PAI-1 gain-of-function genotype, factors increasing PAI-1 levels, and airway obstruction: The GALA II Cohort

SNPs, adipokynes and adiposity in children with asthma

OBJECTIVES

Asthma and obesity are complex disorders influenced by environmental and genetic factors. We performed an integrative review of genetic polymorphisms and adipokines effects in children and adolescents with asthma and obesity.

DATA SOURCES

Articles focused on these issues were collected from SciELO, PubMed, LILACS, Embase and ScienceDirect electronic databases, in 2009-2020 period.

STUDY SELECTIONS

22 articles were selected, including clinical trials, analyses approaches, case-control studies, meta-analysis and Mendelian randomization studies.

RESULTS

Leptin concentrations were higher in obesity and asthma. The high value of BMI and Leptin indicated severe asthma. Adiponectin may be reduced in obese children. The high value of BMI and low level of Adiponectin may indicate severe asthma. Some linkage of PRKCA gene, asthma and BMI was observed. FTO T allele rs62048379 was positively associated with overweight/obesity, related to protein and PUFA:SFA ratio intake and influences the choice of more energy-dense foods. FTO rs9939609 effects are more pronounced among children with insufficient vitamin D levels.

CONCLUSION

Leptin may be a potential predictor for asthma control in children. BMI and Adiponectin could have certain predictive value for asthma. FTO gene was related to a higher mean BMI Z-score and accelerated developmental age per allele. Strong genetic heterogeneity influencing on asthma and obesity susceptibilities is evident and related to distinct genetic features. GWAS with childhood obesity in asthma contributed to greater insights, mainly on later childhood. Standardized definitions for asthma and overweight/obesity in studies approaching adipokines and SNPs would provide stronger evidence in deciding the best management.

The Intrinsically Disordered Loop in the USF1 bHLHZ Domain Modulates Its DNA-Binding Sequence Specificity in Hereditary Asthma

USF1, a basic region/helix-loop-helix/leucine zipper (bHLHZ) transcription factor, binds to the E-box in the PAI-1 (plasminogen activator inhibitor) promoter. Two alleles containing the E-box control PAI-1 transcription; these alleles are termed "4G" and "5G" based on the G tract flanking E-box. USF1-governed transcription of PAI-1 is elevated in heritable asthma sufferers: the 4G/4G genotype has the highest plasma levels of PAI-1. While USF1 uses its basic region to bind E-box, we found that it uses its 12 amino-acid loop to recognize the flanking sequence and discern the single-nucleotide difference between the alleles. We used the bacterial one-hybrid and electrophoretic mobility shift assays to assess protein-DNA recognition, and circular dichroism to examine protein secondary structure. We mutated Ser233 and Thr234 in the USF1 bHLHZ loop to Ala to generate S233A and T234A. Interestingly, USF1 bHLHZ, S233A, and T234A prefer the 5G sequence (USF1 bHLHZ K_d values 4.1 ± 0.3 nM and 7.0 ± 0.4 nM for 5G and 4G, respectively), whereas studies in stimulated human mast cells showed a preference for 4G. We replaced the 8 amino-acid loop of transcription factor Max bHLHZ with the 12 amino-acid USF1 loop: this mutant now distinguishes the 4G/5G polymorphism-while Max bHLHZ does not-confirming that USF1 differentiation of the 4G/5G is driven by the loop.