Molecular detection of lacrimal apparatus and ocular surface - related ABC transporter genes

The ocular system is in constant interaction with the environment and with numerous pathogens. The ATP-binding cassette (ABC) transporters represent one of the largest groups among the transmembrane proteins. Their relevance has been demonstrated for their defense function against biotic and abiotic stress factors, for metabolic processes in tumors and for their importance in the development of resistance to drugs. The aim of this study was to analyze which ABC transporters are expressed at the ocular surface and in the human lacrimal apparatus. Using RT-PCR, all ABC transporters known to date in humans were examined in tissue samples from human cornea, conjunctiva, meibomian glands and lacrimal glands. The RT-PCR analyses revealed the presence of all ABC transporters in the samples examined, although the results for some of the 48 transporters known in human and analyzed were different in the various tissues. The present results provide information on the expression of ABC transporters at the mRNA level on the ocular surface and in the lacrimal system. Their detection forms the basis for follow-up studies at the protein level, which will provide more information about their physiological significance at the ocular surface and in the lacrimal system and which may explain pathological effects such as drug resistance.