Biomedical subjects

Masahiro Fukaya

Publications and source records attributed to Masahiro Fukaya.

At least 19 recordsLinked to original sources

PubMed2006

Effects of RNA interference of Atg4B on the limited proteolysis of LC3 in PC12 cells and expression of Atg4B in various rat tissues.

Atg4B, a mammalian homologue of yeast Atg4, has been shown to play an important role in the processing of LC3, a mammalian homologue of yeast Atg8, but the tissue distribution of Atg4B remains unknown. To better understand the role of Atg4B in rat tissue cells, we prepared antibodies against Atg4B, and PC12 cells in which the expression of Atg4B was knocked down by RNA interference. In the RNA interference-treated PC12 cells, for which the expression of Atg4B was 10% of wild-type PC12 cells, the expression of cytosolic LC3-I was similar to that in wild-type cells. Knockdown cell lysates, however, suppressed the cleavage of recombinant proLC3 to LC3-I. Moreover, the expression of Atg4B protein and mRNA was ubiquitous in rat tissues; however, the expression levels were not identical, but were dependent on the tissue, with the expression high in brain and testicular tissue, and low in muscular and heart tissue. In brain tissue, the expression of Atg4B protein and mRNA was higher in neurons, especially in the cerebellum and olfactory bulb, as evidenced by immunohistochemistry and in situ hybridization. These lines of evidence suggest that Atg4B plays a major role in the processing of LC3 and is widely distributed in rat tissues. In particular, in brain tissues, autophagy may be deeply associated with the metabolism of neurons, especially in the cerebellum.

Animals↗

PubMed2006

NR2B tyrosine phosphorylation modulates fear learning as well as amygdaloid synaptic plasticity.

Phosphorylation of neural proteins in response to a diverse array of external stimuli is one of the main mechanisms underlying dynamic changes in neural circuitry. The NR2B subunit of the NMDA receptor is tyrosine-phosphorylated in the brain, with Tyr-1472 its major phosphorylation site. Here, we generate mice with a knockin mutation of the Tyr-1472 site to phenylalanine (Y1472F) and show that Tyr-1472 phosphorylation is essential for fear learning and amygdaloid synaptic plasticity. The knockin mice show impaired fear-related learning and reduced amygdaloid long-term potentiation. NMDA receptor-mediated CaMKII signaling is impaired in YF/YF mice. Electron microscopic analyses reveal that the Y1472F mutant of the NR2B subunit shows improper localization at synapses in the amygdala. We thus identify Tyr-1472 phosphorylation as a key mediator of fear learning and amygdaloid synaptic plasticity.

Amygdala↗

PubMed2006

Localization of diacylglycerol lipase-alpha around postsynaptic spine suggests close proximity between production site of an endocannabinoid, 2-arachidonoyl-glycerol, and presynaptic cannabinoid CB1 receptor.

2-arachidonoyl-glycerol (2-AG) is an endocannabinoid that is released from postsynaptic neurons, acts retrogradely on presynaptic cannabinoid receptor CB1, and induces short- and long-term suppression of transmitter release. To understand the mechanisms of the 2-AG-mediated retrograde modulation, we investigated subcellular localization of a major 2-AG biosynthetic enzyme, diacylglycerol lipase-alpha (DAGLalpha), by using immunofluorescence and immunoelectron microscopy in the mouse brain. In the cerebellum, DAGLalpha was predominantly expressed in Purkinje cells. DAGLalpha was detected on the dendritic surface and occasionally on the somatic surface, with a distal-to-proximal gradient from spiny branchlets toward somata. DAGLalpha was highly concentrated at the base of spine neck and also accumulated with much lower density on somatodendritic membrane around the spine neck. However, DAGLalpha was excluded from the main body of spine neck and head. In hippocampal pyramidal cells, DAGLalpha was also accumulated in spines. In contrast to the distribution in Purkinje cells, DAGLalpha was distributed in the spine head, neck, or both, whereas somatodendritic membrane was labeled very weakly. These results indicate that DAGLalpha is essentially targeted to postsynaptic spines in cerebellar and hippocampal neurons, but its fine distribution within and around spines is differently regulated between the two neurons. The preferential spine targeting should enable efficient 2-AG production on excitatory synaptic activity and its swift retrograde modulation onto nearby presynaptic terminals expressing CB1. Furthermore, different fine localization within and around spines suggests that the distance between postsynaptic 2-AG production site and presynaptic CB1 is differentially controlled depending on neuron types.

Animals↗

PubMed2006

Expression and distribution of JNK/SAPK-associated scaffold protein JSAP1 in developing and adult mouse brain.

The c-Jun N-terminal kinase (JNK) is one of the three major mitogen-activated protein kinases (MAPKs) playing key roles in various cellular processes in response to both extracellular and intracellular stimuli. JNK/SAPK-associated protein 1 (JSAP1 also referred to as JIP3) is a JNK-associated scaffold that controls the specificity and efficiency of JNK signaling cascades. Here we studied its expression in mouse brains. JSAP1 mRNA was expressed in developing and adult brains, showing spatial patterns similar to JNK1-3 mRNAs. In embryos, JSAP1 immunolabeling was intense for progenitor cells in the ventricular zone throughout the brain and in the external granular layer of the cerebellum, and for neurons and glial cells differentiating in the mantle zone. In adults, JSAP1 was distributed in various neurons and Bergmann glia, with higher levels in striatal cholinergic interneurons, telencephalic parvalbumin-positive interneurons and cerebellar Purkinje cells. In these neurons, JSAP1 was observed as tiny particulate staining in spines, dendrites, perikarya and axons, where it was often associated with the smooth endoplasmic reticulum (sER) and cell membrane. Immunoblots revealed enriched distribution in the microsomal fraction and cytosolic fraction. Therefore, the characteristic cellular expression and subcellular distribution of JSAP1 might be beneficial for cells to efficiently link external stimuli to the JNK MAPK pathway and other intracellular machineries.

Adaptor Proteins, Signal Transducing↗

PubMed2006

The CB1 cannabinoid receptor is the major cannabinoid receptor at excitatory presynaptic sites in the hippocampus and cerebellum.

Endocannabinoids work as retrograde messengers and contribute to short-term and long-term modulation of synaptic transmission via presynaptic cannabinoid receptors. It is generally accepted that the CB1 cannabinoid receptor (CB1) mediates the effects of endocannabinoid in inhibitory synapses. For excitatory synapses, however, contributions of CB1, "CB3," and some other unidentified receptors have been suggested. In the present study we used electrophysiological and immunohistochemical techniques and examined the type(s) of cannabinoid receptor functioning at hippocampal and cerebellar excitatory synapses. Our electrophysiological data clearly demonstrate the predominant contribution of CB1. At hippocampal excitatory synapses on pyramidal neurons the cannabinoid-induced synaptic suppression was reversed by a CB1-specific antagonist, N-(piperidin-1-yl)-5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide (AM251), and was absent in CB1 knock-out mice. At climbing fiber (CF) and parallel fiber (PF) synapses on cerebellar Purkinje cells the cannabinoid-dependent suppression was absent in CB1 knock-out mice. The presence of CB1 at presynaptic terminals was confirmed by immunohistochemical experiments with specific antibodies against CB1. In immunoelectron microscopy the densities of CB1-positive signals in hippocampal excitatory terminals and cerebellar PF terminals were much lower than in inhibitory terminals but were clearly higher than the background. Along the long axis of PFs, the CB1 was localized at a much higher density on the perisynaptic membrane than on the extrasynaptic and synaptic regions. In contrast, CB1 density was low in CF terminals and was not significantly higher than the background. Despite the discrepancy between the electrophysiological and morphological data for CB1 expression on CFs, these results collectively indicate that CB1 is responsible for cannabinoid-dependent suppression of excitatory transmission in the hippocampus and cerebellum.

6-Cyano-7-nitroquinoxaline-2,3-dione↗

PubMed2006

Abundant distribution of TARP gamma-8 in synaptic and extrasynaptic surface of hippocampal neurons and its major role in AMPA receptor expression on spines and dendrites.

Transmembrane alpha-amino-3-hydroxyl-5-isoxazolepropionate (AMPA) receptor regulatory proteins (TARPs) play pivotal roles in AMPA receptor trafficking and gating. Here we examined cellular and subcellular distribution of TARP gamma-8 in the mouse brain. Immunoblot and immunofluorescence revealed the highest concentration of gamma-8 in the hippocampus. Immunogold electron microscopy demonstrated dense distribution of gamma-8 on the synaptic and extrasynaptic surface of hippocampal neurons with very low intracellular labeling. Of the neuronal surface, gamma-8 was distributed at the highest level on asymmetrical synapses of pyramidal cells and interneurons, whereas their symmetrical synapses selectively lacked immunogold labeling. Then, the role of gamma-8 in AMPA receptor expression was pursued in the hippocampus using mutant mice defective in the gamma-8 gene. In the mutant cornu ammonis (CA)1 region, synaptic and extrasynaptic AMPA receptors on dendrites and spines were severely reduced to 35-37% of control levels, whereas reduction was mild for extrasynaptic receptors on somata (74%) and no significant decrease was seen for intracellular receptors within spines. In the mutant CA3 region, synaptic AMPA receptors were reduced mildly at asymmetrical synapses in the stratum radiatum (67% of control level), and showed no significant decrease at mossy fiber-CA3 synapses. Therefore, gamma-8 is abundantly distributed on hippocampal excitatory synapses and extrasynaptic membranes, and plays an important role in increasing the number of synaptic and extrasynaptic AMPA receptors on dendrites and spines, particularly, in the CA1 region. Variable degrees of reduction further suggest that other TARPs may also mediate this function at different potencies depending on hippocampal subregions, input sources and neuronal compartments.

Animals↗

PubMed2006

Putative ABC transporter responsible for acetic acid resistance in Acetobacter aceti.

Two-dimensional gel electrophoretic analysis of the membrane fraction of Acetobacter aceti revealed the presence of several proteins that were produced in response to acetic acid. A 60-kDa protein, named AatA, which was mostly induced by acetic acid, was prepared; aatA was cloned on the basis of its NH2-terminal amino acid sequence. AatA, consisting of 591 amino acids and containing ATP-binding cassette (ABC) sequences and ABC signature sequences, belonged to the ABC transporter superfamily. The aatA mutation with an insertion of the neomycin resistance gene within the aatA coding region showed reduced resistance to acetic acid, formic acid, propionic acid, and lactic acid, whereas the aatA mutation exerted no effects on resistance to various drugs, growth at low pH (adjusted with HCl), assimilation of acetic acid, or resistance to citric acid. Introduction of plasmid pABC101 containing aatA under the control of the Escherichia coli lac promoter into the aatA mutant restored the defect in acetic acid resistance. In addition, pABC101 conferred acetic acid resistance on E. coli. These findings showed that AatA was a putative ABC transporter conferring acetic acid resistance on the host cell. Southern blot analysis and subsequent nucleotide sequencing predicted the presence of aatA orthologues in a variety of acetic acid bacteria belonging to the genera Acetobacter and Gluconacetobacter. The fermentation with A. aceti containing aatA on a multicopy plasmid resulted in an increase in the final yield of acetic acid.

ATP-Binding Cassette Transporters↗

PubMed2005

Target-cell-specific left-right asymmetry of NMDA receptor content in schaffer collateral synapses in epsilon1/NR2A knock-out mice.

Input-dependent left-right asymmetry of NMDA receptor epsilon2 (NR2B) subunit allocation was discovered in hippocampal Schaffer collateral (Sch) and commissural fiber pyramidal cell synapses (Kawakami et al., 2003). To investigate whether this asymmetrical epsilon2 allocation is also related to the types of the postsynaptic cells, we compared postembedding immunogold labeling for epsilon2 in left and right Sch synapses on pyramidal cells and interneurons. To facilitate the detection of epsilon2 density difference, we used epsilon1 (NR2A) knock-out (KO) mice, which have a simplified NMDA receptor subunit composition. The labeling density for epsilon2 but not zeta1 (NR1) and subtype 2/3 glutamate receptor (GluR2/3) in Sch-CA1 pyramidal cell synapses was significantly different between the left and right hippocampus with opposite directions in strata oriens and radiatum; the left to right ratio of epsilon2 labeling density was 1:1.50 in stratum oriens and 1.44:1 in stratum radiatum. No significant difference, however, was detected in CA1 stratum radiatum between the left and right Sch-GluR4-positive (mostly parvalbumin-positive) and Sch-GluR4-negative interneuron synapses. Consistent with the anatomical asymmetry, the amplitude ratio of NMDA EPSCs to non-NMDA EPSCs in pyramidal cells was approximately two times larger in right than left stratum radiatum and vice versa in stratum oriens of epsilon1 KO mice. Moreover, the amplitude of long-term potentiation in the Sch-CA1 synapses of left stratum radiatum was significantly larger than that in the right corresponding synapses. These results indicate that the asymmetry of epsilon2 distribution is target cell specific, resulting in the left-right difference in NMDA receptor content and plasticity in Sch-CA1 pyramidal cell synapses in epsilon1 KO mice.

Animals↗

PubMed2005

Spatial diversity in gene expression for VDCCgamma subunit family in developing and adult mouse brains.

The gamma subunit of voltage-dependent Ca2+ channels (VDCCs) is characterized by molecular diversity and regulation of AMPA-type glutamate receptors as well as VDCCs. In the present study, we examined expressions for the VDCCgamma1-8 subunit mRNAs in developing and adult mouse brains by in situ hybridization. In adult brains, the gamma2 and gamma7 subunit mRNAs were widely expressed in various grey matter regions with the highest level in cerebellar Purkinje cells and granule cells. The gamma3 and gamma8 subunit mRNAs predominated in the telencephalon, with the latter being at striking levels in the hippocampus. The gamma4 subunit mRNA was enriched in the olfactory bulb, striatum, thalamus and hypothalamus. The gamma5 subunit mRNA was abundant in the olfactory bulb, hippocampal CA2, thalamus, inferior colliculus and Bergmann glia. Transcripts of these subunits were detected in embryonic brains: some showed well-preserved spatial patterns (gamma2, gamma5, gamma7 and gamma8), while others underwent developmental up- (gamma3) or down-regulation (gamma4). In contrast, the gamma1 and gamma6 subunit mRNAs were negative or very low throughout brain development. Therefore, the present study has revealed spatial diversity in gene expression for individual VDCCgamma subunits, presumably reflecting functional diversity of this protein family and their differential involvement in neural function.

Animals↗

PubMed2005

Retinotectal transmission in the optic tectum of rainbow trout.

Retinotectal transmission has not yet been well characterized at the cellular level in the optic tectum. To address this issue, we used a teleost, the rainbow trout, and characterized periventricular neurons as postsynaptic cells expected to receive the retinotectal inputs to the optic tectum. The somata of periventricular neurons are localized in the upper zone of the stratum periventriculare (SPV), whereas the lower zone of the SPV comprises the cell body layer of radial glial cells. Ca2+ imaging identified functional ionotropic glutamate receptors in periventricular neurons. We also cloned cDNAs encoding the NR1 subunit of N-methyl-D-aspartic acid (NMDA) receptors and the GluR2 subunit of (+/-)-alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid (AMPA) receptors, and detected their mRNAs in periventricular neurons by in situ hybridization. The presence of the receptor subunit proteins was also confirmed in the dendrites of periventricular neurons by immunoblotting and immunohistochemistry. On the other hand, radial glial cells in the lower zone of the SPV did not respond to glutamate applications, and mRNA and immunoreactivities of ionotropic glutamate receptors were not detected in glial cells. The present findings suggest that glutamatergic transmission at synapses between retinotectal afferents and periventricular neurons is mediated by the functional NMDA and AMPA receptors.

Amino Acid Sequence↗

PubMed2005

Identification and characterization of a novel member of murine semaphorin family.

The semaphorin gene family contains a large number of secreted type or transmembrane type proteins, and some of them function as the repulsive and attractive cues of axon guidance during development. Here we report a novel member of murine class 3 semaphorin genes, semaphorin 3G (Sema3G), mapped on chromosome 14. In adulthood, Sema3G is mainly expressed in the lung and kidney, and a little in the brain. Interestingly, in the adult rodent brain Sema3G is expressed only in the granular layer of the cerebellum, as determined by Northern blot and in situ hybridization analyses. We also found that Sema3G binds Neuropilin-2, but not Neuropilin-1, and induces the repulsion of sympathetic axons, but not dorsal root ganglion axons, indicating that Sema3G utilizes Neuropilin-2 as a receptor to repel specific types of axons.

Animals↗

PubMed2005

NR2 to NR3B subunit switchover of NMDA receptors in early postnatal motoneurons.

The NR3B NMDA receptor subunit is selective to somatic motoneurons in the adult nervous system. Here we report its developmental expression in the mouse brain and spinal cord by in situ hybridization. NR3B mRNA was detected in few neural regions during embryonic and neonatal periods. It first appeared in motoneurons at postnatal day (P)10-P14, and attained the maximal level at P21 and adult stage. This developmental profile was reciprocal with that of NR2 subunits, of which NR2A mRNA was most predominant in embryonic and neonatal motoneurons and downregulated by P14. Interestingly, mRNA of the NR1 subunit, which is required for functional NMDA receptors, displayed a 'V'-shaped change, decreasing with the early postnatal decline of NR2 mRNAs and increasing with the subsequent appearance of NR3B mRNA. Therefore, the major regulatory subunit of NMDA receptors is likely to switch from NR2 to NR3B in somatic motoneurons during the early postnatal period.

Age Factors↗

PubMed2005

Distinct spatio-temporal expression of ABCA and ABCG transporters in the developing and adult mouse brain.

Using in situ hybridization for the mouse brain, we analyzed developmental changes in gene expression for the ATP-binding cassette (ABC) transporter subfamilies ABCA1-4 and 7, and ABCG1, 2, 4, 5 and 8. In the embryonic brains, ABCA1 and A7 were highly expressed in the ventricular (or germinal) zone, whereas ABCA2, A3 and G4 were enriched in the mantle (or differentiating) zone. At the postnatal stages, ABCA1 was detected in both the gray and white matter and in the choroid plexus. On the other hand, ABCA2, A3 and A7 were distributed in the gray matter. In addition, marked up-regulation of ABCA2 occurred in the white matter at 14 days-of-age when various myelin protein genes are known to be up-regulated. In marked contrast, ABCA4 was selective to the choroid plexus throughout development. ABCG1 was expressed in both the gray and white matters, whereas ABCG4 was confined to the gray matter. ABCG2 was diffusely and weakly detected throughout the brain at all stages examined. Immunohistochemistry of ABCG2 showed its preferential expression on the luminal membrane of brain capillaries. Expression signals for ABCG5 and G8 were barely detected at any stages. The distinct spatio-temporal expressions of individual ABCA and G transporters may reflect their distinct cellular expressions in the developing and adult brains, presumably, to regulate and maintain lipid homeostasis in the brain.

ATP-Binding Cassette Transporters↗

PubMed2004

NMDA receptor GluRepsilon/NR2 subunits are essential for postsynaptic localization and protein stability of GluRzeta1/NR1 subunit.

In NMDA receptors, GluRepsilon/NR2 subunits strictly require the GluRzeta1/NR1 subunit to exit from endoplasmic reticulum (ER) to the cell surface in vitro and to the postsynapse in vivo, whereas C terminus-dependent self-surface delivery has been demonstrated for the GluRzeta1 subunit in vitro. To test whether this leads to C terminus-dependent self-postsynaptic expression in neurons in vivo, we investigated the GluRzeta1 subunit in cerebellar granule cells lacking two major GluRepsilon subunits, GluRepsilon1/NR2A and GluRepsilon3/NR2C. In the mutant cerebellum, synaptic labeling for the GluRzeta1 subunit containing the C2 (GluRzeta1-C2) or C2' (GluRzeta1-C2') cassette was reduced at mossy fiber-granule cell synapses to the extrasynaptic level. The loss was not accompanied by decreased transcription and translation levels, increased extrasynaptic labeling, or ER accumulation. Quantitative immunoblot revealed substantial reductions in the mutant cerebellum of GluRzeta1-C2 and GluRzeta1-C2'. The most severe deficit was observed in the postsynaptic density (PSD) fraction: mutant levels relative to the wild-type level were 12.3 +/- 3.3% for GluRzeta1-C2 and 17.0 +/- 4.6% for GluRzeta1-C2'. The GluRzeta1 subunit carrying the C1 cassette (GluRzeta1-C1) was, although low in cerebellar content, also reduced to 12.7 +/- 3.5% in the mutant PSD fraction. Considering a trace amount of other GluRepsilon subunits in the mutant cerebellum, the severe reductions thus represent that the GluRzeta1 subunit, by itself, is virtually unable to accumulate at postsynaptic sites, regardless of C-terminal forms. By protein turnover analysis, the degradation of the GluRzeta1 subunit was accelerated in the mutant cerebellum, being particularly rapid for that carrying the C2 cassette. Therefore, accompanying expression of GluRepsilon subunits is essential for postsynaptic localization and protein stability of the GluRzeta1 subunit.

Animals↗

PubMed2004

Upregulation of GluR2 decreases intracellular Ca2+ following ischemia in developing gerbils.

Developing animals are known to be resistant to cerebral ischemia. To investigate the mechanisms by which developing animals exhibit ischemic resistance, we examined the changes in intracellular calcium ([Ca2+]i) after oxygen-glucose deprivation (OGD) using hippocampal slices from gerbils. We found that increases of [Ca2+]i in hippocampal CA1 neurons is significantly less after OGD in developing gerbils than in adults. Western blot analysis of AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid) receptors (AMPARs) showed that GluR2 expression, but not that of the other AMPARs is significantly higher in developing gerbils than in adults. Expression of the anti-apoptotic proteins such as HSP70, Bcl-XL, and plasma membrane Ca2+-ATPase type1 (PMCA1) are not higher in the developing gerbils than in adults. These results suggest that the higher expression of GluR2 is important for the smaller increases in [Ca2+]i and enhanced resistance to ischemia-induced neuronal damage in developing animals.

Aging↗

PubMed2004

Widespread expression of the AMPA receptor GluR2 subunit at glutamatergic synapses in the rat spinal cord and phosphorylation of GluR1 in response to noxious stimulation revealed with an antigen-unmasking method.

Glutamate, the principal excitatory neurotransmitter in the spinal cord, acts primarily through AMPA receptors. Although all four AMPA subunits are expressed by spinal neurons, we know little about their distribution at glutamatergic synapses. We used an antigen-unmasking technique to reveal the synaptic distribution of glutamate receptor (GluR) 1-4 subunits with confocal microscopy. After pepsin treatment, punctate staining was seen with antibodies against each subunit: GluR2-immunoreactive puncta were distributed throughout the gray matter, whereas GluR1-immunoreactive puncta were restricted to the dorsal horn and were most numerous in laminas I-II. Punctate staining for GluR3 and GluR4 was found in all laminas but was weak in superficial dorsal horn. Colocalization studies showed that GluR2 was present at virtually all (98%) puncta that were GluR1, GluR3, or GluR4 immunoreactive and that most (>90%) immunoreactive puncta in laminas IV, V, and IX showed GluR2, GluR3, and GluR4 immunoreactivity. Evidence that these puncta represented synaptic receptors was obtained with electron microscopy and by examining the association of GluR2- and GluR1-immunoreactive puncta with glutamatergic boutons (identified with vesicular glutamate transporters or markers for unmyelinated afferents). The great majority (96%) of these boutons were associated with GluR2-immunoreactive puncta. Our findings suggest that GluR2 is almost universally present at AMPA-containing synapses, whereas GluR1 is preferentially associated with primary afferent terminals. We also found a substantial, rapid increase in staining for synaptic GluR1 subunits phosphorylated on the S845 residue in the ipsilateral dorsal horn after peripheral noxious stimulation. This finding demonstrates plastic changes, presumably contributing to central sensitization, at the synaptic level.

Animals↗

PubMed2004

Enhanced expression of aconitase raises acetic acid resistance in Acetobacter aceti.

Acetobacter spp. are used for industrial vinegar production because of their high ability to oxidize ethanol to acetic acid and high resistance to acetic acid. Two-dimensional gel electrophoretic analysis of a soluble fraction of Acetobacter aceti revealed the presence of several proteins whose production was enhanced, to various extents, in response to acetic acid in the medium. A protein with an apparent molecular mass of 100 kDa was significantly enhanced in amount by acetic acid and identified to be aconitase by NH2-terminal amino acid sequencing and subsequent gene cloning. Amplification of the aconitase gene by use of a multicopy plasmid in A. aceti enhanced the enzymatic activity and acetic acid resistance. These results showed that aconitase is concerned with acetic acid resistance. Enhancement of the aconitase activity turned out to be practically useful for acetic acid fermentation, because the A. aceti transformant harboring multiple copies of the aconitase gene produced a higher concentration of acetic acid with a reduced growth lag-time.

Acetic Acid↗

PubMed2004

Lysophosphatidic acid and autotaxin stimulate cell motility of neoplastic and non-neoplastic cells through LPA1.

Autotaxin (ATX) is a tumor cell motility-stimulating factor originally isolated from melanoma cell supernatant that has been implicated in regulation of invasive and metastatic properties of cancer cells. Recently, we showed that ATX is identical to lysophospholipase D, which converts lysophosphatidylcholine to a potent bioactive phospholipid mediator, lysophosphatidic acid (LPA), raising the possibility that autocrine or paracrine production of LPA by ATX contributes to tumor cell motility. Here we demonstrate that LPA and ATX mediate cell motility-stimulating activity through the LPA receptor, LPA(1). In fibroblasts isolated from lpa(1)(-/-) mice, but not from wild-type or lpa(2)(-/-), cell motility stimulated with LPA and ATX was completely absent. In the lpa(1)(-/-) cells, LPA-stimulated lamellipodia formation was markedly diminished with a concomitant decrease in Rac1 activation. LPA stimulated the motility of multiple human cancer cell lines expressing LPA(1), and the motility was attenuated by an LPA(1)-selective antagonist, Ki16425. The present study suggests that ATX and LPA(1) represent potential targets for cancer therapy.

Animals↗