Interference RNA for in vivo Knock-down of gene expression or genome-wide screening using shRNA.

With the lack of tools available to manipulate the rat genome, alternative technologies have been investigated to generate loss-of-function rat models by gene invalidation. The recent demonstration that RNA interference (RNAi)-mediated gene silencing occurs in rodents has opened new opportunities for rat functional genetics. In this chapter, we provide some practical guidelines for RNAi working in rat, based on the recent design and development of mice and rat Knock down models.

A novel four transmembrane spanning protein, CLP24. A hypoxically regulated cell junction protein.

A novel hypoxically regulated intercellular junction protein (claudin-like protein of 24 kDa, CLP24) has been identified that shows homology to the myelin protein 22/epithelial membrane protein 1/claudin family of cell junction proteins, which are involved in the modulation of paracellular permeability. The CLP24 protein contains four predicted transmembrane domains and a C-terminal protein-protein interaction domain. These domains are characteristic of the four transmembrane spanning (tetraspan) family of proteins, which includes myelin protein 22, and are involved in cell adhesion at tight, gap and adherens junctions. Expression profiling analyses show that CLP24 is highly expressed in lung, heart, kidney and placental tissues. Cellular studies confirm that the CLP24 protein localizes to cell-cell junctions and co-localizes with the beta-catenin adherens junction-associated protein but not with tight junctions. Over-expression of CLP24 results in decreased adhesion between cells, and functional paracellular flux studies confirm that over-expression of the CLP24 protein modulates the junctional barrier function. These data therefore suggest that CLP24 is a novel, hypoxically regulated tetraspan adherens junction protein that modulates cell adhesion, paracellular permeability and angiogenesis.