Inhibition of Drp1- Fis1 interaction alleviates aberrant mitochondrial fragmentation and acute kidney injury

BACKGROUND

Acute kidney injury (AKI) is a common clinical disorder with complex etiology and poor prognosis, and currently lacks specific and effective treatment options. Mitochondrial dynamics dysfunction is a prominent feature in AKI, and modulation of mitochondrial morphology may serve as a potential therapeutic approach for AKI.

METHODS

We induced ischemia-reperfusion injury (IRI) in mice (bilateral) and Bama pigs (unilateral) by occluding the renal arteries. ATP depletion and recovery (ATP-DR) was performed on proximal renal tubular cells to simulate in vitro IRI. Renal function was evaluated using creatinine and urea nitrogen levels, while renal structural damage was assessed through histopathological staining. The role of Drp1 was investigated using immunoblotting, immunohistochemistry, immunofluorescence, and immunoprecipitation techniques. Mitochondrial morphology was evaluated using confocal microscopy.

RESULTS

Renal IRI induced significant mitochondrial fragmentation, accompanied by Dynamin-related protein 1 (Drp1) translocation to the mitochondria and Drp1 phosphorylation at Ser616 in the early stages (30 min after reperfusion), when there was no apparent structural damage to the kidney. The use of the Drp1 inhibitor P110 significantly improved kidney function and structural damage. P110 reduced Drp1 mitochondrial translocation, disrupted the interaction between Drp1 and Fis1, without affecting the binding of Drp1 to other mitochondrial receptors such as MFF and Mid51. High-dose administration had no apparent toxic side effects. Furthermore, ATP-DR induced mitochondrial fission in renal tubular cells, accompanied by a decrease in mitochondrial membrane potential and an increase in the translocation of the pro-apoptotic protein Bax. This process facilitated the release of dsDNA, triggering the activation of the cGAS-STING pathway and promoting inflammation. P110 attenuated mitochondrial fission, suppressed Bax mitochondrial translocation, prevented dsDNA release, and reduced the activation of the cGAS-STING pathway. Furthermore, these protective effects of P110 were also observed renal IRI model in the Bama pig and folic acid-induced nephropathy in mice.

CONCLUSIONS

Dysfunction of mitochondrial dynamics mediated by Drp1 contributes to renal IRI. The specific inhibitor of Drp1, P110, demonstrated protective effects in both in vivo and in vitro models of AKI.

DUSP1 protects against ischemic acute kidney injury through stabilizing mtDNA via interaction with JNK

The mechanism underlying acute kidney injury (AKI) and AKI-to-Chronic kidney disease (CKD) transition remains unclear, but mitochondrial dysfunction may be a key driving factor. Literature reports suggest that dual-specificity phosphatase 1 (DUSP1) plays a critical role in maintaining mitochondrial function and structural integrity. In this study, ischemic Acute Kidney Injury (AKI) and post-ischemic fibrosis models were established by clamping the renal pedicle with different reperfusion times. To investigate the role of DUSP1, constitutional Dusp1 knockout mice and tubular-specific Sting knockout mice were used. Mitochondrial damage was assessed through electron microscopy observation, measurements of mitochondrial membrane potential, mtDNA release, and BAX translocation. We found that Dusp1 expression was significantly upregulated in human transplant kidney tissue and mouse AKI tissue. Dusp1 gene deletion exacerbated acute ischemic injury, post-ischemic renal fibrosis, and tubular mitochondrial dysfunction in mice. Mechanistically, DUSP1 could directly bind to JNK, and DUSP1 deficiency could lead to aberrant phosphorylation of JNK and BAX mitochondria translocation. BAX translocation promoted mitochondrial DNA (mtDNA) leakage and activated the cGAS-STING pathway. Inhibition of JNK or BAX could inhibit mtDNA leakage. Furthermore, STING knockout or JNK inhibition could significantly mitigate the adverse effects of DUSP1 deficiency in ischemic AKI model. Collectively, our findings suggest that DUSP1 is a regulator for the protective response during AKI. DUSP1 protects against AKI by preventing BAX-induced mtDNA leakage and blocking excessive activation of the cGAS-STING signaling axis through JNK dephosphorylation.

Essential Role of IFT140 in Promoting Dentinogenesis

Primary cilia, with highly regulated cellular sensory functions, play key roles in tissue development and function maintenance. Intraflagellar transport 140 (IFT140) is a subunit of IFT complex A, which is specialized for retrograde transportation in cilia. Mutations of Ift140 are usually associated with syndromic ciliopathy and may cause isolated diseases such as retinal dystrophy, short ribs, and polycystic kidney. However, the role of IFT140 in tooth development has not been well investigated. In this study, a close relationship between IFT140 and dentin formation is disclosed. During tooth development, IFT140 was highly expressed in odontoblasts. To further understand the role of IFT140 in dentinogenesis, Ift140^flox/flox/Osx-Cre mouse was generated. The dentin thickness of Ift140^flox/flox/Osx-Cre mouse is thinner and the dentin formation is slower than that in control. In vitro, deletion of IFT140 in odontoblasts led to poor odontogenic differentiation, abnormal primary cilia, and decreased Sonic hedgehog signaling molecules. More important, due to loss of primary cilia in odontoblasts by IFT140 deletion, reparative dentin formation was impaired in a tooth-drilling model. These results suggest that cilia gene IFT140 is essential in promoting dentin formation and reparation.

Excellent antimicrobial properties of silver-loaded mesoporous silica SBA-15

AIMS

To synthesize silver-loaded mesoporous silica SBA-15 (Ag/SBA-15) materials and examine their antimicrobial action and antimicrobial mechanism.

METHODS AND RESULTS

Ag/SBA-15 materials were prepared by means of incipient wetness impregnation, impregnation and direct hydrothermal synthesis methods. The antimicrobial activity of Ag/SBA-15 was investigated using Escherichia coli as an indicator bacterium, and the antimicrobial mechanism was explored. The properties and Ag(+) release behaviour of Ag/SBA-15 materials were compared. Experimental results showed that Ag/SBA-15 materials resulted in 7·5 log inactivation of E. coli for only 60 min, which exhibited very high antimicrobial activities at room temperature without using any light or electrical power input. The cell wall and cell membrane were destroyed in the antimicrobial process, leading to leakage of intracellular components. The formation of extracellular reactive oxygen species (ROS) involved in the bactericidal process was confirmed. Production of intracellular ROS was also discovered.

CONCLUSIONS

Ag/SBA-15 exhibited high antimicrobial activity against E. coli. This antimicrobial effect was a synergistic action between extracellular ROS and the toxicity of Ag(+) , which induced intracellular ROS production and subsequent cell death.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study revealed for the first time the antimicrobial activities and mechanisms of Ag/SBA-15 materials prepared with different methods.

Breast-Conserving Surgery Is Preferred Though Not Commonly Performed in an Urban Region of China

Introduction: Breast-conserving surgery (BCS) followed by radiation therapy has proven to be as effective as modified radical mastectomy, and has, therefore, been considered as the standard treatment for patients with localized breast cancer in Western societies. However, performance of BCS for the treatment of breast cancer in China is not as common as in Western countries. This study was to evaluate healthy women's attitudes towards BCS in an urban region of China.Method: Between February and March 2009, three hundred and fifty healthy women from three urban suburbs of Taiyuan city in Northern China were invited to complete a self-administered questionnaire. Participants' characteristics, including age, education, occupation, and attitudes towards breast cancer treatment options and involvement of treatment decisions, were collected and analyzed.Results: Three hundred and fifteen women returned the questionnaire. The response rate was 90%. The median age of the participants was 31.2 years old (range: 16 – 69 years old). Among them, 49.2% were married, 27.9% had received high levels of education, and 87.3%, 95.2% and 71.4% would like to know the disease status, to involve making treatment decisions, and to accept BCS, respectively, if they were diagnosed with breast cancer. Women aged above 45 years were more likely to choose BCS compared with those less than 45 years old (73.4% vs 61.5%, P = 0.08). There was no association between choices of surgical approaches and levels of education or occupation. As for breast cancer treatment information sources, 76.8% of the participants mentioned oncologists, followed by the internet (12.1%), friends, and media (10.8%). Almost all responders (93.3%) would like to attend hospitals specialized in cancer treatment if breast lumps were detected.Conclusion: Although only 7.1% of breast cancer patients attending a specialized tumor hospital in Taiyuan city underwent BCS, the current study indicate that most women in Northern China would prefer BCS to mastectomy if they were diagnosed with breast cancer. Therefore, further occupational training is warranted for oncologists in China so that optimal treatments for patients with breast cancer can be carried out.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6077.

The Developing Nature of Menstrual and Reproductive Factors Associated with Breast Cancer Risk among Women in an Urban Region of China

Introduction: The incidence rate of female breast cancer has increased rapidly over the past 20 years in China. It has become the leading cause of newly diagnosed cancer and a major cause of mortality among women in some large Chinese cities with higher socio-economic status. This was partly explained by the change of lifestyle and reproductive risk factors. However, little data exists on the extent to which the menstrual and reproductive factors with breast cancer risk have changed in other less developed Chinese cities.Method: One cross sectional study was conducted in urban region of Taiyuan of China from September 2008 to March 2009. One thousand and five hundreds healthy women were invited to complete a self-administered questionnaire. Participants' characteristics, including age, education, occupation, weight, height, age at menarche, age at first birth, parity, duration of breastfeeding, and age at menopause were collected and analyzed. Study subjects were divided into six groups: younger than or equal to 20, 21 to 30, 31 to 40, 41 to 50, 51 to 60 and older than 60 years old.Results: One thousand four hundreds and twenty eight women returned the questionnaire. The response rate was 95.2%. Median age of women in this study was 39 years old (range: 16 – 86 years old). There was a 4.8cm difference in the mean height between women born in 1990s and 1940s. The average age at menarche dropped from 16 years for women aged above 60 to 14.3 years for those younger than 20 years old. The average birth rate markedly decreased from 4.4 births per woman in the 1960s to 1.1 births per woman in the 1990s. The mean age at first birth increased 5.6 years through the period from the 1940s to 1980s. The breastfeeding time significantly reduced from 20.3 months to 3.6 months over 40 years.Conclusion: This study indicates that there has been significant change in the menstrual and reproductive factors associated with breast cancer risk in the last 40 years. These changes will certainly influence the incidence rate of breast cancer in the local city. Therefore, measures are needed to enhance the awareness of breast cancer and its early-detection methods among the urban region women in China.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6068.

Non-steroidal anti-inflammatory drugs in treatment of postoperative pain after cardiac surgery

PURPOSE

Non-steroidal anti-inflammatory drugs (NSAIDs) are used as analgesic in postoperative pain to reduce opioid side effects, such as drowsiness and nausea. However, NSAIDs have not been used extensively in cardiac surgical patients due to the fear of untoward effects on gastric, renal, and coagulation parameters. This study will evaluate the efficacy and safety of three NSAIDs for pain control in CABG patients.

METHODS

One hundred and twenty patients scheduled for elective CABG surgery were enrolled in randomized, double blind, controlled study. Standardized fast track cardiac anesthesia was used. One dose of drug (75 mg diclofenac, 100 mg ketoprofen, 100 mg indomethacin, or placebo) was given pr one hour before tracheal extubation and a second dose 12 hr later. Pain was treated with morphine iv and acetaminophen po. Visual analogue pain scores were recorded at baseline, 3, 6, 12 and 24 hr after the first dose of drug.

RESULTS

There were no differences among the groups in pain scores. Only patients who received diclofenac required less morphine than patients in the control group (P < 0.05). When the total amounts of pain medications were computed to morphine equivalents, only patients in the diclofenac group received less pain medications than the placebo group (P < 0.05). Proportion of patients with postoperative increase of creatinine level (20% and over) did not differ between placebo and drug groups.

CONCLUSION

Non-steroidal anti-inflammatory drugs may be used for analgesia management post CABG surgery in selected patients. Diclofenac appears to have the best analgesic effects by reducing the morphine and other analgesic requirement postoperatively.

Hybrids of chemical derivatives of Escherichia coli alkaline phosphatase

The activities of hybrid dimers of alkaline phosphatase containing two chemically modified subunits have been investigated. One hybrid species was prepared by dissociation and reconstitution of a mixture of two variants produced by chemical modification of the native enzyme with succinic anhydride and tetranitromethane, respectively. The succinyl-nitrotyrosyl hybrid was separated from the other members of the hybrid set by DEAE-Sephadex chromatography and then converted to a succinyl-aminotyrosyl hybrid by reduction of the modified tyrosine residues with sodium dithionite. A comparison of the activities of these two hybrids with the activities of the succinyl, nitrotyrosyl and aminotyrosyl derivatives has shown that either the subunits of alkaline phosphatase function independently or if the subunits turnover alternately in a reciprocating mechanism, then the intrinsic activity of each subunit must be strongly dependent on its partner subunit.