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Drosophila Rabex-5 restricts Notch activity in hematopoietic cells and maintains hematopoietic homeostasis.

Reimels TA, Pfleger CM - J. Cell. Sci. (2015)

Bottom Line: Rabex-5 negatively regulates Ras, and we show that Ras activity is responsible for specific Rabex-5 hematopoietic phenotypes.Surprisingly, Ras-independent Notch protein accumulation and transcriptional activity in the lymph gland underlie multiple distinct hematopoietic phenotypes of Rabex-5 loss.Thus, Rabex-5 plays an important role in Drosophila hematopoiesis and might serve as an axis coordinating Ras and Notch signaling in the lymph gland.

View Article: PubMed Central - PubMed

Affiliation: Department of Oncological Sciences, The Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA The Graduate School of Biomedical Sciences, The Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.

No MeSH data available.


Related in: MedlinePlus

Notch accumulation upon Rabex-5 loss leads to increased transcriptional outputs. (A) Rabex-5 RNAi, but not RasV12, in hemocytes (srp>GFP, Rabex-5IR and srp>GFP, RasV12) increased β-gal fluorescence intensity across the primary lymph gland lobes compared to that in controls (srp>GFP). (B) Representative image showing individual cells with elevated reporter activity (arrows) in lymph glands expressing GFP in hemocytes. DAPI staining is shown in blue. Scale bars: 10 μm. (C) Rabex-5 RNAi, but not RasV12, in hemocytes (srp>GFP, Rabex-5IR and srp>GFP, RasV12) increased the percentage of lymph glands with elevated reporter activity in individual cells compared to that of controls (srp>GFP). (D) Rabex-5 RNAi, but not RasV12, in hemocytes (srp>GFP, Rabex-5IR and srp>GFP, RasV12) increased the average number of cells per lobe with elevated reporter activity compared to those in controls (srp>GFP). ^P≤0.05, *P≤0.01.
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JCS174433F7: Notch accumulation upon Rabex-5 loss leads to increased transcriptional outputs. (A) Rabex-5 RNAi, but not RasV12, in hemocytes (srp>GFP, Rabex-5IR and srp>GFP, RasV12) increased β-gal fluorescence intensity across the primary lymph gland lobes compared to that in controls (srp>GFP). (B) Representative image showing individual cells with elevated reporter activity (arrows) in lymph glands expressing GFP in hemocytes. DAPI staining is shown in blue. Scale bars: 10 μm. (C) Rabex-5 RNAi, but not RasV12, in hemocytes (srp>GFP, Rabex-5IR and srp>GFP, RasV12) increased the percentage of lymph glands with elevated reporter activity in individual cells compared to that of controls (srp>GFP). (D) Rabex-5 RNAi, but not RasV12, in hemocytes (srp>GFP, Rabex-5IR and srp>GFP, RasV12) increased the average number of cells per lobe with elevated reporter activity compared to those in controls (srp>GFP). ^P≤0.05, *P≤0.01.

Mentions: To establish whether Notch protein accumulation results in increased Notch transcriptional activity, we examined the effect of Rabex-5 knockdown on a Notch transcriptional reporter, 12xSu(H)bs-lacZ (Go et al., 1998). Reducing Rabex-5 across the primary lymph gland lobes (srp>Rabex-5IR) increased β-galactosidase (β-gal) fluorescence intensity compared to that in controls (Fig. 7A). In 81% of control lymph glands, β-gal staining was uniform and low. The remaining 19% of lymph glands showed individual cells with elevated reporter activity (arrows in Fig. 7B, quantification in 7C). Rabex-5 reduction increased the percent of lymph glands showing individual cells with elevated reporter activity from 19% to 75%. Compared to controls, Rabex-5 reduction also increased the average number of individual cells with elevated activity per primary lobe (Fig. 7D). These findings indicate that Notch protein accumulation upon Rabex-5 knockdown in the lymph gland leads to functionally increased Notch transcriptional activity.Fig. 7.


Drosophila Rabex-5 restricts Notch activity in hematopoietic cells and maintains hematopoietic homeostasis.

Reimels TA, Pfleger CM - J. Cell. Sci. (2015)

Notch accumulation upon Rabex-5 loss leads to increased transcriptional outputs. (A) Rabex-5 RNAi, but not RasV12, in hemocytes (srp>GFP, Rabex-5IR and srp>GFP, RasV12) increased β-gal fluorescence intensity across the primary lymph gland lobes compared to that in controls (srp>GFP). (B) Representative image showing individual cells with elevated reporter activity (arrows) in lymph glands expressing GFP in hemocytes. DAPI staining is shown in blue. Scale bars: 10 μm. (C) Rabex-5 RNAi, but not RasV12, in hemocytes (srp>GFP, Rabex-5IR and srp>GFP, RasV12) increased the percentage of lymph glands with elevated reporter activity in individual cells compared to that of controls (srp>GFP). (D) Rabex-5 RNAi, but not RasV12, in hemocytes (srp>GFP, Rabex-5IR and srp>GFP, RasV12) increased the average number of cells per lobe with elevated reporter activity compared to those in controls (srp>GFP). ^P≤0.05, *P≤0.01.
© Copyright Policy - open-access
Related In: Results  -  Collection

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JCS174433F7: Notch accumulation upon Rabex-5 loss leads to increased transcriptional outputs. (A) Rabex-5 RNAi, but not RasV12, in hemocytes (srp>GFP, Rabex-5IR and srp>GFP, RasV12) increased β-gal fluorescence intensity across the primary lymph gland lobes compared to that in controls (srp>GFP). (B) Representative image showing individual cells with elevated reporter activity (arrows) in lymph glands expressing GFP in hemocytes. DAPI staining is shown in blue. Scale bars: 10 μm. (C) Rabex-5 RNAi, but not RasV12, in hemocytes (srp>GFP, Rabex-5IR and srp>GFP, RasV12) increased the percentage of lymph glands with elevated reporter activity in individual cells compared to that of controls (srp>GFP). (D) Rabex-5 RNAi, but not RasV12, in hemocytes (srp>GFP, Rabex-5IR and srp>GFP, RasV12) increased the average number of cells per lobe with elevated reporter activity compared to those in controls (srp>GFP). ^P≤0.05, *P≤0.01.
Mentions: To establish whether Notch protein accumulation results in increased Notch transcriptional activity, we examined the effect of Rabex-5 knockdown on a Notch transcriptional reporter, 12xSu(H)bs-lacZ (Go et al., 1998). Reducing Rabex-5 across the primary lymph gland lobes (srp>Rabex-5IR) increased β-galactosidase (β-gal) fluorescence intensity compared to that in controls (Fig. 7A). In 81% of control lymph glands, β-gal staining was uniform and low. The remaining 19% of lymph glands showed individual cells with elevated reporter activity (arrows in Fig. 7B, quantification in 7C). Rabex-5 reduction increased the percent of lymph glands showing individual cells with elevated reporter activity from 19% to 75%. Compared to controls, Rabex-5 reduction also increased the average number of individual cells with elevated activity per primary lobe (Fig. 7D). These findings indicate that Notch protein accumulation upon Rabex-5 knockdown in the lymph gland leads to functionally increased Notch transcriptional activity.Fig. 7.

Bottom Line: Rabex-5 negatively regulates Ras, and we show that Ras activity is responsible for specific Rabex-5 hematopoietic phenotypes.Surprisingly, Ras-independent Notch protein accumulation and transcriptional activity in the lymph gland underlie multiple distinct hematopoietic phenotypes of Rabex-5 loss.Thus, Rabex-5 plays an important role in Drosophila hematopoiesis and might serve as an axis coordinating Ras and Notch signaling in the lymph gland.

View Article: PubMed Central - PubMed

Affiliation: Department of Oncological Sciences, The Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA The Graduate School of Biomedical Sciences, The Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.

No MeSH data available.


Related in: MedlinePlus