RESUMEN
We reported previously that a signaling pathway consisting of G(i)-Ras-NF-kappaB mediates lysophosphatidic acid (LPA)-induced urokinase plasminogen activator (uPA) upregulation in ovarian cancer cells. However, it is not clear what signaling components link Ras to nuclear factor (NF)-kappaB for this LPA-induced event. In the present study, we found that treatment of protein kinase C (PKC) inhibitors including conventional PKC (cPKC) inhibitor Gö6976 abolished LPA-induced uPA upregulation in ovarian cancer cell lines tested, indicating the importance of cPKC activity in this LPA-induced event. Indeed, LPA stimulation led to the activation of PKCalpha and Ras-PKCalpha interaction. Although constitutively active mutants of PKCalpha (a cPKC), PKCtheta (a novel PKC (nPKC)) and PKCzeta (an atypical PKC (aPKC)) were all able to activate NF-kappaB and upregulate uPA expression, only dominant-negative PKCalpha mutant attenuated LPA-induced NF-kappaB activation and uPA upregulation. These results suggest that PKCalpha, rather than PKC isoforms in other PKC classes, participates in LPA-induced NF-kappaB activation and uPA upregulation in ovarian cancer cells. To determine the signaling components downstream of PKCalpha mediating LPA-induced uPA upregulation, we showed that forced expression of dominant-negative CARMA3 or silencing CARMA3, Bcl10 and MALT1 with specific siRNAs diminished these LPA-induced events. Furthermore, we demonstrated that PKCalpha/CARMA3 signaling axis is important in LPA-induced ovarian cancer cell in vitro invasion.
Asunto(s)
Proteínas Reguladoras de la Apoptosis/fisiología , Proteínas Adaptadoras de Señalización CARD/fisiología , Lisofosfolípidos/fisiología , FN-kappa B/metabolismo , Neoplasias Ováricas/enzimología , Proteína Quinasa C-alfa/fisiología , Transducción de Señal/fisiología , Activador de Plasminógeno de Tipo Uroquinasa/genética , Proteínas ras/metabolismo , Línea Celular Tumoral , Femenino , Humanos , Invasividad Neoplásica , Neoplasias Ováricas/patología , Proteína Quinasa C-alfa/antagonistas & inhibidores , Regulación hacia Arriba/genética , Activador de Plasminógeno de Tipo Uroquinasa/biosíntesisRESUMEN
The membrane redistribution and phosphorylation of focal adhesion kinase (FAK) have been reported to be important for cell migration. We previously showed that Lysophosphatidic acid (LPA) induced FAK membrane redistribution and autophosphorylation in ovarian cancer SK-OV3 cells and the signaling pathway consisting of Gi-Ras-MEKK1 mediated LPA-induced FAK membrane redistribution but not FAK autophosphorylation. We also showed that the disruption of the Gi-Ras-MEKK1 pathway led to a significant reduction in LPA-stimulated cell migration. These findings raised the question of whether LPA-induced FAK autophosphorylation was required for LPA-stimulated cell migration and what signaling mechanism was involved in LPA-induced FAK autophosphorylation. In this study, we expressed the membrane anchored wild-type FAK (CD2-FAK) in SK-OV3 cells and found that the expression of CD2-FAK greatly rescued LPA-stimulated cell migration in Gi or Ras-inhibited cells. However, Gi inhibitor pertussis toxin or dominant-negative H-Ras still significantly inhibited LPA-stimulated cell migration in cells expressing the membrane anchored FAK containing a mutation in the autophosphorylation site [CD2-FAK(Y397A)]. These results suggest that FAK autophosphorylation plays a role in LPA-stimulated cell migration. With the aid of p115RhoGEF-RGS, G12 and G13 minigenes to inhibit G12/13, we found that the G12/13 pathway was required for LPA-induced FAK autophosphorylation and efficient cell migration. Moreover, LPA activated RhoA and Rho kinase (ROCK) in a G12/13-dependent manner and their activities were required for LPA-induced FAK autophosphorylation. However, Rho or ROCK inhibitors displayed no effect on LPA-induced FAK membrane redistribution although they abolished LPA-induced cytoskeleton reorganization. Our studies show that the G12/13-RhoA-ROCK signaling pathway mediates LPA-induced FAK autophosphorylation and contributes to LPA-stimulated cell migration.
Asunto(s)
Movimiento Celular/efectos de los fármacos , Proteína-Tirosina Quinasas de Adhesión Focal/metabolismo , Lisofosfolípidos/farmacología , Neoplasias Ováricas/enzimología , Neoplasias Ováricas/patología , Transducción de Señal , Proteína de Unión al GTP rhoA/metabolismo , Membrana Celular/metabolismo , Citoesqueleto/metabolismo , Femenino , Proteína-Tirosina Quinasas de Adhesión Focal/antagonistas & inhibidores , Proteína-Tirosina Quinasas de Adhesión Focal/genética , Adhesiones Focales/enzimología , Subunidades alfa de la Proteína de Unión al GTP G12-G13/metabolismo , Genes ras/fisiología , Humanos , Péptidos y Proteínas de Señalización Intracelular , Mutación , Toxina del Pertussis/farmacología , Fosforilación/efectos de los fármacos , Proteínas Serina-Treonina Quinasas/metabolismo , Células Tumorales Cultivadas , Proteínas ras/fisiología , Quinasas Asociadas a rhoRESUMEN
The Lactococcus lactis temperate bacteriophage BK5-T is one of twelve type phages that define L. lactis phage species. This paper describes the nucleotide sequence and analysis of a 21-kbp region of the BK5-T genome and completes the nucleotide sequence of the genome of this phage. The 40,003-nucleotide linear genome encodes 63 open reading frames. Sequence runoff experiments showed that the cohesive ends of the BK5-T genome contained a 12-bp 3' single-stranded overhang with the sequence 5'-CACACACATAGG-3'. Two major BK5-T structural proteins, of approximately 30 and 20 kDa, were identified, and N-terminal sequence analysis determined that they were encoded by orf7 and orf12, respectively. A 169-bp fragment containing a 37-bp direct repeat and several smaller repeat sequences conferred resistance to BK5-T infection when introduced in trans to the host cell and is likely a part of the BK5-T origin of replication (ori).
Asunto(s)
Bacteriófagos/genética , Lactococcus lactis/virología , Análisis de Secuencia de ADN , Secuencia de Aminoácidos , Secuencia de Bases , Genoma Viral , Datos de Secuencia Molecular , Sistemas de Lectura Abierta/genética , Origen de Réplica/genética , Proteínas Estructurales Virales/química , Proteínas Estructurales Virales/genéticaRESUMEN
Lactococcus lactis phage BK5-T and Streptococcus thermophilus phage Sfi21, two cos-site temperate Siphoviridae with 40-kb genomes, share an identical genome organization, sequence similarity at the amino acid level over about half of their genomes, and nucleotide sequence identity of 60% over the DNA packaging and head morphogenesis modules. Siphoviridae with similarly organized genomes and substantial protein sequence similarity were identified in several genera of low-GC-content Gram-positive bacteria. These phages demonstrated a gradient of relatedness ranging from nucleotide sequence similarity to protein sequence similarity to gene map similarity over the DNA packaging and head morphogenesis modules. Interestingly, the degree of relatedness was correlated with the evolutionary distance separating their bacterial hosts. These observations suggest elements of vertical evolution in phages. The structural genes from BK5-T shared no sequence relationships with corresponding genes/proteins from lactococcal phages belonging to distinct lactococcal phage species, including phage sk1 (phage species 936) that showed a closely related gene map. Despite a clearly distinct genome organization, lactococcal phages sk1 and c2 showed nine sequence-related proteins. Over the early gene cluster phage BK5-T shared nine regions of high nucleotide sequence similarity, covering at most two adjacent genes, with lactococcal phage r1t (phage species P335). Over the structural genes, the closest relatives of phage r1t were not lactococcal phages belonging to other phage species, but Siphoviridae from Mycobacteria (high-GC-content Gram-positive bacteria). Evidence for recent horizontal gene transfer between distinct phage species was obtained for dairy phages, but these transfers were limited to phages infecting the same bacterial host species.