Spermiogenesis deficiency in mice lacking the Trf2 gene

The discovery of TATA-binding protein-related factors (TRFs) has suggested alternative mechanisms for gene-specific transcriptional regulation and rai sed interest in their biological functions. In contrast to recent observati ons of an embryonic Lethal phenotype for TRF2 inactivation in Caenorhabditi s elegans and Xenopus laevis, we found that Trf2-deficient mice are viable. However, Trf2(-/-) mice are sterile because of a severe defect in spermiog enesis. Postmeiotic round spermatids advance at most to step 7 of different iation but fail to progress to the elongated form, and gene-specific transc ription deficiencies were identified. We speculate that mammals may have ev olved more specialized TRF2 functions in the testis that involve transcript ional regulation of genes essential for spermiogenesis.