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Chuanqing Ding, Ying Liu, Michael Lu; Connexin 26 And 32 Are Found In The Rabbit Lacrimal Acinar and Duct Cells. Invest. Ophthalmol. Vis. Sci. 2011;52(14):3717.
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Gap junctions are composed of connexins, and play important roles in intercellular communications, such as signal propagation, electrolyte and water transport. Although the roles of connexins and gap junctions have been extensively studied in other organs/tissues, there were very few studies have investigated their roles in lacrimal gland (LG). Therefore, the aim of the present study is to investigate the expression of connexins in the rabbit LG.
Total RNA was extracted from whole LGs of adult female rabbit. Total RNA was then reverse transcribed and PCR reactions performed on MyCycler (Bio-Rad). Primers were designed from multiple predicted and published rabbit gene sequences with PRIMER-BLAST designing tool, and synthesized by commercial vendor. Products were electrophoresed on 1.2% agarose gel containing 10 µg/ml ethidium bromide and the gels were photographed on a UV transilluminator. Immunofluorescence was performed using frozen LG sections at 10 µm. Mouse monoclonal anti-connexin 26 (Cx26) was purchased from Invitrogen, dilution at 1:200; and goat polyclonal anti-connexin (Cx32) from Santa Cruz Biotechnology, dilution at 1:100. Slides were analyzed by using a Zeiss LSM 510 confocal scanning microscope.
By using β-actin as positive control, RT-PCR demonstrated the presence of mRNAs of Cx26 and Cx32 as distinctive bands corresponding to their specific base pairs in the rabbit LG. Immunofluorescence showed that Cx26 immunoreactivity appeared to be present only in the duct cells, as punctate stainings. Virtually no or minimal Cx26 immunoreactivity was found in acinar cells. This was in contrast to previous observation in mouse LG, which showed no Cx26 immunoreactivity in duct cells (Walcott et al, 2002). Cx32 immunoreactivity was also present as punctate staining, and was mostly on the basolateral membranes of every acinar cell as linear arrangements. These results were the first demonstration of the presence of Cx26 and Cx32 in rabbit LG.
Cx26 and Cx32, as building blocks of gap junctions, were found in the LGs of rabbit, and therefore may play important roles in lacrimal secretion and dysfunction, such as neural signal propagation and electrolyte transport among adjacent epithelial cells. The distinctive distribution patterns of these two connexins support our notion that the rabbit LG is a heterogenic gland where acinar and duct cells play different roles. The prominent presence of Cx26 in duct cells also suggests the important role lacrimal ducts may play in lacrimal function. More research into this important field is certainly warranted.
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