4,8-dicarboxyl-8,9-iridoid-1-glycoside Promotes Neural Stem Cell Differentiation Through MeCP2

Background

Borojó (Borojoa patinoi Cuatrec) fruit has recently been shown to have a variety of health benefit, but the mechanisms have been little studied. The aim of this study was to investigate the effect of 4,8-dicarboxyl-8,9-iridoid-1-glycoside (388) on proliferation and differentiation of embryonic neural stem cells (NSCs).

Methods

NSCs were treated with 388 and stem cell differentiation was determined by western blotting and immunofluorescence staining. The role of MeCP2 in 388-mediated embryonic NSCs differentiation was examined.

Results

The results showed that in the presence of mitogen when NSCs proliferated and maintained their multipotency, treatment with 388 did not affect the viability of NSCs. Following mitogen withdrawal to initiate NSC differentiation, treatment with 388 at the doses of 10 and 50 μg/mL significantly increased neural differentiation in both cortex and spinal cord-derived culture. 388 also significantly up-regulated MeCP2 expression. The expression of the neuronal and oligodendrocytic markers was enhanced after addition of 388 in the differentiation culture. However, knockdown of MeCP2 results in inhibition of NSC differentiation, and the pro-differentiation effect of 388 was mostly abolished.

Conclusions

This study confirmed that 388 stimulates differentiation of NSCs and identifies its mechanism of action by upregulating MeCP2.

Monocarboxylate transporter 1 and the vulnerability of oligodendrocyte lineage cells to metabolic stresses

AIMS

Oligodendrocytes, especially oligodendrocyte precursor cells, are known to be sensitive to hypoxic and metabolic stresses. Vulnerability of oligodendrocytes is considered a contributing factor to white matter dysfunction. However, little is known about the energy processing characteristics of oligodendrocyte lineage cells under basal and metabolic stress conditions. The aim of this study was to identify the energy requirements and cellular responses of oligodendrocytes at different developmental stages.

METHODS

We compared the metabolic stress responses between myelinating oligodendrocytes (OLs) and oligodendrocyte precursor cells (OPCs). Differential regulation of cellular response was also investigated.

RESULTS

We found that, following cerebral ischemia, monocarboxylate transporter 1 (MCT1) expression was upregulated in the peri-infarct striatum but not in the cortex of the brain. In vitro ischemia models were used to induce oligodendrocyte stress as well. An increase in MCT1 expression was detected in OPCs after a mild oxygen-glucose deprivation. Double-labeled immunohistochemical analysis revealed that OPCs and OLs responded differently to metabolic stresses and that the susceptibility to metabolic stresses of OPCs and OLs was associated with their distinct expression profiles of MCT1.

CONCLUSION

Taken together, this study shows that MCT1 plays a role in the responses of OPCs and OLs to metabolic and ischemic stresses and suggests that redistribution of energy substrates is a determinant in white matter injury.

BNIP3 interacting with LC3 triggers excessive mitophagy in delayed neuronal death in stroke

INTRODUCTION

A basal level of mitophagy is essential in mitochondrial quality control in physiological conditions, while excessive mitophagy contributes to cell death in a number of diseases including ischemic stroke. Signals regulating this process remain unknown. BNIP3, a pro-apoptotic BH3-only protein, has been implicated as a regulator of mitophagy.

AIMS

Both in vivo and in vitro models of stroke, as well as BNIP3 wild-type and knock out mice were used in this study.

RESULTS

We show that BNIP3 and its homologue BNIP3L (NIX) are highly expressed in a "delayed" manner and contribute to delayed neuronal loss following stroke. Deficiency in BNIP3 significantly decreases both neuronal mitophagy and apoptosis but increases nonselective autophagy following ischemic/hypoxic insults. The mitochondria-localized BNIP3 interacts with the autophagosome-localized LC3, suggesting that BNIP3, similar to NIX, functions as a LC3-binding receptor on mitochondria. Although NIX expression is upregulated when BNIP3 is silenced, up-regulation of NIX cannot functionally compensate for the loss of BNIP3 in activating excessive mitophagy.

CONCLUSIONS

NIX primarily regulates basal level of mitophagy in physiological conditions, whereas BNIP3 exclusively activates excessive mitophagy leading to cell death.

Mitochondrial BNIP3 upregulation precedes endonuclease G translocation in hippocampal neuronal death following oxygen-glucose deprivation

Background

Caspase-independent apoptotic pathways are suggested as a mechanism for the delayed neuronal death following ischemic insult. However, the underlying signalling mechanisms are largely unknown. Recent studies imply the involvement of several mitochondrial proteins, including endonuclease G (EndoG) and Bcl-2/adenovirus E1B 19 kDa-interacting protein (BNIP3), in the pathway of non-neuronal cells.

Results

In this report, using western blot analysis and immunocytochemistry, we found that EndoG upregulates and translocates from mitochondria to nucleus in a time-dependent manner in cultured hippocampal neurons following oxygen-glucose deprivation (OGD). Moreover, the translocation of EndoG occurs hours before the observable nuclear pyknosis. Importantly, the mitochondrial upregulation of BNIP3 precedes the translocation of EndoG. Forced expression of BNIP3 increases the nuclear translocation of EndoG and neuronal death while knockdown of BNIP3 decreases the OGD-induced nuclear translocation of EndoG and neuronal death.

Conclusion

These results suggest that BNIP3 and EndoG play important roles in hippocampal neuronal apoptosis following ischemia, and mitochondrial BNIP3 is a signal protein upstream of EndoG that can induce neuronal death.

Genomic organization of the canine p53 gene and its mutational status in canine mammary neoplasia

To determine whether canine malignancies share common genetic lesions with their human counterparts, and are thus potentially interesting model systems in which to pose questions regarding tumor etiology and progression, we have elucidated the entire exon/intron structure of the canine p53 gene. A search for p53 gene abnormalities in mammary tumor tissue was undertaken utilizing single strand conformation polymorphism analysis. Mutations were detected in exons 4, 5, 6, and 7 of the p53 gene and consisted of nonsense, splicing, and frameshift mutations. None of 11 benign tumors and 6 of 40 primary carcinomas (15%) were found to harbor subtle p53 mutations. In 14 carcinomas examined the results in primary tumors and metastases were the same. These findings implicate involvement of this gene in the genesis of some malignant canine tumors, in a fashion similar to their human counterparts.

The ascending branch of the lateral circumflex femoral artery. A new supply for vascularized iliac transplantation

The ascending branch of lateral circumflex femoral a. was studied in 66 adult limbs in terms of its anatomical description and clinical relevance. The anatomical findings suggest that the ascending branch could be used as an ideal supply for vascularized iliac transplantation. This new technique has been widely used in China since 1984 with satisfactory results.

Microsurgical anatomy in China

This is a general review on the recent advances made in China of microsurgical anatomy. In recent years, more than 300 research papers and a number of monographs on microsurgical anatomy have been published in China. In the research of skin and musculocutaneous flaps, much applied anatomical data about more than 30 new donor areas have been collected and the investigations on the patterns of the blood supply of the flaps are instructively significant to clinical practice. New donor areas have also been introduced for scapular, radial, tibial and other bone flaps, and the range of indications for using the periosteal and cartilaginous flaps has been broadened. On the basis of the technique of superficial lymphaticovenous anastomosis, new information for deep typhaticovenous anastomosis has been provided by clinical anatomists. Through experimental research, the anatomists pointed out that lymphatic vessels with contracting ability should be selected for anastomosis in order to enhance the long term effect of the operation. The successful experiment of bridging the peripheral nerve gap with skeletal muscle, which has been clinically used, has opened up a hopeful prospect for solving the problem of the unavailability of autogenous nerve donors. The identification of nerve fascicles in the nerve trunk provides a morphological basis for the selection of different suture patterns. In addition, much research work has been done on the tranplantation of the suprarenal gland, pancreas, parathyroid gland, testis, kidney of foetus and other small organs.

Applied anatomy of the anterolateral femoral flap

A study of the source of the blood supply to the anterolateral femoral flap was carried out on 42 lower limbs of adult cadavers (among them 35 cadavers with injection of red latex and 1 with india ink into the arteries and 6 vascular cast specimens), and the surface locations of the vascular pedicle were detected on 50 healthy adults. It was found that the descending branch of the lateral circumflex femoral vessel was an ideal axial vessel. There are constant perforating branches of the myocutaneous artery or cutaneous branches from the intermuscular space to the anterolateral femoral skin. The area extends about 12 x 30 cm. Within the flap, the anterior branch of the anterolateral cutaneous nerve of the high is located. This flap has been widely used for free transplantation in China since 1983 with satisfactory results.

Experimental study of bridging the peripheral nerve gap with skeletal muscle

A piece of skeletal muscle was used as a conduit to bridge the gap microsurgically between the two ends of the severed sciatic nerve in 30 rats, and a method for histochemical demonstration of acetylcholinesterase was employed to assess the nerve regeneration process 5 weeks or more after the operation. Regenerating nerve fibers were detected in the muscle and could be traced through to the distal stump of the severed sciatic nerve. This suggests that skeletal muscle might serve as a grafting conduit for the repairing of peripheral nerve injuries.