Expression of β1 integrin receptors during rat pancreas development -: Sites and dynamics

The integrin receptors link to extracellular matrix proteins and exert a dynamic role in development by providing the physical basis for cell adhesion and controlling cell growth. In the present study, we examined changes in the expression of beta 1 integrins and its associated alpha-subunits to islet cell development in the rat pancreas. A significant increase in protein expression of integrin alpha 3, alpha 6, and beta 1 was observed from fetal to postnatal life. High mRNA levels of these integrin subunits was detected at embryonic d 18 and dropped significantly after birth with relatively low expression throughout postnatal life. Integrins alpha 3, alpha 5, alpha 6, and beta 1 were expressed in a cell-specific manner in the pancreas with high integrin immunoreactivity in duct and islet regions during fetal life, and a progressive increase later into postnatal life. The coexpression with islet and putative islet precursor markers during fetal and postnatal development suggest a role for these integrin subunits in differentiation and maturation of islets. Functional studies in vitro showed that anti-beta 1 antibody treatment inhibited islet cell adhesion to extracellular matrices and disrupted islet architecture. Blockade of beta 1 integrin receptor and knockdown beta 1 mRNA resulted in a decrease in the expression of insulin mRNA and increased islet cell death. These results suggest that progression in islet cell development is accompanied by and dependent upon cell adhesion via beta 1 integrin and its respective alpha-subunits and suggest that the beta 1 family of integrins may play a critical role in islet cell architecture, development, integrity, and function.