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Enterobacter-activated mosquito immune responses to Plasmodium involve activation of SRPN6 in Anopheles stephensi.

Eappen AG, Smith RC, Jacobs-Lorena M - PLoS ONE (2013)

Bottom Line: Here we demonstrate that SRPN6 is differentially activated by bacteria in Anopheles stephensi, but only when bacteria exposure occurs on the lumenal surface of the midgut epithelium.Our data indicate that AsSRPN6 is strongly induced following exposure to Enterobacter cloacae, a common component of the mosquito midgut microbiota.We conclude that AsSRPN6 is a vital component of the E. cloacae-mediated immune response that restricts Plasmodium development in the mosquito An. stephensi.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Microbiology and Immunology, Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America.

ABSTRACT
Successful development of Plasmodium in the mosquito is essential for the transmission of malaria. A major bottleneck in parasite numbers occurs during midgut invasion, partly as a consequence of the complex interactions between the endogenous microbiota and the mosquito immune response. We previously identified SRPN6 as an immune component which restricts Plasmodium berghei development in the mosquito. Here we demonstrate that SRPN6 is differentially activated by bacteria in Anopheles stephensi, but only when bacteria exposure occurs on the lumenal surface of the midgut epithelium. Our data indicate that AsSRPN6 is strongly induced following exposure to Enterobacter cloacae, a common component of the mosquito midgut microbiota. We conclude that AsSRPN6 is a vital component of the E. cloacae-mediated immune response that restricts Plasmodium development in the mosquito An. stephensi.

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SRPN6 expression following bacterial injection into the mosquito hemocoel.Approximately 2×103 bacteria were injected into the hemocoel of adult female An. stephensi. SRPN6 expression was analyzed by Northern blot in the midgut (A) and carcass (all non-gut tissues) (B) 6 h post bacteria injection of into the hemocoel. Procedures and abbreviations are the same as in Figure 1A. Similar results were obtained in three independent experiments. (C) As a control, expression of the anti-microbial peptide defensin was monitored by semi-quantitative RT-PCR in the carcass samples after bacteria injection. Procedures and abbreviations are the same as in Figure 1B.
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pone-0062937-g002: SRPN6 expression following bacterial injection into the mosquito hemocoel.Approximately 2×103 bacteria were injected into the hemocoel of adult female An. stephensi. SRPN6 expression was analyzed by Northern blot in the midgut (A) and carcass (all non-gut tissues) (B) 6 h post bacteria injection of into the hemocoel. Procedures and abbreviations are the same as in Figure 1A. Similar results were obtained in three independent experiments. (C) As a control, expression of the anti-microbial peptide defensin was monitored by semi-quantitative RT-PCR in the carcass samples after bacteria injection. Procedures and abbreviations are the same as in Figure 1B.

Mentions: The midgut epithelium consists of a single cell layer. On the lumenal side, epithelial cells display an extensive network of protrusions (microvilli), while the basal side is made of a complex invagination network (basal labyrinth) and a basal lamina exposed to the circulating hemolymph. The experiments outlined above examined AsSRPN6 immune activation following bacteria exposure to the lumenal side of the epithelium via feeding. To investigate the signaling requirements needed for AsSRPN6 activation, we sought to determine if bacterial exposure to the basal midgut surface was also capable of AsSRPN6 induction. Following the injection of bacteria into the mosquito hemocoel, the levels of AsSRPN6 expression were analyzed in midgut and carcass tissues (Figure 2). AsSRPN6 transcript was undetectable in midgut samples following injection (Figure 2A), and only weakly detected in carcass samples (Figure 2B). These results suggest that activation of AsSRPN6 midgut expression occurs via specific signaling mediated by the interaction of bacteria with the lumenal midgut surface.


Enterobacter-activated mosquito immune responses to Plasmodium involve activation of SRPN6 in Anopheles stephensi.

Eappen AG, Smith RC, Jacobs-Lorena M - PLoS ONE (2013)

SRPN6 expression following bacterial injection into the mosquito hemocoel.Approximately 2×103 bacteria were injected into the hemocoel of adult female An. stephensi. SRPN6 expression was analyzed by Northern blot in the midgut (A) and carcass (all non-gut tissues) (B) 6 h post bacteria injection of into the hemocoel. Procedures and abbreviations are the same as in Figure 1A. Similar results were obtained in three independent experiments. (C) As a control, expression of the anti-microbial peptide defensin was monitored by semi-quantitative RT-PCR in the carcass samples after bacteria injection. Procedures and abbreviations are the same as in Figure 1B.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3643921&req=5

pone-0062937-g002: SRPN6 expression following bacterial injection into the mosquito hemocoel.Approximately 2×103 bacteria were injected into the hemocoel of adult female An. stephensi. SRPN6 expression was analyzed by Northern blot in the midgut (A) and carcass (all non-gut tissues) (B) 6 h post bacteria injection of into the hemocoel. Procedures and abbreviations are the same as in Figure 1A. Similar results were obtained in three independent experiments. (C) As a control, expression of the anti-microbial peptide defensin was monitored by semi-quantitative RT-PCR in the carcass samples after bacteria injection. Procedures and abbreviations are the same as in Figure 1B.
Mentions: The midgut epithelium consists of a single cell layer. On the lumenal side, epithelial cells display an extensive network of protrusions (microvilli), while the basal side is made of a complex invagination network (basal labyrinth) and a basal lamina exposed to the circulating hemolymph. The experiments outlined above examined AsSRPN6 immune activation following bacteria exposure to the lumenal side of the epithelium via feeding. To investigate the signaling requirements needed for AsSRPN6 activation, we sought to determine if bacterial exposure to the basal midgut surface was also capable of AsSRPN6 induction. Following the injection of bacteria into the mosquito hemocoel, the levels of AsSRPN6 expression were analyzed in midgut and carcass tissues (Figure 2). AsSRPN6 transcript was undetectable in midgut samples following injection (Figure 2A), and only weakly detected in carcass samples (Figure 2B). These results suggest that activation of AsSRPN6 midgut expression occurs via specific signaling mediated by the interaction of bacteria with the lumenal midgut surface.

Bottom Line: Here we demonstrate that SRPN6 is differentially activated by bacteria in Anopheles stephensi, but only when bacteria exposure occurs on the lumenal surface of the midgut epithelium.Our data indicate that AsSRPN6 is strongly induced following exposure to Enterobacter cloacae, a common component of the mosquito midgut microbiota.We conclude that AsSRPN6 is a vital component of the E. cloacae-mediated immune response that restricts Plasmodium development in the mosquito An. stephensi.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Microbiology and Immunology, Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America.

ABSTRACT
Successful development of Plasmodium in the mosquito is essential for the transmission of malaria. A major bottleneck in parasite numbers occurs during midgut invasion, partly as a consequence of the complex interactions between the endogenous microbiota and the mosquito immune response. We previously identified SRPN6 as an immune component which restricts Plasmodium berghei development in the mosquito. Here we demonstrate that SRPN6 is differentially activated by bacteria in Anopheles stephensi, but only when bacteria exposure occurs on the lumenal surface of the midgut epithelium. Our data indicate that AsSRPN6 is strongly induced following exposure to Enterobacter cloacae, a common component of the mosquito midgut microbiota. We conclude that AsSRPN6 is a vital component of the E. cloacae-mediated immune response that restricts Plasmodium development in the mosquito An. stephensi.

Show MeSH
Related in: MedlinePlus