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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

UAS-Dcr2 expression (BM-40-SPARC-Gal4>UAS-Dcr2) does not affect Collagen IV localization (Vkg-GFP) in adipocytes compared to Vkg-GFP control larvae (+) and larvae expressing GAL4 but not Dcr2 (BM-40-SPARC-Gal4).DOI:http://dx.doi.org/10.7554/eLife.07187.005
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fig1s2: UAS-Dcr2 expression (BM-40-SPARC-Gal4>UAS-Dcr2) does not affect Collagen IV localization (Vkg-GFP) in adipocytes compared to Vkg-GFP control larvae (+) and larvae expressing GAL4 but not Dcr2 (BM-40-SPARC-Gal4).DOI:http://dx.doi.org/10.7554/eLife.07187.005

Mentions: Standard fly husbandry techniques and genetic methodologies, including balancers and dominant genetic markers, were used to assess segregation of mutations and transgenes in the progeny of crosses, construct intermediate fly lines and obtain flies of the required genotypes for each experiment (Roote and Prokop, 2013). Flies were maintained at 25°C unless otherwise stated. In the initial screening and most experiments afterwards, the GAL4-UAS binary expression system (Brand and Perrimon, 1993) was used to drive expression of UAS transgenes in fat body adipocytes under temporal and spatial control of transgenic GAL4 drivers BM-40-SPARC-GAL4 (Venken et al., 2011) (a gift from Hugo Bellen), Cg-GAL4 (Asha et al., 2003) (BL7011), r4-GAL4 (Lee and Park, 2004) (a gift from Pierre Leopold) and ppl-GAL4 (Colombani et al., 2003) (a gift from Herve Agaisse). In flies bearing both types of transgenes (a GAL4 driver and a UAS responder), expression of the UAS-transgene is induced by the yeast transcription factor GAL4 according to the pattern of expression of GAL4 specific to the driver transgene. The strength of these drivers is BM-40-SPARC-GAL4 > Cg-GAL4 > r4-GAL4 > ppl-GAL4. While BM-40-SPARC-GAL4 and Cg-GAL4 are expressed in blood cells, r4-GAL4 and ppl-GAL4 are not. UAS-Dcr2 was included in the screening strain for the purpose of enhancing RNAi-mediated knock-down by long dsRNA hairpins (Dietzl et al., 2007). Dcr2 expression in adipocytes showed no visible effect by itself on Collagen IV localization (Figure 1—figure supplement 2). For generation of flip-out clones (Ito et al., 1997) (Figure 2F,G), vials containing L2 larvae were heat-shocked at 37°C for 7 min. For lipid depletion experiments, lipids were extracted from medium by mixing ingredients with chloroform for 2 days, allowing chloroform to evaporate for at least two more days before food preparation (Palm et al., 2012). Genotypes of animals in all experiments are detailed in Supplementary file 2. Origin of mutants and transgenes used can be found in Supplementary file 3. The following strains were used:


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)

UAS-Dcr2 expression (BM-40-SPARC-Gal4>UAS-Dcr2) does not affect Collagen IV localization (Vkg-GFP) in adipocytes compared to Vkg-GFP control larvae (+) and larvae expressing GAL4 but not Dcr2 (BM-40-SPARC-Gal4).DOI:http://dx.doi.org/10.7554/eLife.07187.005
© Copyright Policy
Related In: Results  -  Collection

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

fig1s2: UAS-Dcr2 expression (BM-40-SPARC-Gal4>UAS-Dcr2) does not affect Collagen IV localization (Vkg-GFP) in adipocytes compared to Vkg-GFP control larvae (+) and larvae expressing GAL4 but not Dcr2 (BM-40-SPARC-Gal4).DOI:http://dx.doi.org/10.7554/eLife.07187.005
Mentions: Standard fly husbandry techniques and genetic methodologies, including balancers and dominant genetic markers, were used to assess segregation of mutations and transgenes in the progeny of crosses, construct intermediate fly lines and obtain flies of the required genotypes for each experiment (Roote and Prokop, 2013). Flies were maintained at 25°C unless otherwise stated. In the initial screening and most experiments afterwards, the GAL4-UAS binary expression system (Brand and Perrimon, 1993) was used to drive expression of UAS transgenes in fat body adipocytes under temporal and spatial control of transgenic GAL4 drivers BM-40-SPARC-GAL4 (Venken et al., 2011) (a gift from Hugo Bellen), Cg-GAL4 (Asha et al., 2003) (BL7011), r4-GAL4 (Lee and Park, 2004) (a gift from Pierre Leopold) and ppl-GAL4 (Colombani et al., 2003) (a gift from Herve Agaisse). In flies bearing both types of transgenes (a GAL4 driver and a UAS responder), expression of the UAS-transgene is induced by the yeast transcription factor GAL4 according to the pattern of expression of GAL4 specific to the driver transgene. The strength of these drivers is BM-40-SPARC-GAL4 > Cg-GAL4 > r4-GAL4 > ppl-GAL4. While BM-40-SPARC-GAL4 and Cg-GAL4 are expressed in blood cells, r4-GAL4 and ppl-GAL4 are not. UAS-Dcr2 was included in the screening strain for the purpose of enhancing RNAi-mediated knock-down by long dsRNA hairpins (Dietzl et al., 2007). Dcr2 expression in adipocytes showed no visible effect by itself on Collagen IV localization (Figure 1—figure supplement 2). For generation of flip-out clones (Ito et al., 1997) (Figure 2F,G), vials containing L2 larvae were heat-shocked at 37°C for 7 min. For lipid depletion experiments, lipids were extracted from medium by mixing ingredients with chloroform for 2 days, allowing chloroform to evaporate for at least two more days before food preparation (Palm et al., 2012). Genotypes of animals in all experiments are detailed in Supplementary file 2. Origin of mutants and transgenes used can be found in Supplementary file 3. The following strains were used:

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