ACS DIVISION OF BIOLOGICAL CHEMISTRY

November 27th, 2019 by

November 25th, 2019 by

September 19th, 2019 by

September 13th, 2019 by

August 4th, 2019 by

December 16th, 2015 by

Production of energy in a cell must keep pace with demand. Photoreceptors use ATP to maintain ion gradients in darkness, whereas in light they use it to support phototransduction. Matching production with consumption can be accomplished by coupling production directly to consumption. Alternatively, production can be set by a signal that anticipates demand. In this report we investigate the hypothesis that signaling through phototransduction controls production of energy in mouse retinas. We found that respiration in mouse retinas is not coupled tightly to ATP consumption. By analyzing metabolic flux in mouse retinas, we also found that phototransduction slows metabolic flux through glycolysis and through intermediaes of the citric acid cycle. We also evaluated the relative contributions of regulation of the activities of alpha-Ketoglutarate Dehydrogenase and the Aspartate-Glutamate Carrier 1. In addition, a comprehensive analysis of the retinal metabolome showed that phototransduction also influences steady-state concentrations of 5′GMP, ribose-5-phosphate, ketone bodies and purines.

December 16th, 2015 by

To interpret epigenetic information, chromatin readers utilize various protein domains for recognition of DNA and histone modifications. Some readers possess multidomains for modification recognition and are thus multivalent. Bromodomain- and PHD finger-containing protein 3 (BRPF3) is such a chromatin reader, containing two PHD fingers, one bromodomain and a PWWP domain. However, its molecular and biological functions remain to be investigated. Here we report that endogenous BRPF3 preferentially forms a tetrameric complex with HBO1 (a.k.a. KAT7) and two other subunits, but not with related acetyltransferases such as MOZ, MORF, TIP60 and hMOF (a.k.a. KAT6A, KAT6B, KAT5 and KAT8, respectively). We have also characterized a mutant mouse strain with a LacZ reporter inserted at the Brpf3 locus. Systematic analysis of β-galactosidase activity revealed dynamic spatiotemporal expression of Brpf3 during mouse embryogenesis and high expression in the adult brain and testis. Brpf3 disruption, however, resulted in no obvious gross phenotypes. This is in stark contrast to Brpf1 and Brpf2, whose loss causes lethality at E9.5 and E15.5, respectively. In Brpf3-null mice and embryonic fibroblasts, RT-qPCR uncovered no changes in levels of Brpf1 and Brpf2 transcripts, confirming no compensation from them. These results indicate that BRPF3 forms a functional tetrameric complex with HBO1 but is not required for mouse development and survival, thereby distinguishing BRPF3 from its paralogs, BRPF1 and BRPF2.

December 16th, 2015 by

Bunyaviruses are considered to be emerging pathogens facilitated by the segmented nature of their genome that allows reassortment between different species to generate novel viruses with altered pathogenicity. Bunyaviruses are transmitted via a diverse range of arthropod vectors, as well as rodents, and have established a global disease range with massive importance in healthcare, animal welfare and economics. There are no vaccines or anti-viral therapies available to treat human bunyavirus infections and so development of new anti-viral strategies is urgently required. Bunyamwera virus (BUNV; genus Orthobunyavirus) is the model bunyavirus, sharing aspects of its molecular and cellular biology with all Bunyaviridae family members. Here, we show for the first time that BUNV activates and requires cellular potassium (K+) channels to infect cells. Time of addition assays using K+ channel modulating agents demonstrated that K+ channel function is critical to events shortly after virus entry but prior to viral RNA synthesis/replication. A similar K+ channel dependence was identified for other bunyaviruses namely Schmallenberg virus (Orthobunyavirus) as well as the more distantly related Hazara virus (Nairovirus). Using a rational pharmacological screening regimen, twin-pore domain K+ channels (K2P) were identified as the K+ channel family mediating BUNV K+ channel dependence. As several K2P channel modulators are currently in clinical use, our work suggests they may represent a new and safe drug class for the treatment of potentially lethal bunyavirus disease.

December 16th, 2015 by

December 16th, 2015 by

Amyloid β (Aβ) damages neurons and triggers microglial inflammatory activation in the Alzheimer's disease (AD) brain. BACE1 is the primary enzyme in Aβ generation. Neuroinflammation potentially up-regulates BACE1 expression and increases Aβ production. In Alzheimer's amyloid precursor protein-transgenic mice and SH-SY5Y cell models, we specifically knocked out or knocked down gene expression of mapk14, which encodes p38α-MAPK, a kinase sensitive to inflammatory and oxidative stimuli. Using immunological and biochemical methods, we observed that reduction of p38α-MAPK expression facilitated the lysosomal degradation of BACE1, decreased BACE1 protein and activity, and subsequently attenuated Aβ generation in the AD mouse brain. Inhibition of p38α-MAPK also enhanced autophagy. Blocking autophagy by treating cells with 3-methyladenine or overexpressing dominant-negative ATG5 abolished the deficiency of p38α-MAPK-induced BACE1 protein reduction in cultured cells. Thus, our study demonstrates that p38α-MAPK plays a critical role in the regulation of BACE1 degradation and Aβ generation in AD pathogenesis.