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Published on: October 13, 2018
Mice lacking FABP9/PERF15 develop sperm head abnormalities but are fertile
Vimal Selvaraj1, Atsushi Asano, Jennifer L Page
1Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA. vs88@cornell.edu
Abstract:
The male germ cell-specific fatty acid-binding protein 9 (FABP9/PERF15) is the major component of the murine sperm perforatorium and perinuclear theca. Based on its cytoskeletal association and sequence homology to myelin P2 (FABP8), it has been suggested that FABP9 tethers sperm membranes to the underlying cytoskeleton. Furthermore, its upregulation in apoptotic testicular germ cells and its increased phosphorylation status during capacitation suggested multiple important functions for FABP9. Therefore, we investigated specific functions for FABP9 by means of targeted gene disruption in mice. FABP9(-/-) mice were viable and fertile. Phenotypic analysis showed that FABP9(-/-) mice had significant increases in sperm head abnormalities (~8% greater than their WT cohorts); in particular, we observed the reduction or absence of the characteristic structural element known as the "ventral spur" in ~10% of FABP9(-/-) sperm. However, deficiency of FABP9 affected neither membrane tethering to the perinuclear theca nor the fatty acid composition of sperm. Moreover, epididymal sperm numbers were not affected in FABP9(-/-) mice. Therefore, we conclude that FABP9 plays only a minor role in providing the murine sperm head its characteristic shape and is not absolutely required for spermatogenesis or sperm function.
Insights
Male germ cell-specific fatty acid-binding protein 9 (FABP9) plays a minor role in sperm head formation. FABP9 deficiency in mice resulted in minor sperm head abnormalities but did not affect fertility or sperm function.
Area of Science:
- Reproductive Biology
- Molecular Biology
- Spermatogenesis
Background:
- Male germ cell-specific fatty acid-binding protein 9 (FABP9/PERF15) is a key component of the sperm.
- FABP9's association with the cytoskeleton and its upregulation during apoptosis and capacitation suggest diverse functions.
- Previous hypotheses proposed FABP9 tethers sperm membranes to the cytoskeleton.
Purpose of the Study:
- To investigate the specific functions of FABP9 in male reproduction.
- To determine the role of FABP9 in sperm head morphology and function using gene-targeted mice.
Main Methods:
- Targeted gene disruption to create FABP9 knockout (FABP9(-/-)) mice.
- Phenotypic analysis of FABP9(-/-) mice, including sperm head morphology and epididymal sperm counts.
- Assessment of sperm membrane tethering and fatty acid composition.
Main Results:
- FABP9(-/-) mice were viable and fertile with no significant impact on epididymal sperm numbers.
- A minor increase in sperm head abnormalities was observed in FABP9(-/-) mice (~8%).
- Approximately 10% of FABP9(-/-) sperm showed reduction or absence of the ventral spur; membrane tethering and fatty acid composition remained unaffected.
Conclusions:
- FABP9 plays a limited role in establishing the characteristic murine sperm head shape.
- FABP9 is not essential for spermatogenesis or overall sperm function.
- The protein's primary role may be structural, contributing to the ventral spur formation.
