Small GTPase Rac1: structure, localization, and expression of the human gene.
ABSTRACT Rac1 is a member of the Rho family of small GTPases involved in signal transduction pathways that control proliferation, adhesion, and migration of cells during embryonic development and invasiveness of tumor cells. Here we present the complete structure of the human RAC1 gene and characterize its expression. The gene comprises 7 exons over a length of 29 kb and is localized to chromosome 7p22. The GC-rich gene promoter shows characteristics of a housekeeping gene and Northern blot studies revealed ubiquitous expression of two rac1 transcripts, 1.2 and 2.5 kb in size. The two transcripts are expressed in tissue-specific ratios, reflecting competition between two alternative polyadenylation sites. The RAC1 but not RAC2 gene contains an additional exon 3b that is included by alternative splicing into the variant Rac1b, a constitutively active mutant which induces the formation of lamellipodia in fibroblasts. These data indicate that the RAC1 gene encodes two signaling GTPases. The gene structure reported here will enable studies on the regulation of RAC1 expression during tumorigenesis and development.
SourceAvailable from: Maria João Bugalho[Show abstract] [Hide abstract]
ABSTRACT: CONTEXT: The BRAF V600E mutation is the most frequent genetic alteration in papillary thyroid carcinoma (PTC). In colorectal cancer, BRAF V600E was described to functionally cooperate with Rac1b, a hyperactive splice variant of the small GTPase Rac1, to sustain cell survival. This interplay has never been investigated in PTCs. OBJECTIVE: We aimed to analyze the expression of Rac1b in PTC and correlate its expression with BRAF V600E mutational status, histopathological features and clinical outcome. PATIENTS AND METHODS: 61 patients and 87 samples (61 PTCs, 26 normal thyroid tissues) were included. Patients were divided into two groups based on longitudinal evolution and final outcome. Rac1b expression levels were determined by quantitative RT-PCR and Western blotting. RESULTS: Rac1b was expressed in thyroid and overexpressed in 46% of PTCs. Neither Rac1b overexpression nor V600E mutation correlated with histopathological features classically associated with worse prognosis. Rac1b overexpression was significantly associated with both V600E mutation (P = 0.0008) and poor clinical outcome (P = 0.0029). Whereas BRAF V600E alone did not associate with patient outcome (P = 0.2865), the association of Rac1b overexpression with BRAF V600E was overrepresented in the group with poorer clinical outcome (P = 0.0044). CONCLUSIONS: Present results document, for the first time, expression of Rac1b in normal thyroid cells as well as overexpression in a subset of PTCs. Furthermore, they suggest a possible interplay between BRAF V600E and Rac1b contributing to poor clinical outcome. Future studies are needed to clarify the oncogenic potential of Rac1b in thyroid carcinogenesis.European Journal of Endocrinology 03/2013; DOI:10.1530/EJE-12-0960 · 3.69 Impact Factor
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ABSTRACT: The GTPase Rac1 has been implicated in hypertension as a modulator of mineralocorticoid receptor activity. Our aim is to investigate the frequency of polymorphisms rs10951982 (intron 1, G>A) and rs836478 (intron 3, T>C) in the RAC1 gene and perform association studies with clinical and biochemical parameters in a Chilean pediatric cohort. Two hundred two normotensive (NT) subjects (aged 4-16 years) were divided into 2 groups: NT subjects with hypertensive parents (NH; n = 103) and NT subjects with NT parents (NN; n = 99). We measured markers of inflammation (high-sensitivity C-reactive protein, interleukin 6 (IL-6), interleukin 8, and tumor necrosis factor α), endothelial damage (Plasminogen activator inhibitor-1 metalloproteinase-9, and metalloproteinase-2), and oxidative stress (malondialdehyde). Data were expressed as median and interquartile range (IQR). We found differences in polymorphism rs836478 (intron 3, C>T) in both genotypic (χ(2) = 15.2, 2df; P = 0.0005) and allelic (X(2)=5.5, 1df; P = 0.01) frequencies in NH vs. NN subjects. NH subjects with a TT genotype showed increase MMP9 expression (median = 2.3, IQR - 1.6-3.2; vs. median = 1.6, IQR = 1.6-2.3 AU; P = 0.01) and lower IL-6 expression (median = 8.8, IQR = 7.0-11.8; vs. median = 12.1, IQR = 8.2-14.7 pg/ml; P = 0.02) compared with subjects with TC/CC genotype. No difference in the allelic frequency distribution was seen in the polymorphism rs10951982 (NH vs. NN: χ2=0.2, 1df; P = 0.6). For this SNP, NN subjects with GA/AA genotype showed decreased diastolic BP indexes compared with subjects with native GG genotype (median = 1.08, IQR = 1.0-1.2; vs. median = 0.99, IQR = 0.94-1.1; P = 0.02). We report the frequency of polymorphisms rs836478 and rs10951982 of the RAC1 gene in a Spanish-Amerindian cohort. The polymorphism rs836478 was associated with an increased expression in markers of inflammation and endothelial damage (MMP9 and IL-6) in pediatric subjects with a hypertensive genetic background.American Journal of Hypertension 02/2014; 27(3). DOI:10.1093/ajh/hpt277 · 3.40 Impact Factor
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ABSTRACT: Plants are exploited as a potential source for the large-scale production of noble gold nanoparticles in the recent years owing to their various potential applications in nanobiotechnology and nanomedicine. The present work describes green biosynthetic procedures for the production of gold nanoparticles for the first time by using an aqueous extract of the Dysosma pleiantha rhizome. The biosynthesized gold nanoparticles were confirmed and characterized by ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy, and scanning electron microscopy equipped with energy dispersive spectroscopy. The results revealed that aqueous extract of D. pleiantha rhizome has potential to reduce chloroauric ions into gold nanoparticles and the synthesized gold nanoparticles were showed spherical in shape with an average of 127nm. Further, we investigated the anti-metastatic activity of biosynthesized gold nanoparticles against human fibrosarcoma cancer cell line HT-1080. The results showed that the biosynthesized gold nanoparticles were non-toxic to cell proliferation and, also it can inhibit the chemo-attractant cell migration of human fibrosarcoma cancer cell line HT-1080 by interfering the actin polymerization pathway. Thus, the usage of gold nanoparticles biosynthesized from D. pleiantha rhizome can be used as a potential candidate in the drug and gene delivery to metastatic cancer.Colloids and surfaces B: Biointerfaces 04/2013; 110C:163-170. DOI:10.1016/j.colsurfb.2013.04.037 · 4.29 Impact Factor