Expression of integrin alpha v beta 3 in pig, dog and cattle

The alphav beta3 integrin, also known as vitronectin receptor, is an adhesi ve glycoprotein that promotes angiogenesis in the embryo and tumors such as melanoma. Integrin alphav beta3 is one of the receptors for adenovirus and hantavirus. There is little information on the constitutive expression of this integrin especially in animal species that are used for biomedical res earch. We used light and electron microscope immunocytochemistry and wester n blots to determine integrin alphav beta3 expression in seven organs in th e pig, dog and cattle. Immunohistology showed the integrin expression on th e epithelium of small intestine, bile duct and renal proximal convoluted tu bules in three species. The airway epithelium revealed a weak reaction for integrin alphav beta3. Skin showed the integrin in occasional extravascular cells while skeletal muscles were negative. The integrin was expressed onl y in bronchial vasculature in the lung and occasional dermal microvessels. Many mononuclear cells in the lung and spleen stained for integrin alphav b eta3. Immunogold electron microscopy revealed the expression on the epithel ium but not on the vasculature of the small intestine. Western blots detect ed integrin alphav beta3 in small intestine and lung but not in skeletal mu scles. We conclude the integrin is expressed on the epithelium but not in t he vasculature. The expression differs strikingly among organs in the same species although the inter-species differences are minor. Restriction of th e integrin to absorptive epithelia of small intestine and kidney may sugges t its putative role in endocytosis. Because the integrin is a receptor for adenovirus, these data may be relevant to gene therapy studies.