The semaphorins are a large protein family that is involved in the patterning of neuronal connections in the developing nervous system of both vertebrates and invertebrates. The chemorepulsive axon guidance signal Semaphorin 3A (Sema3A) induces the depolymerization of actin filaments and the collapse of sensory growth cones by activating a receptor complex that contains a plexin as the signal-t...

Mitochondrial ATP-sensitive potassium (mitoKATP) channels play a key role in ischemic preconditioning of the heart. However, the mechanism of cardioprotection remains controversial. We measured rhod-2 fluorescence in adult rabbit ventricular cardiomyocytes as an index of mitochondrial matrix Ca concentration ([Ca ]m), using time-lapse confocal microscopy. To simulate ischemia and reperfusion (I...

Monteith, Gregory R., and Mordecai P. Blaustein. Heterogeneity of mitochondrial matrix free Ca21: resolution of Ca21 dynamics in individual mitochondria in situ. Am. J. Physiol. 276 (Cell Physiol. 45): C1193–C1204, 1999.—The role of mitochondria in Ca21 homeostasis is controversial. We employed the Ca21-sensitive dye rhod 2 with novel, high temporal and spatial resolution imaging to evaluate ch...

The Diaphanous-related formins are effectors for Rho GTPases. Two recent reports have unveiled previously unappreciated activities of Drf3 (mDia2), eliciting cytoskeletal rearrangements at the behest of Cdc42, and of DRF2 (hDia2C), regulating endosome dynamics for RhoD.

OBJECTIVES Cytosolic calcium ([Ca(2+)](i)) mediates ischemia-reperfusion (I/R) injury, but magnitude and time course of I/R-induced [Ca(2+)](i) overload remain unclear. Fluorescent indicators are commonly used to measure [Ca(2+)](i), and have a dissociation constant (K(d)) that depends on pH and temperature. We hypothesized that changes of K(d) during I/R lead to misleading interpretations of [...

Smets, Ilse, Adrian Caplanusi, Sanda Despa, Zsolt Molnar, Mihai Radu, Martin vandeVen, Marcel Ameloot, and Paul Steels. Ca uptake in mitochondria occurs via the reverse action of the Na /Ca exchanger in metabolically inhibited MDCK cells. Am J Physiol Renal Physiol 286: F784–F794, 2004. First published December 9, 2003; 10.1152/ajprenal.00284.2003.—In ischemic or hypoxic tissues, elevated Ca le...

Most organisms anticipate daily environmental variations and orchestrate cellular functions thanks to a circadian clock which entrains robustly to the day/night cycle, despite fluctuations in light intensity due to weather or seasonal variations. Marine organisms are also subjected to fluctuations in light spectral composition as their depth varies, due to differential absorption of different w...

Rho GTPases family members influenced the filopodia, lamellipodia, stress fiber and adhesion plaque of melanoma cells through regulating cytoskeleton recombination. The role of Rho GTPases family in the migration and invasion of melanoma and its molecular mechanism were explored. The morphological difference between three types of melanoma cells (M14, A375 and MV3) and human melanocyte (MC) was...

In ischemic or hypoxic tissues, elevated Ca2+ levels have emerged as one of the main damaging agents among other Ca2+-independent mechanisms of cellular injury. Because mitochondria, besides the endoplasmic reticulum, play a key role in the maintainance of cellular Ca2+ homeostasis, alterations in the mitochondrial Ca2+ content ([Ca2+]m) were monitored in addition to changes in cytosolic Ca2+ c...