Active cell aggregation by immature rat Sertoli cells in primary culture: a role for cell surface glycoproteins.

Follicle stimulating hormone (FSH) stimulates “colony formation” by immature rat Sertoli cells in primary culture. “Colony formation” involves cell aggregation. Consequently, the involvement of cell surface glycoproteins in cell aggregation was investigated by treatment of dissociated 10-day rat testis cells with sodium metaperiodate, glucosamine, various lectins, tunicamycin, and puromycin. Treatment of control cultures with 5 μM glucosamine stimulated cell aggregation; however, glucosamine did not affect FSH-stimulated cultures. Treatment of dissociated testis cells with 5 μM sodium metaperiodate, 10 μg/ml castor bean agglutinin (ricin), or 2.5 μg/ml horseshoe crab agglutinin inhibited FSH stimulation of cell aggregation. A similar inhibition of cell aggregation was observed following addition of 10 μg/ml puromycin or tunicamycin to culture media from 0- to 18-hours incubation. Treatment with soybean agglutinin, concanavalin A, or wheat germ agglutinin had no effect. The galactose-specific lectins, Ricin, Ricinus communis agglutinin I, and Bendeirea simplicifolia agglutinin, inhibit the FSH stimulation of ³H-aminoacid incorporation as well as cell aggregation in 24-hour cultres. The inhibition of cell aggregation by sodium metaperiodate treatment was reversed with 5 μM sodium borohydride reduction. Sodium metaperiodate treatment did not alter cell viability (as assayed with trypan blue dye exclusion), did not alter cell attachment, nor significantly decrease ¹²⁵I-FSH binding by cultured testis cells. The results suggest that FSH stimulation of cell aggregation by immature rat Sertoli cells requires cell surface glycoprotein interactions. Furthermore, the specificity of lectin inhibition suggests that glycoproteins with terminal galactose and sialic acid residues are required for the FSH induction of cell aggregation.