MST2 proteolysis as a mechanism to modulate HIPPO-YAP activity in breast epithelial cells

• Grant number: 17/18641-3
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• Start date: January 10, 2018
• End date: January 09, 2019
• Field of knowledge: Biological Sciences - Morphology - Cytology and Cell Biology
• Principal Investigator: Alexandre Bruni Cardoso
• Grantee: Ana Paula Zen Petisco Fiore
• Supervisor: Michele Pagano
• Host Institution: Instituto de Química (IQ). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Institution abroad: NYU Langone Medical Center, United States
• Associated to the scholarship: 14/25832-1 - Hippo-YAP pathway as a mediator of extracellular matrix signals in non-malignant and malignant epithelial cells of the mammary gland, BP.PD

Abstract

Chemical and mechanical signals from the basement membrane (BM), an extracellular matrix compartment (ECM), reprogram gene expression leading to quiescence and differentiation of mammary gland epithelial cells. Hippo-YAP, a pathway that regulates organ growth and size, act as a "relay" for mechanical signals from the microenvironment. It is known that the inhibition of HIPPO kinases allows the translocation of YAP to the nucleus, where it acts as a transcription co-activator. The nuclear localization of YAP in epithelial cells has been associated with increased proliferation and malignity. We reported previously that in non-malignant breast cells the reduction of nuclear YAP occurs in response to BM inhibitory signals. This mechanism is disrupted in malignant cells, which exhibit constitutively nuclear YAP and continue to grow. However, the molecular machinery that regulates these events remains unknown. The activation of the serine/threonine kinases MST1 and 2 (HIPPO proteins, which are upstream to YAP) lead to phosphorylation and cytoplasmic retention of YAP. We analyzed the correlation of MST2 expression with YAP localization in "normal" and malignant cells. Our results show that while normal cells display high levels of MST2, in malignant cells MST2 is not detectable. This phenomenon is correlated with the sustained nuclear localization of YAP in malignant cells. Interestingly, malignant cells displayed levels of MST2 mRNA similar to normal cells, indicating that MST2 can be post-transcriptionally regulated in malignant cells. The regulation of MST2 in malignant cells may occur through degradation via 26S proteasome, because our experiments showed that inhibition of the proteolytic pathway increased MST2 levels in malignant cells. Recent data from large-scale experiments indicate that MST2 is a target for E3 ligases, but the identity and mechanism of activation of E3 ligases remain elusive. Thus, the main aim of this proposal is to identify and evaluate the activation of E3 ligases responsible for the recognition and regulation of MST2 levels in malignant cells of the human breast. The conclusion of this study may provide relevant information for the understanding of how malignant cells escape proliferation-inhibitory mechanism induced by the signals from the BM, and the regulation of the HIPPO/YAP pathway in tumorigenesis of breast epithelial cells.

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

ZEN PETISCO FIORE, ANA PAULA; RODRIGUES, ANA MARIA; RIBEIRO-FILHO, HELDER VERAS; MANUCCI, ANTONIO CARLOS; DE FREITAS RIBEIRO, PEDRO; SILVA BOTELHO, MAYARA CAROLINNE; VOGEL, CHRISTINE; LOPES-DE-OLIVEIRA, PAULO SERGIO; PAGANO, MICHELE; BRUNI-CARDOSO, ALEXANDRE. Extracellular matrix stiffness regulates degradation of MST2 via SCF beta TrCP. BIOCHIMICA ET BIOPHYSICA ACTA-GENERAL SUBJECTS, v. 1866, n. 12, p. 11-pg., 2022-09-01. (17/25437-3, 17/18641-3, 18/00629-0, 14/25832-1, 14/10492-0, 17/18067-5, 19/26767-2)

ZEN PETISCO FIORE, ANA PAULA; RIBEIRO, PEDRO DE FREITAS; BRUNI-CARDOSO, ALEXANDRE. Sleeping Beauty and the Microenvironment Enchantment: Microenvironmental Regulation of the Proliferation-Quiescence Decision in Normal Tissues and in Cancer Development. FRONTIERS IN CELL AND DEVELOPMENTAL BIOLOGY, v. 6, JUN 7 2018. (17/18067-5, 14/25832-1, 14/10492-0, 17/18641-3)