GABAA receptors (GABAARs) play a crucial inhibitory role in the CNS. Benzodiazepines (BDZs) are positive modulators of specific subtypes of GABAARs, but the underlying mechanism remains obscure. Early studies demonstrated the major impact of BDZs on binding and more recent investigations indicated gating, but it is unclear which transitions are affected. Moreover, the upregulation of GABAAR spontaneous activity by BDZs indicates their impact on receptor gating but the underlying mechanisms remain unknown. Herein, we investigated the effect of a BDZ (flurazepam) on the spontaneous and GABA-induced activity for wild-type (WT, α1β2γ2) and mutated (at the orthosteric binding site α1F64) GABAARs. Surprisingly, in spite of the localization at the binding site, these mutations increased the spontaneous activity. Flurazepam (FLU) upregulated this activity for mutants and WT receptors to a similar extent by affecting opening/closing transitions. Spontaneous activity affected GABA-evoked currents and is manifested as an overshoot after agonist removal that depended on the modulation by BDZs. We explain the mechanism of this phenomenon as a cross-desensitization of ligand-activated and spontaneously active receptors. Moreover, due to spontaneous activity, FLU-pretreatment and co-application (agonist + FLU) protocols yielded distinct results. We provide also the first evidence that GABAAR may enter the desensitized state in the absence of GABA in a FLU-dependent manner. Based on our data and model simulations, we propose that FLU affects agonist-induced gating by modifying primarily preactivation and desensitization. We conclude that the mechanisms of modulation of spontaneous and ligand-activated GABAAR activity concerns gating but distinct transitions are affected in spontaneous and agonist-evoked activity.

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IntroductionLung cancer is the predominant cause of death among cancer patients and non-small cell lung cancer (NSCLC) is the most common type. Cigarette smoking is the prevailing risk factor for NSCLC, nevertheless, this cancer is also diagnosed in never-smokers. B and T lymphocyte attenuator (BTLA) belongs to immunological checkpoints which are key regulatory molecules of the immune response. A growing body of evidence highlights the important role of BTLA in cancer. In our previous studies, we showed a significant association between BTLA gene variants and susceptibility to chronic lymphoblastic leukemia and renal cell carcinoma in the Polish population. The present study aimed to analyze the impact of BTLA polymorphic variants on the susceptibility to NSCLC and NSCLC patients’ overall survival (OS).MethodsUsing TaqMan probes we genotyped seven BTLA single-nucleotide polymorphisms (SNPs): rs2705511, rs1982809, rs9288952, rs9288953, rs1844089, rs11921669 and rs2633582 with the use of ViiA 7 Real-Time PCR System.ResultsWe found that rs1982809 within BTLA is associated with NSCLC risk, where carriers of rs1982809G allele (AG+GG genotypes) were more frequent in patients compared to controls. In subgroup analyses, we also noticed that rs1982809G carriers are significantly overrepresented in never-smokers, but not in smokers compared to controls. Additionally, the global distribution of the haplotypes differed between the never-smokers and smokers, where haplotypes A G G C A, C G A C G, and C G A T G were more frequent in never-smoking patients. Furthermore, the presence rs1982809G (AG+GG genotypes) allele as well as the presence of rs9288953T allele (CT+TT genotypes) increased NSCLC risk in females’ patients. After stratification by histological type, we noticed that rs1982809G and rs2705511C carriers were more frequent among adenocarcinoma patients. Moreover, rs1982809G and rs2705511C correlated with the more advanced stages of NSCLC (stage II and III), but not with stage IV. Furthermore, we showed that rs2705511 and rs1982809 significantly modified OS, while rs9288952 tend to be associated with patients’ survival.ConclusionOur results indicate that BTLA polymorphic variants may be considered low penetrating risk factors for NSCLC especially in never-smokers, and in females, and are associated with OS of NSCLC patients.

In our previous study, while chronic lymphocytic leukemia (CLL) cases showed higher levels of B and T lymphocyte attenuator (BTLA) mRNA compared to controls, lower BTLA protein expression was observed in cases compared to controls. Hence we hypothesize that micro RNA (miR) 155-5p regulates BTLA expression in CLL. In line with earlier data, expression of BTLA mRNA and miR-155-5p is elevated in CLL (p = 0.034 and p = 0.0006, respectively) as well as in MEC-1 cell line (p = 0.009 and 0.016, respectively). Inhibition of miR-155-5p partially restored BTLA protein expression in CLL patients (p = 0.01) and in MEC-1 cell lines (p = 0.058). Additionally, we aimed to evaluate the significance of BTLA deficiency in CLL cells on proliferation and IL-4 production of B cells. We found that secretion of IL-4 is not dependent on BTLA expression, since fractions of BTLA positive and BTLA negative B cells expressing intracellular IL-4 were similar in CLL patients and controls. We demonstrated that in controls the fraction of proliferating cells is lower in BTLA positive than in BTLA negative B cells (p = 0.059), which was not observed in CLL. However, the frequency of BTLA positive Ki67+ B cells in CLL was higher compared to corresponding cells from controls (p = 0.055) while there were no differences between the examined groups regarding frequency of BTLA negative Ki67+ B cells. Our studies suggest that miR-155-5p is involved in BTLA deficiency, affecting proliferation of CLL B cells, which may be one of the mechanisms responsible for CLL pathogenesis.

Background To investigate the association between single nucleotide polymorphisms (SNPs) of PDCD1, CD274, and HAVCR2 genes with the risk and outcomes of non-small cell lung cancer (NSCLC) subtypes: squamous cell lung cancer (LUSC) and lung adenocarcinoma (LUAD). Methods TaqMan SNP genotyping assays or polymerase chain reaction-restriction fragment length polymorphism methods were used to determine genotypes of: PDCD1: rs36084323, rs7421861, rs11568821, rs2227981, rs10204525; CD274: rs822335, rs10815225, rs17718883, rs2297136, rs4742098, rs4143815; HAVCR2: rs10057302, rs1036199. Among 383 NSCLC patients, 112 were diagnosed with LUAD and 116 with LUSC. The control group consisted of 433 unrelated, cancer-free subjects. Results A CC genotype of rs4143815 and GG genotype of rs4742098 were associated with two times higher risk of developing LUSC (CC vs. GG + GC, OR = 2.31; 95% CI = 1.32, 4.06; P = 0.003; GG vs. AA + AG, OR = 2.26; 95% CI = 1.17, 4.36; P = 0.016, respectively). Moreover, rs4143815 was an independent predictor of the age at diagnosis of LUAD. The carriers of C allele were diagnosed 4.81 years later (95% CI = 1.47, 8.15; P = 0.006) than patients with the GG genotype. The rs10057302 CA genotype was an independent predictor of overall survival in LUSC (adjusted HR = 0.13; 95% CI = 0.02, 0.93; P = 0.043). NSCLC carriers of rs11568821 T allele had almost double the risk of death (adjusted HR = 2.05; 95% CI = 1.28, 3.29; P = 0.003) compared to carriers of CC genotype. Conclusions Our results provided additional evidence that SNPs of genes for PD-1, PD-L1 and TIM-3 differentially modulate the risk and prognosis of LUSC and LUAD.