Biomedical subjects

Huub Jorna

Publications and source records attributed to Huub Jorna.

5 recordsLinked to original sources

PubMed2006

Spontaneous rescue from cystic fibrosis in a mouse model.

BACKGROUND: From the original CftrTgH(neoim)Hgu mutant mouse model with a divergent genetic background (129P2, C57BL/6, MF1) we have generated two inbred CftrTgH(neoim)Hgu mutant strains named CF/1-CftrTgH(neoim)Hgu and CF/3-CftrTgH(neoim)Hgu, which are fertile and show normal growth and lifespan. Initial genome wide scan analysis with microsatellite markers indicated that the two inbred strains differed on the genetic level. In order to further investigate whether these genetic differences have an impact on the disease phenotype of cystic fibrosis we characterised the phenotype of the two inbred strains. RESULTS: Reduced amounts, compared to wild type control animals, of correctly spliced Cftr mRNA were detected in the nasal epithelia, lungs and the intestine of both inbred CftrTgH(neoim)Hgu strains, with higher residual amount observed for CF/1-CftrTgH(neoim)Hgu than CF/3-CftrTgH(neoim)Hgu for every investigated tissue. Accordingly the amounts of wild type Cftr protein in the intestine were 9% for CF/1-CftrTgH(neoim)Hgu and 4% for CF/3-CftrTgH(neoim)Hgu. Unlike the apparent strain and/or tissue specific regulation of Cftr mRNA splicing, short circuit current measurements in the respiratory and intestinal epithelium revealed that both strains have ameliorated the basic defect of cystic fibrosis with a presentation of a normal electrophysiology in both tissues. CONCLUSION: Unlike the outbred CftrTgH(neoim)Hgu insertional mouse model, which displayed the electrophysiological defect in the gastrointestinal and respiratory tracts characteristic of cystic fibrosis, both inbred CftrTgH(neoim)Hgu strains have ameliorated the electrophysiological defect. On the basis of these findings both CF/1-CftrTgH(neoim)Hgu and CF/3-CftrTgH(neoim)Hgu offer an excellent model whereby determination of the minimal levels of protein required for the restoration of the basic defect of cystic fibrosis can be studied, along with the modulating factors which may affect this outcome.

Animals↗

PubMed2006

Rescue of functional delF508-CFTR channels in cystic fibrosis epithelial cells by the alpha-glucosidase inhibitor miglustat.

In the disease cystic fibrosis (CF), the most common mutation delF508 results in endoplasmic reticulum retention of misfolded CF gene proteins (CFTR). We show that the alpha-1,2-glucosidase inhibitor miglustat (N-butyldeoxynojirimycin, NB-DNJ) prevents delF508-CFTR/calnexin interaction and restores cAMP-activated chloride current in epithelial CF cells. Moreover, miglustat rescues a mature and functional delF508-CFTR in the intestinal crypts of ileal mucosa from delF508 mice. Since miglustat is an orally active orphan drug (Zavesca) prescribed for the treatment of Gaucher disease, our findings provide the basis for future clinical evaluation of miglustat in CF patients.

1-Deoxynojirimycin↗

PubMed2005

Activation of CFTR by ASBT-mediated bile salt absorption.

In cholangiocytes, bile salt (BS) uptake via the apical sodium-dependent bile acid transporter (ASBT) may evoke ductular flow by enhancing cAMP-mediated signaling to the cystic fibrosis transmembrane conductance regulator (CFTR) anion channel. We considered that ASBT-mediated BS uptake in the distal ileum might also modulate intestinal fluid secretion. Taurocholate (TC) induced a biphasic rise in the short circuit current across ileal tissue, reflecting transepithelial electrogenic ion transport. This response was sensitive to bumetanide and largely abrogated in Cftr-null mice, indicating that it predominantly reflects CFTR-mediated Cl- secretion. The residual response in Cftr-null mice could be attributed to electrogenic ASBT activity, as it matched the TC-coupled absorptive Na+ flux. TC-evoked Cl- secretion required ASBT-mediated TC uptake, because it was blocked by a selective ASBT inhibitor and was restricted to the distal ileum. Suppression of neurotransmitter or prostaglandin release, blocking of the histamine H1 receptor, or pretreatment with 5-hydroxytryptamine did not abrogate the TC response, suggesting that neurocrine or immune mediators of Cl- secretion are not involved. Responses to TC were retained after carbachol treatment and after permeabilization of the basolateral membrane with nystatin, indicating that BS modulate CFTR channel gating rather than the driving force for Cl- exit. TC-induced Cl- secretion was maintained in cGMP-dependent protein kinase II-deficient mice and only partially inhibited by the cAMP-dependent protein kinase inhibitor H89, suggesting a mechanism of CFTR activation different from cAMP or cGMP signaling. We conclude that active BS absorption in the ileum triggers CFTR activation and, consequently, local salt and water secretion, which may serve to prevent intestinal obstruction in the postprandial state.

Absorption↗

PubMed2004

Immunohistochemistry of CFTR in native tissues and primary epithelial cell cultures.

Studies on CFTR protein expression and localization in native tissues or in primary cultures of human epithelial cells are scarce due to the intrinsic instability of this protein, its low expression in most tissues and also to technical difficulties. However, such data are of the highest importance to understand the pathophysiology of CF. The purpose of this article is to outline several assays for the characterization of primary epithelial cultures and to review different CFTR immunostaining protocols.

Cell Culture Techniques↗

PubMed2004

Biochemical methods to assess CFTR expression and membrane localization.

Detection of cystic fibrosis transmembrane conductance regulator (CFTR) protein is usually a difficult task to accomplish due to the low levels of expression and high turnover that this membrane protein is submitted to in the cell. Common biochemical methods can be used for the detection of CFTR but several critical points must be taken into account. The scope of this article is to outline biochemical methods commonly used to assess CFTR expression, processing and membrane localization.

Biotinylation↗