In vitro hypoxic preconditioning (HP) of mesenchymal stem cells (MSCs) could ameliorate their viability and tissue repair capabilities after transplantation into the injured tissue through yet undefined mechanisms. There is also experimental evidence that HP enhances the expression of both stromal-derived factor-1 (SDF-1) receptors, CXCR4 and CXCR7, which are involved in migration and survival of MSCs in vitro, but little is known about their role in the in vivo therapeutic effectiveness of MSCs in renal ischemia/reperfusion (I/R) injury. Here, we evaluated the role of SDF-1-CXCR4/CXCR7 pathway in regulating chemotaxis, viability and paracrine actions of HP-MSCs in vitro and in vivo. Compared with normoxic preconditioning (NP), HP not only improved MSC chemotaxis and viability but also stimulated secretion of proangiogenic and mitogenic factors. Importantly, both CXCR4 and CXCR7 were required for the production of paracrine factors by HP-MSCs though the former was only responsible for chemotaxis while the latter was for viability. SDF-1α expression was upregulated in postischemic kidneys. After 24 h systemical administration following I/R, HP-MSCs but not NP-MSCs were selectively recruited to ischemic kidneys and this improved recruitment was abolished by neutralization of CXCR4, but not CXCR7. Furthermore, the increased recruitment of HP-MSCs was associated with enhanced functional recovery, accelerated mitogenic response, and reduced apoptotic cell death. In addition, neutralization of either CXCR4 or CXCR7 impaired the improved therapeutic potential of HP-MSCs. These results advance our knowledge about SDF-1-CXCR4/CXCR7 axis as an attractive target pathway for improving the beneficial effects of MSC-based therapies for renal I/R.

Cortical areas including the anterior cingulate cortex (ACC) play critical roles in different types of chronic pain. Most of previous studies focus on the sensory inputs from somatic areas, and less information about plastic changes in the cortex for visceral pain. In this study, chronic visceral pain animal model was established by injection with zymosan into the colon of adult male C57/BL6 mice. Whole cell patch-clamp recording, behavioral tests, western blot, and Cannulation and ACC microinjection were employed to explore the role of adenylyl cyclase 1 (AC1) in the ACC of C57/BL6 and AC1 knock out mice. Integrative approaches were used to investigate possible changes of neuronal AC1 in the ACC after the injury. We found that AC1, a key enzyme for pain-related cortical plasticity, was significantly increased in the ACC in an animal model of irritable bowel syndrome. Inhibiting AC1 activity by a selective AC1 inhibitor NB001 significantly reduced the up-regulation of AC1 protein in the ACC. Furthermore, we found that AC1 is required for NMDA GluN2B receptor up-regulation and increases of NMDA receptormediated currents. These results suggest that AC1 may form a positive regulation in the cortex during chronic visceral pain. Our findings demonstrate that the up-regulation of AC1 protein in the cortex may underlie the pathology of chronic visceral pain; and inhibiting AC1 activity may be beneficial for the treatment of visceral pain.

VapBC toxin-antitoxin (TA) systems are defined by the association of a PIN-domain toxin with a DNA-binding antitoxin, and are thought to play important physiological roles in bacteria and archaea. Recently, the PIN-associated gene pair PIN-COG2442 was proposed to encode VapBC-family TA system and found to be abundant in cyanobacteria. However, the features of these predicted TA loci remain under investigation. We here report characterization of the PIN-COG2442 locus vapBC10 (ssr2962/slr1767) on the chromosome of Synechocystis sp. PCC 6803. RT-PCR analysis revealed that the vapBC10 genes were co-transcribed under normal growth conditions. Ectopic expression of the PIN-domain protein VapC10 caused growth arrest of Escherichia coli that does not possess vapBC TA locus. Coincidentally, this growth-inhibition effect could be neutralized by either simultaneous or subsequent production of the COG2442-domain protein VapB10 through formation of the TA complex VapBC10 in vivo. In contrast to the transcription repression activity of the well-studied antitoxins, VapB10 positively auto-regulated the transcription of its own operon via specific binding to the promoter region. Furthermore, in vivo experiments in E. coli demonstrated that the Synechocystis protease ClpXP2s, rather than Lons, could cleave VapB10 and proteolytically activate the VapC10 toxicity. Our results show that the PIN-COG2442 locus vapBC10 encodes a functional VapBC TA system with an alternative mechanism for the transcriptional auto-regulation of its own operon.

Depression is a frequent and serious comorbidity associated with diabetes which adversely affects prognosis and quality of life. Glucagon-like peptide-1 receptor (GLP-1R) agonists, widely used in the treatment of diabetes, are reported to exert neuroprotective effects in the central nervous system. Thus, we aim to evaluate whether GLP-1R agonist exendin-4 (EX-4) could alleviate depression-like behaviors in diabetic mice and to explore its underlying mechanism. The antidepressant effects of EX-4 were evaluated using behavioral tests in db/db mice. The effects of EX-4 on microglial pyroptosis and neuroinflammation were assessed in N9 microglial cells. EX-4 administration alleviated depression-like behaviors in diabetic db/db mice. GLP-1R activation by EX-4 significantly suppressed microglial pyroptosis and neuroinflammation by downregulation of gasdermin D (GSDMD) and interleukin (IL)-1β in diabetic mice and lipopolysaccharide (LPS)-primed N9 microglia. Mechanistically, GLP-1R activation improved mitochondrial function and promoted mitophagy by decreasing the accumulation of mitochondrial reactive oxygen species (mtROS) and intracellular ROS production. EX-4 exhibits antidepressant effects in depression associated with diabetes in diabetic mice, which may be mediated by inhibiting microglial pyroptisis via promoting mitophagy. It is supposed that GLP-1R agonists may be a promising therapy in depression associated with diabetes.