Identification of a Novel Aflatoxin B1-Degrading Strain, Bacillus halotolerans DDC-4, and Its Response Mechanisms to Aflatoxin B1.

Aflatoxin B1 (AFB1) contamination is a food safety issue threatening human health globally. Biodegradation is an effective method for overcoming this problem, and many microorganisms have been identified as AFB1-degrading strains. However, the response mechanisms of these microbes to AFB1 remain unclear. More degrading enzymes, especially of new types, need to be discovered. In this study, a novel AFB1-degrading strain, DDC-4, was isolated using coumarin as the sole carbon source. This strain was identified as Bacillus halotolerans through physiological, biochemical, and molecular methods. The strain's degradation activity was predominantly attributable to thermostable extracellular proteins (degradation rate remained approximately 80% at 90 °C) and was augmented by Cu2+ (95.45% AFB1 was degraded at 48 h). Alpha/beta hydrolase (arylesterase) was selected as candidate AFB1-degrading enzymes for the first time as a gene encoding this enzyme was highly expressed in the presence of AFB1. Moreover, AFB1 inhibited many genes involved in the nucleotide synthesis of strain DDC-4, which is possibly the partial molecular mechanism of AFB1's toxicity to microorganisms. To survive under this stress, sporulation-related genes were induced in the strain. Altogether, our study identified a novel AFB1-degrading strain and explained its response mechanisms to AFB1, thereby providing new insights for AFB1 biodegradation.

Disruption of ER ion homeostasis maintained by an ER anion channel CLCC1 contributes to ALS-like pathologies.

Although anion channel activities have been demonstrated in sarcoplasmic reticulum/endoplasmic reticulum (SR/ER), their molecular identities and functions remain unclear. Here, we link rare variants of Chloride Channel CLIC Like 1 (CLCC1) to amyotrophic lateral sclerosis (ALS)-like pathologies. We demonstrate that CLCC1 is a pore-forming component of an ER anion channel and that ALS-associated mutations impair channel conductance. CLCC1 forms homomultimers and its channel activity is inhibited by luminal Ca2+ but facilitated by phosphatidylinositol 4,5-bisphosphate (PIP2). We identified conserved residues D25 and D181 in CLCC1 N-terminus responsible for Ca2+ binding and luminal Ca2+-mediated inhibition on channel open probability and K298 in CLCC1 intraluminal loop as the critical PIP2-sensing residue. CLCC1 maintains steady-state [Cl-]ER and [K+]ER and ER morphology and regulates ER Ca2+ homeostasis, including internal Ca2+ release and steady-state [Ca2+]ER. ALS-associated mutant forms of CLCC1 increase steady-state [Cl-]ER and impair ER Ca2+ homeostasis, and animals with the ALS-associated mutations are sensitized to stress challenge-induced protein misfolding. Phenotypic comparisons of multiple Clcc1 loss-of-function alleles, including ALS-associated mutations, reveal a CLCC1 dosage dependence in the severity of disease phenotypes in vivo. Similar to CLCC1 rare variations dominant in ALS, 10% of K298A heterozygous mice developed ALS-like symptoms, pointing to a mechanism of channelopathy dominant-negatively induced by a loss-of-function mutation. Conditional knockout of Clcc1 cell-autonomously causes motor neuron loss and ER stress, misfolded protein accumulation, and characteristic ALS pathologies in the spinal cord. Thus, our findings support that disruption of ER ion homeostasis maintained by CLCC1 contributes to ALS-like pathologies.

RNA sequencing analysis of cortex and hippocampus in a kainic acid rat model of temporal lobe epilepsy to identify mechanisms and therapeutic targets related to inflammation, immunity and cognition.

Temporal lobe epilepsy (TLE) is the most common type of refractory epilepsy, in which inflammation is suggested to cause abnormal neuronal connections and neural networks. However, the expression of inflammatory genes in epilepsy remains incomplete, particularly in the context of the cortex, which is a hub of epileptic transmission but also is essential for mediating sensory, motor and cognitive function. Here, a rat model of epilepsy was established by kainic acid (KA) administration Gene transcriptome was explored in 4 signature phases in the hippocampus and cortex: acute damage (3 h), onset of epileptogenesis (3 d), spontaneous epilepsy (2 w) and cognitive impairment (9 w). Gene ontology (GO) and kyoto encyclopedia of genes and genomes (KEGG) analysis was applied to unravel the significantly altered pathways. We found, in both the hippocampus and cortex, the inflammatory gene was up-regulated in the acute phase, followed by a gradual decline; the phagocytosis and glial activation were remarkably increased since day 3; persistently down-regulated synaptic transmission and neuronal development started from the 3 h phase and lasted through the 9 w phase. While, the changed gene expression in the cortex fall into the same categories but were relatively lagging behind that in the hippocampus, also showing less number and distinct genes. Collectively, this study demonstrated the changes of gene transcriptome in the cortex and hippocampus in the signature phases after the KA administration, illustrating the association between epileptogenesis, inflammation genes and cognitive dysfunction, and may benefit identifying novel therapeutic targets for treating TLE and its comorbidities.

Conjugated Linoleic Acid Ameliorates High Fructose-Induced Hyperuricemia and Renal Inflammation in Rats via NLRP3 Inflammasome and TLR4 Signaling Pathway.

SCOPE: Conjugated linoleic acid (CLA), a bioactive substance predominantly found in ruminant products, improves insulin resistance and exhibits anti-inflammatory activity. The chief objective of the study is to investigate the effects and potential mechanisms of CLA on high fructose-induced hyperuricemia and renal inflammation. METHODS AND RESULTS: Hyperuricemia and renal inflammation are induced in rats by 10% fructose. Hyperuricemia, insulin resistance, and renal inflammation are evaluated. CLA potently ameliorates fructose-induced hyperuricemia with insulin resistance and significantly reduces the levels of inflammation factors in serum and kidney. It reverses fructose-induced upregulation of glucose transporter 9 (GLUT9) and urate transporter 1 (URAT1) in the kidney. Moreover, CLA dramatically inhibits the activation of the nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome. Additionally, CLA suppresses toll-like receptor 4 (TLR4)/myeloid differentiation factor 88 (MyD88) signaling activation to inhibit nuclear factor-kB (NF-kB) signaling in the kidney of fructose-fed rats. CONCLUSION: CLA ameliorates hyperuricemia along with insulin resistance and renal inflammatory, which may be associated with the suppression of renal GLUT9 and URAT1 in fructose-fed rats. Its molecular mechanism may be related to the inhibition of NLRP3 inflammasome and TLR4/MyD88 signaling pathway. Therefore, CLA may be a promising candidate for preventing fructose-induced hyperuricemia and renal inflammation.