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Nuclear PTEN deficiency and heterozygous PTEN loss have distinct impacts on brain and lymph node size
Atsushi Igarashi1, Takashi Kato1, Hiromi Sesaki1
1Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Abstract:
Defects in PTEN, a critical tumor suppressor, are associated with tumorigenesis and aberrant organ sizes. It has been shown that heterozygous PTEN loss increases brains and neuron size, while the specific loss of nuclear PTEN has the opposite effect. Here, we investigate the impact of a combination of heterozygous PTEN loss and nuclear PTEN loss on the size of various organs, including the brain, liver, thymus, spleen, and inguinal lymph node. We found that the effect of the combination varies among organs. Notably, the combination of heterozygous PTEN loss and nuclear PTEN loss restored the normal size of brains and neurons. In contrast, the liver's size was unaffected by either single PTEN defects or their combination. Strikingly, the size of the inguinal lymph node was greatly increased due to lymphoma by the combination of the two PTEN defects. These data suggest that nuclear PTEN and non-nuclear PTEN function in an antagonistic manner in the brain while acting synergistically in the inguinal lymph node.
Insights
Investigating PTEN defects reveals complex organ size regulation. Combined PTEN losses restore brain size but cause lymphoma and enlarged lymph nodes, indicating antagonistic and synergistic roles.
Area of Science:
- Oncology
- Cell Biology
- Genetics
Background:
- Defects in the PTEN tumor suppressor gene are linked to cancer and abnormal organ growth.
- Heterozygous PTEN loss enlarges the brain and neurons, while nuclear PTEN loss reduces their size.
Purpose of the Study:
- To examine the combined effects of heterozygous PTEN loss and nuclear PTEN loss on organ sizes.
- To elucidate the distinct roles of nuclear and non-nuclear PTEN in organ development and tumorigenesis.
Main Methods:
- Comparative analysis of organ sizes (brain, liver, thymus, spleen, inguinal lymph node) in genetically modified models.
- Assessment of PTEN's nuclear and non-nuclear functions in regulating cell proliferation and organ homeostasis.
Main Results:
- The combined PTEN defects normalized brain and neuron size, contrasting with individual defects.
- Liver size remained unaffected by single or combined PTEN alterations.
- Inguinal lymph node size significantly increased due to lymphoma, driven by the combined PTEN defects.
Conclusions:
- Nuclear and non-nuclear PTEN exhibit antagonistic functions in the brain but synergistic roles in the inguinal lymph node.
- PTEN's dual localization is critical for precise organ size control and tumor suppression.
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