Distribution of cytoplasmic and axonemal dyneins in rat tissues

Microtubule-associated protein 1C (MAP 1C) is now defined as brain cytoplasmic dynein. Recent studies have suggested that cytoplasmic dynein is a motor protein responsible for the intracellular microtubule-based motility in neuronal and non-neuronal cells. We have prepared an antibody against bovine brain MAP 1C and have examined the localizations of cytoplasmic dynein in rat tissues. Immunoblots of extracts from the tissues showed that the dynein was present in brain, testis, liver, kidney and lung. Immunohistochemical experiments have demonstrated that dynein is localized in Purkinje cells of cerebellum and axons of central and peripheral nervous systems. In non-neuronal tissues, the antibody staining was intense in many types of cells, such as hepatocytes, epithelia of renal convoluted tubules, secretory cells of adrenal medulla and spermatids. Glomeruli of kidney, bronchial epithelia and type II pneumocytes of lung, pancreatic islets and acini, adrenal cortex and Sertoli cells were moderately positive upon exposure to the cytoplasmic dynein antibody. On the other hand, the localization of axonemal dynein was examined using antibodies against flagellar dynein of sea urchin spermatozoa. Anti-axonemal dynein labeled cilia and flagella in rat tissues whereas anti-MAP 1C did not stain axonemes. We also tested for immunological cross-reactivity between cytoplasmic and axonemal dyneins to probe for molecular similarities. Anti-axonemal dynein reacted with MAP 1C weakly. These results have confirmed that cytoplasmic dyneins are distributed widely among rat organs, not only in neuronal but also in non-neuronal tissues. There is no similarity in the localization of cytoplasmic and axonemal dyneins but there is some similarity in molecular antigenicity.