Effects of leptin on Jurkat cell metabolism

• Grant number: 21/13119-2
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate (Direct)
• Start date: May 01, 2022
• End date: April 30, 2023
• Field of knowledge: Biological Sciences - Physiology - General Physiology
• Principal Investigator: Renata Gorjao
• Grantee: Vinicius Leonardo Sousa Diniz
• Supervisor: Philip Newsholme
• Host Institution: Pró-Reitoria de Pós-Graduação e Pesquisa. Universidade Cruzeiro do Sul (UNICSUL). São Paulo , SP, Brazil
• Institution abroad: Curtin University, Australia
• Associated to the scholarship: 17/07818-0 - Effects of leptin on lymphocyte metabolism and differentiation, BP.DD

Abstract

The main physiological function of leptin is to signal negative energy balance and decrease energy reserves. In addition to the important function in metabolism, leptin can participate in several processes, including immune response modulation. Lymphocytes express the long form of the leptin receptor (OB-Rb) and, therefore, suffer direct effects from leptin on their functions. The activation of lymphocytes is associated with specific metabolic pathways to optimize their function. The integration of multiple extracellular signals affects transcriptional programs and signaling pathways that determine, in CD4+ T cells, multiple events that include the modulation of energy metabolism, cell proliferation, and cytokine production. The main pathway of leptin is the JAK-STAT pathway, however, leptin activates other signaling pathways that are important for cell metabolism such as the target protein of rapamycin in mammals (mTOR), AMP-activated protein kinase (AMPK), and Hypoxia-inducible factor 1-alpha (HIF1a). mTOR and AMPK play important and distinct roles in metabolism and immunity. The HIF1± dependent transcriptional program is important to mediate glycolytic activity, thus contributing to the polarization toward Th1 and Th17 profiles. The mTOR protein is involved with greater differentiation to Th1 lymphocytes and less polarization toward T regulatory (Treg) cells. Although many studies addressing the effect of leptin on the immune system have been published, the effect of this adipokine on the metabolism of these cells is still unclear. Description of leptin effects on the metabolism of immune cells, as well as the signaling pathways used in these processes, will be of great help in the development of therapeutic alternatives for the treatment of diseases such as T cell lymphoma (TCL). Therefore, our study aims to evaluate the effect of leptin on signaling pathways and the metabolism of T lymphocytes. Initially, Jurkat cells will be treated for 24 h with recombinant human leptin at 0, 50, 100, and 200 ng/mL. Oxygen consumption rate (OCR) and proton production rate (PPR) will be measured as previously described using the Seahorse Extracellular Flux Analyzer. The phosphorylation and total expression of proteins involved with leptin signaling related to cell metabolism will be evaluated by Western blotting. Metabolic profiling will be analyzed by using NMR and mass spectrometry, available in the Australian National Phenome Centre at Murdoch University (Perth, WA). We expect, at the end of this project, to determine the lymphocyte bioenergetic characteristics modulated by leptin and the signaling pathways involved in this process. (AU)