Cullin 3–Mediated Regulation of Intracellular Iron Homeostasis Promotes Thymic Invariant NKT Cell Maturation

The E3 ubiquitin ligase cullin 3 (Cul3) is critical for invariant NKT (iNKT) cell development, as iNKT cells lacking Cul3 accumulate in the immature developmental stages. However, the mechanisms by which Cul3 mediates iNKT cell development remain unknown. In this study, we investigated the role of Cul3 in both immature and mature thymic iNKT cells using a mouse model with a T cell–specific deletion of Cul3. We found that mature iNKT cells lacking Cul3 proliferated and died more than wild-type cells did. These cells also displayed increased glucose metabolism and autophagy. Interestingly, we found that tight regulation of iron homeostasis is critical for iNKT cell development. Without Cul3, mature iNKT cells harbored higher levels of cytosolic iron, a phenotype associated with increased cell death. Taken together, our data suggest that Cul3 promotes iNKT cell development partially through intracellular iron homeostasis. ImmunoHorizons, 2023, 7: 235–242

Metabolic modulation by CDK4/6 inhibitor promotes chemokine-mediated recruitment of T cells into mammary tumors

Inhibitors of cyclin-dependent kinases 4 and 6 (CDK4/6i) delay progression of metastatic breast cancer. However, complete responses are uncommon and tumors eventually relapse. Here, we show that CDK4/6i can enhance efficacy of T cell-based therapies, such as adoptive T cell transfer or T cell-activating antibodies anti-OX40/anti-4-1BB, in murine breast cancer models. This effect is driven by the induction of chemokines CCL5, CXCL9, and CXCL10 in CDK4/6i-treated tumor cells facilitating recruitment of activated CD

Novel Roles for Cullin 3 in T Cell-Mediated Immunity

The proper development and function of T lymphocytes depend on a variety of processes. However, the roles of both intracellular iron metabolism and the E3 ubiquitin ligase Cullin 3 in controlling T cell-mediated immunity are vastly understudied. Here, we show that intracellular iron metabolism is crucial for proper CD4 T cell proliferation and mitochondrial function after activation. T cell receptor stimulation leads to coordinated changes in the expression of iron intake, storage, and export proteins as well as drastic loss of cytosolic labile iron levels. This change in cellular iron levels is important for T cell proliferation, as blocking labile iron flux during activation is associated with decreased proliferative capacity. We found that iron controls activated CD4 T cell proliferation by modulating IL-2 receptor signaling and supporting optimal mitochondrial function. We also show that Cullin 3 modulates invariant natural killer T (iNKT) cell development by regulating cellular iron homeostasis. In the absence of Cullin 3, iNKT cells fail to develop and acquire their classical effector phenotype. This block in iNKT cell development also results in hyperproliferation and death of mature iNKT cells lacking Cullin 3. Additionally, Cullin 3 deficient iNKT cells display higher glycolytic activity compared to WT cells, which appears to be detrimental for mature thymic iNKT cells. We also show that mature iNKT cells lacking Cullin 3 harbor higher labile iron levels than wild type cells, potentially leading to increased cell death by ferroptosis during iNKT cell development. Feeding a low iron diet to mice with a T cell-specific deletion of Cullin 3 appears to rescue cellular iron accumulation in mature iNKT cells, revealing a role for Cullin 3 in controlling iNKT cell development by modulating intracellular iron metabolism. Cullin 3 also appears to promote naive CD4 T cell peripheral maintenance by regulating iron homeostasis and tonic signaling. We found that Cullin 3 deficiency leads to a severe loss of naive CD4 T cells in the peripheral tissues. Residual naive CD4 T cells exhibit a pre-activated phenotype characterized by increased proliferation, cytokine production, and TCR signaling molecule expression. Additionally, naive CD4 T cells lacking Cullin 3 resemble effector cells in terms of their expression of iron homeostatic molecules and labile iron levels. Cullin 3 also appears to restrain naive CD4 T cell responses after stimulation, as Cullin 3 deficient naive CD4 T cells proliferate better and secrete more inflammatory cytokines in comparison to wild type cells. This heightened proliferative capacity is also accompanied by an increase in glycolytic metabolism in Cullin 3 deficient naive CD4 T cells. Interestingly, these phenotypes appear to be dependent upon the presence of a polyclonal T cell pool, as expression of the OT-II transgenic T cell receptor by Cullin 3 deficient naive cells prevents naive T cell atrophy. We hypothesize that Cullin 3 may maintain naive CD4 T cell quiescence by modulating intracellular iron levels and inhibiting aberrant T cell receptor signaling in response to either self or gut microbial peptides. In all, my thesis work furthers our understanding of the role of Cullin 3 in controlling T cell-mediated immune responses.PHDImmunologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/172581/1/eyarosz_1.pd

Security sphere : digital image processing

Thesis (M.Eng. and S.B.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2001.Includes bibliographical references (p. 75).by Matthew James Yarosz.M.Eng.and S.B

Regulation of nkt cell metabolism by plzf

Cellular metabolism and signaling pathways are the key regulators to determine T cell fate, survival and function, particularly during activation. Resting CD4 and CD8 T cells use oxidative phosphorylation as a primary energy source but switches to glycolysis upon activation, which is necessary to produce biomolecules for cell proliferation and function. Failure of this reprogramming is detrimental for T cell mediated immunity. However, little is understood about how NKT cells control their metabolism to survive and function. We found that NKT cells operate distinctly different metabolic programming from CD4 T cells for their survival and function. Supporting evidence includes that, unlike CD4 T cells, oxidative phosphorylation seems to be preferred over glycolysis in NKT cells even after stimulation as revealed by lower level of intracellular lactate produced by NKT cells than CD4 cells after activation. These cells also seem to have high energy as revealed by higher ATP in NKT cells. Although the proper maintenance and functions of stimulated NKT cells need glucose, they are sensitive to the elevated glycolytic potential compared to CD4 T cells resulting in spontaneous cell death accompanied by hyperproliferation. Importantly, PLZF is the essential regulator of NKT cells\u27 metabolism so that similar changes of glucose metabolism were found in CD4 T cells expressing PLZF. Conversely, NKT cells with haplodeficient PLZF were more tolerant to increased glycolysis, strongly supporting the key role of PLZF in NKT cell metabolism and homeostasis. We are currently investigating the underlying mechanisms by which PLZF controls metabolism in NKT cells using several approaches including metabolomics