Role of mitochondria-associated membranes (MAMs) in neutrophils under diabetic kidney injury.

Abstract

Type 2 diabetes mellitus (type 2 DM) is a metabolic condition resulting from insulin resistance (IR) that, in 2021, affected approximately 537 million people between 20 and 79 years. Diabetes is a leading cause of chronic kidney disease (CKD) and end-stage renal disease (ESRD), commonly known as diabetic kidney disease (DKD). DKD affects approximately 40% of people with type 2 DM in the United States. Previous studies indicate that IR is associated with a chronic state of inflammation, with increased expression of inflammatory mediators. These immunological alterations are driven by metabolic changes, contributing locally and systemically to the progression of DKD. One of the biomarkers of DKD is the number of neutrophils in the kidney. It is known that, once at the site of action, neutrophils release neutrophil extracellular traps (NETs), which compromise vascular integrity and cause endothelial damage, in part due to the release of reactive oxygen species. As in other cells, neutrophils can modulate their mitochondrial dynamics in response to environmental signals, allowing them to perform various functions, such as chemotaxis, ROS generation, degranulation, and NET formation. Despite the importance of mitochondria, the mitochondrial profile of neutrophils in diabetes is still poorly understood, so it is essential to understand how this organelle may respond to environmental signals. The mitochondrial function is controlled through communication between organelles, a crucial process to maintain cellular homeostasis. This interorganellar communication can occur through direct and indirect contact. Among the many interactions in the cell, this project aims to study the communication between the endoplasmic reticulum (ER) and mitochondria. Mitochondria establish contact with the ER through mitochondria-associated membranes (MAMs). The MAM is a space that plays a fundamental role in controlling several cellular functions, including autophagy, mitochondrial fusion and fission, regulation of redox potential, cellular homeostasis, and production of NETs. Given the role of the MAM in cellular activity, we hypothesize that MAM modulation is essential in neutrophil functionality and progression of DKD. To evaluate this, we will work with different experimental approaches, such as functional and metabolic analysis of neutrophils in the context of DKD, and MAM-specific gene and protein expression. We will also genetically modify zebrafish (Danio rerio), creating a knock-out (KO) model of mitofusin 2 (mfn2), responsible for anchoring organelles in the MAM, specific to neutrophils. DRD will be induced in the animal through a glucose-rich diet, a well-established protocol in the laboratory. We hope to demonstrate that interactions between the ER and mitochondria are essential for neutrophil activation and progression of the inflammatory response and kidney injury.