STIM1 Regulates Platelet-Derived Growth Factor-Induced Migration and Ca2+ Influx in Human Airway Smooth Muscle Cells

It is suggested that migration of airway smooth muscle (ASM) cells plays an important role in the pathogenesis of airway remodeling in asthma. Increases in intracellular Ca²⁺ concentrations ([Ca²⁺]_i) regulate most ASM cell functions related to asthma, such as contraction and proliferation. Recently, STIM1 was identified as a sarcoplasmic reticulum (SR) Ca²⁺ sensor that activates Orai1, the Ca²⁺ channel responsible for store-operated Ca²⁺ entry (SOCE). We investigated the role of STIM1 in [Ca²⁺]_i and cell migration induced by platelet-derived growth factor (PDGF)-BB in human ASM cells. Cell migration was assessed by a chemotaxis chamber assay. Human ASM cells express STIM1, STIM2, and Orai1 mRNAs. SOCE activated by thapsigargin, an inhibitor of SR Ca²⁺-ATPase, was significantly blocked by STIM1 siRNA and Orai1 siRNA but not by STIM2 siRNA. PDGF-BB induced a transient increase in [Ca²⁺]_i followed by sustained [Ca²⁺]_i elevation. Sustained increases in [Ca²⁺]_i due to PDGF-BB were significantly inhibited by a Ca²⁺ chelating agent EGTA or by siRNA for STIM1 or Orai1. The numbers of migrating cells were significantly increased by PDGF-BB treatment for 6 h. Knockdown of STIM1 and Orai1 by siRNA transfection inhibited PDGF-induced cell migration. Similarly, EGTA significantly inhibited PDGF-induced cell migration. In contrast, transfection with siRNA for STIM2 did not inhibit the sustained elevation of [Ca²⁺]_i or cell migration induced by PDGF-BB. These results demonstrate that STIM1 and Orai1 are essential for PDGF-induced cell migration and Ca²⁺ influx in human ASM cells. STIM1 could be an important molecule responsible for airway remodeling.     

Persistence of the Potassium Uptake Rhythm in the Presence of Exogenous Sucrose in Lemna gibba G3

The potassium uptake rhythm in a flow medium culture of Lemnagibba G3 persisted in darkness for 3 days, when the flow mediumcontained sucrose (1%). The rhythm was damped out after thatin darkness but it persisted longer when the plants were keptunder continuous weak light (80 lux). The rhythm was not dampedout when a daily light pulse (4,200 lux for 15 min) was applied.A single light pulse (4,200 lux for 15 min) at hour 48 of theprolonged dark period caused the rhythm to start again. DCMU(1 µM) slightly reduced the amplitude of the rhythm butdid not nullify the effect of the inserted light pulse. (Received September 16, 1981; Accepted February 2, 1982)     

Preparation and structures of the cluster dimers consisting of Rh2Mo2S4 single-cubane units connected by two bidentate N-donor ligands

Reactions of a single-cubane cluster [{Rh(cod)}₂{MoCl(dtc)}₂(μ₃-S)₄] (cod = 1,5-cyclooctadiene, dtc = diethyldithiocarbamate) with 1 equiv. of L (L = pyrazine, 4,4′-bipyridyl, trans-1,2-bis(4-pyridyl)ethylene) in the presence of 2 equiv. of AgBF₄ in CH₂Cl₂ gave doubly bridged double-cubane clusters [({Rh(cod)}₂{Mo(dtc)}₂(μ₃-S)₄)₂(μ-L)₂][BF₄]₄, whose structures were determined by the single-crystal X-ray analysis.     

Banding pattern analysis of polymorphic karyotypes in the black rat by a new differential staining technique

Polymorphic karyotypes of black rats (Rattus rattus) collected in Japan, Australia and India were analysed by a new differential staining technique by which banding patterns in the metaphase chromosomes are revealed. The technique consists in two steps: immersion of slides in a mixture of 2 x SSC and 0.1% (w/v) SDS (sodium dodecyl sulfate) for a few seconds at room temperature, and staining in Giemsa. By this treatment characteristic banding patterns were obtained in each chromosome pair. From the banding pattern analysis, subtelocentric pairs No. 1 and 9, which are polymorphic in respect to the acrocentrics and the subtelocentrics, were proven to have originated by pericentric inversion in the acrocentrics. The origin of two large metacentrics observed in Australian and Indian black rats was confirmed to have been developed by Robertsonian fusion of the acrocentrics No. 4 and 7 and No. 11 and 12 present in the Asian type black rat.Contribution No. 873 from the National Institute of Genetics, Japan. Supported by a grant-in-aid from the Ministry of Education of Japan (Nos. 92159 and 92332).     

Eleostearic acid induces RIP1-mediated atypical apoptosis in a kinase-independent manner via ERK phosphorylation,ROS generation and mitochondrial dysfunction

RIP1 is a serine/threonine kinase, which is involved in apoptosis and necroptosis. In apoptosis, caspase-8 and FADD have an important role. On the other hand, RIP3 is a key molecule in necroptosis. Recently, we reported that eleostearic acid (ESA) elicits caspase-3- and PARP-1-independent cell death, although ESA-treated cells mediate typical apoptotic morphology such as chromatin condensation, plasma membrane blebbing and apoptotic body formation. The activation of caspases, Bax and PARP-1, the cleavage of AIF and the phosphorylation of histone H2AX, all of which are characteristics of typical apoptosis, do not occur in ESA-treated cells. However, the underlying mechanism remains unclear. To clarify the signaling pathways in ESA-mediated apoptosis, we investigated the functions of RIP1, MEK, ERK, as well as AIF. Using an extensive study based on molecular biology, we identified the alternative role of RIP1 in ESA-mediated apoptosis. ESA mediates RIP1-dependent apoptosis in a kinase independent manner. ESA activates serine/threonine phosphatases such as calcineurin, which induces RIP1 dephosphorylation, thereby ERK pathway is activated. Consequently, localization of AIF and ERK in the nucleus, ROS generation and ATP reduction in mitochondria are induced to disrupt mitochondrial cristae, which leads to cell death. Necrostatin (Nec)-1 blocked MEK/ERK phosphorylation and ESA-mediated apoptosis. Nec-1 inactive form (Nec1i) also impaired ESA-mediated apoptosis. Nec1 blocked the interaction of MEK with ERK upon ESA stimulation. Together, these findings provide a new finding that ERK and kinase-independent RIP1 proteins are implicated in atypical ESA-mediated apoptosis.     

Spinal Cord Stimulation Exerts Neuroprotective Effects against Experimental Parkinson’s Disease

In clinical practice, deep brain stimulation (DBS) is effective for treatment of motor symptoms in Parkinson’s disease (PD). However, the mechanisms have not been understood completely. There are some reports that electrical stimulation exerts neuroprotective effects on the central nervous system diseases including cerebral ischemia, head trauma, epilepsy and PD, although there are a few reports on neuroprotective effects of spinal cord stimulation (SCS). We investigated the neuroprotective effects of high cervical SCS on PD model of rats. Adult female Sprague-Dawley rats received hour-long SCS (2, 50 or 200 Hz) with an epidural electrode at C1–2 level for 16 consecutive days. At 2 days after initial SCS, 6-hydroxydopamine (6-OHDA) was injected into the right striatum of rats. Behavioral evaluations of PD symptoms were employed, including cylinder test and amphetamine-induced rotation test performed at 1 and 2 weeks after 6-OHDA injection. Animals were subsequently euthanized for immunohistochemical investigations. In order to explore neurotrophic and growth factor upregulation induced by SCS, another cohort of rats that received 50 Hz SCS was euthanized at 1 and 2 weeks after lesion for protein assays. Behavioral tests revealed that the number of amphetamine-induced rotations decreased in SCS groups. Immunohistochemically, tyrosine hydroxylase (TH)-positive fibers in the striatum were significantly preserved in SCS groups. TH-positive neurons in the substantia nigra pars compacta were significantly preserved in 50 Hz SCS group. The level of vascular endothelial growth factor (VEGF) was upregulated by SCS at 1 week after the lesion. These results suggest that high cervical SCS exerts neuroprotection in PD model of rats, at least partially by upregulation of VEGF. SCS is supposed to suppress or delay PD progression and might become a less invasive option for PD patients, although further preclinical and clinical investigations are needed to confirm the effectiveness and safety.     

Molecular mechanism for pore-formation in lipid membranes by the hemolytic lectin CEL-III from marine invertebrate Cucumaria echinata.

The pore-forming activity of CEL-III, a Gal/GalNAc specific lectin from the Holothuroidea Cucumaria echinata, was examined using artificial lipid membranes as a model system of erythrocyte membrane. The carboxyfluorescein (CF)-leakage studies clearly indicated that CEL-III induced the formation of pores in the dipalmitoyl phosphatidyl choline (DPPC)-lactosyl ceramide (LacCer) liposomes effectively but not in the DPPC-glucosyl ceramide (GlcCer) liposomes or DPPC liposomes. Such a leakage of CF was strongly inhibited by lactose, a potent inhibitor of CEL-III, suggesting that the leakage is mediated through the specific binding of CEL-III to the carbohydrate chains on the surface of the liposomes. The leakage of CF from the DPPC-lactosyl ceramide liposomes was pH-dependent, and it increased with increasing pH. The immunoblotting analysis and circular dichroism data indicated that upon interaction with liposomes, CEL-III associated to form an oligomer concomitantly with a marked conformational change. Furthermore, channel measurements showed that CEL-III has an ability to form small ion channels in the planar lipid bilayers consisting of diphytanoylphosphatidylcholine and human globoside (Gb4Cer)/LacCer.