Biology subjects

Zablocki, K. O.

Publications and source records attributed to Zablocki, K. O..

3 recordsLinked to original sources

bioRxiv2024

Chitinase-1 inhibition reverses metabolic dysregulation and restores homeostasis in MASH animal models

OATD-01 is a chitinase-1 (CHIT1) inhibitor, reducing inflammation and fibrosis in animal models where chronic inflammation leads to tissue remodeling. CHIT1, predominantly secreted by macrophages, is overexpressed in metabolic-dysfunction-associated steatohepatitis (MASH). In this study, we demonstrated the efficacy of OATD-01 in two murine and a rat model of MASH. RNA-Seq analysis revealed that OATD-01 reversed MASH-dysregulated genes. Apart from the attenuation of inflammation and fibrosis, OATD-01 regulated metabolic processes such as lipid metabolism and glycolysis. We demonstrated that both genetic and pharmacological inactivation of CHIT1 resulted in inhibition of glycolysis and glucose uptake in primary macrophages. As a consequence, we observed increased ATP, lower citrate and increased acetate levels, resulting in a reduced IL-1{beta} secretion. These results revealed the key role for CHIT1 in regulating metabolism. OATD-01 is a macrophage modulator that can directly restore metabolic balance and consequently inhibit inflammation and fibrosis, supporting its use for MASH treatment.

pharmacology and toxicology↗

bioRxiv2022

Metabotropic purinergic receptor profiles and calcium signalling in primary mice myoblasts differ depending on their muscle origin and are altered in cells with mutated dystrophin gene (mdx mice)

Mortality of Duchenne Muscular Dystrophy (DMD) is a direct consequence of progressive wasting of muscle fibres leading to skeletal muscle deterioration and cardiomyopathy. However pathophysiological effects of mutations in the dystrophin encoding gene, which result in improper muscle maturation are detectable in muscle precursor cells which do not express dystrophin gene at the protein level because of early stage of differentiation thus irrespectively of changes in dystrophin-encoding gene. Among these abnormalities elevated activity of P2X7 receptors and increased store-operated calcium entry, have been identified in mdx mouse myoblasts. Moreover the increased response of immortalized mdx myoblasts to agonists activating metabotropic purinergic receptors was characterised. Experiments on immortalized myoblasts do not allow indicating potentially specific effects of mdx mutation on cells derived from particular muscles. Moreover an immortalization of cells itself may influence their metabolism in poorly defined way. Therefore here the metabotropic response of primary myoblasts derived from various muscles of normal and mdx mice to nucleotide stimulation has been investigated. Transcript and protein level of P2Y receptors, sensitivity to antagonist, and cellular localization clearly indicate P2RY2 as the most affected in mdx myoblasts. This meets our previous conclusion drawn from experiments with immortalized cells. However a pattern of expression and activity of P2Y receptors among myoblasts derived from four muscles differ. Also cellular levels of some other proteins belonging to the "calcium signalling toolkit" differ in myoblasts from various muscle and are differently changed due to mdx mutation. Finally, these results complement and strongly support previously formulated conclusion that phenotypic effects of DMD emerge as early as in undifferentiated muscle and therefore traditional understanding of DMD pathogenesis needs re-evaluation.

biochemistry↗

bioRxiv2021

Effect of lipopolysaccharide (LPS) on HAEC cells. Does nicotinamide N-methyltranferase sensitize HAEC cells to LPS?

Treatment of endothelial cells with bacterial lipopolysaccharide (LPS) evokes a number of metabolic and functional consequences which built a multifaceted physiological response of endothelium to bacterial infection. Here effects of LPS on human aortic endothelial cells (HAEC) have been investigated. Among the spectrum of biochemical changes substantially elevated N-nicotinamide methyltransferase (NNMT) protein level was particularly intriguing. This important enzyme may potentially affect cellular metabolism by two means: direct regulation of methylnicotinamide level and availability of nicotinamide, that at least potentially may influence NAD+ synthesis, and regulation of S-adenosylmethionine concentration and therefore controlling methylation of many proteins including chromatin. This may have epigenetic consequences. This paper is focused on NNMT, despite the fact that in the presence of LPS additional effects of this compound mask pure (canonical) consequences of the elevated NNMT protein which are an increased MNA synthesis or reduced NAD+ level. On the other hand, however, it has been shown that silencing of the NNMT-encoding gene prevents several changes which are observed in control HAECs treated with LPS. They include significantly increased calcium response to thapsigargin (store-operated calcium entry), altered energy metabolism which is switched to anaerobic glycolysis and rearrangement of the mitochondrial network. However, a biochemical mechanism behind the protective consequences of the NNMT deficiency in cells treated with LPS remains unexplained.

biochemistry↗