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p73 in apoptosis
1Centre for Cancer Research and Cancer Therapy, Institute of Molecular Biology, University of Essen, Medical School, Hufelandstr. 55, D-45122 Essen, Germany.
Abstract:
The TP53 tumour-suppressor gene belongs to a family that includes the two recently identified homologues TP63 and TP73. Overexpression of p73 can activate typical p53-responsive genes and induce apoptosis like p53. In addition, activation of p73 has been implicated in apoptotic cell death induced by aberrant cell proliferation and some forms of DNA-damage. These data together with the localization of TP73 on chromosome 1p36, a region frequently deleted in a variety of human cancers, led to the hypothesis that p73 has tumour suppressor activity just like p53. However, despite its proapoptotic activity in vitro, the lack of tumour-formation in p73 knock-out mice and primary human tumour data demonstrating overexpression of wild-type p73 currently argue against p73 being a classical tumour suppressor. Interestingly, in contrast to TP53, TP73 gives rise to a complex pattern of pro- and antiapoptotic p73 isoforms generated by differential splicing and alternative promoter usage. Therefore further insight into the function and regulation of these structurally and functionally diverse p73 proteins is needed to elucidate the role of TP73 for apoptosis and human tumorigenesis.
Insights
The TP73 gene, similar to TP53, can induce apoptosis but may not act as a classical tumor suppressor. Its complex isoforms and regulation require further study for cancer insights.
Area of Science:
- Molecular Biology
- Genetics
- Cancer Research
Background:
- TP53 is a well-known tumor suppressor gene.
- TP73 is a homolog of TP53, sharing some functions like inducing apoptosis.
- TP73 is located on chromosome 1p36, a region often deleted in cancers.
Purpose of the Study:
- To investigate the tumor suppressor role of TP73.
- To understand the function and regulation of TP73 isoforms.
- To elucidate the role of TP73 in apoptosis and human tumorigenesis.
Main Methods:
- In vitro studies of p73's apoptotic activity.
- Analysis of p73 knockout mice.
- Examination of primary human tumor data for TP73 expression.
Main Results:
- p73 overexpression can activate p53-responsive genes and induce apoptosis.
- p73 knockout mice do not form tumors.
- Primary human tumors show overexpression of wild-type p73.
- TP73 produces diverse pro- and anti-apoptotic isoforms via alternative splicing and promoter usage.
Conclusions:
- Despite pro-apoptotic activity, TP73's role as a classical tumor suppressor is questionable.
- The complex nature of TP73 isoforms suggests a nuanced function in cancer.
- Further research is needed to fully understand TP73's role in apoptosis and tumorigenesis.