Biology subjects

Kaufman, B. A.

Publications and source records attributed to Kaufman, B. A..

3 recordsLinked to original sources

bioRxiv2018

Acute Psychological Stress Triggers Circulating Cell-Free Mitochondrial DNA

Intrinsic biological mechanisms transduce psychological stress into physiological adaptation, but the role of mitochondria and mitochondrial DNA (mtDNA) in this process has not been defined in humans. Here, we show that similar to physical injury, psychological stress triggers elevation in circulating cell- free mtDNA (ccf-mtDNA). Healthy midlife adults exposed on two separate occasions to a brief psychological challenge exhibit a 2-3-fold increase in ccf-mtDNA, with no change in nuclear DNA levels, establishing the magnitude and specificity to ccf-mtDNA. In cell-based studies, we show that glucocorticoid signaling - a consequence of psychological stress in humans - is sufficient to induce mtDNA extrusion in a time frame consistent with human psychophysiology. Collectively, these findings provide the first evidence that psychological stress induces ccf-mtDNA and implicate glucocorticoid signaling as a trigger for ccf-mtDNA release. Further work is needed to examine the functional significance of psychological stress-induced ccf-mtDNA as a mitokine in humans.

molecular biology↗

bioRxiv2018

Petite Integration Factor 1 (PIF1) helicase deficiency increases weight gain in Western diet-fed female mice without increased inflammatory markers or decreased glucose clearance

Petite Integration Factor 1 (PIF1) is a multifunctional helicase present in nuclei and mitochondria. PIF1 knock out (KO) mice exhibit accelerated weight gain and decreased wheel running on a normal chow diet. In the current study, we investigated whether Pif1 removal alters whole body metabolism in response to weight gain. PIF1 KO and wild type (WT) C57BL/6J mice were fed a Western diet (WD) rich in fat and carbohydrates before evaluation of their metabolic phenotype. Compared with weight gain-resistant WT female mice, WD-fed PIF1 KO females, but not males, showed accelerated adipose deposition, decreased locomotor activity, and reduced whole-body energy expenditure without increased dietary intake. Surprisingly, PIF1 KO females were protected against obesity-induced alterations in fasting blood glucose and glucose clearance. WD-fed PIF1 KO females developed mild hepatic steatosis and associated changes in liver gene expression that were absent in weight-matched, WD-fed female controls, linking hepatic steatosis to Pif1 ablation rather than increased body weight. WD-fed PIF1 KO females also showed decreased gene expression of inflammatory markers in adipose tissue. Collectively, these data separated weight gain from inflammation and impaired glucose homeostasis. They also support a role for Pif1 in weight gain resistance and liver metabolic dysregulation during nutrient stress.

physiology↗

bioRxiv2018

Targeted Reduction of Pathogenic Heteroplasmy Through Binding of G-Quadruplex DNA

Pathogenic mitochondrial DNA (mtDNA) variants are typically heteroplasmic, with coexistence of variant and wild type genomes. Because heteroplasmy dictates phenotype, the reduction of heteroplasmy is potentially therapeutic. We identified pathogenic variants that increased the potential for formation of non-canonical G-quadruplexes (GQ) within mtDNA. The Leigh Syndrome (LS)-associated mt.10191T>C variant has a high probability of local GQ formation that was enhanced by the variant. Structural studies of mt.10191C-containing oligonucleotides confirmed the formation of GQ, and its interaction with the small molecule GQ-binding agent berberine increased GQ stability. The GQ formed at mt.10191 impeded polymerase processivity, and inhibition was enhanced by the mt.10191C variant. We applied a cyclical treatment of two GQ binding compounds, berberine or RHPS4, to primary fibroblasts from LS patients with heteroplasmic mt.10191T>C mutation. This treatment induced alternating mtDNA depletion and repopulation and was effective in shifting heteroplasmy towards the nonpathogenic allele, leading to an increase in complex I protein levels. This study demonstrates the potential for using small-molecule GQ-binding agents to induce beneficial shifts in mitochondrial heteroplasmy.

genetics↗