Abstract
Fat storage-inducing transmembrane protein 2 (FIT2) is an endoplasmic reticulum (ER)-localized protein that plays an important role in lipid droplet (LD) formation in animal cells. However, no obvious homologue of FIT2 is found in plants. Here, we tested the function of FIT2 in plant cells by ectopically expressing mouse (Mus musculus) FIT2 in Nicotiana tabacum suspension-cultured cells, Nicotiana benthamiana leaves and Arabidopsis thaliana plants. Confocal microscopy indicated that the expression of FIT2 dramatically increased the number and size of LDs in leaves of N. benthamiana and Arabidopsis, and lipidomics analysis and mass spectrometry imaging confirmed the accumulation of neutral lipids in leaves. FIT2 also increased seed oil content by ~13% in some stable, overexpressing lines of Arabidopsis. When expressed transiently in leaves of N. benthamiana or suspension cells of N. tabacum, FIT2 localized specifically to the ER and was often concentrated at certain regions of the ER that resembled ER-LD junction sites. FIT2 also colocalized at the ER with other proteins known to be involved in triacylglycerol biosynthesis or LD formation in plants, but not with ER resident proteins involved in electron transfer or ER-vesicle exit sites. Collectively, these results demonstrate that mouse FIT2 promotes LD accumulation in plants, a surprising functional conservation in the context of a plant cell given the apparent lack of FIT2 homologues in higher plants. These results suggest also that FIT2 expression represents an effective synthetic biology strategy for elaborating neutral lipid compartments in plant tissues for potential biofuel or bioproduct purposes.
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Claims 9
Claim · model-written summary
FIT2 increased lipid droplet number and size in N. benthamiana leaves.
- Taxon
- N. benthamiana
Nicotiana benthamianae0 - Treatment
- expression of FIT2e0
- Gene
- FIT2e0
- Outcome
- number and size of LDse0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“expression of FIT2 dramatically increased the number and size of LDs in leaves of N. benthamiana and Arabidopsis”
Claim · model-written summary
FIT2 increased lipid droplet number and size in Arabidopsis leaves.
- Taxon
- Arabidopsis
Arabidopsise0 - Treatment
- expression of FIT2e0
- Gene
- FIT2e0
- Outcome
- number and size of LDse0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“expression of FIT2 dramatically increased the number and size of LDs in leaves of N. benthamiana and Arabidopsis”
Claim · model-written summary
Neutral lipids accumulated in leaves.
- Outcome
- accumulation of neutral lipids in leavese0
Not reportedTaxon
Verbatim
e0“lipidomics analysis and mass spectrometry imaging confirmed the accumulation of neutral lipids in leaves.”
Claim · model-written summary
FIT2 increased seed oil by about 13% in some Arabidopsis lines.
- Taxon
- ArabidopsisArabidopsise0
- Treatment
- FIT2e0
- Outcome
- seed oil contente0
- Direction
- increasede0
- Value
- ~13%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“FIT2 also increased seed oil content by ~13% in some stable, overexpressing lines of Arabidopsis.”
Claim · model-written summary
FIT2 localized to the ER in N. benthamiana leaves.
- Taxon
- N. benthamianaNicotiana benthamianae0
- Gene
- FIT2e0
- Outcome
- localized specifically to the ERe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When expressed transiently in leaves of N. benthamiana or suspension cells of N. tabacum, FIT2 localized specifically to the ER”
Claim · model-written summary
FIT2 localized to the ER in N. tabacum cells.
- Taxon
- N. tabacum
Nicotiana tabacume0 - Gene
- FIT2e0
- Outcome
- localized specifically to the ERe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When expressed transiently in leaves of N. benthamiana or suspension cells of N. tabacum, FIT2 localized specifically to the ER”
Claim · model-written summary
FIT2 concentrated at ER regions resembling ER-LD junctions.
Not reportedTaxon
Verbatim
e0“FIT2 localized specifically to the ER and was often concentrated at certain regions of the ER that resembled ER-LD junction sites.”
Claim · model-written summary
FIT2 colocalized with proteins involved in triacylglycerol synthesis or LD formation.
- Taxon
- plantsViridiplantaee0
- Gene
- FIT2e0
- Outcome
- colocalized at the ERe0
Verbatim
e0“FIT2 also colocalized at the ER with other proteins known to be involved in triacylglycerol biosynthesis or LD formation in plants”
Claim · model-written summary
FIT2 did not colocalize with ER proteins for electron transfer or vesicle exit.
- Outcome
- not with ER resident proteins involved in electron transfer or ER-vesicle exit sitese0
Not reportedTaxon
Verbatim
e0“but not with ER resident proteins involved in electron transfer or ER-vesicle exit sites.”
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