Correlation Between PTEN and VEGF Expressions During the Development of Gas Gland in Japanese Eel (Anguilla japonica) Stimulated by Exogenous Hypophyseal Factors

Organogenesis requires support of the vascular system and control of proliferation activity. VEGF, a selective mitogen for vascular endothelial cells, is important for vessel development. PTEN, known as a tumor suppressor, regu- lates cell size and modulates VEGF-mediated signaling on angiogenesis. However, it is not yet clear if PTEN controls tis- sue mass by suppressing angiogenesis provoked by VEGF and their correlations in postnatal tissue development in vivo. We used a primitive vertebrate, Japanese eel (Anguilla japonica), to study this question. Swim bladder gas glands (a so- matic tissue composed mainly by the capillaries) from normal eels or eels injected with hypophyseal factors were used to examine the expression of VEGF A, PTEN, IGF-1, and Flk-1 by RT-PCR. Two forms of PTEN (PTEN a, long form, and PTEN b, short form) cDNA have been cloned. There was no correlation between VEGF expression and gas gland tissue mass while a negative correlation between PTEN expression and tissue mass was noted; further, a higher correlation be- tween the tissue mass and the ratio of VEGF to PTEN was shown. In summary, we have shown the involvement of VEGF and PTEN in postnatal tissue development, the ratio of VEGF to PTEN may represent the growth status of the tissue.