Mislocalization of delta F508 CFTR in cystic fibrosis sweat gland.

Misprocessing and mislocalization of the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) has been described for the major CF-causing mutation (delta F508) in heterologous expression systems in vitro. We have generated monoclonal antibodies (mAbs) to CFTR with the aim of localizing the protein and its CF variants in vivo. Of the tissues where CFTR was observed, only the sweat gland is readily available and does not undergo secondary changes due to CF disease pathology. Sweat ducts from CF patients homozygous for delta F508 did not show the typical apical membrane staining seen in control biopsies. This demonstrates that the biosynthetic arrest and intracellular retention of delta F508 CFTR initially observed in vitro does occur in vivo and emphasizes the need to focus efforts on understanding the mislocalization.     

Correlation between ovarian growth,vitellogenin titer,and yolk polypeptide pattern in the haemolymph ofCalliphora vicina

Summary During the first egg maturation cycle ofCalliphora vicina changes in the vitellogenin titer and yolk polypeptide pattern of the haemolymph are correlated with the intensity of follicular growth, and the rate of yolk deposition.Acknowledgments. Support from The Danish Natural Science Research Council (grant: 11-0423) and access to facilities at the laboratory of Dr Bente L. Hansen (Institute of Medical Microbiology) is gratefully acknowledged.     

The accumulation pattern of ingested gossypol in selected organs of the rat

Summary Bound gossypol levels in the spleen and kidney of rats ingesting dietary gossypol (0.98%) varied directly with the feeding intervals of 6,14, 28 and 35 days. Free gossypol level in the kidney, spleen and lungs increased for 14 days and then tended to decrease as the feeding period was extended.     

VEGFR1-positive haematopoietic bone marrow progenitors initiate the pre-metastatic niche

The cellular and molecular mechanisms by which a tumour cell undergoes metastasis to a predetermined location are largely unknown. Here we demonstrate that bone marrow-derived haematopoietic progenitor cells that express vascular endothelial growth factor receptor 1 (VEGFR1; also known as Flt1) home to tumour-specific pre-metastatic sites and form cellular clusters before the arrival of tumour cells. Preventing VEGFR1 function using antibodies or by the removal of VEGFR1(+) cells from the bone marrow of wild-type mice abrogates the formation of these pre-metastatic clusters and prevents tumour metastasis, whereas reconstitution with selected Id3 (inhibitor of differentiation 3)-competent VEGFR1+ cells establishes cluster formation and tumour metastasis in Id3 knockout mice. We also show that VEGFR1+ cells express VLA-4 (also known as integrin alpha4beta1), and that tumour-specific growth factors upregulate fibronectin--a VLA-4 ligand--in resident fibroblasts, providing a permissive niche for incoming tumour cells. Conditioned media obtained from distinct tumour types with unique patterns of metastatic spread redirected fibronectin expression and cluster formation, thereby transforming the metastatic profile. These findings demonstrate a requirement for VEGFR1+ haematopoietic progenitors in the regulation of metastasis, and suggest that expression patterns of fibronectin and VEGFR1+VLA-4+ clusters dictate organ-specific tumour spread.     

Investigating metal-binding in proteins by nuclear magnetic resonance

Metal ions play a key role for the function of many proteins. The interaction of the metal ion with the protein and its involvement in the function of the protein vary widely. In some proteins, the metal ion is bound tightly to the ligand residues and may be the key player in the function of the protein, as in the case of blue copper proteins. In other proteins, the metal ion is bound only temporarily and loosely to the protein, as in the case of some metalloenzymes and other proteins where the metal ion acts as a cofactor necessary for the function of the protein. Such proteins are often known as metal ion-activated proteins. The review focuses on recent nuclear magnetic resonance (NMR) studies of a series of metal-dependent proteins and the characterization of the metal-binding sites. In particular, we focus on NMR techniques for studying metal binding to proteins such as chemical shift mapping, paramagnetic NMR and changes in backbone dynamics upon metal binding. Received 12 October 2006; received after revision 30 November 2006; accepted 5 February 2007