Identification of antigenically related polypeptides at centrioles and basal bodies.

Abstract

An antigen localized at the centriolar region has been identified by indirect immunofluorescence studies in African green monkey kidney, human, hamster, rat, and mouse cells. The antigen consists of two polypeptides of 14,000 and 17,000 daltons. A related antigen is also present at the basal body region in ciliated cells from chicken, cat, mouse, pig, steer, and rabbit trachea and from rabbit fimbria. Immunoelectron microscopy shows that the immunoreactive antigen is indeed located in the region around the basal bodies of ciliated cat tracheal cells. Thus, we have found an antigen that is common to a variety of cell types from many different animal sources and is specifically associated with both centrioles and basal bodies. The possible role of the antigen in differentiation is discussed.Immunofluorescent staining at the centriolar region ofcells has been observed in several different systems by using both immune (1) and preimmune sera (2). The sera that give staining at the centriolar region also have been shown to stain the basal body regions of ciliated cells (1, 2). The centriolar staining by the above sera was observed as 0.2-to 0.9-,um granules, which appear in pairs near the interphase nuclei in most of the cells. Kasamatsu et al. (3,4) have shown similar staining at centriolar and basal body regions by using both preimmune and immune sera. However, they demonstrated the centriolar staining as a single 2-ntm structure at the centriolar region of TC7 cells at frequencies of only 15-20%. Thus, the sera in our studies seem to detect an antigen different from that described by others. The appearance of this antigen is stimulated up to a frequency of about 80% by simian virus 40 (SV40) infection (3). A wild-type SV40 small-tumor antigen gene function is required for the stimulation of this host antigen, and protein synthesis up to 5 hr after infection is essential (4). Two polypeptides with apparent molecular sizes of 14,000 and 17,000 daltons are detected on NaDodSOJpolyacrylamide gels (4). These two polypeptides were shown to be the antigens which give rise to the specific immunostaining because the immunoglobulin fraction that adsorbed to the TC7 14,000-to 17,000-dalton polypeptides also stained the centriolar and the basal body regions (4). We shall refer to the two immunoreactive polypeptides together as the centriolar antigen.Centrioles and basal bodies of ciliated cells are considered to be related based on structural similarities (for review, see refs. 5-7). A cultured cell normally possesses a pair ofcentrioles, whereas a differentiated ciliated epithelial cell may have several hundred basal bodies. During the differentiation to a multiciliated cell, the formation of cilia is preceded by the formation of the appropriate number of basal bodies, which then become arranged in rows beneath the cell surface. Each basal body gives rise to a single cilium. In cultured 3T3 cells, it has been shown that one centriole of the pair generates a primary cilium at a particular phase ofthe cell cycle (G1) (...

The centriolar antigen expression in TC7 cells is dependent on growth conditions and occurs at a particular time point in G1

“…In this regard, the serum-deprived TC7 cell population in culture may share the same physiological state with the in vivo differentiated cells. Yet in culture, many secondary cells, mostly fibroblasts, exhibited the Cagpositive staining with a very low incidence in the exponentially growing cells (Lin et al, 1981). The increase in the proportion of Cag-positive cells observed in TC7 cells, as described in this study, was not observed in NIH3T3 cells either during their growth cycle or after serum deprivation (unpublished result of P. Segarini).…”

“…We have observed that the Cag was always expressed at the basal body region in all multiciliated cells examined, of tracheal or ovarian origin, isolated from many animals (Lin et al, 1981). In this regard, the serum-deprived TC7 cell population in culture may share the same physiological state with the in vivo differentiated cells.…”

“…This incidence, however, increases to 60-80% within 20 hr after SV40 infection (Kasamatsu and Nehorayan, 1979;Kasamatsu et al, 1980;Lin et al, 1981). The syntheses of both RNA and protein, which occur early, 0 to 5 hr after viral infection, are essential for the stimulation of Cag (Kasamatsu et al, 1980;Shyamala et al, 1982).…”

“…We have tentatively named these polypeptides centriolar antigen (Cag), since in the multiciliated cells the antigen can be localized by electron microscopy to a region surrounding the basal bodies that are considered to be structurally identical to centrioles (Lin et al, 1981).…”

Ciliary dysfunction in polycystic kidney disease: an emerging model with polarizing potential

“…The basal body is integrated into the cytoskeleton through its projections of transitional fibers, basal foot processes, and bundles of thin filaments connecting it to the other centriole. Together, the basal body and centriole form a centrosome, which serve as the cell's main microtubule organizing center (118,119).…”