Cellular distribution of parchorin, a chloride intracellular channel-related protein, in various tissues

The cellulardistribution of parchorin, a new chloride intracellular channel familymember, was investigated in rabbit tissues by immunohistochemistryusing an antibody recognizing the sequence containing aparchorin-specific repeat. Parchorin preferentially resides in theepithelium of the ducts of the lacrymal, parotid, submandibular, andmammary glands and the pancreas, prostate, and testis. In the tracheaand lung, parchorin was found in the airway epithelium and type IIalveolar cells. In the kidney, parchorin was distributed mainly fromthe thick ascending limb to the distal convoluted tubule. In the eye,both pigment and nonpigment epithelia of the ciliary body werepositive, whereas only the pigment epithelium was positive in theretina. Parchorin was also present in the cochlea and semicircularcanal. The amount of parchorin in the gastric mucosa, but not in thesubmandibular glands, increased after weaning. In the mammary gland,parchorin expression was greater in a lactating rabbit (1 wk afterdelivery) compared with a pregnant (3 wk) rabbit. The cellulardistribution and changes in expression indicate that parchorin plays animportant role, possibly in chloride transport, in the cells thatcreate an ion gradient for water movement.