Mitochondria with tubulovesicular cristae in renal oncocytomas

The Emerging Role of Mitochondrial Targeting in Kidney Disease

Renal disease affects millions of people worldwide, imposing an enormous financial burden for health-care systems. Recent evidence suggests that mitochondria play an important role in the pathogenesis of different forms of renal disease, including genetic defects, acute kidney injury, chronic kidney disease, aging, renal tumors, and transplant nephropathy. Renal mitochondrial abnormalities and dysfunction affect several cellular pathways, leading to increased oxidative stress, apoptosis, microvascular loss, and fibrosis, all of which compromise renal function. Over recent years, compounds that specifically target mitochondria have emerged as promising therapeutic options for patients with renal disease. Although the most compelling evidence is based on preclinical studies, several compounds are currently being tested in clinical trials. This chapter provides an overview of the involvement of mitochondrial dysfunction in renal disease and summarizes the current knowledge on mitochondria-targeted strategies to attenuate renal disease.

Amazing structure of respirasome: unveiling the secrets of cell respiration

Respirasome, a huge molecular machine that carries out cellular respiration, has gained growing attention since its discovery, because respiration is the most indispensable biological process in almost all living creatures. The concept of respirasome has renewed our understanding of the respiratory chain organization, and most recently, the structure of respirasome solved by Yang's group from Tsinghua University (Gu et al. Nature 237(7622):639-643, 2016) firstly presented the detailed interactions within this huge molecular machine, and provided important information for drug design and screening. However, the study of cellular respiration went through a long history. Here, we briefly showed the detoured history of respiratory chain investigation, and then described the amazing structure of respirasome.

Chromophobe renal cell carcinoma, oncocytic variant: Cytological and ultrastructural observations

There is only one report on cytological findings of oncocytic variant of chromophobe renal cell carcinoma (RCC). In this article, we report a new case with focus on cytological, and ultrastructural findings. A 60-year-old Japanese man was found to have a right renal tumor on medical checkup. In imprint cytological materials, the smears consisted of slightly discohesive clusters and isolated tumor cells with granular green colored cytoplasm on Papanicolaou staining. Nuclei were generally round and centrally located in the cytoplasm, but nuclear irregularity or perinuclear halo was absent. Ultrastructurally, the tumor was full of mitochondria with tubulovesicular cristae. Fluorescence in situ hybridization study using histological material showed multiple chromosomal losses including chromosomes 7, 10, 13, and 17. This finding supports the hypothesis that this variant may ultrastructurally show the nature of chromophobe RCC rather than renal oncocytoma.

Chronic kidney disease, severe arterial and arteriolar sclerosis and kidney neoplasia: on the spectrum of kidney involvement in MELAS syndrome

BACKGROUND

MELAS syndrome (MIM ID#540000), an acronym for Mitochondrial Encephalopathy, Lactic Acidosis and Stroke-like episodes, is a genetically heterogeneous mitochondrial disorder with protean manifestations and occasional kidney involvement. Interest in the latter is rising due to the identification of cases with predominant kidney involvement and to the hypothesis of a link between mitochondrial DNA and kidney neoplasia.

CASE PRESENTATION

We report the case of a 41-year-old male with full blown MELAS syndrome, with lactic acidosis and neurological impairment, affected by the "classic" 3243A > G mutation of mitochondrial DNA, with kidney cancer. After unilateral nephrectomy, he rapidly developed severe kidney functional impairment, with nephrotic proteinuria. Analysis of the kidney tissue at a distance from the two tumor lesions, sampled at the time of nephrectomy was performed in the context of normal blood pressure, recent onset of diabetes and before the appearance of proteinuria. The morphological examination revealed a widespread interstitial fibrosis with dense inflammatory infiltrate and tubular atrophy, mostly with thyroidization pattern. Vascular lesions were prominent: large vessels displayed marked intimal fibrosis and arterioles had hyaline deposits typical of hyaline arteriolosclerosis. These severe vascular lesions explained the different glomerular alterations including ischemic and obsolescent glomeruli, as is commonly observed in the so-called "benign" arteriolonephrosclerosis. Some rare glomeruli showed focal segmental glomerulosclerosis; as the patient subsequently developed nephrotic syndrome, these lesions suggest that silent ischemic changes may result in the development of focal segmental glomerulosclerosis secondary to nephron loss.

CONCLUSIONS

Nephron loss may trigger glomerular sclerosis, at least in some cases of MELAS-related nephropathy. Thus the incidence of kidney disease in the "survivors" of MELAS syndrome may increase as the support therapy of these patients improves.