Spermiogenesis initiation in Caenorhabditis elegans involves a casein kinase 1 encoded by the spe-6 gene.
Immature spermatids from Caenorhabditis elegans are stimulated by an external activation signal to reorganize their membranes and cytoskeleton to form crawling spermatozoa. This rapid maturation, termed spermiogenesis, occurs without any new gene expression. To better understand this signal transduction pathway, we isolated suppressors of a mutation in the spe-27 gene, which is part of the pathway. The suppressors bypass the requirement for spe-27, as well as three other genes that act in this pathway, spe-8, spe-12, and spe-29. Eighteen of the suppressor mutations are new alleles of spe-6, a previously identified gene required for an early stage of spermatogenesis. The original spe-6 mutations are loss-of-function alleles that prevent major sperm protein (MSP) assembly in the fibrous bodies of spermatocytes and arrest development in meiosis. We have isolated the spe-6 gene and find that it encodes a predicted protein-serine/threonine kinase in the casein kinase 1 family. The suppressor mutations appear to be reduction-of-function alleles. We propose a model whereby SPE-6, in addition to its early role in spermatocyte development, inhibits spermiogenesis until the activation signal is received. The activation signal is transduced through SPE-8, SPE-12, SPE-27, and SPE-29 to relieve SPE-6 repression, thus triggering the formation of crawling spermatozoa.
Muhlrad
Paul J
PJ
Department of Molecular and Cellular Biology, The University of Arizona, Tucson, Arizona 85721, USA.
Ward
Samuel
S
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017173:Caenorhabditis elegans / Q000166:cytology / Q000201:enzymology / Q000235:genetics*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics; D047388:Casein Kinases; D002874:Chromosome Mapping; D018509:DNA, Helminth; D005786:Gene Expression Regulation; D008297:Male; D008969:Molecular Sequence Data; D009154:Mutation; D011494:Protein Kinases / Q000235:genetics*; D017434:Protein Structure, Tertiary; D015398:Signal Transduction; D013091:Spermatogenesis / Q000235:genetics*; D013489:Suppression, Genetic; D013737:Testis / Q000648:ultrastructure
D029742:Caenorhabditis elegans Proteins; D018509:DNA, Helminth; D011494:Protein Kinases; D047388:Casein Kinases