Serine 39 in the GTP-binding domain of Drp1 is involved in shaping mitochondrial morphology.

Continuous fusion and fission are critical for mitochondrial health. In this study, we further characterize the role played by dynamin-related protein 1 (Drp1) in mitochondrial fission. We show that a single amino acid change in Drp1 at position 39 from serine to alanine (S39A) within the GTP-binding (GTPase) domain results in a fused mitochondrial network in human SH-SY5Y neuroblastoma cells. Interestingly, the phosphorylation of Ser-616 and Ser-637 of Drp1 remains unaffected by the S39A mutation, and mitochondrial bioenergetic profile and cell viability in the S39A mutant were comparable to those observed in the control. This leads us to propose that the serine 39 residue of Drp1 plays a crucial role in mitochondrial distribution through its involvement in the GTPase activity. Furthermore, this amino acid mutation leads to structural anomalies in the mitochondrial network. Taken together, our results contribute to a better understanding of the function of the Drp1 protein.

Tyrosine kinase expression analyses in canine mammary gland tumours - A pilot study.

Messenger RNA levels of oncogenic tyrosine kinases were determined in canine mammary tumours using real-time RT-PCR. The following tyrosine kinases and vascular endothelial growth factors (VEGF) were examined in malignant and healthy mammary tissues of 13 dogs: VEGFR1, VEGFR2, EGFR, ErbB2, PDGFR1, c-KIT and c-MET. Expression levels of all these factors were significantly higher in tumour samples than in normal mammary tissues taken from the same animal. Higher grading was associated with higher VEGFR1 levels. Grade III tumours showed significantly higher VEGF, c-MET and c-KIT mRNA expression, while Grade I tumours with lower malignancy showed significantly higher PDGFR1 and EGFR expression than tumours classified as Grade II or III. The increased presence of VEGF, VEGFR1, c-KIT and c-MET is a negative prognostic factor as these signal transduction molecules contribute to increased tumour malignancy. The presented data provide evidence, for the first time, for the existence of a complex overexpression and dysregulation of VEGF and several oncogenic tyrosine kinases such as VEGR1, PDGFR1, c-KIT and c-MET in canine mammary tumours. Therefore, canine mammary tumours may be potential targets for tyrosine kinase inhibitor therapy.

Assessment of adrenocortical reserve capacity and inflammatory parameters in critically ill dogs.

Inflammatory markers and adrenocorticotropic hormone (ACTH) stimulation test results may help us recognise critically ill dogs with poor disease outcome. Systemic inflammatory response syndrome (SIRS) criteria, the fast version of the Acute Patient Physiologic and Laboratory Evaluation Score (APPLEfast), complete blood count, albumin and C-reactive protein (CRP) levels, baseline and stimulated cortisol levels and Δcortisol value were recorded in 50 client-owned dogs admitted to the Small Animal Hospital of the University of Veterinary Medicine Budapest with various inflammatory or neoplastic conditions. Increasing APPLEfast score was associated with a decreasing chance of survival (P = 0.0420). The Δcortisol value was significantly higher in SIRS dogs than in non-SIRS dogs (mean ± SD ΔcortisolSIRS: 342.5 ± 273.96; mean ± SD Δcortisolnon-SIRS: 175.3 ± 150.35; P = 0.0443). Elevated baseline or stimulated cortisol levels were associated with a higher chance of non-survival (P = 0.0135 and P = 0.0311, respectively). These data indicate that pathologically higher baseline and stimulated cortisol levels represent an exaggerated stress response in critically ill dogs, which is negatively associated with survival.

alpha-Lipoic acid modulates thiol antioxidant defenses and attenuates exercise-induced oxidative stress in standardbred trotters.

Several micronutrient supplementation strategies are used to cope with oxidative stress, although their benefits have recently been questioned. The aim of the present study was to examine the effects of DL-alpha-lipoic acid (LA) in response to acute exercise and during recovery in horses. Six standardbred trotters were tested on the treadmill before and after 5-week LA supplementation (25 mg/kg body weight/day). According to electron paramagnetic resonance measurements, strenuous aerobic exercise increased significantly free radical formation in the gluteus medius muscle, which was prevented by LA supplementation. The activities of thioredoxin reductase and glutathione reductase in muscle were significantly increased in LA-treated horses, but neither LA nor exercise affected muscle thioredoxin activity. LA increased the concentration of total glutathione in muscle at rest and during recovery. Treatment with LA blunted the exercise-induced increase in plasma oxygen radical absorbance capacity and decreased the post-exercise levels of lipid hydroperoxides in plasma and malondialdehyde in plasma and in muscle. These findings suggest that LA enhances thiol antioxidant defences and decreases exercise-induced oxidative stress in skeletal muscle.