Research Article

Unconventional endocannabinoid signaling governs sperm activation via the sex hormone progesterone

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Science  29 Apr 2016:
Vol. 352, Issue 6285, pp. 555-559
DOI: 10.1126/science.aad6887
  • Fig. 1 Inhibition of sperm mSHs removes P4-dependent CatSper activation.

    (A) (Left) Representative ICatSper recorded from control human spermatozoa in the absence (black) and presence (red) of P4. (Right) ICatSper recorded from human spermatozoa pretreated with MAFP, an irreversible serine hydrolase inhibitor, for 30 min in the absence or presence of P4. (B) Fold increase of ICatSper in response to P4, PGE1, and MAFP. (C) Human capacitated spermatozoa do not hyperactivate in response to P4 if pretreated with MAFP, as recorded with computer-aided sperm analyses (CASA). (D) Arachidonoylglycerols are inhibitors of ICatSper. ICatSper densities are obtained at +80 mV (positive scale) or –80 mV (negative scale). (E) Representative ICatSper in the absence (black) or presence of the corresponding endocannabinoid. Data are represented as means ± SEM; numbers in parentheses indicate the number of experiments; and ****P < 0.0001, ***P < 0.001. , **P < 0.005.

  • Fig. 2 Photoreactive progesterone analog P4* activates ICatSper and associates with P4 receptor.

    (A) P4* consists of an active group (progesterone), a diazirine–UV-sensitive moiety, and a biotin tag that allows for pull-down of bound proteins. CMO, (O-carboxymethyl)oxime; PEG, polyethylene glycol. (B) Western blot from P4* binding experiments resolves biotinylated (P4*-bound) proteins. Lanes are labeled –, mock-irradiated cells; +, UV-treated cells; P4, P4 (20 μM); E, estrogen (0.5 μM); and Ru, Ru486 (0.5 μM). Acetylated α-tubulin (middle) staining was used as the loading control. (Bottom) The blot was probed with AbA. One experiment out of six independent pull-downs is shown. (C) ABHD2 is present in the human sperm transcriptome. mRNA sequencing (mRNA-Seq) reads from human blood monocytes and sperm cells. FPKM, fragments per kilobase of transcript per million mapped reads. Red line indicates expected number of sequencing reads for genes with similar expression levels in the two samples. CatSperG and AKAP4 indicate sperm-specific transcripts; CD14 and CD33 indicate monocyte-specific transcripts. Transcripts for FAAH and abhd2 are also shown. (D) Immunostaining of human spermatozoa with AbA and a corresponding differential interference contrast (DIC) image of the same cell.

  • Fig. 3 ABHD2 is expressed in human spermatozoa and acts as a P4-dependent lipid hydrolase.

    (A) ABHD2 expression in sperm from various mammalian species: Hs, humans; Sd, boar; Bt, bovine; Mm, mouse; and Rn, rat. Acetylated α-tubulin was used as the loading control. (B) Western blot from P4*-binding experiments of recombinant ABHD2 expressed in human embryonic kidney 293 (HEK293) cells resolves biotinylated proteins. Lane labeling is as in Fig. 2B. FLAG staining was used as the loading control for recombinant ABHD2 expression. (C) AbA prevents P4 activation of human ICatSper. Representative ICatSper treated with nonspecific IgG (left) or ABHD2 immunoglobulin G (IgG) (right). ICatSper values were recorded from control sperm or sperm treated with 1:100 dilutions of either nonspecific IgG or AbA for ~30 min. (D) ICatSper densities extracted from ramps shown in (C). (E) Monoacylglycerol hydrolysis by recombinant ABHD2 and ABHD12 in the presence or absence of 0.5 μM P4. Data are represented as means ± SEM; numbers in parentheses indicate number of experiments; and ****P < 0.0001, ***P < 0.001, **P < 0.005.

  • Fig. 4 ABHD2 regulates Ca2+ influx in human flagellum and is involved in mouse acrosome reaction.

    (A) Representative images from calcium imaging experiments before and after P4 treatment with regions of interest (ROIs) indicated. (B) Preincubation with either MAFP or AbA impeded P4-induced calcium influx. ΔF/F, the change in intensity from the original intensity before stimulation. Between 40 and 60 sperm flagella were assessed per condition. (C) Immunostaining of mouse cauda epididymal spermatozoa with AbA shows acrosomal localization. (Right) An overlay with DIC images. Nuclei were stained by 4′,6-diamidino-2-phenylindole (DAPI). (D) Percentage of AR murine spermatozoa in response to indicated treatments. Live, capacitated mouse spermatozoa were incubated with 3 μM P4, 3 μM AA, 2 μM MAFP, or vehicle (ethanol), after which they were imaged for the presence of intact acrosome. Data are represented as means ± SEM; numbers in parentheses indicate number of experiments; and **P < 0.005.

Supplementary Materials

  • Unconventional endocannabinoid signaling governs sperm activation via sex hormone progesterone

    Melissa R. Miller, Nadja Mannowetz, Anthony T. Iavarone, Rojin Safavi, Elena O. Gracheva, James F. Smith, Rose Z. Hill, Diana M. Bautista, Yuriy Kirichok, Polina V. Lishko

    Materials/Methods, Supplementary Text, Tables, Figures, and/or References

    Download Supplement
    • Materials and Methods
    • Supplementary Text
    • Figs. S1 to S16
    • Movie legends S1 to S6
    • Database captions S1 and S2
    • References
    Database S1
    Peptide mass spectrometry database.
    Database S2
    Transcriptomes
    Comparative gene expression profile (mRNA-Seq reads) of peripheral blood mononuclear cells (PBMCs) versus human spermatozoa. Signals <1 reads are within statistical noise and, therefore, scored as nonexpressed sequences.

    Images, Video, and Other Other Media

    Movie S1
    Elevation of intracellular [Ca2+] in human sperm in response to 1 μM P4.
    Movie S2
    Elevation of intracellular [Ca2+] in human sperm in response to 1 μM P4 (zoomed area).
    Movie S3
    Flagellar intracellular [Ca2+] fails to rise in response to 1 μM P4 when sperm where pretreated with 2 μM MAFP.
    Movie S4
    Flagellar intracellular [Ca2+] fails to rise in response to 1 μM P4 when sperm where pretreated with 2 μM MAFP (zoomed area).
    Movie S5
    Flagellar intracellular [Ca2+] fails to rise in response to P4 when sperm where preincubated with anti-ABHD2 antibody. Experiment was done in the presence of 1:100 anti-ABHD2 IgG ABa.
    Movie S6
    Flagellar intracellular [Ca2+] fails to rise in response to P4 when sperm where preincubated with anti-ABHD2 antibody. Experiment was done in the presence of 1:100 anti-ABHD2 IgG ABa (zoomed area).
    Correction (28 April 2016): In this revision, the authors have made changes to the methods, including a reagent name, timing, and units of measure. The cover page was in error, lacking Tables S15 and S16.
    The original version is accessible here.

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