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Peaks and valleys of prolactin-driven gene expression during parental care

Rayna M Harris
January 06, 2020

Peaks and valleys of prolactin-driven gene expression during parental care

Parental care of offspring is essential to maximize fitness in many species throughout the animal kingdom. New parents undergo major changes in physiology and behavior to promote offspring survival in predictable and unpredictable conditions. While much is known about neuroendocrine mechanisms modulating these changes, we know less about genomic mechanisms driving these changes in male and female parents. To fill this gap, our team characterized gene expression states of the hypothalamus, pituitary, and gonads of mothers and fathers of the socially monogamous, bi-parental rock dove (Columba livia) at multiple stages of parenting. Next, we manipulated the timeline of the offspring development to distinguish genomic signatures that are driven by external cues from the offspring from internal cues from within the parent. We developed an R workflow for rapid and reproducible hypothesis testing related to specific tissues, sexes, and timepoints from our dataset of 1000 samples. Data and analyses are available at https://github.com/macmanes-lab/DoveParentsRNAseq. Preliminary findings suggest that gene expression of hundreds of genes in the pituitary mirrors that of circulating prolactin levels in the blood. Removal of offspring around the time of chicks hatching causes circulating prolactin to plummet and gene expression patterns shift to a non-parental state; however, prolonging incubation or delaying hatch has a much more subtle effect on gene expression. By characterizing and manipulating parental care and measuring the effects on hormones and gene expression in both male and female parents over time, we provide a more complete picture of how the hypothalamic-pituitary-gonadal axis responds to predictable and unpredictable changes during offspring development.

Rayna M Harris

January 06, 2020
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  1. Peaks and valleys of prolactin-driven
    gene expression during parental care
    Dr. Rayna M. Harris
    raynamharris
    Postdoc, UC Davis
    1

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  2. Meet the co-authors (*here at SICB)
    Dr. Rayna Harris
    Dr. Suzanne Austin
    Dr. Andrew
    Lang
    Dr. Matthew MacManes
    Dr. Rebecca
    Calisi
    Rechelle Viernes
    Dr. Jesse Krause
    April Booth
    Victoria Farrar
    University of California, Davis University of New Hampshire
    * *
    *
    Funded by NSF IOS-Animal Behavior.
    We are grateful to the members of our labs and and the labs of John Wingfield and Titus Brown lab for discussion. 2
    *

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  3. Like humans, Rock Doves are bi-parental.
    However, both male and female Rock Doves lactate.
    Image by Victoria Farrar
    Calisi & a Working Group of
    Mothers in Science 2018 PNAS 3
    Calisi 2018 Science

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  4. What molecular profiles characterize parental care
    transitions in the reproductive axis (HPG) of
    bi-parental Rock Doves?
    4
    https://github.com/macmanes-lab/DoveParentsRNAseq

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  5. Experimental design for characterizing HPG gene
    activity over the course of bi-parental care.
    5
    https://github.com/macmanes-lab/DoveParentsRNAseq
    N= 12 per group
    576 RNA-seq
    samples

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  6. What explains the
    most variation in
    gene expression?
    Tissue, sex, or
    treatment?
    6
    https://github.com/macmanes-lab/DoveParentsRNAseq
    Kallisto -> Limma -> Rtsne or PCA

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  7. Gene expression in
    each tissue is quite
    distinct.
    7
    https://github.com/macmanes-lab/DoveParentsRNAseq
    Kallisto -> Limma -> Rtsne or PCA

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  8. Sex differences are
    most pronounced in
    the gonads.
    8
    https://github.com/macmanes-lab/DoveParentsRNAseq
    Kallisto -> Limma -> Rtsne or PCA

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  9. 9
    https://github.com/macmanes-lab/DoveParentsRNAseq
    Treatment effects are
    most pronounced in
    the pituitary.
    Kallisto -> Limma -> Rtsne or PCA

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  10. What gene
    explains the most
    variation?
    Prolactin.
    10
    https://github.com/macmanes-lab/DoveParentsRNAseq
    PC loadings calculated and visualized
    with `factoextra`

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  11. Confirms that prolactin is an
    important regulator of reproductive
    axis and parental care behavior.
    11

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  12. Levels of prolactin,
    in the the blood are
    correlated with
    prolactin (PRL)
    expression in the
    pituitary.
    12
    https://github.com/macmanes-lab/DoveParentsRNAseq
    DESeq2: pituitary only, treatment * sex

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  13. 13
    Imagine PRL
    expression as a
    song.
    What genes
    work in concert
    to create a
    “transcriptional
    symphony”?
    https://github.com/macmanes-lab/DoveParentsRNAseq
    Made with `ggplot`. Played lived on a
    keyboard.

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  14. WGCNA identified
    96 genes that are
    coexpressed with
    PRL in the pituitary.
    ShinyGO
    categorized these
    genes by their
    Biological Process.
    14
    https://github.com/macmanes-lab/DoveParentsRNAseq
    Thanks to Dr. Sarah Davies for the
    WGCNA suggestion via Twitter :)

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  15. The top GO terms
    are related to the
    cell cycle process,
    cell proliferation,
    reproduction, and
    stress response.
    15
    https://github.com/macmanes-lab/DoveParentsRNAseq
    Genes identified with WGCNA.
    GO terms identified with ShinyGo.

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  16. BRCA1 helps
    repair DNA.
    Mutations can lead
    to increased risk
    for breast cancer.
    BRCA1 peaks
    when PRL peaks
    around the time
    chicks hatch.
    16
    https://github.com/macmanes-lab/DoveParentsRNAseq

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  17. Understanding the dynamics of PRL
    and BRCA1 during avian parental
    care could advance cancer
    research.
    17

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  18. RNA-seq is not just for
    data-driven discovery.
    It can be used to test
    hypotheses too.
    18

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  19. Hypotheses
    Hypothesis 1 (H1)
    Changes in transcription
    during parental care are
    based on an internal
    clock-timing mechanism.
    19
    Hypothesis 2 (H2)
    Changes in transcription
    during parental care are
    based on external sensory
    information, like the the
    presence or absence of
    eggs or chicks.

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  20. Egg and chick replacement manipulations.
    20
    https://github.com/macmanes-lab/DoveParentsRNAseq

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  21. When chicks hatch
    early, gene
    expression is very
    similar to incubation
    to day 9 and very
    different from
    normal hatch.
    21
    https://github.com/macmanes-lab/DoveParentsRNAseq
    DESeq2: treatment * sex
    log fold change
    pituitary
    H1 H2

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  22. All three
    manipulations are
    more similar to
    their calendar day
    equivalent than to
    their external
    environment.
    22
    https://github.com/macmanes-lab/DoveParentsRNAseq
    DESeq2: treatment * sex
    log fold change
    pituitary
    H1 H2 H1
    H2 H1
    H2

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  23. Egg and chick removal manipulations.
    23
    https://github.com/macmanes-lab/DoveParentsRNAseq

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  24. Offspring removal
    manipulations also
    suggest that
    transcription is
    regulated by an
    internal clock.
    24
    https://github.com/macmanes-lab/DoveParentsRNAseq

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  25. And prolactin (PRL)
    still explains most
    of the variation.
    25
    https://github.com/macmanes-lab/DoveParentsRNAseq

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  26. This suggests that pituitary
    gene expression is driven by an
    internal clock that regulates
    prolactin-driven expression of
    parental care
    behaviors.
    26

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  27. 27
    Thanks for listening.
    What questions do you have?
    Dr. Rayna M. Harris
    raynamharris
    Postdoc, UC Davis

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