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mRNAs for microtubule proteins are specifically colocalized during the sequential formation of basal body, flagella, and cytoskeletal microtubules in the differentiation of Naegleria gruberi.

Han JW, Park JH, Kim M, Lee J - J. Cell Biol. (1997)

Bottom Line: At 70 min after the initiation of differentiation, these mRNAs were relocalized to the base of the growing flagella, adjacent to the basal bodies and microtubule organizing center for the cytoskeletal microtubules.Within an additional 15 min, the mRNAs were translocated to the posterior of the flagellated cells, and by the end of differentiation (120 min), very low levels of the mRNAs were observed.Cytochalasin D inhibited stage-specific localization of the mRNAs, demonstrating that RNA localization was actin dependent.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Yonsei University, Seoul, Korea 120-749.

ABSTRACT
We have examined the distribution of four mRNAs-alpha-tubulin, beta-tubulin, flagellar calmodulin, and Class I mRNA-during differentiation of Naegleria gruberi amebas into flagellates by in situ hybridization. Three of the four mRNAs-alpha-tubulin, beta-tubulin, and Class I mRNA-began to be colocalized at the periphery of the cells as soon as transcription of the respective genes was activated and before any microtubular structures were observable. At 70 min after the initiation of differentiation, these mRNAs were relocalized to the base of the growing flagella, adjacent to the basal bodies and microtubule organizing center for the cytoskeletal microtubules. Within an additional 15 min, the mRNAs were translocated to the posterior of the flagellated cells, and by the end of differentiation (120 min), very low levels of the mRNAs were observed. Cytochalasin D inhibited stage-specific localization of the mRNAs, demonstrating that RNA localization was actin dependent. Since cytochalasin D also blocked differentiation, this raises the possibility that actin-dependent RNA movement is an essential process for differentiation.

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A schematic presentation of localization of the DS mRNAs during differentiation of N. gruberi amebas into flagellates. This  diagram is drawn based on data of our own and from references 6, 10, and 25. Formation of CSMT from the base of flagella is not  shown. The dotted area represents the site of localization of the DS mRNAs.
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Figure 7: A schematic presentation of localization of the DS mRNAs during differentiation of N. gruberi amebas into flagellates. This diagram is drawn based on data of our own and from references 6, 10, and 25. Formation of CSMT from the base of flagella is not shown. The dotted area represents the site of localization of the DS mRNAs.

Mentions: Naegleria gruberi amebas differentiate into swimming flagellates in less than 2 h after initiation of differentiation (6). During differentiation, N. gruberi changes its shape sequentially from an amorphous ameba to a sphere and then to a flagellate with a regular contour, forming two basal bodies, two flagella, and cytoskeletal microtubules (CSMT)1 de novo (see Fig. 7). Using a monoclonal antibody against Naegleria α-tubulin, Walsh showed that Naegleria amebas do not have microtubulebased structures except for the mitotic spindle fibers in dividing cells (25). Microtubule structures first appear in the cytoplasm of a cell ∼50–55 min after initiation of differentiation, and then two basal bodies are formed on the cell periphery. Two flagella begin to appear from the basal bodies, and, at 70 min after initiation of differentiation, 50% of the cells have visible flagella. When the flagella reach about 10 μm in length, 80 min after initiation, a complex array of CSMT is observed radiating from the base of the flagella at which the basal bodies are located. At 120 min after the initiation, the flagella reach full length (∼15 μm) and the cytoskeletal microtubules elongate, reaching the distal end of the cell (25). Thus, the formation of basal bodies appears to be the key step in the formation of the flagella and the CSMT during the differentiation of N. gruberi.


mRNAs for microtubule proteins are specifically colocalized during the sequential formation of basal body, flagella, and cytoskeletal microtubules in the differentiation of Naegleria gruberi.

Han JW, Park JH, Kim M, Lee J - J. Cell Biol. (1997)

A schematic presentation of localization of the DS mRNAs during differentiation of N. gruberi amebas into flagellates. This  diagram is drawn based on data of our own and from references 6, 10, and 25. Formation of CSMT from the base of flagella is not  shown. The dotted area represents the site of localization of the DS mRNAs.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2139841&req=5

Figure 7: A schematic presentation of localization of the DS mRNAs during differentiation of N. gruberi amebas into flagellates. This diagram is drawn based on data of our own and from references 6, 10, and 25. Formation of CSMT from the base of flagella is not shown. The dotted area represents the site of localization of the DS mRNAs.
Mentions: Naegleria gruberi amebas differentiate into swimming flagellates in less than 2 h after initiation of differentiation (6). During differentiation, N. gruberi changes its shape sequentially from an amorphous ameba to a sphere and then to a flagellate with a regular contour, forming two basal bodies, two flagella, and cytoskeletal microtubules (CSMT)1 de novo (see Fig. 7). Using a monoclonal antibody against Naegleria α-tubulin, Walsh showed that Naegleria amebas do not have microtubulebased structures except for the mitotic spindle fibers in dividing cells (25). Microtubule structures first appear in the cytoplasm of a cell ∼50–55 min after initiation of differentiation, and then two basal bodies are formed on the cell periphery. Two flagella begin to appear from the basal bodies, and, at 70 min after initiation of differentiation, 50% of the cells have visible flagella. When the flagella reach about 10 μm in length, 80 min after initiation, a complex array of CSMT is observed radiating from the base of the flagella at which the basal bodies are located. At 120 min after the initiation, the flagella reach full length (∼15 μm) and the cytoskeletal microtubules elongate, reaching the distal end of the cell (25). Thus, the formation of basal bodies appears to be the key step in the formation of the flagella and the CSMT during the differentiation of N. gruberi.

Bottom Line: At 70 min after the initiation of differentiation, these mRNAs were relocalized to the base of the growing flagella, adjacent to the basal bodies and microtubule organizing center for the cytoskeletal microtubules.Within an additional 15 min, the mRNAs were translocated to the posterior of the flagellated cells, and by the end of differentiation (120 min), very low levels of the mRNAs were observed.Cytochalasin D inhibited stage-specific localization of the mRNAs, demonstrating that RNA localization was actin dependent.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Yonsei University, Seoul, Korea 120-749.

ABSTRACT
We have examined the distribution of four mRNAs-alpha-tubulin, beta-tubulin, flagellar calmodulin, and Class I mRNA-during differentiation of Naegleria gruberi amebas into flagellates by in situ hybridization. Three of the four mRNAs-alpha-tubulin, beta-tubulin, and Class I mRNA-began to be colocalized at the periphery of the cells as soon as transcription of the respective genes was activated and before any microtubular structures were observable. At 70 min after the initiation of differentiation, these mRNAs were relocalized to the base of the growing flagella, adjacent to the basal bodies and microtubule organizing center for the cytoskeletal microtubules. Within an additional 15 min, the mRNAs were translocated to the posterior of the flagellated cells, and by the end of differentiation (120 min), very low levels of the mRNAs were observed. Cytochalasin D inhibited stage-specific localization of the mRNAs, demonstrating that RNA localization was actin dependent. Since cytochalasin D also blocked differentiation, this raises the possibility that actin-dependent RNA movement is an essential process for differentiation.

Show MeSH
Related in: MedlinePlus