Maze Therapeutics, 171 Oyster Point Blvd, Suite 300, South San Francisco, CA 94080, USA. Electronic address:
Published: July 2022
AI Article Synopsis
Article Abstract
Glycogen is the primary energy reserve in mammals, and dysregulation of glycogen metabolism can result in glycogen storage diseases (GSDs). In muscle, glycogen synthesis is initiated by the enzymes glycogenin-1 (GYG1), which seeds the molecule by autoglucosylation, and glycogen synthase-1 (GYS1), which extends the glycogen chain. Although both enzymes are required for proper glycogen production, the nature of their interaction has been enigmatic. Here, we present the human GYS1:GYG1 complex in multiple conformations representing different functional states. We observe an asymmetric conformation of GYS1 that exposes an interface for close GYG1 association, and propose this state facilitates handoff of the GYG1-associated glycogen chain to a GYS1 subunit for elongation. Full activation of GYS1 widens the GYG1-binding groove, enabling GYG1 release concomitant with glycogen chain growth. This structural mechanism connecting chain nucleation and extension explains the apparent stepwise nature of glycogen synthesis and suggests distinct states to target for GSD-modifying therapeutics.
Background: Hepatic glycogen storage diseases (GSDs) are characterised by enzyme defects affecting liver glycogen metabolism, where carbohydrate supplementation to prevent overnight hypoglycaemia is common. Concerns around sleep quality in hepatic GSDs relate to emerging evidence that overnight dysglycaemia impacts sleep quality.
Methods: This prospective observational study reported sleep quality and duration in children with hepatic GSDs over 7 days utilising: actigraphy (Actiwatch 2 by Phillips Respironics), sleep diaries, proxy reported age-appropriate sleep and quality-of-life (QoL) questionnaires, in the context of nocturnal glycaemic profiles continuous glucose monitor (CGM, Dexcom G6) and nocturnal dietary management strategies.
Section of Infection and Immunity, Herman Ostrow School of Dentistry, Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA 90089, USA. Electronic address:
Metabolism is typically contextualized in conjunction with proliferation and growth. The roles of metabolic enzymes beyond metabolism-such as in innate immune responses-are underexplored. Using a focused short hairpin RNA (shRNA)-mediated screen, we identified CTP synthetase 1 (CTPS1), a rate-limiting enzyme of pyrimidine synthesis, as a negative regulator of interferon induction.
Institut Químic de Sarrià (IQS), Universitat Ramon Llull (URL), Barcelona 08017, Spain; Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, Barcelona 08028, Spain.
Glycogen is a glucose-storage polysaccharide molecule present in animals, fungi and bacteria. The enzyme glycogenin can self-glycosylate, forming an oligosaccharide chain that primes glycogen synthesis. This priming role of glycogenin was first believed to be essential for glycogen synthesis, but glycogen was then found in the skeletal muscle, heart, liver and brain of glycogenin-knockout mice (Gyg KO), thereby showing that glycogen can be synthesized without glycogenin.
A biosensor for biochemical oxygen demand (BOD) was developed based on intracellular 5'-adenosine triphosphate (ATP) measurements in Saccharomyces cerevisiae. Intracellular ATP was measured using an engineered protein named ATeam, comprising a bacterial FF-ATP synthase ε subunit sandwiched between cyan fluorescent protein and mVenus, a modified yellow fluorescent protein. Because the binding of ATP to ATeam induces changes in the fluorescence spectra owing to Fӧrster resonance energy transfer, S.
In this study, two high-content flavonoid derivatives [3-8 biapigenin (HM 104) and quercetin-3--β--galactopyranoside (HM 111)] were obtained through the bioactivity-guided isolation of antidiabetic compounds from flowers. HM 104 and HM 111 exhibited good glucose consumption in fatty acid-induced insulin-resistant HepG2 cells. Moreover, both active compounds enhanced glucose uptake by restoring the expression of key regulators of glucose metabolism, including insulin receptor substrate 1, phosphoinositide 3-kinase, protein kinase B, and glucose transporter type 4, and by mitigating the expression of forkhead box O1 and the factors involved in gluconeogenesis.
