Amplification of Olfactory Signals by Anoctamin 9 is Essential for Mammalian Olfaction: a Risk Factor for the Covid-19-associated Anosmia

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Abstract

Sensing smells of foods, prey, or predators determines animal survival. Olfactory sensory neurons in the olfactory epithelium (OE) detect odorants, where cAMP and Ca 2+ play a significant role in transducing odorant inputs to electrical activity. Here we show Anoctamin 9, a cation channel activated by cAMP/PKA pathway, is expressed in the OE and amplifies olfactory signals. Ano9 - deficient mice had reduced olfactory behavioral sensitivity, electro-olfactogram signals, and neural activity in the olfactory bulb. In line with the difference in olfaction between birds and other vertebrates, chick ANO9 failed to respond to odorants, whereas chick CNGA2, a major transduction channel, showed greater responses to cAMP. Importantly, single-cell transcriptome data from Covid-19 patients revealed that Ano9 transcripts were markedly suppressed among genes in the olfactory signal pathway. The signal amplification by ANO9 is essential for mammalian olfactory transduction, whose downregulation may be a risk factor for the olfactory dysfunction in Covid-19 patients.

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  1. SciScore for 10.1101/2022.03.02.482745: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    EthicsConsent: Due to the domestic law that cadavers must be donated and managed under informed consent and ethical process, the institutional review board (IRB) of The Catholic University of Korea has decreed that studies involving cadavers do not need to be reviewed.
    IRB: Due to the domestic law that cadavers must be donated and managed under informed consent and ethical process, the institutional review board (IRB) of The Catholic University of Korea has decreed that studies involving cadavers do not need to be reviewed.
    Euthanasia Agents: Briefly, male and female adult mice (9-12 weeks old) were anesthetized with intraperitoneal injection of Ketamine/Xylazine (90 mg/10 mg/kg).
    Sex as a biological variableHuman Samples: Two tissue samples of the human OE were acquired from two male cadavers (age: 68 years and 80 years).
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Cell Line Authenticationnot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    KLH/BSA conjugation was performed for effective immunization and generation of anti-peptide antibodies.
    anti-peptide
    suggested: None
    monoclonal anti-c-Fos antibody (1:1000, ab208942, Abcam), Tuj-1 (1:500, T5076, Sigma), Ac-Tub (1:500, T7451, Sigma), or olfactory marker protein (1:200, 019-22291, FUJIFILM Wako Chemicals) was diluted in 0.1% Triton X-100 in 1 x PBS containing 1% bovine serum albumin.
    anti-c-Fos
    suggested: (Abcam Cat# ab208942, RRID:AB_2747772)
    Tuj-1
    suggested: None
    Ac-Tub
    suggested: None
    The cell lysates were mixed with anti-ANO9 antibodies and incubated overnight in 4°C.
    anti-ANO9
    suggested: None
    Then, these immunoprecipitants were blotted with anti- phosphoserine antibodies Statistical analysis: All results are expressed as means ± standard errors (S.E.).
    anti- phosphoserine
    suggested: None
    Experimental Models: Cell Lines
    SentencesResources
    The transfected HEK 293T cells were incubated at 5% CO2 at 37◦C in the Dulbecco’s modified Eagle’s medium supplemented with 10% fetal bovine serum, 10 units/ml penicillin, and 10 μg/ml streptomycin.
    HEK 293T
    suggested: None
    Experimental Models: Organisms/Strains
    SentencesResources
    Adult male and female C57BL/6 background, transgenic, and Ano9 KO mice were used for electrophysiological recordings, in-vivo Ca2+ imaging, or behavioral tests.
    C57BL/6
    suggested: None
    To delete Ano9 in the whole body, the mice genotyped for the presence of the loxP sites (Ano9fl/fl) were crossed with B6.C-Tg(CMV-cre)1Cgn/J (CMV-cre) to produce CMV-cre;Ano9fl/- mice.
    B6.C-Tg(CMV-cre)1Cgn/J
    suggested: RRID:IMSR_JAX:006054)
    CMV-cre;Ano9fl/-
    suggested: None
    The CMV-cre;Ano9fl/- mice were crossed with Ano9fl/fl mice to generate Ano9 deficient mice (CMV-cre;Ano9fl/fl).
    Ano9fl/fl
    suggested: None
    CMV-cre;Ano9fl/fl
    suggested: None
    Recombinant DNA
    SentencesResources
    We subcloned chick Ano9 into pEGFP-N1 vector from the XM_015286257.2:1133-3649 PREDICTED: Gallus gallus anoctamin 9 (Ano9), transcript variant X3, mRNA.
    pEGFP-N1
    suggested: RRID:Addgene_172284)
    Software and Algorithms
    SentencesResources
    Imaging data were analyzed with NeuroPlex.
    NeuroPlex
    suggested: (NeuroPlex, RRID:SCR_016193)
    The electrical signals were digitized at 500 Hz and analyzed using pClamp 10.
    pClamp
    suggested: (pClamp, RRID:SCR_011323)
    Multiple sequence alignment was obtained using the CLUSTAL OMEGA program (https://www.ebi.ac.uk/Tools/msa/clustalo/) to compare the ANO9 sequences of various species.
    CLUSTAL OMEGA
    suggested: (Clustal Omega, RRID:SCR_001591)
    The analysis was performed with tailored Python and R scripts utilizing the following packages: Scanpy (v.1.7.1) 82 was used to import data and SciPy (v.1.4.1) for t-test 83 (see Code availability)
    Python
    suggested: (IPython, RRID:SCR_001658)
    SciPy
    suggested: (SciPy, RRID:SCR_008058)

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).


    Results from LimitationRecognizer: An explicit section about the limitations of the techniques employed in this study was not found. We encourage authors to address study limitations.

    Results from TrialIdentifier: No clinical trial numbers were referenced.


    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.


    Results from JetFighter: We did not find any issues relating to colormaps.


    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    Results from scite Reference Check: We found no unreliable references.


    About SciScore

    SciScore is an automated tool that is designed to assist expert reviewers by finding and presenting formulaic information scattered throughout a paper in a standard, easy to digest format. SciScore checks for the presence and correctness of RRIDs (research resource identifiers), and for rigor criteria such as sex and investigator blinding. For details on the theoretical underpinning of rigor criteria and the tools shown here, including references cited, please follow this link.