Thymosin beta 4 may translocate from the cytoplasm in to the nucleus in HepG2 cells following serum starvation. An ultrastructural study.

Piludu M, Piras M, Pichiri G, Coni P, Orrù G, Cabras T, Messana I, Faa G, Castagnola M

PloS one2 Apr 2015Cited by 15 (Europe PMC)

PMID25835495PMCIDPMC4383617DOI10.1371/journal.pone.0119642PepBankPUB-25835495

Summary

Due to its actin-sequestering properties, thymosin beta-4 (Tβ4) is considered to play a significant role in the cellular metabolism. Several physiological properties of Tβ4 have been reported;, however, many questions concerning its cellular function remain to be ascertained. To better understand the role of this small peptide we have analyzed by means of transmission immunoelectron microscopy techniques the ultrastructural localization of Tβ4 in HepG2 cells. Samples of HepG2 cells were fixed in a mixture of 3% formaldehyde and 0.1% glutaraldehyde in 0.1 M cacodylate buffer and processed for standard electron microscopic techniques. The samples were dehydrated in a cold graded methanol series and embedded in LR gold resin. Ultrathin sections were labeled with rabbit antibodies to Tβ4, followed by gold-labeled goat anti-rabbit, stained with uranyl acetate and bismuth subnitrate, observed and photographed in a JEOL 100S transmission electron microscope. High-resolution electron microscopy showed that Tβ4 was mainly restricted to the cytoplasm of HepG2 growing in complete medium. A strong Tβ4 reactivity was detected in the perinuclear region of the cytoplasmic compartment where gold particles appeared strictly associated to the nuclear membrane. In the nucleus specific Tβ4 labeling was observed in the nucleolus. The above electron microscopic results confirm and extend previous observations at light microscopic level, highlighting the subcellular distribution of Tβ4 in both cytoplasmic and nuclear compartments of HepG2 cells. The meaning of Tβ4 presence in the nucleolus is not on the best of our knowledge clarified yet. It could account for the interaction of Tβ4 with nucleolar actin and according with this hypothesis, Tβ4 could contribute together with the other nucleolar acting binding proteins to modulate the transcription activity of the RNA polymerases.

CC BYText from Europe PMC. Highlighted sentences are the source of results.

Results from this study3

No result from this study comes from a test of the peptide.

Natural levels measured3

These results measure the body's own peptide. Nobody was given the peptide. They are not evidence about taking it. They are left out of key results, evidence counts and charts.

01LabEndogenous levelIn vitro (cells)Mechanism
In HepG2 cells grown in complete medium, immunoelectron microscopy showed the cell's own Tβ4 mainly in the cytoplasm.
In plain wordsIn cells, the cell's own Tβ4 sat mainly in the cytoplasm when the cells grew in complete medium.
Peptide
Thymosin beta-4 (human)
Outcome
Not applicableTβ4 localization in cells grown in complete medium
Study
humann: not reported in source
HepG2 cells
Outcome group
Receptor activity and mechanism · Liver
Source sentences
Summary
High-resolution electron microscopy showed that Tβ4 was mainly restricted to the cytoplasm of HepG2 growing in complete medium.
1 context sentence(design, population, supporting numbers)
Summary · context
To better understand the role of this small peptide we have analyzed by means of transmission immunoelectron microscopy techniques the ultrastructural localization of Tβ4 in HepG2 cells.
This result measures the body's own Thymosin beta-4 (human). Nobody was given the peptide. It is not evidence about taking it.
Show in the study text Report a problemFND-2583549501
02LabEndogenous levelIn vitro (cells)Mechanism
In HepG2 cells, strong Tβ4 reactivity was found in the perinuclear cytoplasm, with gold particles tied to the nuclear membrane.
In plain wordsIn cells, the cell's own Tβ4 was strongest in the area around the nucleus, next to the nuclear membrane.
Peptide
Thymosin beta-4 (human)
Outcome
Not applicableTβ4 localization in perinuclear region
Study
humann: not reported in source
HepG2 cells
Outcome group
Receptor activity and mechanism · Liver
Source sentences
Summary
A strong Tβ4 reactivity was detected in the perinuclear region of the cytoplasmic compartment where gold particles appeared strictly associated to the nuclear membrane.
1 context sentence(design, population, supporting numbers)
Summary · context
To better understand the role of this small peptide we have analyzed by means of transmission immunoelectron microscopy techniques the ultrastructural localization of Tβ4 in HepG2 cells.
This result measures the body's own Thymosin beta-4 (human). Nobody was given the peptide. It is not evidence about taking it.
Show in the study text Report a problemFND-2583549502
03LabEndogenous levelIn vitro (cells)Mechanism
In HepG2 cells, specific Tβ4 labeling was seen in the nucleolus.
In plain wordsIn cells, the cell's own Tβ4 was also found in the nucleolus.
Peptide
Thymosin beta-4 (human)
Outcome
Not applicableTβ4 localization in nucleolus
Study
humann: not reported in source
HepG2 cells
Outcome group
Receptor activity and mechanism · Liver
Source sentences
Summary
In the nucleus specific Tβ4 labeling was observed in the nucleolus.
1 context sentence(design, population, supporting numbers)
Summary · context
To better understand the role of this small peptide we have analyzed by means of transmission immunoelectron microscopy techniques the ultrastructural localization of Tβ4 in HepG2 cells.
This result measures the body's own Thymosin beta-4 (human). Nobody was given the peptide. It is not evidence about taking it.
Show in the study text Report a problemFND-2583549503

AI wrote and checked these results. AI can make mistakes, so check important results against the source.

Version history

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Version 2Current
13 Oct 2026, 01:52 UTC
Study results updated
Version 1
12 Oct 2026, 18:17 UTC
First added · source update from Europe PMC

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