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- Bergö, Martin, 1970, et al.
(författare)
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Inactivation of Icmt inhibits transformation by oncogenic K-Ras and B-Raf
- 2004
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Ingår i: J Clin Invest. ; 113:4, s. 539-550
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Tidskriftsartikel (refereegranskat)abstract
- Isoprenylcysteine carboxyl methyltransferase (Icmt) methylates the carboxyl-terminal isoprenylcysteine of CAAX proteins (e.g., Ras and Rho proteins). In the case of the Ras proteins, carboxyl methylation is important for targeting of the proteins to the plasma membrane. We hypothesized that a knockout of Icmt would reduce the ability of cells to be transformed by K-Ras. Fibroblasts harboring a floxed Icmt allele and expressing activated K-Ras (K-Ras-Icmt(flx/flx)) were treated with Cre-adenovirus, producing K-Ras-Icmt(Delta/Delta) fibroblasts. Inactivation of Icmt inhibited cell growth and K-Ras-induced oncogenic transformation, both in soft agar assays and in a nude mice model. The inactivation of Icmt did not affect growth factor-stimulated phosphorylation of Erk1/2 or Akt1. However, levels of RhoA were greatly reduced as a consequence of accelerated protein turnover. In addition, there was a large Ras/Erk1/2-dependent increase in p21(Cip1), which was probably a consequence of the reduced levels of RhoA. Deletion of p21(Cip1) restored the ability of K-Ras-Icmt(Delta/Delta) fibroblasts to grow in soft agar. The effect of inactivating Icmt was not limited to the inhibition of K-Ras-induced transformation: inactivation of Icmt blocked transformation by an oncogenic form of B-Raf (V599E). These studies identify Icmt as a potential target for reducing the growth of K-Ras- and B-Raf-induced malignancies.
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| 2. |
- Bergö, Martin, 1970, et al.
(författare)
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On the physiological importance of endoproteolysis of CAAX proteins: heart-specific RCE1 knockout mice develop a lethal cardiomyopathy
- 2004
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Ingår i: J Biol Chem. ; 279:6, s. 4729-4736
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Tidskriftsartikel (refereegranskat)abstract
- Proteins terminating with a CAAX motif, such as the Ras proteins and the nuclear lamins, undergo post-translational modification of a C-terminal cysteine with an isoprenyl lipid via a process called protein prenylation. After prenylation, the last three residues of CAAX proteins are clipped off by Rce1, an integral membrane endoprotease of the endoplasmic reticulum. Prenylation is crucial to the function of many CAAX proteins, but the physiologic significance of endoproteolytic processing has remained obscure. To address this issue, we used Cre/loxP recombination techniques to create mice lacking Rce1 in the heart, an organ where Rce1 is expressed at particularly high levels. The hearts from heart-specific Rce1 knockout mice manifested reduced levels of both the Rce1 mRNA and CAAX endoprotease activity, and the hearts manifested an accumulation of CAAX protein substrates. The heart-specific Rce1 knockout mice initially appeared healthy but died starting at 3-5 months of age. By 10 months of age, approximately 70% of the mice had died. Pathological studies revealed that the heart-specific Rce1 knockout mice had a dilated cardiomyopathy. By contrast, liver-specific Rce1 knockout mice appeared healthy, had normal transaminase levels, and had normal liver histology. These studies indicate that the endoproteolytic processing of CAAX proteins is essential for cardiac function but is less important for the liver.
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| 3. |
- Ekbom, K, et al.
(författare)
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Age at onset and sex ratio in cluster headache: observations over three decades
- 2002
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Ingår i: Cephalalgia : an international journal of headache. - : SAGE Publications. - 0333-1024. ; 22:2, s. 94-100
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Tidskriftsartikel (refereegranskat)abstract
- Five hundred and fifty-four patients with episodic cluster headache (ECH) and chronic cluster headache (CCH) were examined between 1963 and 1997. Mean age at onset was significantly higher in women with CCH compared with women with ECH and in men with ECH or CCH. In women with CCH age at onset was evenly distributed from 10 to 69 years, whereas in men with CCH and in both sexes with ECH, there was a peak when they were in their 20s. In women with ECH a second peak of onset occurred in their 50s. Although not statistically significant, primary CCH started later in women (mean 50.8 years) than secondary CCH (mean 35.5 years). There was a significant variation in the male : female ratio with respect to age at onset, being largest between 30 and 49 years of age (ECH 7.2 : 1; CCH 11.0 : 1) and lowest after 50 (ECH 2.3 : 1; CCH 0.6 : 1). During the observation period of more than 30 years there was a trend towards a decreasing male preponderance; the male: female ratio was significantly higher among patients with onset before rather than after 1970. The proportion of episodic vs. chronic CH did not change during the study period. The nature of the sex- and age-related pattern of cluster headache onset remains to be elucidated but mechanisms associated with sex hormone regulation, perhaps of hypothalamic origin, may be involved, as well as environmental factors related to lifestyle.
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| 6. |
- Talebnia Rowshan, Farid, 1974, et al.
(författare)
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Physiological and morphological study of encapsulated Saccharomyces cerevisiae
- 2007
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Ingår i: Enzyme and Microbial Technology. - : Elsevier BV. - 0141-0229 .- 1879-0909. ; 41:6-7, s. 683-688
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Tidskriftsartikel (refereegranskat)abstract
- The impact of encapsulation on the anaerobic growth pattern of S. cerevisiae CBS 8066 in a defined synthetic medium over 20 consecutive batch cultivations was investigated. In this period, the ethanol yield increased from 0.43 to 0.46 g/g, while the biomass and glycerol yields decreased by 5 8 and 23%, respectively. The growth rate of the encapsulated cells in the first batch was 0.13 h(-1), but decreased gradually to 0.01 h(-1) within the 20 sequential batch cultivations. Total RNA content of these yeast cells decreased by 39% from 90.3 to 55 mg/g, while the total protein content decreased by 24% from 460 to 350 mg/g. On the other hand, the stored carbohydrates, that is, glycogen and trehalose content, increased by factors of 4.5 and 4 within 20 batch cultivations, respectively. Higher biomass concentrations inside capsules led to a lower glucose diffusion rate through the membrane, and volumetric mass transfer coefficient for glucose was drastically decreased from 6.28 to 1.24 (cm(3)/min) by continuing the experiments. Most of the encapsulated yeast existed in the form of single and non-budding cells after long-term application. (C) 2007 Elsevier Inc. All rights reserved.
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