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Serotonin modulates insect hemocyte phagocytosis via two different serotonin receptors.

Qi YX, Huang J, Li MQ, Wu YS, Xia RY, Ye GY - Elife (2016)

Bottom Line: Biochemical and functional experiments showed that naive hemocytes primarily express 5-HT1B and 5-HT2B receptors.The blockade of 5-HT1B significantly reduced phagocytic ability; however, the blockade of 5-HT2B increased hemocyte phagocytosis.Combined, these data demonstrate that 5-HT mediates hemocyte phagocytosis through 5-HT1B and 5-HT2B receptors and serotonergic signaling performs critical modulatory functions in immune systems of animals separated by 500 million years of evolution.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Rice Biology, Institute of Insect Sciences, Zhejiang University, Hangzhou, China.

ABSTRACT
Serotonin (5-HT) modulates both neural and immune responses in vertebrates, but its role in insect immunity remains uncertain. We report that hemocytes in the caterpillar, Pieris rapae are able to synthesize 5-HT following activation by lipopolysaccharide. The inhibition of a serotonin-generating enzyme with either pharmacological blockade or RNAi knock-down impaired hemocyte phagocytosis. Biochemical and functional experiments showed that naive hemocytes primarily express 5-HT1B and 5-HT2B receptors. The blockade of 5-HT1B significantly reduced phagocytic ability; however, the blockade of 5-HT2B increased hemocyte phagocytosis. The 5-HT1B- Drosophila melanogaster mutants showed higher mortality than controls when infected with bacteria, due to their decreased phagocytotic ability. Flies expressing 5-HT1B or 5-HT2B RNAi in hemocytes also showed similar sensitivity to infection. Combined, these data demonstrate that 5-HT mediates hemocyte phagocytosis through 5-HT1B and 5-HT2B receptors and serotonergic signaling performs critical modulatory functions in immune systems of animals separated by 500 million years of evolution.

No MeSH data available.


Related in: MedlinePlus

A schematic diagram of serotonin signaling on hemocyte phagocytosis.LPS enhances the expression of TPH, which catalyzes tryptophan into 5-HT via 5-HTP. 5-HT, which secreted from hemocytes, activates the hemocyte-membrane receptor 5-HT1B and 5-HT2B. The immune responses of P. rapae are labeled in purple: activation of 5-HT1B promotes hemocyte phagocytosis and activation of 5-HT2B lead to opposite effects. LPS increases 5-HT1B expression but decreases that of 5-HT2B. The immune responses of Drosophila are labeled in green arrows: activation of 5-HT1B promotes hemocyte phagocytosis and activation of 5-HT2B lead to the same effects.DOI:http://dx.doi.org/10.7554/eLife.12241.015
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fig9: A schematic diagram of serotonin signaling on hemocyte phagocytosis.LPS enhances the expression of TPH, which catalyzes tryptophan into 5-HT via 5-HTP. 5-HT, which secreted from hemocytes, activates the hemocyte-membrane receptor 5-HT1B and 5-HT2B. The immune responses of P. rapae are labeled in purple: activation of 5-HT1B promotes hemocyte phagocytosis and activation of 5-HT2B lead to opposite effects. LPS increases 5-HT1B expression but decreases that of 5-HT2B. The immune responses of Drosophila are labeled in green arrows: activation of 5-HT1B promotes hemocyte phagocytosis and activation of 5-HT2B lead to the same effects.DOI:http://dx.doi.org/10.7554/eLife.12241.015


Serotonin modulates insect hemocyte phagocytosis via two different serotonin receptors.

Qi YX, Huang J, Li MQ, Wu YS, Xia RY, Ye GY - Elife (2016)

A schematic diagram of serotonin signaling on hemocyte phagocytosis.LPS enhances the expression of TPH, which catalyzes tryptophan into 5-HT via 5-HTP. 5-HT, which secreted from hemocytes, activates the hemocyte-membrane receptor 5-HT1B and 5-HT2B. The immune responses of P. rapae are labeled in purple: activation of 5-HT1B promotes hemocyte phagocytosis and activation of 5-HT2B lead to opposite effects. LPS increases 5-HT1B expression but decreases that of 5-HT2B. The immune responses of Drosophila are labeled in green arrows: activation of 5-HT1B promotes hemocyte phagocytosis and activation of 5-HT2B lead to the same effects.DOI:http://dx.doi.org/10.7554/eLife.12241.015
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4829436&req=5

fig9: A schematic diagram of serotonin signaling on hemocyte phagocytosis.LPS enhances the expression of TPH, which catalyzes tryptophan into 5-HT via 5-HTP. 5-HT, which secreted from hemocytes, activates the hemocyte-membrane receptor 5-HT1B and 5-HT2B. The immune responses of P. rapae are labeled in purple: activation of 5-HT1B promotes hemocyte phagocytosis and activation of 5-HT2B lead to opposite effects. LPS increases 5-HT1B expression but decreases that of 5-HT2B. The immune responses of Drosophila are labeled in green arrows: activation of 5-HT1B promotes hemocyte phagocytosis and activation of 5-HT2B lead to the same effects.DOI:http://dx.doi.org/10.7554/eLife.12241.015
Bottom Line: Biochemical and functional experiments showed that naive hemocytes primarily express 5-HT1B and 5-HT2B receptors.The blockade of 5-HT1B significantly reduced phagocytic ability; however, the blockade of 5-HT2B increased hemocyte phagocytosis.Combined, these data demonstrate that 5-HT mediates hemocyte phagocytosis through 5-HT1B and 5-HT2B receptors and serotonergic signaling performs critical modulatory functions in immune systems of animals separated by 500 million years of evolution.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Rice Biology, Institute of Insect Sciences, Zhejiang University, Hangzhou, China.

ABSTRACT
Serotonin (5-HT) modulates both neural and immune responses in vertebrates, but its role in insect immunity remains uncertain. We report that hemocytes in the caterpillar, Pieris rapae are able to synthesize 5-HT following activation by lipopolysaccharide. The inhibition of a serotonin-generating enzyme with either pharmacological blockade or RNAi knock-down impaired hemocyte phagocytosis. Biochemical and functional experiments showed that naive hemocytes primarily express 5-HT1B and 5-HT2B receptors. The blockade of 5-HT1B significantly reduced phagocytic ability; however, the blockade of 5-HT2B increased hemocyte phagocytosis. The 5-HT1B- Drosophila melanogaster mutants showed higher mortality than controls when infected with bacteria, due to their decreased phagocytotic ability. Flies expressing 5-HT1B or 5-HT2B RNAi in hemocytes also showed similar sensitivity to infection. Combined, these data demonstrate that 5-HT mediates hemocyte phagocytosis through 5-HT1B and 5-HT2B receptors and serotonergic signaling performs critical modulatory functions in immune systems of animals separated by 500 million years of evolution.

No MeSH data available.


Related in: MedlinePlus