scholarly journals Actin mRNA localizes in the absence of protein synthesis.

1990 ◽  
Vol 111 (6) ◽  
pp. 2397-2403 ◽  
Author(s):  
C L Sundell ◽  
R H Singer
Keyword(s):  
Protein Synthesis ◽  
Spatial Distribution ◽  
Chicken Embryo ◽  
Mrna Localization ◽  
Cell Periphery ◽  
Nascent Polypeptide ◽  
Actin Mrna ◽  
Chicken Embryo Fibroblasts ◽  
In Cells

Actin mRNA is localized in chicken embryo fibroblasts to the distal regions of leading lamellae, but not within the ruffling edges. In this investigation we have addressed the role of actin translation in this process. The translocation of actin mRNA to the cell periphery was studied by monitoring the distribution of actin mRNA in cells during spreading. Within 90 min, actin mRNA moved from a perinuclear to a peripheral distribution. Formation of lamellipodia preceded actin mRNA localization, indicating that localization is not a prerequisite for this event. Neither puromycin (which dissociates ribosomes from mRNA) nor cycloheximide (which stabilizes ribosomes on mRNA) had any effect on this movement of actin mRNA. Anchoring of actin mRNA was studied using cells with peripherally localized actin mRNA. No change in actin mRNA localization was observed for 30 min in the same inhibitors. These data indicate that the presence of the nascent polypeptide is not necessary for translocation of actin mRNA to the cell periphery, or anchoring at that site. This suggests that the mRNA contains information concerning its spatial distribution within the cytoplasm.

scholarly journals Visualization of mRNA translation in living cells

2006 ◽  
Vol 175 (1) ◽  
pp. 67-76 ◽  
Author(s):  
Alexis J. Rodriguez ◽  
Shailesh M. Shenoy ◽  
Robert H. Singer ◽  
John Condeelis
Keyword(s):  
Mrna Translation ◽  
Leading Edge ◽  
Intercellular Junctions ◽  
Mrna Localization ◽  
Living Cells ◽  
C2c12 Cells ◽  
Cell Periphery ◽  
Actin Mrna ◽  
Cell Asymmetry ◽  
Cellular Compartments

The role of mRNA localization is presumably to effect cell asymmetry by synthesizing proteins in specific cellular compartments. However, protein synthesis has never been directly demonstrated at the sites of mRNA localization. To address this, we developed a live cell method for imaging translation of β-actin mRNA. Constructs coding for β-actin, containing tetracysteine motifs, were transfected into C2C12 cells, and sites of nascent polypeptide chains were detected using the biarsenial dyes FlAsH and ReAsH, a technique we call translation site imaging. These sites colocalized with β-actin mRNA at the leading edge of motile myoblasts, confirming that they were translating. β-Actin mRNA lacking the sequence (zipcode) that localizes the mRNA to the cell periphery, eliminated the translation there. A pulse-chase experiment on living cells showed that the recently synthesized protein correlated spatially with the sites of its translation. Additionally, localization of β-actin mRNA and translation activity was enhanced at cell contacts and facilitated the formation of intercellular junctions.

scholarly journals Hook3 is a scaffold for the opposite-polarity microtubule-based motors cytoplasmic dynein-1 and KIF1C

2019 ◽  
Vol 218 (9) ◽  
pp. 2982-3001 ◽  
Author(s):  
Agnieszka A. Kendrick ◽  
Andrea M. Dickey ◽  
William B. Redwine ◽  
Phuoc Tien Tran ◽  
Laura Pontano Vaites ◽  
...  
Keyword(s):  
Cytoplasmic Dynein ◽  
Opposite Polarity ◽  
Full Length ◽  
Cell Periphery ◽  
Long Distance ◽  
Short Region ◽  
Cargo Transport ◽  
In Cells

The unidirectional and opposite-polarity microtubule-based motors, dynein and kinesin, drive long-distance intracellular cargo transport. Cellular observations suggest that opposite-polarity motors may be coupled. We recently identified an interaction between the cytoplasmic dynein-1 activating adaptor Hook3 and the kinesin-3 KIF1C. Here, using in vitro reconstitutions with purified components, we show that KIF1C and dynein/dynactin can exist in a complex scaffolded by Hook3. Full-length Hook3 binds to and activates dynein/dynactin motility. Hook3 also binds to a short region in the “tail” of KIF1C, but unlike dynein/dynactin, this interaction does not activate KIF1C. Hook3 scaffolding allows dynein to transport KIF1C toward the microtubule minus end, and KIF1C to transport dynein toward the microtubule plus end. In cells, KIF1C can recruit Hook3 to the cell periphery, although the cellular role of the complex containing both motors remains unknown. We propose that Hook3’s ability to scaffold dynein/dynactin and KIF1C may regulate bidirectional motility, promote motor recycling, or sequester the pool of available dynein/dynactin activating adaptors.

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