Conservation of the sizes for one but not another class of exons in two chick collagen genes

Type III collagen is often found in the same tissues as type I collagen, yet the function and nature of the fibrils formed by the two collagens differ markedly. To understand the evolutionary history of the collagen gene family in more detail, we isolated the gene for type III collagen and compared its structure with that of the gene for alpha 2(I) collagen. This comparison points to a remarkable conservation in the size distribution of the exons coding for the helical part of these two collagen polypeptides: equivalent amino acid segments in the helical domain of each polypeptide are encoded by exons of equal sizes in each gene. This suggests that after the interstitial collagen genes had been duplicated from a common ancestor about 2-5 X 10(8) years ago, no recombinations between these exons were tolerated, although the same recombinational phenomena must have played an important part in shaping the structure of the progenitor for these genes. This fixation of the size distribution of the exons which code for the interstitial collagen helical domains is found despite the persistence in these exons of sequence elements that should have favoured recombinational rearrangements, and contrasts with the variations in the pattern of sizes of some exons coding for the amino and carboxyl propeptides of these collagens.     

High-throughput oncogene mutation profiling in human cancer

Systematic efforts are underway to decipher the genetic changes associated with tumor initiation and progression. However, widespread clinical application of this information is hampered by an inability to identify critical genetic events across the spectrum of human tumors with adequate sensitivity and scalability. Here, we have adapted high-throughput genotyping to query 238 known oncogene mutations across 1,000 human tumor samples. This approach established robust mutation distributions spanning 17 cancer types. Of 17 oncogenes analyzed, we found 14 to be mutated at least once, and 298 (30%) samples carried at least one mutation. Moreover, we identified previously unrecognized oncogene mutations in several tumor types and observed an unexpectedly high number of co-occurring mutations. These results offer a new dimension in tumor genetics, where mutations involving multiple cancer genes may be interrogated simultaneously and in 'real time' to guide cancer classification and rational therapeutic intervention.     

Inhibition of Rho-associated kinase relieves C5a-induced proteinuria in murine nephrotic syndrome

Childhood nephrotic syndrome is mainly caused by minimal change disease which is named because only subtle ultrastructural alteration could be observed at electron microscopic level in the pathological kidney. Glomerular podocytes are presumed to be the target cells whose protein sieving capability is compromised by a yet unidentified permeability perturbing factor. In a cohort of children with non-hereditary idiopathic nephrotic syndrome, we found the complement fragment C5a was elevated in their sera during active disease. Administration of recombinant C5a induced profound proteinuria and minimal change nephrotic syndrome in mice. Purified glomerular endothelial cells, instead of podocytes, were demonstrated to be responsible for the proteinuric effect elicited by C5a. Further studies depicted a signaling pathway involving Rho/Rho-associated kinase/myosin activation leading to endothelial cell contraction and cell adhesion complex breakdown. Significantly, application of Rho-associated kinase inhibitor, Y27632, prevented the protein leaking effects observed in both C5a-treated purified endothelial cells and mice. Taken together, our study identifies a previously unknown mechanism underlying nephrotic syndrome and provides a new insight toward identifying Rho-associated kinase inhibition as an alternative therapeutic option for nephrotic syndrome.