Controlling fertilization and cAMP signaling in sperm by optogenetics.

Vera Jansen,Melanie Balbach,Dagmar Wachten,Luis Alvarez,Peter Hegemann,U Benjamin Kaupp,Timo Strünker

doi:10.7554/elife.05161

Vera Jansen, Melanie Balbach + Show 5 more

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https://doi.org/10.7554/elife.05161

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Abstract

Optogenetics is a powerful technique to control cellular activity by light. The light-gated Channelrhodopsin has been widely used to study and manipulate neuronal activity in vivo, whereas optogenetic control of second messengers in vivo has not been examined in depth. In this study, we present a transgenic mouse model expressing a photoactivated adenylyl cyclase (bPAC) in sperm. In transgenic sperm, bPAC mimics the action of the endogenous soluble adenylyl cyclase (SACY) that is required for motility and fertilization: light-stimulation rapidly elevates cAMP, accelerates the flagellar beat, and, thereby, changes swimming behavior of sperm. Furthermore, bPAC replaces endogenous adenylyl cyclase activity. In mutant sperm lacking the bicarbonate-stimulated SACY activity, bPAC restored motility after light-stimulation and, thereby, enabled sperm to fertilize oocytes in vitro. We show that optogenetic control of cAMP in vivo allows to non-invasively study cAMP signaling, to control behaviors of single cells, and to restore a fundamental biological process such as fertilization.

Highlights

Almost every eukaryotic cell contains a specialized surface protrusion called the primary cilium (Singla and Reiter, 2006)
We engineered a targeting vector to express the beta subunit of photo activated adenylyl cyclase from the soil bacterium Beggiatoa under the control of the protamine 1 promoter (Prm1, Figure 1A) that is exclusively active in post-meiotic spermatids (Zambrowicz et al, 1993)
We report on a transgenic mouse model designed to control cAMP signaling in sperm using optogenetics

Summary

Introduction

Almost every eukaryotic cell contains a specialized surface protrusion called the primary cilium (Singla and Reiter, 2006). Called flagella, are used both as sensory antenna and motors that move fluids or propel cells (Salathe, 2007; Bloodgood, 2010; Lindemann and Lesich, 2010; Pichlo et al, 2014). Signaling in cilia and flagella is tightly regulated, spatially confined, and relies on a cilia-specific transport machinery (Rosenbaum and Witman, 2002; Delling et al, 2013; Chung et al, 2014; Pichlo et al, 2014). Ciliary cAMP signaling is involved in neural tube development by regulating the Sonic hedgehog (Shh) pathway (Mukhopadhyay et al, 2013)

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