Acute kidney injury and regulated cell death / 生理学报

Acute kidney injury (AKI) refers to a clinical syndrome in which renal function declines rapidly in a short period of time caused by various pathological factors. During the development of AKI, renal tubules with the functions of reabsorption and excretion are prone to cell death due to external pathological stimuli, which is an important cause of impaired renal function. In recent years, a variety of new cell death pathways have been gradually recognized. Researchers have now found that regulated cell death (RCD), such as necroptosis, pyroptosis and ferroptosis, are important regulatory mechanisms of AKI. This article will summarize the research advances of various types of RCD involved in the process of AKI, aiming to deepen the understanding of AKI and provide innovative thoughts for the clinical treatment of AKI.

Advances in mechanism of autophagy in renal tubular injury / 生理学报

Autophagy is a lysosome-dependent degradation process that eliminates damaged macromolecular proteins and aging organelles to maintain intracellular homeostasis. Autophagy is observed in almost all eukaryotic cells and plays important roles in many cellular physiological processes, including the cell proliferation and growth, cellular functional alteration and phenotypical transition. Renal tubule is an important target for renal injury under different pathological conditions. Following the discoveries of the molecular basis of autophagy, accumulated lines of evidence have indicated that autophagy dysfunction in tubule is involved in the pathogenesis of many renal diseases. This review will summarize the recent progress in molecule mechanism of autophagy and its roles in renal tubular injury.

Isolation and culture of renal glomeruli from rats / 生理学报

The aim of the study was to establish a method for isolation and culture of rat renal glomeruli. The renal glomeruli of Sprague Dawley (SD) rats were isolated by a sieving method, and Bowman's capsule was removed by digesting the glomeruli in 0.5% type IV collagenase. The inverted phase contrast microscope was used to observe the structure of isolated renal glomeruli, and trypan blue staining was used to identify the activity of cells in glomeruli. Expressions of nephrin and α-smooth muscle actin (α-SMA) were observed by double-labeling immunofluorencence. Effects of Ang II on reactive oxygen species (ROS) generation were detected by dihydroethidium (DHE) staining. The levels of transforming growth factor-beta 1 (TGF-β1) and collagen IV mRNA were measured by real-time PCR. The results showed that the renal glomeruli with high purity and intact capillary structure were isolated by the modified protocol. The cells in the isolated glomeruli remained alive after 48 h of culture in DMEM. Confocal microscopy observations showed that nephrin and α-SMA were highly expressed in the isolated glomeruli. Treatment of the isolated renal glomeruli with Ang II enhanced ROS production. Furthermore, Ang II increased the mRNA levels of TGF-β1 and collagen IV. In conclusion, we have established a modified method that can isolate glomeruli from rat kidney, and the isolated glomeruli can be used for further observation in cultured condition. The protocol will provide a useful method for preclinical research on kidney diseases.

Expression of renin/prorenin receptor in rat kidney and cultured mesangial cells / 生理学报

The renin/prorenin receptor (RnR) has recently been cloned and demonstrated to exist in different cells in the cardiovascular and renal systems, playing an important role in physiological and pathophysiological situations. In the present study, we used immunofluorescence method to identify whether and where the RnR expressed in cultured rat renal mesangial cells (MCs) and rat kidney. By using the prorenin handle region peptide (HRP) as a decoy peptide of the RnR, we observed the distribution of the HRP-RnR complex in the MCs. Our results showed that the RnR was localized in the perinuclear zone and plasma membrane of the MCs. At the organ level, the RnR was observed in the mesangium of cortical glomeruli in rat kidney. The FITC-labeled HRP (FITC-HRP) translocated from cell culture medium into the cytoplasm within 30 s. Colocalization of the HRP and RnR was observed mainly on the cell membrane and in the perinuclear zone of cytoplasm by using immunofluorescence and confocal microscopy. At 30 min the FITC-HRP was mainly observed in the nucleus while the RnR remained in the perinuclear zone of cytoplasm. Taken together, our results confirm the expression of RnR in the renal MCs. It is suggested that internalization of the RnR after binding with its ligand is at least one of the pathways through which the RnR exerts its biological actions.

Blockade of NMDA receptor enhances corticosterone-induced downregulation of brain-derived neurotrophic factor gene expression in the rat hippocampus through cAMP response element binding protein pathway / 生理学报

High concentration of corticosterone leads to morphological and functional impairments in hippocampus, ranging from a reversible atrophy of pyramidal CA3 apical dendrites to the impairment of long-term potentiation (LTP) and hippocampus-dependent learning and memory. Glutamate and N-methyl-D-aspartate (NMDA) receptor play an important role in this effect. Because of the importance of brain-derived neurotrophic factor (BDNF) in the functions of the hippocampal neurons, alteration of the expression of BDNF is thought to be involved in the corticosterone effect on the hippocampus. To determine whether change in BDNF in the hippocampus is involved in the corticosterone effect, we injected corticosterone (2 mg/kg, s.c.) to Sprague-Dawley rats and measured the mRNA, proBDNF and mature BDNF protein levels in the hippocampus. We also measured the phosphorylation level of the transcription factor cAMP response element binding protein (CREB). Furthermore, we intraperitoneally injected NMDA receptor antagonist MK801 (0.1 mg/kg) 30 min before corticosterone administration to investigate whether and how MK801 affected the regulation of BDNF gene expression by corticosterone. Our results showed that 3 h after single s.c. injection of corticsterone, the expression of BDNF mRNA, proBDNF and mature BDNF protein decreased significantly (P<0.01). MK801 promoted the downregulation of BDNF gene expression in the rat hippocampus by corticosterone. We also found that either applying corticosterone or co-applying corticosterone with MK801 downregulated the phosphoration level of CREB, the latter (corticosterone plus MK801) being more effective (P<0.05). Taken together, our results indicate that corticosterone downregulates BDNF gene expression in the rat hippocampus through CREB pathway and that blockade of NMDA receptor enhances this effect of corticosterone in reducing BDNF expression.

Construction of pcDNA3.1AM and expression of adrenomedullin in mammalian cells / 生理学报

The newly discovered endogenous vasodilating and diuretic peptide adrenomedullin (AM) was considered to be of attractive value in clinical treatment of hypertension and congestive heart failure. In order to explore the treatment of cardiovascular diseases by expressing AM in vivo, AM cDNA was inserted into mammalian expressing vector pcDNA3.1, and in vitro expression of AM was carried out in cultured K(562) cell line. AM mRNA was amplified by RT-PCR from the total RNA isolated from the adrenal glands of rats and was inserted into pcDNA3.1 vector to form pcDNA3.1AM, the recombinant pcDNA3.1AM was then transferred into cultured K(562) cell line by liposome. The expression of AM in pcDNA3.1AM transferred cell was identified by RT-PCR and dot immunoblot assay. The results demonstrated that there were AM mRNA in the pcDNA3.1AM-transferred K(562) cell line and AM peptides in the culturing medium, indicating that the recombinant pcDNA3.1AM vector can express AM in mammalian cell line.