Cancer cells use self-inflicted DNA breaks to evade growth limits imposed by genotoxic stress.

Genotoxic therapy such as radiation serves as a frontline cancer treatment, yet acquired resistance that leads to tumor reoccurrence is frequent. We found that cancer cells maintain viability during irradiation by reversibly increasing genome-wide DNA breaks, thereby limiting premature mitotic progression. We identify caspase-activated DNase (CAD) as the nuclease inflicting these de novo DNA lesions at defined loci, which are in proximity to chromatin-modifying CCCTC-binding factor (CTCF) sites.

Chromatin Reorganization during Myoblast Differentiation Involves the Caspase-Dependent Removal of SATB2.

The induction of lineage-specific gene programs are strongly influenced by alterations in local chromatin architecture. However, key players that impact this genome reorganization remain largely unknown. Here, we report that the removal of the special AT-rich binding protein 2 (SATB2), a nuclear protein known to bind matrix attachment regions, is a key event in initiating myogenic differentiation.

Stable suppression of skeletal muscle fructose-1,6-bisphosphatase during ground squirrel hibernation: Potential implications of reversible acetylation as a regulatory mechanism.

Mammalian hibernation is a period that involves substantial metabolic change in order to promote survival in harsh conditions, with animals typically relying on non-carbohydrate fuel stores during long bouts of torpor. However, the use and maintenance of carbohydrate fuel stores remains important during periods of arousal from torpor as well as when exiting hibernation. Gluconeogenesis plays a key role in maintaining glucose stores; however, little is known about this process within the muscles of hibernating mammals.

Purification and characterization of skeletal muscle pyruvate kinase from the hibernating ground squirrel, Urocitellus richardsonii: potential regulation by posttranslational modification during torpor.

Ground squirrel torpor during winter hibernation is characterized by numerous physiological and biochemical changes, including alterations to fuel metabolism. During torpor, many tissues switch from carbohydrate to lipid catabolism, often by regulating key enzymes within glycolytic and lipolytic pathways. This study investigates the potential regulation of pyruvate kinase (PK), a key member of the glycolytic pathway, within the skeletal muscle of hibernating ground squirrels.

Evolution of caspase-mediated cell death and differentiation: twins separated at birth.

The phenotypic and biochemical similarities between caspase-mediated apoptosis and cellular differentiation are striking. They include such diverse phenomenon as mitochondrial membrane perturbations, cytoskeletal rearrangements and DNA fragmentation. The parallels between the two disparate processes suggest some common ancestry and highlight the paradoxical nature of the death-centric view of caspases.

Erratum to: The beneficial role of proteolysis in skeletal muscle growth and stress adaptation.

[This corrects the article DOI: 10.1186/s13395-016-0086-6.].

The beneficial role of proteolysis in skeletal muscle growth and stress adaptation.

Muscle atrophy derived from excessive proteolysis is a hallmark of numerous disease conditions. Accordingly, the negative consequences of skeletal muscle protein breakdown often overshadow the critical nature of proteolytic systems in maintaining normal cellular function. Here, we discuss the major cellular proteolysis machinery-the ubiquitin/proteosome system, the autophagy/lysosomal system, and caspase-mediated protein cleavage-and the critical role of these protein machines in establishing and preserving muscle health.

Caspase 3 cleavage of Pax7 inhibits self-renewal of satellite cells.

Compensatory growth and regeneration of skeletal muscle is dependent on the resident stem cell population, satellite cells (SCs). Self-renewal and maintenance of the SC niche is coordinated by the paired-box transcription factor Pax7, and yet continued expression of this protein inhibits the myoblast differentiation program. As such, the reduction or removal of Pax7 may denote a key prerequisite for SCs to abandon self-renewal and acquire differentiation competence.

Purification and properties of glyceraldehyde-3-phosphate dehydrogenase from the skeletal muscle of the hibernating ground squirrel, Ictidomys tridecemlineatus.

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) from the skeletal muscle of euthermic and torpid Ictidomys tridecemlineatus was purified to electrophoretic homogeneity using a novel method involving Blue-agarose and Phenyl-agarose chromatography. Kinetic analysis of the enzymes isolated from the two conditions suggested the existence of two structurally distinct proteins, with GAPDH V max being 40-60% less for the enzyme from the torpid condition (in both glycolytic and gluconeogenic directions) as compared to the euthermic enzyme form. Thermal denaturation, in part determined by differential scanning fluorimetry, revealed that purified GAPDH from the torpid animals was significantly more stable that the enzyme from the euthermic condition.

Novel detection method for chemiluminescence derived from the Kinase-Glo luminescent kinase assay platform: Advantages over traditional microplate luminometers.

The efficacy of cellular signal transduction is of paramount importance for the proper functioning of a cell and an organism as a whole. Protein kinases are responsible for much of this transmission and thus have been the focal point of extensive research. While there are numerous commercially available protein kinase assays, the Kinase-Glo luminescent kinase assay (Promega) provides an easy-to-use and high throughput platform for determining protein kinase activity.

Stable Suppression of Lactate Dehydrogenase Activity during Anoxia in the Foot Muscle of Littorina littorea and the Potential Role of Acetylation as a Novel Posttranslational Regulatory Mechanism.

The intertidal marine snail, Littorina littorea, has evolved to withstand extended bouts of oxygen deprivation brought about by changing tides or other potentially harmful environmental conditions. Survival is dependent on a strong suppression of its metabolic rate and a drastic reorganization of its cellular biochemistry in order to maintain energy balance under fixed fuel reserves. Lactate dehydrogenase (LDH) is a crucial enzyme of anaerobic metabolism as it is typically responsible for the regeneration of NAD(+), which allows for the continued functioning of glycolysis in the absence of oxygen.

Hexokinase regulation in the hepatopancreas and foot muscle of the anoxia-tolerant marine mollusc, Littorina littorea.

Hexokinase from the hepatopancreas and foot muscle of Littorina littorea undergoes stable modification of its kinetic and structural properties in response to prolonged oxygen deprivation. In the hepatopancreas, a reduction in the Km glucose for hexokinase from the anoxic animal suggests a more active enzyme form during anoxia. Conversely, in the foot muscle, an increase in Km ATP and a decrease in Vmax for anoxic snail hexokinase were consistent with a less active enzyme form during anoxia.

Glucose-6-phosphate dehydrogenase regulation in the hepatopancreas of the anoxia-tolerant marine mollusc, Littorina littorea.

Glucose-6-phosphate dehydrogenase (G6PDH) gates flux through the pentose phosphate pathway and is key to cellular antioxidant defense due to its role in producing NADPH. Good antioxidant defenses are crucial for anoxia-tolerant organisms that experience wide variations in oxygen availability. The marine mollusc, Littorina littorea, is an intertidal snail that experiences daily bouts of anoxia/hypoxia with the tide cycle and shows multiple metabolic and enzymatic adaptations that support anaerobiosis.

Purification and Properties of White Muscle Lactate Dehydrogenase from the Anoxia-Tolerant Turtle, the Red-Eared Slider, Trachemys scripta elegans.

Lactate dehydrogenase (LDH; E.C. 1.

Insights into the in vivo regulation of glutamate dehydrogenase from the foot muscle of an estivating land snail.

Land snails, Otala lactea, survive in seasonally hot and dry environments by entering a state of aerobic torpor called estivation. During estivation, snails must prevent excessive dehydration and reorganize metabolic fuel use so as to endure prolonged periods without food. Glutamate dehydrogenase (GDH) was hypothesized to play a key role during estivation as it shuttles amino acid carbon skeletons into the Krebs cycle for energy production and is very important to urea biosynthesis (a key molecule used for water retention).

Regulation of liver glutamate dehydrogenase by reversible phosphorylation in a hibernating mammal.

Glutamate dehydrogenase (GDH) is a key enzyme that links amino acid and carbohydrate metabolism in cells. Regulation is likely most important when organisms are confronted with extreme stresses such as the low environmental temperatures and lack of food associated with winter. Many small mammals, such as Richardson's ground squirrels, Spermophilus richardsonii, cope with these conditions by hibernating.