The pdx1-/- zebrafish mutant was recently established as a novel animal model of diabetic retinopathy. Here, we investigate whether knockout of pdx1 also leads to diabetic kidney disease (DKD). pdx1-/- larvae exhibit several signs of early DKD such as glomerular hypertrophy, impairments in the filtration barrier corresponding to microalbuminuria and glomerular basement membrane (GBM) thickening. Adult pdx1-/- mutants show progressive GBM thickening in comparison to the larval state. Heterozygous pdx1 knockout also leads to glomerular hypertrophy as initial establishment of DKD similar to the pdx1-/- larvae. RNA sequencing (RNA-seq) of adult pdx1+/- kidneys uncovered regulations in multiple expected diabetic pathways related to podocyte disruption and hinting at early vascular dysregulation without obvious morphological alterations. Metabolome analysis and pharmacological intervention experiments revealed the contribution of phosphatidylethanolamine (PtdE) in the early establishment of kidney damage. In conclusion, this study identified the pdx1 mutant as a novel model for the study of DKD showing signs of the early disease progression already in larval stage and several selective features of later DKD in adult mutants.

Uncontrolled proliferation and altered metabolic reprogramming are hallmarks of cancer. Active glycolysis and glutaminolysis are characteristic features of these hallmarks and required for tumorigenesis. A fine balance between cancer metabolism and autophagy is a prerequisite of homeostasis within cancer cells. Here we show that glutamate pyruvate transaminase 2 (GPT2), which serves as a pivot between glycolysis and glutaminolysis, is highly upregulated in aggressive breast cancers, particularly the triple‐negative breast cancer subtype. Abrogation of this enzyme results in decreased tricarboxylic acid cycle intermediates, which promotes the rewiring of glucose carbon atoms and alterations in nutrient levels. Concordantly, loss of GPT2 results in an impairment of mechanistic target of rapamycin complex 1 activity as well as the induction of autophagy. Furthermore, in vivo xenograft studies have shown that autophagy induction correlates with decreased tumor growth and that markers of induced autophagy correlate with low GPT2 levels in patient samples. Taken together, these findings indicate that cancer cells have a close network between metabolic and nutrient sensing pathways necessary to sustain tumorigenesis and that aminotransferase reactions play an important role in maintaining this balance.

Memory CD8+ T cells mature after antigen clearance and ultimately express CD8 protein at levels higher than those detected in effector CD8+ T cells. However, it is not clear whether engagement of CD8 in the absence of antigenic stimulation will result in the functional activation of T cells. Here, we found that CD8 antibody‐mediated activation of memory CD8+ T cells triggered T cell receptor (TCR) downstream signaling, enhanced T cell‐mediated cytotoxicity and promoted effector cytokine production in a glucose‐ and glutamine‐dependent manner. Furthermore, pretreatment of memory CD8+ T cells with an agonistic anti‐CD8 antibody enhanced their tumoricidal activity in vitro and in vivo. From these studies, we conclude that CD8 agonism activates glucose and glutamine metabolism in memory T cells and enhances the efficacy of memory T cell‐based cancer immunotherapy.

The <i>pdx1</i>^-/- zebrafish mutant was recently established as a novel animal model of diabetic retinopathy. Here, we investigate whether knockout of <i>pdx1</i> also leads to diabetic kidney disease (DKD). <i>pdx1</i>^-/- larvae exhibit several signs of early DKD such as glomerular hypertrophy, impairments in the filtration barrier corresponding to microalbuminuria and glomerular basement membrane (GBM) thickening. Adult <i>pdx1</i>^-/- mutants show progressive GBM thickening in comparison to the larval state. Heterozygous <i>pdx1</i> knockout also leads to glomerular hypertrophy as initial establishment of DKD similar to the <i>pdx1^-/-</i> larvae. RNA sequencing (RNA-seq) of adult <i>pdx1^+/-</i> kidneys uncovered regulations in multiple expected diabetic pathways related to podocyte disruption and hinting at early vascular dysregulation without obvious morphological alterations. Metabolome analysis and pharmacological intervention experiments revealed the contribution of phosphatidylethanolamine (PtdE) in the early establishment of kidney damage. In conclusion, this study identified the <i>pdx1</i> mutant as a novel model for the study of DKD showing signs of the early disease progression already in larval stage and several selective features of later DKD in adult mutants.

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