HIF1 and DROSHA are involved in MMACHC repression in hypoxia.

The MMACHC gene encodes for an enzyme involved in intracellular vitamin B12 metabolism, and autosomal recessive defects in MMACHC represent the most common disorder of intracellular vitamin B12 metabolism. Recent studies have identified increased levels of reactive oxygen species in cells and tissues with MMACHC dysfunction, suggesting a role for oxidative stress in disease. To investigate the link between oxidative stress and MMACHC, we exposed mice as well as human and mouse cells to hypoxia, and found significant repression of MMACHC in all investigated tissues (retina, eyecup, liver, kidney) and cell lines (HeLa, ARPE-19, human and mouse fibroblasts, 661W). Furthermore, in HeLa cells, we found transcriptional repression already at 5% oxygen, which was stable during prolonged hypoxia up to 5 days, and a return of MMACHC transcripts to normal levels only 24 h after reoxygenation. This hypoxia-induced downregulation of MMACHC was not due to altered function of the known MMACHC controlling transcription factor complex HCFC1/THAP11/ZNF143. Using in vitro RNA interference against hypoxia-induced transcription factors (HIF1A, HIF2A and REST) as well as the microRNA transcription machinery (DROSHA), we observed release of hypoxia-dependent downregulation of MMACHC expression by HIF1A and DROSHA knockdowns, whose combined effect was additive. Together, these results strongly indicate that MMACHC is a hypoxia-regulated gene whose downregulation appears to be partially mediated through both hypoxia-induced transcription factor and microRNA machinery. These findings suggest that oxidative stress could impair vitamin B12 metabolism by repression of MMACHC in healthy as well as in diseased individuals.

Absence of MMACHC in peripheral retinal cells does not lead to an ocular phenotype in mice.

Combined methylmalonic aciduria with homocystinuria (cblC type) is a rare disease caused by mutations in the MMACHC gene. MMACHC encodes an enzyme crucial for intracellular vitamin B12 metabolism, leading to the accumulation of toxic metabolites e.g. methylmalonic acid (MMA) and homocysteine (Hcy), and secondary disturbances in folate and one-carbon metabolism when not fully functional. Patients with cblC deficiency often present in the neonatal or early childhood period with a severe multisystem pathology, which comprises a broad spectrum of treatment-resistant ophthalmological phenotypes, including retinal degeneration, impaired vision, and vascular changes. To examine the potential function of MMACHC in the retina and how its loss may impact disease, we performed gene expression studies in human and mouse, which showed that local expression of MMACHC in the retina and retinal pigment epithelium is relatively stable over time. To study whether functional MMACHC is required for retinal function and tissue integrity, we generated a transgenic mouse lacking Mmachc expression in cells of the peripheral retina. Characterization of this mouse revealed accumulation of cblC disease related metabolites, including MMA and the folate-dependent purine synthesis intermediates AICA-riboside and SAICA-riboside in the retina. Nevertheless, fundus appearance, morphology, vasculature, and cellular composition of the retina, as well as ocular function, remained normal in mice up to 6 or 12 months of age. Our data indicates that peripheral retinal neurons do not require intrinsic expression of Mmachc for survival and function and questions whether a local MMACHC deficiency is responsible for the retinal phenotypes in patients.

Effectiveness of a 5-Week Inpatient Dialectical Behavior Therapy for Borderline Personality Disorder.

OBJECTIVE: The goal of this study was to evaluate whether symptoms are reduced and emotion regulation improves when patients with borderline personality disorder (BPD) receive a 5-week course of inpatient dialectical behavioral therapy (DBT) and if changes in emotion regulation are associated with changes in symptoms. METHODS: Forty-four patients with BPD receiving a 5-week course of DBT in a German psychiatry clinic participated. The short version of the "Borderline Symptom List" (BSL-23) was the patient-reported outcome. To measure emotion regulation, the "Self-Report Measure for the Assessment of Emotion Regulation Skills" (SEK-27) was administered. Wilcoxon tests were performed to evaluate whether pre-post changes in the BSL-23 and SEK-27 reached statistical significance. Effect sizes (d) were calculated and correlations between the pre-post differences for both measures were computed to test associations between changes in emotion regulation and changes in symptoms. Completer (n=33) and intention-to-treat (n=43) analyses were performed. RESULTS: Symptoms (BSL-23) were reduced and emotion regulation (SEK-27) improved during the 5-week inpatient DBT treatment (completer and intention-to-treat analysis: P<0.001). Effect sizes reached d=0.47 for the BSL-23 and d=0.84 for the SEK-27 in the completer analysis, and d=0.38 for the BSL-23 and d=0.68 for the SEK-27 in the intention-to-treat analysis. Improvements in emotion regulation (SEK-27) were correlated with reductions in symptoms (BSL-23) in both the completer (r=0.54; P=0.001) and the intention-to-treat (r=0.59; P<0.001) analyses. CONCLUSIONS: These findings indicate that a 5-week course of inpatient DBT can effectively reduce symptoms in patients with BPD and that the more patients' emotion regulation improves, the more the patients benefit from the therapy.

Suicidal Ideation and Skill Use During In-patient Dialectical Behavior Therapy for Borderline Personality Disorder. A Diary Card Study.

Associations between suicidal ideation and skill use were investigated during in-patient dialectical behavior therapy (DBT) for borderline personality disorder (BPD). Participants were N = 44 patients with BPD undergoing a 5-week in-patient DBT program in a psychiatric clinic. They filled in a diary card each treatment day resulting in 1,334 skill use ratings and 1,364 suicidal ideation ratings. Treatment days were categorized as days with successful skill use (using skills and perceiving them as effective), days with no skill use, days with unsuccessful skill use (using skills but perceiving them as ineffective). Multilevel models were performed to account for the nested data structure. The results showed that suicidal ideation improved more for patients who applied skills successfully more often during treatment (p < 0.05). Moreover, suicidal ideation was lower on treatment days with successful skill use compared to treatment days with no skill use and compared to treatment days with unsuccessful skill use (p < 0.05). When treatment days with no skill use were compared to treatment days with unsuccessful skill use, suicidal ideation was higher on treatment days with unsuccessful skill use (p < 0.05). To conclude, using skills successfully on as many treatment days as possible is associated with lower suicidal ideation.

Oxytocin Reduces Alcohol Cue-Reactivity in Alcohol-Dependent Rats and Humans.

Approved pharmacological treatments for alcohol use disorder are limited in their effectiveness, and new drugs that can easily be translated into the clinic are warranted. One of those candidates is oxytocin because of its interaction with several alcohol-induced effects. Alcohol-dependent rats as well as post-mortem brains of human alcoholics and controls were analyzed for the expression of the oxytocin system by qRT-PCR, in situ hybridization, receptor autoradiography ([125I]OVTA binding), and immunohistochemistry. Alcohol self-administration and cue-induced reinstatement behavior was measured after intracerebroventricular injection of 10 nM oxytocin in dependent rats. Here we show a pronounced upregulation of oxytocin receptors in brain tissues of alcohol-dependent rats and deceased alcoholics, primarily in frontal and striatal areas. This upregulation stems most likely from reduced oxytocin expression in hypothalamic nuclei. Pharmacological validation showed that oxytocin reduced cue-induced reinstatement response in dependent rats-an effect that was not observed in non-dependent rats. Finally, a clinical pilot study (German clinical trial number DRKS00009253) using functional magnetic resonance imaging in heavy social male drinkers showed that intranasal oxytocin (24 IU) decreased neural cue-reactivity in brain networks similar to those detected in dependent rats and humans with increased oxytocin receptor expression. These studies suggest that oxytocin might be used as an anticraving medication and thus may positively affect treatment outcomes in alcoholics.