Expression of RNAs for Calmodulin, Actins, and Tubulins in Rat Testis Cells1

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Abstract
Messenger RNAs encoding calmodulin, .alpha.- and .beta.-tubulins, and actins were analyzed in nucleic acid isolated from purified rat testis cell populations. Cell-specific patterns were discovered that suggest coordinate regulation of members of different gene families. Genes that are candidates for coordinate regulation include those encoding 1.4 kb calmodulin RNA and 1.8 kb .alpha.-tubulin RNAs; 1.6 kb calmodulin RNA and a 1.8 kb .beta.-tubulin RNa; and 1.6 kb actin and 2.1 kb .beta.-tubulin RNAs. The steady state level of the 2.2 kb actin RNA(s) varies less than any other RNA analyzed. Actin RNAs of approximately 1.6 kb are observed in fractions enriched for A spermatogonia or round spermatids or cytoplasts shed from elongating spermatids. The level of 1.8 kb .alpha.-tubulin RNA increases in a fraction enriched for leptotene-zygotene spermatocytes and peaks in pachytene spermatocytes. As the level of this .alpha.-tubulin RNA species decreases in maturing spermatids a new 2.1 kb .alpha.-tubulin RNA increases. .beta.-Tubulin RNAs of 2.7 and 1l8 kb are present in somatic and premeiotic cell fractions. .beta.-Tubulin RNA transcripts of 1.8 kb that increase in pachytene spermatocytes are derived from a different gene than that expressed in premeiotic cells. The major RNA that hybridizes to the chicken calmodulin cDNA is 1.4 kb; it increases during the development of spermatocytes, reaching a maximum level in pachytene spermatocytes before it declines during spermiogenesis. Calmodulin RNAs of 1.6 and 1.0 kb are clearly evident in the round spermatid fraction. These data reveal that mechanisms exist for cell-selective elevation of mRNAs encoding cytoskeletal proteins during rat spermatogenesis.