Secretoglobins: Lacrimal Gland-Specific Rabbit Lipophilin mRNAs

RNAs encoding secretoglobin subunits, also known as lipophilins, are found in rabbit lacrimal glands. Some secretoglobins in other species are tissue- and/or sex-specific, whereas other secretoglobins are expressed in a variety of tissues of both sexes. In this study the tissue-specific and sexual dimorphic expression patterns of rabbit lacrimal gland lipophilins AL, AL2, BL, CL, and CL2 were determined. RNAs from male and female rabbit lacrimal glands were compared in a differential display analysis, and a new rabbit lacrimal gland secretoglobin, lipophilin AL2, was identified. Next, RNAs from male and female rabbit harderian, lacrimal, mandibular, sublingual, and parotid glands and from liver, kidney, pancreas, testis (male), ovary, and mammary gland (female) were isolated, electrophoresed in agarose gels, and transferred to nylon membranes. cDNA probes encoding the lipophilins AL, AL2, BL, and CL/CL2 were hybridized to the RNA in the blots. Rabbit mRNAs encoding the lipophilins AL, AL2, BL, CL, and CL2 were detected only in the lacrimal gland. Lipophilin AL2 mRNA was detected only in male rabbit lacrimal gland. In the rabbit, several lipophilins were expressed only in the lacrimal gland.