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Plasma membrane overgrowth causes fibrotic collagen accumulation and immune activation in Drosophila adipocytes.

Zang Y, Wan M, Liu M, Ke H, Ma S, Liu LP, Ni JQ, Pastor-Pareja JC - Elife (2015)

Bottom Line: Deposits also form in the absence of negative Toll immune regulator Cactus, excess PM being caused in this case by increased secretion.Finally, we show that trimeric Collagen accumulation, downstream of Toll or endocytic defects, activates a tissue damage response.It also places fibrotic deposits both downstream and upstream of immune signaling, consistent with the chronic character of fibrotic diseases.

View Article: PubMed Central - PubMed

Affiliation: School of Life Sciences, Tsinghua University, Beijing, China.

ABSTRACT
Many chronic diseases are associated with fibrotic deposition of Collagen and other matrix proteins. Little is known about the factors that determine preferential onset of fibrosis in particular tissues. Here we show that plasma membrane (PM) overgrowth causes pericellular Collagen accumulation in Drosophila adipocytes. We found that loss of Dynamin and other endocytic components causes pericellular trapping of outgoing Collagen IV due to dramatic cortex expansion when endocytic removal of PM is prevented. Deposits also form in the absence of negative Toll immune regulator Cactus, excess PM being caused in this case by increased secretion. Finally, we show that trimeric Collagen accumulation, downstream of Toll or endocytic defects, activates a tissue damage response. Our work indicates that traffic imbalances and PM topology may contribute to fibrosis. It also places fibrotic deposits both downstream and upstream of immune signaling, consistent with the chronic character of fibrotic diseases.

No MeSH data available.


Related in: MedlinePlus

(A) PM of fat body adipocytes stained with anti-Trol antibody (magenta).Pericellular accumulation of Perlecan (Trol) in r4>shii adipocytes is suppressed by additionally knocking down expression of vkg and Cg25C Collagen IV chains. (B) Localization of 26-29-protease (26-29-pCA06735 GFP-trap) and Ferritin 1HCH (Fer1HCHG188 GFP-trap) in adipocytes from wild type L3 larvae, Cg>shii L3 larvae and Cg>sec23i L2 larvae. Note intracellular accumulation upon sec23 knock-down, which confirms that 26-29-p and Fer1HCH are indeed adipocyte-secreted. (C) Western blots of hemolymph extracted from wild type (w1118), Fer1HCHG188, Drs-GFP, BM-40-SPARC>ecr-GFP and 26-29-pCA06735 larvae probed with anti-GFP antibody (1:5000). The amount of blood loaded in each well is equivalent to 2.5 larvae. Whereas Fer1HCH-GFP (expected molecular weight 50 kDa), Drs-GFP (34 kDa) and secr-GFP (27 kDa) are detected in the hemolymph as clear single bands, 26-29-p (87 kDa) seems to be processed. (D) Dorsal view of a live larva expressing secr-GFP in adipocytes (BM-40-SPARC>secr-GFP) showing accumulation of GFP in pericardial cells, a hemolymph filtering nephrocyte-like cell type.DOI:http://dx.doi.org/10.7554/eLife.07187.013
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fig5s1: (A) PM of fat body adipocytes stained with anti-Trol antibody (magenta).Pericellular accumulation of Perlecan (Trol) in r4>shii adipocytes is suppressed by additionally knocking down expression of vkg and Cg25C Collagen IV chains. (B) Localization of 26-29-protease (26-29-pCA06735 GFP-trap) and Ferritin 1HCH (Fer1HCHG188 GFP-trap) in adipocytes from wild type L3 larvae, Cg>shii L3 larvae and Cg>sec23i L2 larvae. Note intracellular accumulation upon sec23 knock-down, which confirms that 26-29-p and Fer1HCH are indeed adipocyte-secreted. (C) Western blots of hemolymph extracted from wild type (w1118), Fer1HCHG188, Drs-GFP, BM-40-SPARC>ecr-GFP and 26-29-pCA06735 larvae probed with anti-GFP antibody (1:5000). The amount of blood loaded in each well is equivalent to 2.5 larvae. Whereas Fer1HCH-GFP (expected molecular weight 50 kDa), Drs-GFP (34 kDa) and secr-GFP (27 kDa) are detected in the hemolymph as clear single bands, 26-29-p (87 kDa) seems to be processed. (D) Dorsal view of a live larva expressing secr-GFP in adipocytes (BM-40-SPARC>secr-GFP) showing accumulation of GFP in pericardial cells, a hemolymph filtering nephrocyte-like cell type.DOI:http://dx.doi.org/10.7554/eLife.07187.013

Mentions: We asked next whether other proteins besides Collagen IV were pericellularly trapped due to PM overgrowth. Apart from Collagen IV, the main components of basement membranes are Perlecan, Laminin and Nidogen (Yurchenco, 2011). Whereas evidence exists of significant Laminin and Nidogen production outside the fat body (Urbano et al., 2009; Zhu et al., 2012), production of Perlecan has not been studied. Through iYFPi (in vivo YFP interference, Figure 4A), we knocked down expression of Perlecan-YFP (trolCPTI-002049 [Rees et al., 2011]), a YFP-trap insertion predicted to label all Perlecan isoforms and found that Perlecan present in imaginal discs originated entirely in the fat body (Figure 4B), same as Collagen IV. Also similar to Collagen IV, Trol-YFP was pericellularly accumulated in endocytosis-defective adipocytes (Figure 5A,B). This accumulation of Trol (terribly reduced optic lobes) depended on Collagen IV, as it was suppressed by Collagen IV knock-down (Figure 5C). Through antibody staining, we confirmed Perlecan accumulation (Figure 5—figure supplement 1) and additionally observed accumulation of Nidogen, again in a Collagen-dependent manner (Figure 5D), but not Laminin (anti-LanB1 staining, not shown).10.7554/eLife.07187.011Figure 4.Perlecan, like Collagen IV, originates in the fat body.


Plasma membrane overgrowth causes fibrotic collagen accumulation and immune activation in Drosophila adipocytes.

Zang Y, Wan M, Liu M, Ke H, Ma S, Liu LP, Ni JQ, Pastor-Pareja JC - Elife (2015)

(A) PM of fat body adipocytes stained with anti-Trol antibody (magenta).Pericellular accumulation of Perlecan (Trol) in r4>shii adipocytes is suppressed by additionally knocking down expression of vkg and Cg25C Collagen IV chains. (B) Localization of 26-29-protease (26-29-pCA06735 GFP-trap) and Ferritin 1HCH (Fer1HCHG188 GFP-trap) in adipocytes from wild type L3 larvae, Cg>shii L3 larvae and Cg>sec23i L2 larvae. Note intracellular accumulation upon sec23 knock-down, which confirms that 26-29-p and Fer1HCH are indeed adipocyte-secreted. (C) Western blots of hemolymph extracted from wild type (w1118), Fer1HCHG188, Drs-GFP, BM-40-SPARC>ecr-GFP and 26-29-pCA06735 larvae probed with anti-GFP antibody (1:5000). The amount of blood loaded in each well is equivalent to 2.5 larvae. Whereas Fer1HCH-GFP (expected molecular weight 50 kDa), Drs-GFP (34 kDa) and secr-GFP (27 kDa) are detected in the hemolymph as clear single bands, 26-29-p (87 kDa) seems to be processed. (D) Dorsal view of a live larva expressing secr-GFP in adipocytes (BM-40-SPARC>secr-GFP) showing accumulation of GFP in pericardial cells, a hemolymph filtering nephrocyte-like cell type.DOI:http://dx.doi.org/10.7554/eLife.07187.013
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4490375&req=5

fig5s1: (A) PM of fat body adipocytes stained with anti-Trol antibody (magenta).Pericellular accumulation of Perlecan (Trol) in r4>shii adipocytes is suppressed by additionally knocking down expression of vkg and Cg25C Collagen IV chains. (B) Localization of 26-29-protease (26-29-pCA06735 GFP-trap) and Ferritin 1HCH (Fer1HCHG188 GFP-trap) in adipocytes from wild type L3 larvae, Cg>shii L3 larvae and Cg>sec23i L2 larvae. Note intracellular accumulation upon sec23 knock-down, which confirms that 26-29-p and Fer1HCH are indeed adipocyte-secreted. (C) Western blots of hemolymph extracted from wild type (w1118), Fer1HCHG188, Drs-GFP, BM-40-SPARC>ecr-GFP and 26-29-pCA06735 larvae probed with anti-GFP antibody (1:5000). The amount of blood loaded in each well is equivalent to 2.5 larvae. Whereas Fer1HCH-GFP (expected molecular weight 50 kDa), Drs-GFP (34 kDa) and secr-GFP (27 kDa) are detected in the hemolymph as clear single bands, 26-29-p (87 kDa) seems to be processed. (D) Dorsal view of a live larva expressing secr-GFP in adipocytes (BM-40-SPARC>secr-GFP) showing accumulation of GFP in pericardial cells, a hemolymph filtering nephrocyte-like cell type.DOI:http://dx.doi.org/10.7554/eLife.07187.013
Mentions: We asked next whether other proteins besides Collagen IV were pericellularly trapped due to PM overgrowth. Apart from Collagen IV, the main components of basement membranes are Perlecan, Laminin and Nidogen (Yurchenco, 2011). Whereas evidence exists of significant Laminin and Nidogen production outside the fat body (Urbano et al., 2009; Zhu et al., 2012), production of Perlecan has not been studied. Through iYFPi (in vivo YFP interference, Figure 4A), we knocked down expression of Perlecan-YFP (trolCPTI-002049 [Rees et al., 2011]), a YFP-trap insertion predicted to label all Perlecan isoforms and found that Perlecan present in imaginal discs originated entirely in the fat body (Figure 4B), same as Collagen IV. Also similar to Collagen IV, Trol-YFP was pericellularly accumulated in endocytosis-defective adipocytes (Figure 5A,B). This accumulation of Trol (terribly reduced optic lobes) depended on Collagen IV, as it was suppressed by Collagen IV knock-down (Figure 5C). Through antibody staining, we confirmed Perlecan accumulation (Figure 5—figure supplement 1) and additionally observed accumulation of Nidogen, again in a Collagen-dependent manner (Figure 5D), but not Laminin (anti-LanB1 staining, not shown).10.7554/eLife.07187.011Figure 4.Perlecan, like Collagen IV, originates in the fat body.

Bottom Line: Deposits also form in the absence of negative Toll immune regulator Cactus, excess PM being caused in this case by increased secretion.Finally, we show that trimeric Collagen accumulation, downstream of Toll or endocytic defects, activates a tissue damage response.It also places fibrotic deposits both downstream and upstream of immune signaling, consistent with the chronic character of fibrotic diseases.

View Article: PubMed Central - PubMed

Affiliation: School of Life Sciences, Tsinghua University, Beijing, China.

ABSTRACT
Many chronic diseases are associated with fibrotic deposition of Collagen and other matrix proteins. Little is known about the factors that determine preferential onset of fibrosis in particular tissues. Here we show that plasma membrane (PM) overgrowth causes pericellular Collagen accumulation in Drosophila adipocytes. We found that loss of Dynamin and other endocytic components causes pericellular trapping of outgoing Collagen IV due to dramatic cortex expansion when endocytic removal of PM is prevented. Deposits also form in the absence of negative Toll immune regulator Cactus, excess PM being caused in this case by increased secretion. Finally, we show that trimeric Collagen accumulation, downstream of Toll or endocytic defects, activates a tissue damage response. Our work indicates that traffic imbalances and PM topology may contribute to fibrosis. It also places fibrotic deposits both downstream and upstream of immune signaling, consistent with the chronic character of fibrotic diseases.

No MeSH data available.


Related in: MedlinePlus