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Proc Natl Acad Sci U S A. 2018 Sep 11;115(37):9252-9257. doi: 10.1073/pnas.1806077115. Epub 2018 Aug 23.

Specific oxylipins enhance vertebrate hematopoiesis via the receptor GPR132.

Author information

1
Stem Cell Program, Boston Children's Hospital, Boston, MA 02115.
2
Division of Hematology/Oncology, Boston Children's Hospital, Boston, MA 02115.
3
Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138.
4
Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138.
5
Center for Experimental Therapeutics and Reperfusion Injury, Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women's Hospital, Boston, MA 02115.
6
Stem Cell Program, Boston Children's Hospital, Boston, MA 02115; zon@enders.tch.harvard.edu.
7
Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115.

Abstract

Epoxyeicosatrienoic acids (EETs) are lipid-derived signaling molecules with cardioprotective and vasodilatory actions. We recently showed that 11,12-EET enhances hematopoietic induction and engraftment in mice and zebrafish. EETs are known to signal via G protein-coupled receptors, with evidence supporting the existence of a specific high-affinity receptor. Identification of a hematopoietic-specific EET receptor would enable genetic interrogation of EET signaling pathways, and perhaps clinical use of this molecule. We developed a bioinformatic approach to identify an EET receptor based on the expression of G protein-coupled receptors in cell lines with differential responses to EETs. We found 10 candidate EET receptors that are expressed in three EET-responsive cell lines, but not expressed in an EET-unresponsive line. Of these, only recombinant GPR132 showed EET-responsiveness in vitro, using a luminescence-based β-arrestin recruitment assay. Knockdown of zebrafish gpr132b prevented EET-induced hematopoiesis, and marrow from GPR132 knockout mice showed decreased long-term engraftment capability. In contrast to high-affinity EET receptors, GPR132 is reported to respond to additional hydroxy-fatty acids in vitro, and we found that these same hydroxy-fatty acids enhance hematopoiesis in the zebrafish. We conducted structure-activity relationship analyses using both cell culture and zebrafish assays on diverse medium-chain fatty acids. Certain oxygenated, unsaturated free fatty acids showed high activation of GPR132, whereas unoxygenated or saturated fatty acids had lower activity. Absence of the carbon-1 position carboxylic acid prevented activity, suggesting that this moiety is required for receptor activation. GPR132 responds to a select panel of oxygenated polyunsaturated fatty acids to enhance both embryonic and adult hematopoiesis.

KEYWORDS:

GPCR; free fatty acid; hematopoiesis; zebrafish

PMID:
30139917
PMCID:
PMC6140511
DOI:
10.1073/pnas.1806077115
[Indexed for MEDLINE]
Free PMC Article

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