Sustained elevation of [Ca 2؉ ] i has been implicated in many cellular events. We previously reported that ␣ subunits of G 12 family G proteins (G␣ 12/13 ) participate in sustained Ca 2؉ influx required for the activation of nuclear factor of activated T cells (NFAT), a Ca 2؉ -responsive transcriptional factor, in rat neonatal cardiac fibroblasts. Here, we demonstrate that G␣ 12/13 -me-

In the present study, we examined signal transduction mechanism of reactive oxygen species (ROS) production and the role of ROS in angiotensin II-induced activation of mitogen-activated protein kinases (MAPKs) in rat neonatal cardiomyocytes. Among three MAPKs, c-Jun NH 2 -terminal kinase (JNK) and p38 MAPK required ROS production for activation, as an NADPH oxidase inhibitor, diphenyleneiodonium, inhibited the activation.

G-protein (G␤␥)-mediated voltage-dependent inhibition of N-and P/Q-type Ca2ϩ channels contributes to presynaptic inhibition and short-term synaptic plasticity. The voltage dependence derives from the dissociation of G␤␥ from the inhibited channels, but the underlying molecular and biophysical mechanisms remain largely unclear. In this study we investigated the role in this process of Ca 2ϩ channel ␤ subunit (Ca v ␤) and a rigid ␣-helical structure between the ␣-interacting domain (AID), the primary Ca v ␤ docking site on the channel ␣ 1 subunit, and the pore-lining IS6 segment. G␤␥ inhibition of P/Q-type channels was reconstituted in giant inside-out membrane patches from Xenopus oocytes. Large populations of channels devoid of Ca v ␤ were produced by washing out a mutant Ca v ␤ with a reduced affinity for the AID. These ␤-less channels were still inhibited by G␤␥, but without any voltage dependence, indicating that Ca v ␤ is indispensable for voltage-dependent G␤␥ inhibition. A truncated Ca v ␤ containing only the AID-binding guanylate kinase (GK) domain could fully confer voltage dependence to G␤␥ inhibition. G␤␥ did not alter inactivation properties, and channels recovered from G␤␥ inhibition exhibited the same activation property as un-inhibited channels, indicating that G␤␥ does not dislodge Ca v ␤ from the inhibited channel. Furthermore, voltage-dependent G␤␥ inhibition was abolished when the rigid ␣-helix between the AID and IS6 was disrupted by insertion of multiple glycines, which also eliminated Ca v ␤ regulation of channel gating, revealing a pivotal role of this rigid ␣-helix in both processes. These results suggest that depolarization-triggered movement of IS6, coupled to the subsequent conformational change of the G␤␥-binding pocket through a rigid ␣-helix induced partly by the Ca v ␤ GK domain, causes the dissociation of G␤␥ and is fundamental to voltage-dependent G␤␥ inhibition.

The mechanism of epithelial-mesenchymal transition (EMT) consists of the cellular phenotypic transition from epithelial to mesenchymal status. The cells exhibiting EMT exist in cancer stem cell (CSC) population, which is involved in drug resistance. CSCs demonstrating EMT feature remain after cancer treatment, which leads to drug resistance, recurrence, metastasis and malignancy of cancer. In this context, the recent advance of nanotechnology in the medical application has ascended the possibility to target CSCs using nanomedicines. In this review article, we focused on the mechanism of CSCs and EMT, especially into the signaling pathways in EMT, regulation of EMT and CSCs by microRNAs and nanomedicine-based approaches to target CSCs.

Yamaguchi T, Suzuki T, Arai H, Tanabe S, Atomi Y. Continuous mild heat stress induces differentiation of mammalian myoblasts, shifting fiber type from fast to slow. Am J Physiol Cell Physiol 298: C140 -C148, 2010. First published July 15, 2009; doi:10.1152/ajpcell.00050.2009.-Local hyperthermia has been widely used as physical therapy for a number of diseases such as inflammatory osteoarticular disorders, tendinitis, and muscle injury. Local hyperthermia is clinically applied to improve blood and lymphatic flow to decrease swelling of tissues (e.g., skeletal muscle). As for muscle repair following injury, the mechanisms underlying the beneficial effects of hyperthermia-induced muscle repair are unknown. In this study, we investigated the direct effects of continuous heat stress on the differentiation of cultured mammalian myoblasts. Compared with control cultures grown at 37°C, incubation at 39°C (continuous mild heat stress; CMHS) enhanced myotube diameter, whereas myotubes were poorly formed at 41°C by primary human skeletal muscle culture cells, human skeletal muscle myoblasts (HSMMs), and C2C12 mouse myoblasts. In HSMMs and C2C12 cells exposed to CMHS, mRNA and protein levels of myosin heavy chain (MyHC) type I were increased compared with the control cultures. The mRNA level of MyHC IIx was unaltered in HSMMs and decreased in C2C12 cells, compared with cells that were not exposed to heat stress. These results indicated a fast-to-slow fiber-type shift in myoblasts. We also examined upstream signals that might be responsible for the fast-to-slow shift of fiber types. CMHS enhanced the mRNA and protein levels of peroxisome proliferator-activated receptor-␥ coactivator (PGC)-1␣ in HSMMS and C2C12 cells but not the activities of MAPKs (ERK1/2 and p38 MAPK) in HSMMs and C2C12 cells. These data suggest that CMHS induces a fast-to-slow fiber-type shift of mammalian myoblasts through PGC-1␣.

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Background Migraine is the leading cause of days lost due to disability in the world among people less than 50 years of age. There is a paucity of evidence on the impact of migraine and other headache disorders and the cost and productivity losses in the workplace. Methods Employee population survey assessed prevalence, characteristics, and disability of headache disorders at a Japanese information technology company. This study was supported by the World Health Organization Western Pacific Region Office and International Headache Society. Results 2458 (1963men, 495 women) out of 2494 responded to the survey that utilized ICHD-3 beta criteria. Among these, 13% (205 male/123 female) had migraine (M), 53% (1093 male/207 female) had tension-type headache (TTH) and 4% (61 male/27 female) had migraine and TTH (M/TTH). The number of days when productivity at work was reduced by half or more because of headache was significantly higher in migraine compared to TTH. The norm-based scoring of SF-12v2 was significantly lower in M/TTH and M than TTH. The economic loss due to absenteeism for migraine was calculated to be $ 238.3US$/year/person for day-off and 90.2US$/year/person for half-day off using migraine disability assessment score (MIDAS). The economic loss due to presenteeism for migraine was calculated to be $ 375.4US$/year/person using MIDAS and 2217US$/year/person using work productivity and activity impairment questionnaire (WPAI). Furthermore, estimated cost of productivity loss associated with presenteeism using WPAI was calculated at 21.3 billion US$/year in Japan as a whole. Conclusions This study revealed a high prevalence and disease burden among employees with migraine that is associated with substantial losses in productivity and employer cost. These results support the development and implementation of workplace programs to improve migraine management in the workplace and reduce the burden and costs associated with lost workplace productivity.

The oncogenic G(12/13) subfamily of heterotrimeric G proteins transduces extracellular signals that regulate the actin cytoskeleton, cell cycle progression, and gene transcription. Previously, structural analyses of fully functional G alpha(12/13) subunits have been hindered by insufficient amounts of homogeneous, functional protein. Herein, we report that substitution of the N-terminal helix of G alpha(i1) for the corresponding region of G alpha12 or G alpha13 generated soluble chimeric subunits (G alpha(i/12) and G alpha(i/13)) that could be purified in sufficient amounts for crystallographic studies. Each chimera bound guanine nucleotides, G betagamma subunits, and effector proteins and exhibited GAP responses to p115RhoGEF and leukemia-associated RhoGEF. Like their wild-type counterparts, G alpha(i/13), but not G alpha(i/12), stimulated the activity of p115RhoGEF. Crystal structures of the G alpha(i/12) x GDP x AlF4(-) and G alpha(i/13) x GDP complexes were determined using diffraction data extending to 2.9 and 2.0 A, respectively. These structures reveal not only the native structural features of G alpha12 and G alpha13 subunits, which are expected to be important for their interactions with GPCRs and effectors such as G alpha-regulated RhoGEFs, but also novel conformational changes that are likely coupled to GTP hydrolysis in the G alpha(12/13) class of heterotrimeric G proteins.