Characterizing the Role of Spegless, a Novel Inner Nuclear Membrane Protein required for spermatogenesis and oogenesis in Drosophila melanogaster

Fat is a large cadherin that plays a role in both tissue growth and planar cell polarity (PCP). How Fat regulates these cellular processes is not fully understood. A yeast two-hybrid screen previously identified proteins that can bind the cytoplasmic domain of Fat. Using genome-wide RNAi libraries of transgenic flies, I knocked down the function of each gene identified through the screen in the Drosophila eye. Through analysis of adult eye size and photoreceptor organization, several genes were identified as having possible roles in PCP or tissue growth. One gene, which I analyzed further, was a previously uncharacterized gene, CG9723, which I have named spegless (speg). When disrupted, speg had overgrowth phenotypes similar to Hpo pathway mutations in the eye. Speg is a multi-pass transmembrane protein with a conserved domain of unknown function that I have confirmed is an inner nuclear membrane protein. I generated a null allele of speg and subsequent in depth analysis of speg null mutants revealed that Speg is essential for the development of the testes and ovaries. In Drosophila, testes development is a complex process regulated by the interplay between germline stem cells and somatic (cyst) stem cells. Sperm develop in units called cysts and flies lacking speg had small testes that lacked proper cyst structure and cyst cell membrane markers. Speg is important in the cyst cells as cyst cell expression of Speg could largely rescue speg mutant phenotypes. speg mutant testes had fewer differentiated sperm cells and rarely produced late stage sperm. Speg mutants did not disrupt overall nuclear membrane structure. Also, speg mutant ovaries contained no germ cells. Thus, Speg is a novel, conserved, inner nuclear membrane protein with an essential role in the development of Drosophila testes and ovaries.

Department dc:contributor.department

Molecular and Medical Genetics

Year dc:date.issued

2014

Author dc:creator

• Rosenfeld, Robyn

Advisor dc:contributor.advisor

• McNeill, Helen

• Fat
• Germ cells
• Nuclear membrane
• Oogenesis
• Spermatogenesis

Handle dc:identifier.uri

http://hdl.handle.net/1807/98139

OAI identifier oai:identifier

oai:utoronto.scholaris.ca:1807/98139