Hello researchers,

            I am Today's presenter, Fumitaka Kubota, coming to you from Gunma University Graduate School of Medicine in a beautiful city of Maebashi in central Japan. I am going to make a brief introduction to our paper entitled “Cadherin-6 is required for zebrafish nephrogenesis during early development” which appeared in “International Journal of Developmental Biology” 2007.

            Cadherins are the molecules responsible for calcium-dependent isophilic cell-to-cell adhesions. They are required for different developmental processes including cell segregation, domain establishment, tissue organization and neurite path finding. Cadherins make a large group of related molecules called cadherin superfamily.

            Cadherin-6 is a member of Type II classic cadherin also known as K-cadherin or kidney cadherin. It is expressed in developing kidney and in renal cancer cells. Cadherin-6 is shared by different vertebrates including human, mouse, chicken and Xenopus.

            We cloned a zebrafish version of cadherin-6, and made its functional analyses in kidney development. Our in situ hybridization showed that cadherin-6 was expressed in the rostral part of pronephros, including glomeruli and pronephric tubules in zebrafish embryos. It was also expressed in some parts of the central nervous systems and the digestive system primordia as shown in previous literatures.

            When we knocked down cadherin-6 by injecting anti-sense Morpholino to one-cell embryos, many of the embryos showed a variety of malformations as small head, small eyes, and bent tail. By 42 hours post fertilization, edema in the body cavities had developed in many of the affected embryos. We then supposed that the edema was caused by disturbed renal function. So we studied histological changes in renal primordia in the knocked down embryos using renal markers, Pax2.1 and Wt1.

            As we expected, Morpholino-injected embryos had disturbed pronephros, including malformed glomeruli, disarranged tubules and constricted pronephric ducts. Renal epithelia showed disorganized arrangements. These effects of Morpholino were successfully rescued by co-injection of synthetic RNA of cadherin-6.

            Based on the results, we concluded that, cadherin-6 plays a pivotal role in zebrafish nephrogenesis. It is known that, cadherin-17 is involved in the development of the distal part of pronephric ducts and cloaca. We are now interested in differential or mutual involvement of these cadherins in renal developments.

            This talk was presented by Fumitaka Kubota from Gunma University Graduate School of Medicine, in Maebashi, Gunma, Japan, recorded January 2007. Thank you very much.