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Proliferation and Differentiation of Murine Myeloid Precursor 32D/G-CSF-R Cells
Published on: February 21, 2018
Characterization of endogenous human promyelocytic leukemia isoforms
Wilfried Condemine1, Yuki Takahashi, Jun Zhu
1Centre National de la Recherche Scientifique UMR7151, Equipe Labellisée par La Ligne Contre le Cancer, Paris Cedex, France.
Abstract:
Promyelocytic leukemia (PML) has been implicated in a variety of functions, including control of TP53 function and modulation of cellular senescence. Sumolated PML is the organizer of mature PML bodies, recruiting a variety of proteins onto these nuclear domains. The PML gene is predicted to encode a variety of protein isoforms. Overexpression of only one of them, PML-IV, promotes senescence in human diploid fibroblasts, whereas PML-III was proposed to specifically interact with the centrosome. We show that all PML isoform proteins are expressed in cell lines or primary cells. Unexpectedly, we found that PML-III, PML-IV, and PML-V are quantitatively minor isoforms compared with PML-I/II and could not confirm the centrosomal targeting of PML-III. Stable expression of each isoform, in a pml-null background, yields distinct subcellular localization patterns, suggesting that, like in other RBCC/TRIM proteins, the COOH-terminal domains of PML are involved in interactions with specific cellular components. Only the isoform-specific sequences of PML-I and PML-V are highly conserved between man and mouse. That PML-I contains all conserved exons and is more abundantly expressed than PML-IV suggests that it is a critical contributor to PML function(s).
Insights
Promyelocytic leukemia (PML) isoforms exhibit distinct cellular localizations, with PML-I/II being the most abundant. Isoform-specific domains of PML proteins mediate interactions with cellular components, highlighting PML-I as a critical functional contributor.
Area of Science:
- Cell Biology
- Molecular Biology
- Cancer Research
Background:
- Promyelocytic leukemia (PML) protein regulates TP53 function and cellular senescence.
- PML protein organizes nuclear bodies and recruits other proteins.
- The PML gene encodes multiple protein isoforms with diverse proposed functions.
Purpose of the Study:
- To investigate the expression and subcellular localization of different Promyelocytic leukemia (PML) protein isoforms.
- To determine the functional significance of distinct PML isoforms and their domains.
- To identify conserved sequences among PML isoforms across species.
Main Methods:
- Analysis of PML isoform expression in cell lines and primary cells.
- Stable expression of PML isoforms in a pml-null background.
- Subcellular localization studies of individual PML isoforms.
- Comparative sequence analysis of human and mouse PML isoforms.
Main Results:
- All predicted PML isoforms are expressed, but PML-III, PML-IV, and PML-V are minor compared to PML-I/II.
- Centrosomal targeting of PML-III was not confirmed.
- Stable expression of each isoform revealed distinct subcellular localization patterns.
- Isoform-specific sequences of PML-I and PML-V are conserved between humans and mice.
Conclusions:
- PML protein isoforms display unique localization patterns, suggesting domain-specific interactions.
- PML-I, being the most abundant and conserved isoform, likely plays a critical role in PML functions.
- The COOH-terminal domains of PML proteins are implicated in interactions with specific cellular components.
