Quantitative proteomic analysis of dexamethasone-induced effects on osteoblast differentiation, proliferation, and apoptosis in MC3T3-E1 cells using SILAC.

SUMMARY: The impairment of osteoblast differentiation is one cause of the glucocorticoid-induced osteoporosis (GCOP). The quantitative proteomic analysis of the dexamethasone (DEX)-induced effects of osteoblast differentiation, proliferation, and apoptosis using stable-isotope labeling by amino acids in cell culture (SILAC) demonstrated drastic changes of some key proteins in MC3T3-E1 cells. INTRODUCTION: The impairment of osteoblast differentiation is one of the main explanations of GCOP. SILAC enables accurate quantitative proteomic analysis of protein changes in cells to explore the underlying mechanism of GCOP. METHODS: Osteoprogenitor MC3T3-E1 cells were treated with or without 10(−6) M DEX for 7 days, and the differentiation ability, proliferation, and apoptosis of the cells were measured. The protein level changes were analyzed using SILAC and liquid chromatography-coupled tandem mass spectrometry. RESULTS: In this study, 10(−6) M DEX inhibited both osteoblast differentiation and proliferation but induced apoptosis in osteoprogenitor MC3T3-E1 cells on day 7. We found that 10(−6) M DEX increased the levels of tubulins (TUBA1A, TUBB2B, and TUBB5), IQGAP1, S100 proteins (S100A11, S100A6, S100A4, and S100A10), myosin proteins (MYH9 and MYH11), and apoptosis and stress proteins, while inhibited the protein levels of ATP synthases (ATP5O, ATP5H, ATP5A1, and ATP5F1), G3BP-1, and Ras-related proteins (Rab-1A, Rab-2A, and Rab-7) in MC3T3-E1 cells. CONCLUSIONS: Several members of the ATP synthases, myosin proteins, small GTPase superfamily, and S100 proteins may participate in functional inhibition of osteoblast progenitor cells by GCs. Such protein expression changes may be of pathological significance in coping with GCOP.

[Clinical application of self-made drainage tubes in different layers of soft tissue for negative-pressure wound therapy in 33 patients].

From January 2014 to June 2018, 28 patients with different types of deep soft tissue injury or infection were admitted to the Affiliated Jiangyin Hospital of Medical College of Southeast University; 5 patients were admitted to the Zhengzhou First People's Hospital. There were 24 males and 9 females, aged 18-89 (40±20) years. Disposable suction tubes with holes cut on side walls were used as self-made drainage tubes. The authors placed the self-made drainage tubes on different deep soft tissue layers and wound surfaces after debridement. The effective drainage sections of the wound surface drainage tubes were wrapped with silver ion antimicrobial functional active dressings. Bio-permeable membrane was used to close the operative area. The drainage tubes in the deep layer of wound and wound surface were connected in parallel by a tee and connected to wall-hanging medical negative-pressure suction device to conduct negative-pressure wound treatment at -20.0 to -10.6 kPa. The deep drainage tubes were usually removed or changed 4 or 5 days after surgery.The drainage tubes in the wound surface were synchronously replaced when removing or replacing he drainage tubes in the deep layer of wound. On 4 to 15 days after surgery, the deep drainage tubes were removed. On 8 to 25 days after surgery, the wound surface drainage tubes were removed. Then the treatment was changed to a conventional dressing change until the wounds were completely healed or the wound bed was ready for skin grafts or tissue flaps. The indwelling time of deep drainage tubes in this group of patients was (6.2±2.8) days, and the indwelling time of wound surface drainage tubes was (12.0±3.0) days. The wound healing time was (22±5) days, the hospital stay time was (29±7) days, and wound bacteria were reduced from 6 species and 11 strains before treatment to 3 species and 4 strains after treatment. No adverse events such as wound bleeding, irritative pain, and chronic sinus occurred during treatment. Twenty-three patients were followed up for 13 to 28 months, no treatment-related complications were observed.

[Application of self-made vacuum sealing drainage device in postoperative fixation and drainage of abdominal pedicled flaps in 8 patients with deep burns of upper limbs].

From January 2013 to December 2017, 8 patients with deep burns of upper limbs were admitted to our hospital, including 6 males and 2 females, aged 23-48 years. The wound area of full-thickness burns to burns with tendon and bone injury was 4.5 cm×2.0 cm-20.0 cm×10.5 cm. After debridement, thin abdominal flaps with subdermal vascular network in the size of 5.0 cm×2.5 cm-22.0 cm×12.0 cm were applied to cover the wounds, and the donor sites were sutured directly by relaxation. The disposable suction tubes with holes cut on side walls were used as drainage tubes. The part of drainage tubes with holes were wrapped with nano-silver antimicrobial dressings and then placed at the lowest position of pedicle and donor site of abdominal flap and the space between the injured limb and the abdominal wall. The loose nano-silver antibacterial dressing was used to fill the webs of fingers and the gap between the injured limb and the abdominal wall. The transparent film dressing was used to close the surgical area and then connected with a low negative voltage electric suction device to continuously suck at a negative pressure of -15 to -10 kPa. The self-made vacuum sealing drainage device was replaced at intervals of 4 to 5 days until pedicle breakage was performed 2 to 3 weeks after operation. The pedicled abdominal flaps of 8 patients had no torsion or avulsion, no pedicle blood supply disorder, and no infection or skin erosion in the operation area, and all the flaps survived after pedicle breakage.

A stress-induced cellular aging model with postnatal neural stem cells.

This corrects the article DOI: 10.1038/cddis.2014.82.

A stress-induced cellular aging model with postnatal neural stem cells.

Aging refers to the physical and functional decline of the tissues over time that often leads to age-related degenerative diseases. Accumulating evidence implicates that the senescence of neural stem cells (NSCs) is of paramount importance to the aging of central neural system (CNS). However, exploration of the underlying molecular mechanisms has been hindered by the lack of proper aging models to allow the mechanistic examination within a reasonable time window. In the present study, we have utilized a hydroxyurea (HU) treatment protocol and effectively induced postnatal subventricle NSCs to undergo cellular senescence as determined by augmented senescence-associated-ß-galactosidase (SA-ß-gal) staining, decreased proliferation and differentiation capacity, increased G0/G1 cell cycle arrest, elevated reactive oxygen species (ROS) level and diminished apoptosis. These phenotypic changes were accompanied by a significant increase in p16, p21 and p53 expression, as well as a decreased expression of key proteins in various DNA repair pathways such as xrcc2, xrcc3 and ku70. Further proteomic analysis suggests that multiple pathways are involved in the HU-induced NSC senescence, including genes related to DNA damage and repair, mitochondrial dysfunction and the increase of ROS level. Intriguingly, compensatory mechanisms may have also been initiated to interfere with apoptotic signaling pathways and to minimize the cell death by downregulating Bcl2-associated X protein (BAX) expression. Taken together, we have successfully established a cellular model that will be of broad utilities to the molecular exploration of NSC senescence and aging.

Requirement for high mobility group protein HMGI-C interaction with STAT3 inhibitor PIAS3 in repression of alpha-subunit of epithelial Na+ channel (alpha-ENaC) transcription by Ras activation in salivary epithelial cells.

Previously, we have demonstrated that oxidative stress or Ras/ERK activation leads to the transcriptional repression of alpha-subunit of epithelial Na(+) channel (ENaC) in lung and salivary epithelial cells. Here, we further investigated the coordinated molecular mechanisms by which alpha-ENaC expression is regulated. Using both stable and transient transfection assays, we demonstrate that the overexpression of high mobility group protein I-C (HMGI-C), a Ras/ERK-inducible HMG-I family member, represses glucocorticoid receptor (GR)/dexamethasone (Dex)-stimulated alpha-ENaC/reporter activity in salivary epithelial cells. Northern analyses further confirm that the expression of endogenous alpha-ENaC gene in salivary Pa-4 cells is suppressed by an ectopic HMGI-C overexpression. Through yeast two-hybrid screening and co-immunoprecipitation assays from eukaryotic cells, we also discovered the interaction between HMGI-C and PIAS3 (protein inhibitor of activated STAT3 (signal transducer and activator of transcription 3)). A low level of ectopically expressed PIAS3 cooperatively inhibits GR/Dex-dependent alpha-ENaC transcription in the presence of HMGI-C. Reciprocally, HMGI-C expression also coordinately enhances PIAS3-mediated repression of STAT3-dependent transactivation. Moreover, overexpression of antisense HMGI-C construct is capable of reversing the repression mediated by Ras V12 on GR- and STAT3-dependent transcriptional activation. Together, our results demonstrate that Ras/ERK-mediated induction of HMGI-C is required to effectively repress GR/Dex-stimulated transcription of alpha-ENaC gene and STAT3-mediated transactivation. These findings delineate a network of inhibitory signaling pathways that converge on HMGI-C.PIAS3 complex, causally associating Ras/ERK activation with the repression of both GR and STAT3 signaling pathways in salivary epithelial cells.

Oxidative stress disrupts glucocorticoid hormone-dependent transcription of the amiloride-sensitive epithelial sodium channel alpha-subunit in lung epithelial cells through ERK-dependent and thioredoxin-sensitive pathways.

The amiloride-sensitive epithelial Na(+) channel (ENaC) plays a critical role in the maintenance of alveolar fluid balance. It is generally accepted that reactive oxygen and nitrogen species can inhibit ENaC activity and aggravate acute lung injury; however, the molecular mechanism for free radical-mediated ENaC inhibition is unclear. Previously, we showed that the expression of the alpha-subunit of ENaC, alpha-ENaC, which is indispensable for ENaC activity, is repressed by Ras activation in salivary epithelial cells. Here, we investigated whether exogenous H(2)O(2) modulates alpha-ENaC gene expression in lung epithelial cells through a similar molecular mechanism. Utilizing transient transfection reporter assays and site-directed mutagenesis analyses, we found that the glucocorticoid response element (GRE), located at -1334 to -1306 base pairs of the alpha-ENaC 5'-flanking region, is the major enhancer for the stimulated alpha-ENaC expression in A549 lung epithelial cells. We further demonstrate that the presence of an intact GRE is necessary and sufficient for oxidants to repress alpha-ENaC expression. Consistent with our hypothesis, exogenous H(2)O(2)-mediated repression of alpha-ENaC GRE activity is partially blocked by either a specific inhibitor for extracellular signal-regulated kinase (ERK) pathway activation, U0126, or dominant negative ERK, suggesting that, in part, activated ERK may mediate the repressive effects of H(2)O(2) on alpha-ENaC expression. In addition, overexpression of thioredoxin restored glucocorticoid receptor action on the alpha-ENaC GRE in the presence of exogenous H(2)O(2). Taken together, we hypothesize that oxidative stress impairs Na(+) transport activity by inhibiting dexamethasone-dependent alpha-ENaC GRE activation via both ERK-dependent and thioredoxin-sensitive pathways. These results suggest a putative mechanism whereby cellular redox potentials modulate the glucocorticoid receptor/dexamethasone effect on alpha-ENaC expression in lung and other tight epithelia.