Limits...
CaM kinase I alpha-induced phosphorylation of Drp1 regulates mitochondrial morphology.

Han XJ, Lu YF, Li SA, Kaitsuka T, Sato Y, Tomizawa K, Nairn AC, Takei K, Matsui H, Matsushita M - J. Cell Biol. (2008)

Bottom Line: VDCC-associated Ca2+ signaling stimulates phosphorylation of dynamin-related protein 1 (Drp1) at serine 600 via activation of Ca2+/calmodulin-dependent protein kinase Ialpha (CaMKIalpha).In neurons and HeLa cells, phosphorylation of Drp1 at serine 600 is associated with an increase in Drp1 translocation to mitochondria, whereas in vitro, phosphorylation of Drp1 results in an increase in its affinity for Fis1.CaMKIalpha is a widely expressed protein kinase, suggesting that Ca2+ is likely to be functionally important in the control of mitochondrial dynamics through regulation of Drp1 phosphorylation in neurons and other cell types.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology and 2Department of Neuroscience, Okayama University Graduate School of Medicine and Dentistry, Okayama 700-8558, Japan.

ABSTRACT
Mitochondria are dynamic organelles that frequently move, divide, and fuse with one another to maintain their architecture and functions. However, the signaling mechanisms involved in these processes are still not well characterized. In this study, we analyze mitochondrial dynamics and morphology in neurons. Using time-lapse imaging, we find that Ca2+ influx through voltage-dependent Ca2+ channels (VDCCs) causes a rapid halt in mitochondrial movement and induces mitochondrial fission. VDCC-associated Ca2+ signaling stimulates phosphorylation of dynamin-related protein 1 (Drp1) at serine 600 via activation of Ca2+/calmodulin-dependent protein kinase Ialpha (CaMKIalpha). In neurons and HeLa cells, phosphorylation of Drp1 at serine 600 is associated with an increase in Drp1 translocation to mitochondria, whereas in vitro, phosphorylation of Drp1 results in an increase in its affinity for Fis1. CaMKIalpha is a widely expressed protein kinase, suggesting that Ca2+ is likely to be functionally important in the control of mitochondrial dynamics through regulation of Drp1 phosphorylation in neurons and other cell types.

Show MeSH
Effects of high K+ on mitochondrial dynamics and morphology in neurons. (A) Neurons (10 DIV) were transfected with pDsRed2-Mito to label mitochondria. Neurons (at 11 DIV) were then treated with 45 mM K+ for 15 min, and mitochondrial fluorescence was analyzed by time-lapse imaging. Arrows show ringlike mitochondria formation in dendrites. Bar, 10 μm. (B) Higher magnification in dendrites show details of ringlike mitochondrial formation induced by treatment with 45 mM K+. Arrows show mitochondrial fission. Time in minutes after application of high K+ is indicated at the bottom of each panel. Bar, 1 μm. (C) Ultrastructure of mitochondria analyzed by electron microscopy. Panels i and ii show examples of mitochondria from control neurons. The remaining panels (iii–vii) show examples of mitochondria in neurons treated with 45 mM K+ for 15 min. (ii) Mitochondria in dendrites from control neurons were rod shaped, and their cristae were clear. (iii–vii) Mitochondria from neurons treated with 45 mM K+ formed clusters that exhibited less electron-dense matrices and contained less cristae. (v–vii) 45-mM K+ treatment caused mitochondrial fission. Arrows in v–vii show connections between dividing mitochondria. The dividing mitochondria shared continuous outer membrane with separate inner membranes (arrowhead in vi). Bars: (i and iii)1 μm; (ii and iv–vii) 200 nm.
© Copyright Policy
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC2500141&req=5

fig1: Effects of high K+ on mitochondrial dynamics and morphology in neurons. (A) Neurons (10 DIV) were transfected with pDsRed2-Mito to label mitochondria. Neurons (at 11 DIV) were then treated with 45 mM K+ for 15 min, and mitochondrial fluorescence was analyzed by time-lapse imaging. Arrows show ringlike mitochondria formation in dendrites. Bar, 10 μm. (B) Higher magnification in dendrites show details of ringlike mitochondrial formation induced by treatment with 45 mM K+. Arrows show mitochondrial fission. Time in minutes after application of high K+ is indicated at the bottom of each panel. Bar, 1 μm. (C) Ultrastructure of mitochondria analyzed by electron microscopy. Panels i and ii show examples of mitochondria from control neurons. The remaining panels (iii–vii) show examples of mitochondria in neurons treated with 45 mM K+ for 15 min. (ii) Mitochondria in dendrites from control neurons were rod shaped, and their cristae were clear. (iii–vii) Mitochondria from neurons treated with 45 mM K+ formed clusters that exhibited less electron-dense matrices and contained less cristae. (v–vii) 45-mM K+ treatment caused mitochondrial fission. Arrows in v–vii show connections between dividing mitochondria. The dividing mitochondria shared continuous outer membrane with separate inner membranes (arrowhead in vi). Bars: (i and iii)1 μm; (ii and iv–vii) 200 nm.

Mentions: Cultured hippocampal neurons were transfected with pDsRed2-Mito to label mitochondria. The movement and morphology of mitochondria were monitored using live-cell imaging. As previously demonstrated (Ligon and Steward, 2000), mitochondria were found in neuronal axons and dendrites, exhibiting an elongated shape and dynamic movement. Treatment with 45 mM K+ for 15 min had a marked effect on mitochondrial shape and movement. Elongated mitochondria became much shorter and rounder in morphology (Fig. 1 A and Fig. S1, A and C, available at http://www.jcb.org/cgi/content/full/jcb.200802164/DC1). In time-lapse imaging, 45-mM K+ stimulation was found to trigger a rapid halt to movement (mitochondrial movement was reduced to 16.5% of control at 1 min, recovering to 26.3% at 10 min and 29.6% at 15 min; Fig. S1, A and B). High K+ treatment also caused mitochondria to form ringlike structures that were the sites of fission events giving rise to smaller, round mitochondrial structures (Fig. 1 B).


CaM kinase I alpha-induced phosphorylation of Drp1 regulates mitochondrial morphology.

Han XJ, Lu YF, Li SA, Kaitsuka T, Sato Y, Tomizawa K, Nairn AC, Takei K, Matsui H, Matsushita M - J. Cell Biol. (2008)

Effects of high K+ on mitochondrial dynamics and morphology in neurons. (A) Neurons (10 DIV) were transfected with pDsRed2-Mito to label mitochondria. Neurons (at 11 DIV) were then treated with 45 mM K+ for 15 min, and mitochondrial fluorescence was analyzed by time-lapse imaging. Arrows show ringlike mitochondria formation in dendrites. Bar, 10 μm. (B) Higher magnification in dendrites show details of ringlike mitochondrial formation induced by treatment with 45 mM K+. Arrows show mitochondrial fission. Time in minutes after application of high K+ is indicated at the bottom of each panel. Bar, 1 μm. (C) Ultrastructure of mitochondria analyzed by electron microscopy. Panels i and ii show examples of mitochondria from control neurons. The remaining panels (iii–vii) show examples of mitochondria in neurons treated with 45 mM K+ for 15 min. (ii) Mitochondria in dendrites from control neurons were rod shaped, and their cristae were clear. (iii–vii) Mitochondria from neurons treated with 45 mM K+ formed clusters that exhibited less electron-dense matrices and contained less cristae. (v–vii) 45-mM K+ treatment caused mitochondrial fission. Arrows in v–vii show connections between dividing mitochondria. The dividing mitochondria shared continuous outer membrane with separate inner membranes (arrowhead in vi). Bars: (i and iii)1 μm; (ii and iv–vii) 200 nm.
© Copyright Policy
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2500141&req=5

fig1: Effects of high K+ on mitochondrial dynamics and morphology in neurons. (A) Neurons (10 DIV) were transfected with pDsRed2-Mito to label mitochondria. Neurons (at 11 DIV) were then treated with 45 mM K+ for 15 min, and mitochondrial fluorescence was analyzed by time-lapse imaging. Arrows show ringlike mitochondria formation in dendrites. Bar, 10 μm. (B) Higher magnification in dendrites show details of ringlike mitochondrial formation induced by treatment with 45 mM K+. Arrows show mitochondrial fission. Time in minutes after application of high K+ is indicated at the bottom of each panel. Bar, 1 μm. (C) Ultrastructure of mitochondria analyzed by electron microscopy. Panels i and ii show examples of mitochondria from control neurons. The remaining panels (iii–vii) show examples of mitochondria in neurons treated with 45 mM K+ for 15 min. (ii) Mitochondria in dendrites from control neurons were rod shaped, and their cristae were clear. (iii–vii) Mitochondria from neurons treated with 45 mM K+ formed clusters that exhibited less electron-dense matrices and contained less cristae. (v–vii) 45-mM K+ treatment caused mitochondrial fission. Arrows in v–vii show connections between dividing mitochondria. The dividing mitochondria shared continuous outer membrane with separate inner membranes (arrowhead in vi). Bars: (i and iii)1 μm; (ii and iv–vii) 200 nm.
Mentions: Cultured hippocampal neurons were transfected with pDsRed2-Mito to label mitochondria. The movement and morphology of mitochondria were monitored using live-cell imaging. As previously demonstrated (Ligon and Steward, 2000), mitochondria were found in neuronal axons and dendrites, exhibiting an elongated shape and dynamic movement. Treatment with 45 mM K+ for 15 min had a marked effect on mitochondrial shape and movement. Elongated mitochondria became much shorter and rounder in morphology (Fig. 1 A and Fig. S1, A and C, available at http://www.jcb.org/cgi/content/full/jcb.200802164/DC1). In time-lapse imaging, 45-mM K+ stimulation was found to trigger a rapid halt to movement (mitochondrial movement was reduced to 16.5% of control at 1 min, recovering to 26.3% at 10 min and 29.6% at 15 min; Fig. S1, A and B). High K+ treatment also caused mitochondria to form ringlike structures that were the sites of fission events giving rise to smaller, round mitochondrial structures (Fig. 1 B).

Bottom Line: VDCC-associated Ca2+ signaling stimulates phosphorylation of dynamin-related protein 1 (Drp1) at serine 600 via activation of Ca2+/calmodulin-dependent protein kinase Ialpha (CaMKIalpha).In neurons and HeLa cells, phosphorylation of Drp1 at serine 600 is associated with an increase in Drp1 translocation to mitochondria, whereas in vitro, phosphorylation of Drp1 results in an increase in its affinity for Fis1.CaMKIalpha is a widely expressed protein kinase, suggesting that Ca2+ is likely to be functionally important in the control of mitochondrial dynamics through regulation of Drp1 phosphorylation in neurons and other cell types.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology and 2Department of Neuroscience, Okayama University Graduate School of Medicine and Dentistry, Okayama 700-8558, Japan.

ABSTRACT
Mitochondria are dynamic organelles that frequently move, divide, and fuse with one another to maintain their architecture and functions. However, the signaling mechanisms involved in these processes are still not well characterized. In this study, we analyze mitochondrial dynamics and morphology in neurons. Using time-lapse imaging, we find that Ca2+ influx through voltage-dependent Ca2+ channels (VDCCs) causes a rapid halt in mitochondrial movement and induces mitochondrial fission. VDCC-associated Ca2+ signaling stimulates phosphorylation of dynamin-related protein 1 (Drp1) at serine 600 via activation of Ca2+/calmodulin-dependent protein kinase Ialpha (CaMKIalpha). In neurons and HeLa cells, phosphorylation of Drp1 at serine 600 is associated with an increase in Drp1 translocation to mitochondria, whereas in vitro, phosphorylation of Drp1 results in an increase in its affinity for Fis1. CaMKIalpha is a widely expressed protein kinase, suggesting that Ca2+ is likely to be functionally important in the control of mitochondrial dynamics through regulation of Drp1 phosphorylation in neurons and other cell types.

Show MeSH