Adenine Nucleotide Metabolism and a Role for AMP in Modulating Flagellar Waveforms in Mouse Sperm1

Abstract

While most ATP, the main energy source driving sperm motility, is derived from glycolysis and oxidative phosphorylation, the metabolic demands of the cell require the efficient use of power stored in high-energy phosphate bonds. In times of high energy consumption, adenylate kinase (AK) scavenges one ATP molecule by transphosphorylation of two molecules of ADP, simultaneously yielding one molecule of AMP as a by-product. Either ATP or ADP supported motility of detergent-modeled cauda epididymal mouse sperm, indicating that flagellar AKs are functional. However, the ensuing flagellar waveforms fueled by ATP or ADP were qualitatively different. Motility driven by ATP was rapid but restricted to the distal region of the sperm tail, whereas ADP produced slower and more fluid waves that propagated down the full flagellum. Characterization of wave patterns by tracing and superimposing the images of the flagella, quantifying the differences using digital image analysis, and computer-assisted sperm analysis revealed differences in the amplitude, periodicity, and propagation of the waves between detergent-modeled sperm treated with either ATP or ADP. Surprisingly, addition of AMP to the incubation medium containing ATP recapitulated the pattern of sperm motility seen with ADP alone. In addition to AK1 and AK2, which we previously demonstrated are present in outer dense fibers and mitochondrial sheath of the mouse sperm tail, we show that another AK, AK8, is present in a third flagellar compartment, the axoneme. These results extend the known regulators of sperm motility to include AMP, which may be operating through an AMP-activated protein kinase.

Targeted Disruption of Glycogen Synthase Kinase 3a (Gsk3a) in Mice Affects Sperm Motility Resulting in Male Infertility1

“…A strikingly similar attenuated flagellar beat and impaired sperm hyperactivation was also seen in sperm lacking the sperm-specific catalytic subunit of PKA, Cαs [25]. Flagellar beat waveform features seen with Gsk3a null sperm were observed in membrane permeabilized sperm activated in the presence of AMP [32] and also in sperm lacking the nucleoside transport protein Slc29a (ENT1) [33]. Further studies with sperm from Gsk3a (-/-) null mice are required where quantitation of flagellar beat amplitude and frequency can be coupled to biochemical changes in null sperm.…”

CFAP45 deficiency causes situs abnormalities and asthenospermia by disrupting an axonemal adenine nucleotide homeostasis module

“…10e–g ). AK8 has been shown to have high affinity for AMP in vitro 51 and localize to mouse sperm flagellar axonemes 19 .…”

“…The observation that ADP can rescue the inhibitory effects of high ATP concentrations on flagellar beating 16 – 18 suggests that both ATP and ADP cooperatively regulate dynein ATPases. It has been also shown that adenosine monophosphate (AMP) incubated with ATP can mimic the modulatory effect of ADP alone on flagellar beat pattern 19 . The mechanism underlying this effect is not fully understood but explained in part by adenylate kinase (AK), which reversibly catalyses the reaction ATP + AMP ↔ 2 ADP and maintains balanced nucleotide pools to support ciliary beating 20 .…”

Human prostasomes from normozoospermic and non‐normozoospermic men show a differential protein expression pattern

“…LHDC, an enzyme that catalyzes the reversible conversion of pyruvate to lactate with a concomitant production of NAD + needed for a rapid glycolysis, appears to have a key role in sperm capacitation thanks to the high concentration of pyruvate present in the female reproductive tract (Hereng et al ., ). Another enzyme that plays an important role in energy production and sperm motility in AK1; this enzyme, located in the flagellum, catalyzes the production of ATP using ADP as a substrate and thus provides an extra source of ATP needed to get slower and more fluid waves that propagate down the flagellum (Cao et al ., ; Vadnais et al ., ). Consequently, a reduction on the quantity or quality of those proteins both in the spermatozoa itself or in the prostasomes reservoir may have an extremely detrimental effect over fertility as it may compromise the sperm energy production.…”