Messenger RNA in the cytoskeletal framework: analysis by in situ hybridization
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Abstract:
The possibility of an association of mRNA with the cytoskeletal framework (CF) of ascidian (Styela plicata) follicle cells was examined in this study. The approach was to extract the follicle cells with Triton X-100 and determine whether mRNA persisted in the insoluble residue by two methods, in situ hybridization with poly(U) and actin DNA probes and the incorporation of radioactive isotopes into RNA. Triton X-100 extraction of follicle cells yielded a filamentous CF containing approximately 70% of the total poly (A) but only 9% of the total lipid, 23% of the total protein, and 28% of the total RNA. In situ hybridization with a poly (U) probe indicated that approximately 70% of the poly (A) was associated with the CF. In situ hybridization with a cloned actin DNA probe indicated that approximately 60% of the actin mRNA was associated with the CF. Autoradiography of detergent-extracted follicle cells, which had been labeled with [3H]uridine or [3H]adenosine, indicated that greater than 90% of the newly synthesized poly (A)+RNA was preserved in the CF. Thus more newly synthesized mRNA than steady-state mRNA may be present in the Triton X-100 insoluble fraction. It is concluded that a significant proportion of the mRNA complement of ascidian follicle cells is associated with the CF.
Insights
Messenger RNA (mRNA) is associated with the cytoskeletal framework (CF) in ascidian follicle cells. This study reveals a significant portion of cellular mRNA is bound to the CF, impacting cellular organization and gene expression.
Area of Science:
- Cell Biology
- Molecular Biology
- Developmental Biology
Background:
- The localization of messenger RNA (mRNA) within cells is crucial for regulating protein synthesis and cellular function.
- The cytoskeletal framework (CF) provides structural support and facilitates intracellular transport, but its role in mRNA localization is not fully understood.
Purpose of the Study:
- To investigate the association of mRNA with the cytoskeletal framework (CF) in ascidian (Styela plicata) follicle cells.
- To determine the proportion of total and newly synthesized mRNA associated with the detergent-insoluble fraction representing the CF.
Main Methods:
- Follicle cells were extracted using Triton X-100 to isolate the filamentous cytoskeletal framework (CF).
- In situ hybridization with poly(U) and actin DNA probes was employed to localize polyadenylated mRNA and actin mRNA within the CF.
- Incorporation of radioactive isotopes ([3H]uridine, [3H]adenosine) into RNA was used to assess the association of newly synthesized mRNA with the CF via autoradiography.
Main Results:
- Triton X-100 extraction yielded a CF containing a significant portion of total poly(A) (approx. 70%) and mRNA (approx. 60% of actin mRNA).
- In situ hybridization confirmed the association of poly(A) and actin mRNA with the CF.
- Autoradiography demonstrated that over 90% of newly synthesized poly(A)+RNA remained associated with the CF after detergent extraction, suggesting newly synthesized mRNA is preferentially bound.
Conclusions:
- A significant proportion of mRNA in ascidian follicle cells is associated with the cytoskeletal framework.
- This association may be particularly strong for newly synthesized mRNA, potentially influencing its translation and stability.
- The findings highlight the role of the CF in mRNA localization and regulation within these cells.