RESUMO
Tropomyosins were first identified in neuronal systems in 1973. Although numerous isoforms were found and described since then, many aspects of their function and interactions remained unknown. Tropomyosin isoforms show different sorting pattern in neurogenesis. As one example, TM5NM1/2 is present in developing axons, but it is replaced by TMBr-3 in mature neurons, suggesting that these tropomyosin isoforms contribute differently to the establishment of the functional features of the neuronal actin networks. We developed a method for the efficient purification of TMBr-3 and TM5NM1 as recombinant proteins using bacterial expression system and investigated their interactions with actin. We found that both isoforms bind actin filaments, however, the binding of TM5NM1 was much stronger than that of TMBr-3. TMBr-3 and TM5NM1 modestly affected actin assembly kinetics, in an opposite manner. Consistently with the higher affinity of TM5NM1 it inhibited actin filament disassembly more efficiently than TMBr-3. Similarly to other previously studied tropomyosins TM5NM1 inhibited the Arp2/3 complex-mediated actin assembly. Notably, TMBr-3 did not influence the Arp2/3 complex-mediated polymerization. This is a unique feature of TMBr-3, since so far it is the only known tropomyosin supporting the activity of the Arp2/3 complex, indicating that TMBr-3 may colocalize and work simultaneously with Arp2/3 complex in neuronal cells.
Assuntos
Actinas/metabolismo , Tropomiosina/isolamento & purificação , Tropomiosina/metabolismo , Citoesqueleto de Actina/metabolismo , Complexo 2-3 de Proteínas Relacionadas à Actina/metabolismo , Sequência de Aminoácidos , Animais , Éxons/genética , Fluorescência , Cinética , Camundongos , Dados de Sequência Molecular , Polimerização , Ligação Proteica , Isoformas de Proteínas/química , Isoformas de Proteínas/metabolismo , Coelhos , Fatores de Tempo , Tropomiosina/químicaRESUMO
The C1858T allele of the PTPN22 gene has been reported to confer risk for RA; but in some reports, the effect was restricted to RF- and/or anti-CCP-seropositive patients. Hungarian RA patients and matched controls were genotyped. The 1858T allele showed an increased prevalence in RA patients compared to controls. The 1858T allele represents a risk factor in the whole RA population (P = 0.001); an association was found both in RF-seropositive (P = 0.001) and anti-CCP-seropositive patients (P = 0.001), and in subjects with the combination of these factors (P = 0.002). In TT homozygotes, the estimated susceptibility to RA was more than double (OR = 5.04) of that seen in TC heterozygotes (OR = 1.89); the same gene dosage effect was observed in all seropositive RA subgroups. Our data show that the Hungarian RA patients belong to the populations in which the 1858T allele represents a susceptibility factor both in the RF- and/or anti-CCP-seropositive subjects, and the association exhibit a gene dosage dependency.
Assuntos
Artrite Reumatoide/enzimologia , Artrite Reumatoide/genética , Predisposição Genética para Doença/genética , Polimorfismo Genético/genética , Proteína Tirosina Fosfatase não Receptora Tipo 22/genética , Adulto , Distribuição por Idade , Idoso , Artrite Reumatoide/etnologia , Análise Mutacional de DNA , Feminino , Dosagem de Genes/genética , Frequência do Gene/genética , Marcadores Genéticos/genética , Testes Genéticos , Genótipo , Homozigoto , Humanos , Hungria/etnologia , Ativação Linfocitária/genética , Masculino , Pessoa de Meia-Idade , Fator Reumatoide/genética , Distribuição por Sexo , Linfócitos T/enzimologiaRESUMO
We studied plasma concentrations of free carnitine and 30 carnitine esters by electron spray ionization (ESI) tandem mass spectrometry in 37 pregnant women at the 20th and 30th weeks of gestation and at delivery, and in their neonates at birth, and in 22 age-matched nonpregnant women. The plasma levels of acetylcarnitine and carnitine esters with more than five carbons were significantly higher, whereas the concentration of free carnitine was significantly lower at term than at the 20th week of pregnancy (16.75 +/- 0.89 versus 19.61 +/- 1.25). Almost all of C2- to C12-carnitine esters were significantly lower, whereas C16- and C18-carnitines with in-chain modifications were significantly higher in mothers at delivery compared with nonpregnant women. Plasma levels of free carnitine and C2-, C3-, C4-, C5-, C6-, and C16-carnitines were significantly lower, while concentrations of carnitine esters with 8, 10, 12 and 18 carbons in the acyl chain as well as C14:1-, C14:2-, and C16:1-OH-carnitines were significantly higher in mothers at term than in their neonates. The data of the present study clearly show dynamic features of plasma carnitine profile during pregnancy and indicate an extraordinarily active participation of the carnitine in the intermediary metabolism both in the pregnant woman and in the neonate.
