Glucagon-like peptide-1 receptor undergoes importin-α-dependent nuclear localization in rat aortic smooth muscle cells

Role of G-protein coupled receptors in cardiovascular diseases

Cardiovascular diseases (CVDs) are the leading cause of death globally, with CVDs accounting for nearly 30% of deaths worldwide each year. G-protein-coupled receptors (GPCRs) are the most prominent family of receptors on the cell surface, and play an essential regulating cellular physiology and pathology. Some GPCR antagonists, such as β-blockers, are standard therapy for the treatment of CVDs. In addition, nearly one-third of the drugs used to treat CVDs target GPCRs. All the evidence demonstrates the crucial role of GPCRs in CVDs. Over the past decades, studies on the structure and function of GPCRs have identified many targets for the treatment of CVDs. In this review, we summarize and discuss the role of GPCRs in the function of the cardiovascular system from both vascular and heart perspectives, then analyze the complex ways in which multiple GPCRs exert regulatory functions in vascular and heart diseases. We hope to provide new ideas for the treatment of CVDs and the development of novel drugs.

Nuclear import of PTPN18 inhibits breast cancer metastasis mediated by MVP and importin β2

Distant metastasis is the primary cause of breast cancer-associated death. The existing information, such as the precise molecular mechanisms and effective therapeutic strategies targeting metastasis, is insufficient to combat breast cancer. This study demonstrates that the protein tyrosine phosphatase PTPN18 is downregulated in metastatic breast cancer tissues and is associated with better metastasis-free survival. Ectopic expression of PTPN18 inhibits breast cancer cell metastasis. PTPN18 is translocated from the cytoplasm to the nucleus by MVP and importin β2 in breast cancer. Then, nuclear PTPN18 dephosphorylates ETS1 and promotes its degradation. Moreover, nuclear PTPN18 but not cytoplasmic PTPN18 suppresses transforming growth factor-β signaling and epithelial-to-mesenchymal transition by targeting ETS1. Our data highlight PTPN18 as a suppressor of breast cancer metastasis and provide an effective antimetastatic therapeutic strategy.

Importin alpha 1 is required for the nucleus entry of Fowl Adenovirus serotype 4 Fiber-1 protein

Fiber-1 protein (F1) is the structural protein of Fowl Adenovirus serotype 4 (FAdV-4), which could recondite the receptors of host cytomembrane. In this study, we firstly determined that F1 protein located in nucleus of LMH cells after infection with FAdV-4. We additionally revealed that F1 protein had a classic NLS, and the NLS was required for F1 nucleus entry, which was intently associated to the 26th Pro in NLS. The time rule result indicated that some F1 proteins firstly positioned in the nucleus 6 h posttranfection, and it entirely located in the nucleus 12 h posttranfection, then it ordinarily placed in cytoplasm 18 h posttranfection by means of microscopic fluorescence observation and Western Blotting. Then after transfection with pCI-neo-flag-F1 or infection with FAdV-4, the importin alpha 1 was once investigated whether or not it was required for F1 protein nucleus entry through immunofluorescence and/or Co-IP, results demonstrated that the F1 protein and importin alpha 1 co-located in the nucleus 6 h and 12 h posttranfection. The tiers of F1 protein vicinity in nucleus have been additionally investigated after knockdown expression or overexpression of importin alpha 1, and the results further revealed that importin alpha 1 used to be required for F1 protein nucleus entry. Finally, the function of F1 protein nucleus entry was investigated by qPCR, RT-PCR and Western Blotting, and the results revealed that F1 protein nucleus location was conducive to the proliferation of FAdV-4. In summary, we firstly reveal that the F1 protein of FAdV-4 locates in nucleus infected with FAdV-4, and confirm that importin alpha 1 binds to the NLS of F1 protein to nucleus localization, which promotes the proliferation of FAdV-4.

Karyopherin-mediated nucleocytoplasmic transport

Efficient and regulated nucleocytoplasmic trafficking of macromolecules to the correct subcellular compartment is critical for proper functions of the eukaryotic cell. The majority of the macromolecular traffic across the nuclear pores is mediated by the Karyopherin-β (or Kap) family of nuclear transport receptors. Work over more than two decades has shed considerable light on how the different Kap family members bring their respective cargoes into the nucleus or the cytoplasm in efficient and highly regulated manners. In this Review, we overview the main features and established functions of Kap family members, describe how Kaps recognize their cargoes and discuss the different ways in which these Kap-cargo interactions can be regulated, highlighting new findings and open questions. We also describe current knowledge of the import and export of the components of three large gene expression machines - the core replisome, RNA polymerase II and the ribosome - pointing out the questions that persist about how such large macromolecular complexes are trafficked to serve their function in a designated subcellular location.

Expression of neurotensin receptor-1 (NTS1) in primary breast tumors, cellular distribution, and association with clinical and biological factors

PURPOSE

Neurotensin receptor-1 (NTS₁) is increasingly recognized as a potential target in diverse tumors including breast cancer, but factors associated with NTS₁ expression have not been fully clarified.

METHODS

We studied NTS₁ expression using the Tissue MicroArray (TMA) of primary breast tumors from Institut Bergonié. We also studied association between NTS₁ expression and clinical, pathological, and biological parameters, as well as patient outcomes.

RESULTS

Out of 1419 primary breast tumors, moderate to strong positivity for NTS₁ (≥ 10% of tumoral cells stained) was seen in 459 samples (32.4%). NTS₁ staining was cytoplasmic in 304 tumors and nuclear in 155 tumors, a distribution which appeared mutually exclusive. Cytoplasmic overexpression of NTS₁ was present in 21.5% of all breast tumors. In multivariate analysis, factors associated with cytoplasmic overexpression of NTS₁ in breast cancer samples were higher tumor grade, Ki67 ≥ 20%, and higher pT stage. Cytoplasmic NTS₁ was more frequent in tumors other than luminal A (30% versus 17.3%; p < 0.0001). Contrastingly, the main "correlates" of a nuclear location of NTS₁ were estrogen receptor (ER) positivity, low E&E (Elston and Ellis) grade, Ki67 < 20%, and lower pT stage. In NTS₁-positive samples, cytoplasmic expression of NTS₁ was associated with shorter 10-year metastasis-free interval (p = 0.033) compared to NTS₁ nuclear staining. Ancillary analysis showed NTS₁ expression in 73% of invaded lymph nodes from NTS₁-positive primaries.

CONCLUSION

NTS₁ overexpression was found in about one-third of breast tumors from patients undergoing primary surgery with two distinct patterns of distribution, cytoplasmic distribution being more frequent in aggressive subtypes. These findings encourage the development of NTS₁-targeting strategy, including radiopharmaceuticals for imaging and therapy.