ Channel OfDictyostelium discoideumIs Necessary For Ca++, But Not cAMP Chemotaxis, And Plays A Fundamental Role In Natural Aggregation

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