ADAM19: A Novel Target for Metabolic Syndrome in Humans and Mice

Adam19 Deficiency Impacts Pulmonary Function: Human GWAS Follow-up in a Mouse Knockout Model

PURPOSE

Over 550 loci have been associated with human pulmonary function in genome-wide association studies (GWAS); however, the causal role of most remains uncertain. Single nucleotide polymorphisms in a disintegrin and metalloprotease domain 19 (ADAM19) are consistently related to pulmonary function in GWAS. Thus, we used a mouse model to investigate the causal link between Adam19 and pulmonary function.

METHODS

We created an Adam19 knockout (KO) mouse model and validated the gene targeting using RNA-Seq and RT-qPCR. Mouse body composition was assessed using dual-energy X-ray absorptiometry. Mouse lung function was measured using flexiVent.

RESULTS

Contrary to prior publications, the KO was not neonatal lethal. KO mice had lower body weight and shorter tibial length than wild-type (WT) mice. Their body composition revealed lower soft weight, fat weight, and bone mineral content. Adam19 KO had decreased baseline respiratory system elastance, minute work of breathing, tissue damping, tissue elastance, and forced expiratory flow at 50% forced vital capacity but higher FEV0.1 and FVC. Adam19 KO had attenuated tissue damping and tissue elastance in response to methacholine following LPS exposure. Adam19 KO also exhibited attenuated neutrophil extravasation into the airway after LPS administration compared to WT. RNA-Seq analysis of KO and WT lungs identified several differentially expressed genes (Cd300lg, Kpna2, and Pttg1) implicated in lung biology and pathogenesis. Gene set enrichment analysis identified negative enrichment for TNF pathways.

CONCLUSION

Our murine findings support a causal role of ADAM19, implicated in human GWAS, in regulating pulmonary function.

Loss of ADAM29 does not affect viability and fertility in mice but improves wound healing

ADAM29 (a disintegrin and metalloprotease domain 29) is a member of the membrane-anchored ADAM family of proteins, which is highly expressed in testis and may mediate different physiological and pathological processes. Although the functions of many ADAM family members have been well characterized, the biological relevance of ADAM29 has remained largely unknown. Here, we report the generation of an Adam29-deficient mouse model to delve deeper into the in vivo functions of this ADAM family member. We show that ADAM29 depletion does not affect mice viability, development, or fertility, but somehow impinges on metabolism and energy expenditure. We also report herein that ADAM29 deficiency leads to an accelerated wound healing process, without affecting cell reprogramming in mouse-derived fibroblasts. Collectively, our findings provide new insights into ADAM29 biological functions, highlighting the importance of non-catalytic ADAM proteases.

Exome-wide association analysis of CT imaging-derived hepatic fat in a medical biobank

Nonalcoholic fatty liver disease is common and highly heritable. Genetic studies of hepatic fat have not sufficiently addressed non-European and rare variants. In a medical biobank, we quantitate hepatic fat from clinical computed tomography (CT) scans via deep learning in 10,283 participants with whole-exome sequences available. We conduct exome-wide associations of single variants and rare predicted loss-of-function (pLOF) variants with CT-based hepatic fat and perform cross-modality replication in the UK Biobank (UKB) by linking whole-exome sequences to MRI-based hepatic fat. We confirm single variants previously associated with hepatic fat and identify several additional variants, including two (FGD5 H600Y and CITED2 S198_G199del) that replicated in UKB. A burden of rare pLOF variants in LMF2 is associated with increased hepatic fat and replicates in UKB. Quantitative phenotypes generated from clinical imaging studies and intersected with genomic data in medical biobanks have the potential to identify molecular pathways associated with human traits and disease.

The water extracts of Euonymus alatus (Thunb.) Siebold attenuate diabetic retinopathy by mediating angiogenesis

ETHNOPHARMACOLOGICAL RELEVANCE

Euonymus alatus (Thunb.) Siebold (family Celastraceae) is a deciduous woody shrub that is recorded in ShenNong BenCaoJing. It has been widely used for diabetes in traditional Chinese medicine.

AIM OF THE STUDY

This study aimed to identify the most effective extract of Euonymus alatus (EA) against high glucose-induced endothelial cells in vitro, evaluate its pharmacological effect on retinopathy in diabetic mice and explore its underlying mechanism by RNA sequencing.

METHODS

Retinal vascular endothelial cells (RF/6A) were treated with normal glucose (5.5 mmol/L glucose), high glucose (25 mmol/L glucose) or high glucose plus methanol extracts of EA (MEA), ethyl acetate extracts of EA (EEA) or water extracts of EA (WEA). The cytotoxicity and cell viability were determined by Cell Counting Kit-8 (CCK-8) assay. Cell migration was examined using the Transwell assay, and tube formation ability was measured using the Matrigel assay. Then, the KK-Ay mice were administered WEA or water for 12 weeks. The velocities of ocular blood flow were determined by Doppler ultrasound. RNA sequencing and reverse transcription quantitative PCR (RT-qPCR) were performed on WEA-stimulated RF/6A cells to reveal the underlying mechanism.

RESULTS

The cytotoxicity assay found that 30 μg/mL MEA, 20 μg/mL EEA and 30 μg/mL WEA had no toxic effect on RF/6A cells. The cell viability results showed that MEA, EEA and WEA all decreased cell viability. Compared with the high-glucose group, both MEA and WEA decreased the number of migrated cells, while the inhibition rate of WEA was higher. The Matrigel results showed that 30 μg/mL WEA effectively reduced the total tube length. Moreover, WEA improved the haemodynamics of the central retinal artery. RNA sequencing coupled with RT-qPCR verified that WEA regulated angiogenesis-related factors in high glucose-stimulated RF/6A cells.

CONCLUSIONS

WEA inhibits the migration and tube formation of RF/6A cells and improves diabetic retinopathy (DR) by mediating angiogenesis.

RNA-Seq Analysis of the Key Long Noncoding RNAs and mRNAs Related to the Regulation of Acute Heat Stress in Rainbow Trout

Simple Summary

At present, climate warming is a very serious environmental problem. A sudden and large increase or decrease in temperature is likely to cause stress response in animals. Rainbow trout is a kind of cultured cold-water fish, which is very sensitive to high temperature. Therefore, it is very vulnerable to heat waves during production. The current study found that the behavior, antioxidant capacity, and natural immune function of rainbow trout under acute heat stress were significantly enhanced in the early stages of stress response, but its anti-stress ability decreased with an increase in stress intensity and duration. Transcriptome sequencing and bioinformatics analysis showed that some non-coding RNAs could competitively bind to target genes, and jointly participate in metabolism, apoptosis, and the immune regulation of rainbow trout under stress environments. In conclusion, our study can lay a theoretical foundation for the breeding of heat-resistant rainbow trout varieties.

Abstract

As the global climate warms, more creatures are threatened by high temperatures, especially cold-water fish such as rainbow trout. Evidence has demonstrated that long noncoding RNAs (lncRNAs) play a pivotal role in regulating heat stress in animals, but we have little understanding of this regulatory mechanism. The present study aimed to identify potential key lncRNAs involved in regulating acute heat stress in rainbow trout. lncRNA and mRNA expression profiles of rainbow trout head kidney were analyzed via high-throughput RNA sequencing, which exhibited that 1256 lncRNAs (802 up-regulation, 454 down-regulation) and 604 mRNAs (353 up-regulation, 251 down-regulation) were differentially expressed. These differentially expressed genes were confirmed to be primarily associated with immune regulation, apoptosis, and metabolic process signaling pathways through Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis and coding-noncoding co-expression network analysis. These results suggested that 18 key lncRNA-mRNA pairs are essential in regulating acute heat stress in rainbow trout. Overall, these analyses showed the effects of heat stress on various physiological functions in rainbow trout at the transcriptome level, providing a theoretical basis for improving the production and breeding of rainbow trout and the selection of new heat-resistant varieties.

Implications of ADAM17 activation for hyperglycaemia, obesity and type 2 diabetes

In this review, we focus specifically on the role that the metalloproteinase, A Disintegrin and Metalloproteinase 17 [ADAM17] plays in the development and progression of the metabolic syndrome. There is a well-recognised link between the ADAM17 substrate tumour necrosis factor α (TNF-α) and obesity, inflammation and diabetes. In addition, knocking out ADAM17 in mice leads to an extremely lean phenotype. Importantly, ADAM17-deficient mice exhibit one of the most pronounced examples of hypermetabolism in rodents to date. It is vital to further understand the mechanistic role that ADAM17 plays in the metabolic syndrome. Such studies will demonstrate that ADAM17 is a valuable therapeutic target to treat obesity and diabetes.

Advances in Understanding TKS4 and TKS5: Molecular Scaffolds Regulating Cellular Processes from Podosome and Invadopodium Formation to Differentiation and Tissue Homeostasis

Scaffold proteins are typically thought of as multi-domain "bridging molecules." They serve as crucial regulators of key signaling events by simultaneously binding multiple participants involved in specific signaling pathways. In the case of epidermal growth factor (EGF)-epidermal growth factor receptor (EGFR) binding, the activated EGFR contacts cytosolic SRC tyrosine-kinase, which then becomes activated. This process leads to the phosphorylation of SRC-substrates, including the tyrosine kinase substrates (TKS) scaffold proteins. The TKS proteins serve as a platform for the recruitment of key players in EGFR signal transduction, promoting cell spreading and migration. The TKS4 and the TKS5 scaffold proteins are tyrosine kinase substrates with four or five SH3 domains, respectively. Their structural features allow them to recruit and bind a variety of signaling proteins and to anchor them to the cytoplasmic surface of the cell membrane. Until recently, TKS4 and TKS5 had been recognized for their involvement in cellular motility, reactive oxygen species-dependent processes, and embryonic development, among others. However, a number of novel functions have been discovered for these molecules in recent years. In this review, we attempt to cover the diverse nature of the TKS molecules by discussing their structure, regulation by SRC kinase, relevant signaling pathways, and interaction partners, as well as their involvement in cellular processes, including migration, invasion, differentiation, and adipose tissue and bone homeostasis. We also describe related pathologies and the established mouse models.

Identification and characterization of adipose surface epitopes

Adipose tissue is a central regulator of metabolism and an important pharmacological target to treat the metabolic consequences of obesity, such as insulin resistance and dyslipidemia. Among the various cellular compartments, the adipocyte cell surface is especially appealing as a drug target as it contains various proteins that when activated or inhibited promote adipocyte health, change its endocrine function and eventually maintain or restore whole-body insulin sensitivity. In addition, cell surface proteins are readily accessible by various drug classes. However, targeting individual cell surface proteins in adipocytes has been difficult due to important functions of these proteins outside adipose tissue, raising various safety concerns. Thus, one of the biggest challenges is the lack of adipose selective surface proteins and/or targeting reagents. Here, we discuss several receptor families with an important function in adipogenesis and mature adipocytes to highlight the complexity at the cell surface and illustrate the problems with identifying adipose selective proteins. We then discuss that, while no unique adipocyte surface protein might exist, how splicing, posttranslational modifications as well as protein/protein interactions can create enormous diversity at the cell surface that vastly expands the space of potentially unique epitopes and how these selective epitopes can be identified and targeted.

Genome organization and chromatin analysis identify transcriptional downregulation of insulin-like growth factor signaling as a hallmark of aging in developing B cells

BACKGROUND

Aging is characterized by loss of function of the adaptive immune system, but the underlying causes are poorly understood. To assess the molecular effects of aging on B cell development, we profiled gene expression and chromatin features genome-wide, including histone modifications and chromosome conformation, in bone marrow pro-B and pre-B cells from young and aged mice.

RESULTS

Our analysis reveals that the expression levels of most genes are generally preserved in B cell precursors isolated from aged compared with young mice. Nonetheless, age-specific expression changes are observed at numerous genes, including microRNA encoding genes. Importantly, these changes are underpinned by multi-layered alterations in chromatin structure, including chromatin accessibility, histone modifications, long-range promoter interactions, and nuclear compartmentalization. Previous work has shown that differentiation is linked to changes in promoter-regulatory element interactions. We find that aging in B cell precursors is accompanied by rewiring of such interactions. We identify transcriptional downregulation of components of the insulin-like growth factor signaling pathway, in particular downregulation of Irs1 and upregulation of Let-7 microRNA expression, as a signature of the aged phenotype. These changes in expression are associated with specific alterations in H3K27me3 occupancy, suggesting that Polycomb-mediated repression plays a role in precursor B cell aging.

CONCLUSIONS

Changes in chromatin and 3D genome organization play an important role in shaping the altered gene expression profile of aged precursor B cells. Components of the insulin-like growth factor signaling pathways are key targets of epigenetic regulation in aging in bone marrow B cell precursors.

The Metalloproteinase ADAM28 Promotes Metabolic Dysfunction in Mice

Obesity and diabetes are major causes of morbidity and mortality globally. The current study builds upon our previous association studies highlighting that A Disintegrin And Metalloproteinase 28 (ADAM28) appears to be implicated in the pathogenesis of obesity and type 2 diabetes in humans. Our novel study characterised the expression of ADAM28 in mice with the metabolic syndrome and used molecular inhibition approaches to investigate the functional role of ADAM28 in the pathogenesis of high fat diet-induced obesity. We identified that ADAM28 mRNA and protein expression was markedly increased in the livers of mice with the metabolic syndrome. In addition, noradrenaline, the major neurotransmitter of the sympathetic nervous system, results in elevated Adam28 mRNA expression in human monocytes. Downregulation of ADAM28 with siRNA technology resulted in a lack of weight gain, promotion of insulin sensitivity/glucose tolerance and decreased liver tumour necrosis factor-α (TNF-α) levels in our diet-induced obesity mouse model as well as reduced blood urea nitrogen, alkaline phosphatase and aspartate aminotransferase. In addition, we show that ADAM28 knock-out mice also displayed reduced body weight, elevated high density lipoprotein cholesterol levels, and reductions in blood urea nitrogen, alkaline phosphatase, and aspartate aminotransferase. The results of this study provide important insights into the pathogenic role of the metalloproteinase ADAM28 in the metabolic syndrome and suggests that downregulation of ADAM28 may be a potential therapeutic strategy in the metabolic syndrome.