| 1. |
- Hinojosa-Kurtzberg, A Marina, et al.
(författare)
-
Novel MUC1 splice variants contribute to mucin overexpression in CFTR-deficient mice.
- 2003
-
Ingår i: American journal of physiology. Gastrointestinal and liver physiology. - : American Physiological Society. - 0193-1857 .- 1522-1547. ; 284:5
-
Tidskriftsartikel (refereegranskat)abstract
- A cystic fibrosis (CF) mouse expressing the human mucin MUC1 transgene (CFM) reverted the CF/Muc1(-/-) phenotype (little mucus accumulated in the intestine) to that of CF mice expressing mouse Muc1, which exhibited increased mucus accumulation. Western blots and immunohistochemical analysis showed that the MUC1 protein was markedly increased in CFM mice in which it was both membrane bound and secreted into the intestinal lumen. Studies to determine the reason for increased levels of the extracellular domain of MUC1 mucin identified mRNA and protein of two novel splice variants and the previously described secreted MUC1 lacking the cytoplasmic tail (MUC1/SEC). Novel MUC1 splice variants, CT80 and CT58, were both transmembrane proteins with cytoplasmic tails different from the normal MUC1. The MUC1-CT80 and MUC1/SEC forms are found expressed mainly in the CFM mice intestines. Thus MUC1 expression is increased, and it appears that alternate cytoplasmic tails may change its role in signaling. MUC1 could be an important contributor to the CF intestinal phenotype.
|
|
| 2. |
- Malmberg, Emily, 1978, et al.
(författare)
-
Increased levels of mucins in the cystic fibrosis mouse small intestine, and modulator effects of the Muc1 mucin expression.
- 2006
-
Ingår i: American journal of physiology. Gastrointestinal and liver physiology. - : American Physiological Society. - 0193-1857 .- 1522-1547. ; 291:2
-
Tidskriftsartikel (refereegranskat)abstract
- The mouse model (Cftr(tm1UNC)/Cftr(tm1UNC)) for cystic fibrosis (CF) shows mucus accumulation and increased Muc1 mucin mRNA levels due to altered splicing (Hinojosa-Kurtzberg AM, Johansson MEV, Madsen CS, Hansson GC, and Gendler SJ. Am J Physiol Gastrointest Liver Physiol 284: G853-G862, 2003). However, it is not known whether Muc1 is a major mucin contributing to the increased mucus and why CF/Muc1-/- mice show lower mucus accumulation. To address this, we have purified mucins from the small intestine of CF mice using guanidinium chloride extraction, ultracentrifugation, and gel filtration and analyzed them by slot blot, gel electrophoresis, proteomics, and immunoblotting. Normal and CF mice with wild-type (WT) Muc1 or Muc1-/- or that are transgenic for human MUC1 (MUC1.Tg, on a Muc1-/- background) were analyzed. The total amount of mucins, both soluble and insoluble in guanidinium chloride, increased up to 10-fold in the CF mice compared with non-CF animals, whereas the CF mice lacking Muc1 showed intermediate levels between the CF and non-CF mice. However, the levels of Muc3 (orthologue of human MUC17) were increased in the CF/Muc1-/- mice compared with the CF/MUC1.Tg animals. The amount of MUC1 mucin was increased several magnitudes in the CF mice, but MUC1 did still not appear to be a major mucin. The amount of insoluble mucus of the large intestine was also increased in the CF mice, an effect that was partially restored in the CF/Muc1-/- mice. The thickness of the firmly adherent mucus layer of colon in the Muc1-/- mice was significantly lower than that of WT mice. The results suggest that MUC1 is not a major component in the accumulated mucus of CF mice and that MUC1 can influence the amount of other mucins in a still unknown way.
|
|
| 3. |
- Thomsson, Kristina A, 1969, et al.
(författare)
-
Intestinal mucins from cystic fibrosis mice show increased fucosylation due to an induced Fucalpha1-2 glycosyltransferase.
- 2002
-
Ingår i: The Biochemical journal. - 0264-6021. ; 367:Pt 3, s. 609-16
-
Tidskriftsartikel (refereegranskat)abstract
- In gene-targeted mouse models for cystic fibrosis (CF), the disease is mainly manifested by mucus obstruction in the intestine. To explore the mucus composition, mucins insoluble and soluble in 6 M guanidinium chloride were purified by three rounds of isopycnic ultracentrifugation from the small and large intestines of CF mice (Cftr(m1UNC)/Cftr(m1UNC)) and compared with wild-type mice. The amino acid composition was typical of that for mucins and showed increased amounts of the insoluble (2.5-fold increase) and soluble (7-fold increase) mucins in the small intestine of the CF mice compared with wild-type mice. Mucins from the large intestine of both wild-type and CF mice showed a high but constant level of fucosylation. In contrast, the insoluble and soluble mucins of the small intestine in CF mice revealed a large increase in fucose, whereas those of wild-type mice contained only small amounts of fucose. This increased fucosylation was analysed by releasing the O-linked oligosaccharides followed by GC-MS. NMR spectroscopy revealed that the increased fucosylation was due to an increased expression of blood group H epitopes (Fucalpha1-2Gal-). Northern-blot analysis, using a probe for the murine Fucalpha1-2 fucosyltransferase (Fut2), showed an up-regulation of this mRNA in the small intestine of the CF mice, suggesting that this enzyme is responsible for the observed increase in blood group H-type glycosylation. The reason for this up-regulation could be a direct or indirect effect of a non-functional CF transmembrane conductance regulator (CFTR) caused by the absence of CFTR channel.
|
|
