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Comparisons of CapG and gelsolin- macrophages: demonstration of a unique role for CapG in receptor-mediated ruffling, phagocytosis, and vesicle rocketing.

Witke W, Li W, Kwiatkowski DJ, Southwick FS - J. Cell Biol. (2001)

Bottom Line: However, the loss of CapG in bone marrow macrophages profoundly inhibits macrophage colony stimulating factor-stimulated ruffling; reintroduction of CapG protein by microinjection fully restores this function.These motile functions are not impaired in gelsolin- macrophages and no additive effects are observed in CapG/gelsolin double- macrophages, establishing that CapG function is distinct from, and does not overlap with, gelsolin in macrophages.These primary effects on macrophage motile function suggest that CapG may be a useful target for the regulation of macrophage-mediated inflammatory responses.

View Article: PubMed Central - PubMed

Affiliation: Hematology Division, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA.

ABSTRACT
Capping the barbed ends of actin filaments is a critical step for regulating actin-based motility in nonmuscle cells. The in vivo function of CapG, a calcium-sensitive barbed end capping protein and member of the gelsolin/villin family, has been assessed using a Capg allele engineered into mice. Both CapG- mice and CapG/gelsolin double- mice appear normal and have no gross functional abnormalities. However, the loss of CapG in bone marrow macrophages profoundly inhibits macrophage colony stimulating factor-stimulated ruffling; reintroduction of CapG protein by microinjection fully restores this function. CapG- macrophages also demonstrate approximately 50% impairment of immunoglobulin G, and complement-opsonized phagocytosis and lanthanum-induced vesicle rocketing. These motile functions are not impaired in gelsolin- macrophages and no additive effects are observed in CapG/gelsolin double- macrophages, establishing that CapG function is distinct from, and does not overlap with, gelsolin in macrophages. Our observations indicate that CapG is required for receptor-mediated ruffling, and that it is a major functional component of macrophage phagocytosis. These primary effects on macrophage motile function suggest that CapG may be a useful target for the regulation of macrophage-mediated inflammatory responses.

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Related in: MedlinePlus

Cytosolic [Ca2+] changes in wild-type and Capg−/− macrophages after stimulation with PAF. Adherent macrophages were loaded with Fura-2 as described in the Materials and methods, and fluorescence was monitored over time. Intracellular Ca2+ was calibrated as described in the Materials and methods. Arrows depict the time point when a final concentration of 20 ng/ml of PAF was added to the buffer. This experiment is representative of 7 determinations in wild-type and 10 determinations in Capg−/− macrophages. The peak [Ca2+]I was 800 nM in wild-type and 750 nM in Capg−/− cells.
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fig7: Cytosolic [Ca2+] changes in wild-type and Capg−/− macrophages after stimulation with PAF. Adherent macrophages were loaded with Fura-2 as described in the Materials and methods, and fluorescence was monitored over time. Intracellular Ca2+ was calibrated as described in the Materials and methods. Arrows depict the time point when a final concentration of 20 ng/ml of PAF was added to the buffer. This experiment is representative of 7 determinations in wild-type and 10 determinations in Capg−/− macrophages. The peak [Ca2+]I was 800 nM in wild-type and 750 nM in Capg−/− cells.

Mentions: Using Fura-2 as an indicator, we have examined the ability of wild-type and Capg−/− macrophages to respond to the agonist platelet-activating factor (PAF). This inflammatory mediator binds to a specific receptor whose signal transduction is mediated through G proteins and phosphoinositides (Mazer et al., 1992). As shown in Fig. 7 , Capg−/− cells responded with a rapid rise in intracellular [Ca2+] ([Ca2+]I) that was comparable to wild-type macrophages. Wild-type cells demonstrated a more persistent elevation in [Ca2+]I than cells. However, over time, resting values reached comparable levels and after a second exposure to PAF, cells responded with a second rise in [Ca2+]I that was somewhat greater than wild-type cells.


Comparisons of CapG and gelsolin- macrophages: demonstration of a unique role for CapG in receptor-mediated ruffling, phagocytosis, and vesicle rocketing.

Witke W, Li W, Kwiatkowski DJ, Southwick FS - J. Cell Biol. (2001)

Cytosolic [Ca2+] changes in wild-type and Capg−/− macrophages after stimulation with PAF. Adherent macrophages were loaded with Fura-2 as described in the Materials and methods, and fluorescence was monitored over time. Intracellular Ca2+ was calibrated as described in the Materials and methods. Arrows depict the time point when a final concentration of 20 ng/ml of PAF was added to the buffer. This experiment is representative of 7 determinations in wild-type and 10 determinations in Capg−/− macrophages. The peak [Ca2+]I was 800 nM in wild-type and 750 nM in Capg−/− cells.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2196452&req=5

fig7: Cytosolic [Ca2+] changes in wild-type and Capg−/− macrophages after stimulation with PAF. Adherent macrophages were loaded with Fura-2 as described in the Materials and methods, and fluorescence was monitored over time. Intracellular Ca2+ was calibrated as described in the Materials and methods. Arrows depict the time point when a final concentration of 20 ng/ml of PAF was added to the buffer. This experiment is representative of 7 determinations in wild-type and 10 determinations in Capg−/− macrophages. The peak [Ca2+]I was 800 nM in wild-type and 750 nM in Capg−/− cells.
Mentions: Using Fura-2 as an indicator, we have examined the ability of wild-type and Capg−/− macrophages to respond to the agonist platelet-activating factor (PAF). This inflammatory mediator binds to a specific receptor whose signal transduction is mediated through G proteins and phosphoinositides (Mazer et al., 1992). As shown in Fig. 7 , Capg−/− cells responded with a rapid rise in intracellular [Ca2+] ([Ca2+]I) that was comparable to wild-type macrophages. Wild-type cells demonstrated a more persistent elevation in [Ca2+]I than cells. However, over time, resting values reached comparable levels and after a second exposure to PAF, cells responded with a second rise in [Ca2+]I that was somewhat greater than wild-type cells.

Bottom Line: However, the loss of CapG in bone marrow macrophages profoundly inhibits macrophage colony stimulating factor-stimulated ruffling; reintroduction of CapG protein by microinjection fully restores this function.These motile functions are not impaired in gelsolin- macrophages and no additive effects are observed in CapG/gelsolin double- macrophages, establishing that CapG function is distinct from, and does not overlap with, gelsolin in macrophages.These primary effects on macrophage motile function suggest that CapG may be a useful target for the regulation of macrophage-mediated inflammatory responses.

View Article: PubMed Central - PubMed

Affiliation: Hematology Division, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA.

ABSTRACT
Capping the barbed ends of actin filaments is a critical step for regulating actin-based motility in nonmuscle cells. The in vivo function of CapG, a calcium-sensitive barbed end capping protein and member of the gelsolin/villin family, has been assessed using a Capg allele engineered into mice. Both CapG- mice and CapG/gelsolin double- mice appear normal and have no gross functional abnormalities. However, the loss of CapG in bone marrow macrophages profoundly inhibits macrophage colony stimulating factor-stimulated ruffling; reintroduction of CapG protein by microinjection fully restores this function. CapG- macrophages also demonstrate approximately 50% impairment of immunoglobulin G, and complement-opsonized phagocytosis and lanthanum-induced vesicle rocketing. These motile functions are not impaired in gelsolin- macrophages and no additive effects are observed in CapG/gelsolin double- macrophages, establishing that CapG function is distinct from, and does not overlap with, gelsolin in macrophages. Our observations indicate that CapG is required for receptor-mediated ruffling, and that it is a major functional component of macrophage phagocytosis. These primary effects on macrophage motile function suggest that CapG may be a useful target for the regulation of macrophage-mediated inflammatory responses.

Show MeSH
Related in: MedlinePlus