Organelle crosstalk in the kidney.

Organelle damage can cause various kidney diseases. In particular, organelle stress such as decreased proteostatic activity in the endoplasmic reticulum (ER) and altered energy metabolism in mitochondria contribute to glomerular and tubulointerstitial damage, resulting in the progression and development of kidney diseases. The ER regulates protein quality control via the unfolded protein response (UPR) pathway. Pathogenic ER stress leads to dysregulation of this pathway, and a maladaptive UPR is highly deleterious to renal cell function, and thereby has been implicated in the pathophysiology of various kidney diseases. The UPR pathway in the ER also regulates mitochondrial metabolic status, indicating the pathophysiological significance of organelle crosstalk between the ER and mitochondria via the UPR pathway. In recent years, it has become obvious that communication among organelles also is conducted through direct interactions at membrane contact sites (MCSs). Organelles exchange materials including lipids, ions, and proteins at the MCS. Accordingly, alterations to these networks, such as impaired ER-mitochondria MCSs, have been linked to several diseases such as neurodegeneration and diabetes. In this review, we describe the roles of organelles in kidney diseases and the mechanisms underlying organelle communication at the MCS, and especially at the mitochondria-associated ER membrane. Potential treatment options that are focused on organelle crosstalk are discussed, in addition to the relationship between this phenomenon and various diseases, especially kidney diseases.