Research article

The role of Drosophila Merlin in spermatogenesis

Natalia V Dorogova¹ , Elena M Akhmametyeva² , Sergei A Kopyl¹ , Natalia V Gubanova¹ , Olga S Yudina¹ , Leonid V Omelyanchuk¹ and Long-Sheng Chang²

¹  Institute of Cytology and Genetics, Russian Academy of Sciences, Novosibirsk, Russia

²  Center for Childhood Cancer, Research Institute at Nationwide Children's Hospital and Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio, USA

author email corresponding author email

BMC Cell Biology 2008, 9:1doi:10.1186/1471-2121-9-1

Published:	10 January 2008

Abstract

Background

Drosophila Merlin, the homolog of the human Neurofibromatosis 2 (NF2) gene, is important for the regulation of cell proliferation and receptor endocytosis. Male flies carrying a Mer³ allele, a missense mutation (Met¹⁷⁷→Ile) in the Merlin gene, are viable but sterile; however, the cause of sterility is unknown.

Results

Testis examination reveals that hemizygous Mer³ mutant males have small seminal vesicles that contain only a few immotile sperm. By cytological and electron microscopy analyses of the Mer³, Mer⁴ (Gln¹⁷⁰→stop), and control testes at various stages of spermatogenesis, we show that Merlin mutations affect meiotic cytokinesis of spermatocytes, cyst polarization and nuclear shaping during spermatid elongation, and spermatid individualization. We also demonstrate that the lethality and sterility phenotype of the Mer⁴ mutant is rescued by the introduction of a wild-type Merlin gene. Immunostaining demonstrates that the Merlin protein is redistributed to the area associated with the microtubules of the central spindle in telophase and its staining is less in the region of the contractile ring during meiotic cytokinesis. At the onion stage, Merlin is concentrated in the Nebenkern of spermatids, and this mitochondrial localization is maintained throughout sperm formation. Also, Merlin exhibits punctate staining in the acrosomal region of mature sperm.

Conclusion

Merlin mutations affect spermatogenesis at multiple stages. The Merlin protein is dynamically redistributed during meiosis of spermatocytes and is concentrated in the Nebenkern of spermatids. Our results demonstrated for the first time the mitochondrial localization of Merlin and suggest that Merlin may play a role in mitochondria formation and function during spermatogenesis.