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TANGO1 and Mia2/cTAGE5 (TALI) cooperate to export bulky pre-chylomicrons/VLDLs from the endoplasmic reticulum

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ABSTRACT

Santos et al. show that TANGO1 and a TANGO1-like protein, TALI, bind each other and function together as receptors to export bulky ApoB-containing lipid particles from the endoplasmic reticulum. However, TANGO1-mediated export of bulky collagens by the same cells is TALI independent.

No MeSH data available.


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KO of TANGO, but not TALI, blocks procollagen XII export from the ER. (A) Scheme depicting the methodology used to differentiate Caco-2 cells and induce secretion of collagens. (B) Lysates and supernatants of differentiated parental, TANGO1-KO, or TALI-KO Caco-2 cells, induced with ascorbic acid for 20 h, underwent Western blotting for collagen XII. Intensities of signal in the supernatant were recorded by densitometry. (C) Ratio of external versus internal collagen XII normalized to parental cells. Error bars: SEM. (D) Differentiated parental, TANGO1-KO, or TALI-KO Caco-2 cells, induced with ascorbic acid for 20 h, were fixed with methanol and immunostained for collagen XII (red) and PDI (green). DAPI is shown in blue. Bars, 10 µm. n = 3.
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fig5: KO of TANGO, but not TALI, blocks procollagen XII export from the ER. (A) Scheme depicting the methodology used to differentiate Caco-2 cells and induce secretion of collagens. (B) Lysates and supernatants of differentiated parental, TANGO1-KO, or TALI-KO Caco-2 cells, induced with ascorbic acid for 20 h, underwent Western blotting for collagen XII. Intensities of signal in the supernatant were recorded by densitometry. (C) Ratio of external versus internal collagen XII normalized to parental cells. Error bars: SEM. (D) Differentiated parental, TANGO1-KO, or TALI-KO Caco-2 cells, induced with ascorbic acid for 20 h, were fixed with methanol and immunostained for collagen XII (red) and PDI (green). DAPI is shown in blue. Bars, 10 µm. n = 3.

Mentions: Because TANGO1 is known for its role in exporting procollagens from the ER, we tested whether loss of TANGO1 and TALI affected collagen secretion in differentiated Caco-2 cells in FCS-free medium with ascorbic acid for 20 h (Fig. 5 A). Media and the cell lysates of cells deleted of TANGO1 or TALI were analyzed by Western blotting. This approach revealed that KO of TANGO1, but not of TALI, resulted in an accumulation of intracellular collagen XII and a considerable reduction in its secreted levels (Fig. 5, B and C). To assess in which cellular compartment collagen XII was arrested in the absence of TANGO1, we stained cells for collagen XII and the ER resident protein PDI. Immunofluorescence analysis showed that collagen XII was arrested at the ER only in the absence of TANGO1, but not in parental cells or TALI-KO cells (Fig. 5 D). These experiments show that although TANGO1 and TALI cooperate to export pre-chylomicrons and pre-VLDLs from the ER, TALI does not participate in the TANGO1-mediated export of procollagen XII from the ER.


TANGO1 and Mia2/cTAGE5 (TALI) cooperate to export bulky pre-chylomicrons/VLDLs from the endoplasmic reticulum
KO of TANGO, but not TALI, blocks procollagen XII export from the ER. (A) Scheme depicting the methodology used to differentiate Caco-2 cells and induce secretion of collagens. (B) Lysates and supernatants of differentiated parental, TANGO1-KO, or TALI-KO Caco-2 cells, induced with ascorbic acid for 20 h, underwent Western blotting for collagen XII. Intensities of signal in the supernatant were recorded by densitometry. (C) Ratio of external versus internal collagen XII normalized to parental cells. Error bars: SEM. (D) Differentiated parental, TANGO1-KO, or TALI-KO Caco-2 cells, induced with ascorbic acid for 20 h, were fixed with methanol and immunostained for collagen XII (red) and PDI (green). DAPI is shown in blue. Bars, 10 µm. n = 3.
© Copyright Policy - openaccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4862334&req=5

fig5: KO of TANGO, but not TALI, blocks procollagen XII export from the ER. (A) Scheme depicting the methodology used to differentiate Caco-2 cells and induce secretion of collagens. (B) Lysates and supernatants of differentiated parental, TANGO1-KO, or TALI-KO Caco-2 cells, induced with ascorbic acid for 20 h, underwent Western blotting for collagen XII. Intensities of signal in the supernatant were recorded by densitometry. (C) Ratio of external versus internal collagen XII normalized to parental cells. Error bars: SEM. (D) Differentiated parental, TANGO1-KO, or TALI-KO Caco-2 cells, induced with ascorbic acid for 20 h, were fixed with methanol and immunostained for collagen XII (red) and PDI (green). DAPI is shown in blue. Bars, 10 µm. n = 3.
Mentions: Because TANGO1 is known for its role in exporting procollagens from the ER, we tested whether loss of TANGO1 and TALI affected collagen secretion in differentiated Caco-2 cells in FCS-free medium with ascorbic acid for 20 h (Fig. 5 A). Media and the cell lysates of cells deleted of TANGO1 or TALI were analyzed by Western blotting. This approach revealed that KO of TANGO1, but not of TALI, resulted in an accumulation of intracellular collagen XII and a considerable reduction in its secreted levels (Fig. 5, B and C). To assess in which cellular compartment collagen XII was arrested in the absence of TANGO1, we stained cells for collagen XII and the ER resident protein PDI. Immunofluorescence analysis showed that collagen XII was arrested at the ER only in the absence of TANGO1, but not in parental cells or TALI-KO cells (Fig. 5 D). These experiments show that although TANGO1 and TALI cooperate to export pre-chylomicrons and pre-VLDLs from the ER, TALI does not participate in the TANGO1-mediated export of procollagen XII from the ER.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Santos et al. show that TANGO1 and a TANGO1-like protein, TALI, bind each other and function together as receptors to export bulky ApoB-containing lipid particles from the endoplasmic reticulum. However, TANGO1-mediated export of bulky collagens by the same cells is TALI independent.

No MeSH data available.


Related in: MedlinePlus