Development of the NOGGO GIS v1 Assay, a Comprehensive Hybrid-Capture-Based NGS Assay for Therapeutic Stratification of Homologous Repair Deficiency Driven Tumors and Clinical Validation

The worldwide approval of the combination maintenance therapy of olaparib and bevacizumab in advanced high-grade serous ovarian cancer requires complex molecular diagnostic assays that are sufficiently robust for the routine detection of driver mutations in homologous recombination repair (HRR) genes and genomic instability (GI), employing formalin-fixed (FFPE) paraffin-embedded tumor samples without matched normal tissue. We therefore established a DNA-based hybrid capture NGS assay and an associated bioinformatic pipeline that fulfils our institution's specific needs. The assay´s target regions cover the full exonic territory of relevant cancer-related genes and HRR genes and more than 20,000 evenly distributed single nucleotide polymorphism (SNP) loci to allow for the detection of genome-wide allele specific copy number alterations (CNA). To determine GI status, we implemented an %CNA score that is robust across a broad range of tumor cell content (25-85%) often found in routine FFPE samples. The assay was established using high-grade serous ovarian cancer samples for which BRCA1 and BRCA2 mutation status as well as Myriad MyChoice homologous repair deficiency (HRD) status was known. The NOGGO (Northeastern German Society for Gynecologic Oncology) GIS (GI-Score) v1 assay was clinically validated on more than 400 samples of the ENGOT PAOLA-1 clinical trial as part of the European Network for Gynaecological Oncological Trial groups (ENGOT) HRD European Initiative. The "NOGGO GIS v1 assay" performed using highly robust hazard ratios for progression-free survival (PFS) and overall survival (OS), as well a significantly lower dropout rate than the Myriad MyChoice clinical trial assay supporting the clinical utility of the assay. We also provide proof of a modular and scalable routine diagnostic method, that can be flexibly adapted and adjusted to meet future clinical needs, emerging biomarkers, and further tumor entities.

Pathologic responses in oligometastatic NSCLC patients treated with neoadjuvant immune checkpoint blockade with and without chemotherapy followed by surgery

OBJECTIVES

Immune checkpoint inhibitors (ICI) have significantly improved outcome of patients with advanced NSCLC and recently also showed benefit in early-stage disease. Patients with oligometastatic disease (OMD) harbor limited metastases, resectable primary tumors and derive benefit from treatment with multimodal locally ablative and systemic therapy approaches. Nothing is known about feasibility and efficacy of neoadjuvant ICI in this setting.

MATERIAL AND METHODS

We here provide data from a multicenter retrospective study comprising 13 patients with NSCLC and OMD (≤3 distant metastases) from 5 university medical centers in Germany who have been treated with neoadjuvant ICI alone (n = 4) or in combination with chemotherapy (CT) (n = 9) prior to resection of the primary tumor. We analyzed complete (pCR) and major pathological remission (MPR) rates.

RESULTS

These data show that neoadjuvant immunotherapy applied mostly in combination with CT results in high rates of pCR and MPR (54 and 69%, respectively). Up to now, 85% of patients are free of progression with a median follow-up of 9 months (3-28 months). Single cell RNASeq analysis of tumor tissue from one patient treated with CT-ICI indicates a strong predominance of adaptive immune cell populations over a small minority of epithelial (tumor) cells.

CONCLUSION

Neoadjuvant ICI with or without CT is a promising therapeutic concept in patients with OMD.

European and US Real-World Treatment Patterns in Patients with Epidermal Growth Factor Receptor Mutation-Positive Non-Small Cell Lung Cancer: A Retrospective Medical Record Review

BACKGROUND

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) are the preferred first-line (1L) therapy for EGFR mutation-positive (EGFRm) advanced/metastatic non-small cell lung cancer (NSCLC).

OBJECTIVE

Our objective was to describe real-world treatment patterns and T790M testing practices in patients with 1L disease progression (Europe/USA) following treatment with first- or second-generation EGFR-TKIs.

METHODS

This was a retrospective, non-interventional medical record review of patients with EGFRm locally advanced/metastatic NSCLC from routine clinical practice (EGFR-TKI initiation: 1 January 2015 to 31 December 2017; follow-up: last available medical record). Endpoints were demographic/clinical characteristics, incidence of central nervous system (CNS) metastases/leptomeningeal disease, second-line (2L) treatment, T790M mutation testing, and osimertinib treatment prevalence.

RESULTS

Among 469 patients, 73% (n = 341/469) progressed on 1L EGFR-TKI treatment. Of those who progressed, 74% (n = 252/341) were tested for T790M, with 50% (n = 126/252) testing positive; 75% (n = 94/126) of T790M-positive patients received osimertinib (mostly 2L). Of the patients with progression, 24% (n = 83/341) did not receive 2L treatment, and 88% (n = 73/83) of these patients died. At diagnosis of advanced disease, 9% of patients (n = 41) had CNS metastases; at EGFR-TKI initiation, 14% of patients (n = 68) had CNS metastases. Over the study period, 11% of patients (n = 42) developed CNS metastases not detected at NSCLC diagnosis.

CONCLUSIONS

Rates of resistance mutation testing and subsequent utilization of recommended 2L therapies could be improved. As more targeted therapies are developed, it will be crucial to improve the molecular testing rates to ensure patients receive appropriate, effective, and timely treatment.

Improving professional health literacy in hospitals: study protocol of a participatory codesign and implementation study

INTRODUCTION

In connection with a hospital stay, patients have to make important health-related decisions. They need to find, understand, assess and apply health-related information, and therefore, require health literacy. Adequately responding to the needs of patients requires promoting the communication skills of healthcare professionals within healthcare organisations. Health-literate healthcare organisations can provide an environment strengthening professionals' and patients' health literacy. When developing health-literate healthcare organisations, it has to be considered that implementing organisational change is typically challenging. In this study, a communication concept based on previously evaluated communication training is codesigned, implemented and evaluated in four clinical departments of a university hospital.

METHOD AND ANALYSIS

In a codesign phase, focus group interviews among employees and patients as well as a workshop series with employees and hospital management are used to tailor the communication concept to the clinical departments and to patients' needs. Also, representatives responsible for the topic of health literacy are established among employees. The communication concept is implemented over a 12-month period; outcomes studied are health literacy on the organisational and patient levels. Longitudinal survey data acquired from a control cohort prior to the implementation phase are compared with data of an intervention cohort after the implementation phase. Moreover, survey data from healthcare professionals before and after the implementation are compared. For formative evaluation, healthcare professionals are interviewed in focus groups.

ETHICS AND DISSEMINATION

The study protocol was approved by the Ethics Committee of the Medical Faculty of the University of Oldenburg and is in accordance with the Declaration of Helsinki. Study participants are asked to provide written informed consent. The results are disseminated via direct communication within the hospital, publications and conference presentations. If the intervention turns out to be successful, the intervention and implementation strategies will be made available to other hospitals.

TRIAL REGISTRATION NUMBER

DRKS00019830.

BRAF mutations and BRAF mutation functional class have no negative impact on the clinical outcome of advanced NSCLC and associate with susceptibility to immunotherapy

OBJECTIVE

BRAF mutations have been subtyped in three functional classes with different oncogenic modes of action. The clinical impact of BRAF mutational subtypes in non-small-cell lung cancer (NSCLC) remains to be defined. So far, ambiguous results were reported from analyses of heterogeneous patient cohorts.

METHODS

We studied patients with metastatic or recurrent NSCLC who were sequentially enrolled in precision oncology programs at two large German lung cancer centres from 2009 to 2019. The study period allowed evaluating the specific impact of BRAF V600E-targeting.

RESULTS

In a cohort of 72 patients, BRAF mutation subtyping revealed p.V600E mutations in 31 cases (43%), whereas 41 cases (57%) harboured 18 different BRAF mutational subtypes of functional classes II/III. Functionally relevant comutations were observed in 6.4% of class I, and 24.4% of class II/III BRAF mutations. Most patients were treated with chemotherapy. Targeted therapy was administered in 11 patients with a response rate of 72.7%. PD-1/PD-L1-immunotherapy was given in 14 patients with a response rate of 28.6%. Overall survival of patients with BRAF-mutated NSCLC was inferior (HR 1.38, p = 0.048) as compared to patients with BRAF wild-type cancers. Median time-to-treatment-failure with BRAF-targeting agents was shorter as compared to approved targeted therapy of other oncogenic drivers (HR 1.97, p = 0.05). Survival outcomes were not impacted by BRAF mutation subtype functional class.

CONCLUSIONS

Patients with BRAF-mutated NSCLC have an inferior prognosis, which is not determined by BRAF mutation functional class. In contrast to NSCLC with other tractable driver mutations, BRAF-mutated NSCLC exhibit high susceptibility to immune checkpoint inhibitors.

Optimizing therapy sequence to prevent patient attrition in EGFR mutation-positive advanced or metastatic NSCLC

Clinical trial and real-world data in non-small-cell lung cancer indicate that 10-60% of patients that progressed on first- or second-generation EGFR-targeting tyrosine kinase inhibitors (TKI) do not receive systemic second-line therapy. In our article, we discuss efficacy, safety and treatment duration with different EGFR-TKIs and stress the need for delivery of the most efficacious therapy in the first-line. We also provide our perspective on analysis of circulating tumor DNA and the role of EGFR-TKI in combined therapies. Finally, we review new therapeutic options to overcome resistance to EGFR-TKI. We believe that overall treatment duration and access to different medications in subsequent lines of therapy should be considered when planning the optimal treatment strategy.

Risk stratification of EGFR+ lung cancer diagnosed with panel-based next-generation sequencing

OBJECTIVE

Panel-based next-generation sequencing (NGS) is increasingly used for the diagnosis of EGFR-mutated non-small-cell lung cancer (NSCLC) and could improve risk assessment in combination with clinical parameters.

MATERIALS AND METHODS

To this end, we retrospectively analyzed the outcome of 400 tyrosine kinase inhibitor (TKI)-treated EGFR⁺ NSCLC patients with validation of results in an independent cohort (n = 130).

RESULTS

EGFR alterations other than exon 19 deletions (non-del19), TP53 co-mutations, and brain metastases at baseline showed independent associations of similar strengths with progression-free (PFS hazard ratios [HR] 2.1-2.3) and overall survival (OS HR 1.7-2.2), in combination defining patient subgroups with distinct outcome (EGFR⁺NSCLC risk Score, "ENS", p < 0.001). Co-mutations beyond TP53 were rarely detected by our multigene panel (<5%) and not associated with clinical endpoints. Smoking did not affect outcome independently, but was associated with non-del19 EGFR mutations (p < 0.05) and comorbidities (p < 0.001). Laboratory parameters, like the blood lymphocyte-to-neutrophil ratio and serum LDH, correlated with the metastatic pattern (p < 0.01), but had no independent prognostic value. Reduced ECOG performance status (PS) was associated with comorbidities (p < 0.05) and shorter OS (p < 0.05), but preserved TKI efficacy. Non-adenocarcinoma histology was also associated with shorter OS (p < 0.05), but rare (2-3 %). The ECOG PS and non-adenocarcinoma histology could not be validated in our independent cohort, and did not increase the range of prognostication alongside the ENS.

CONCLUSIONS

EGFR variant, TP53 status and brain metastases predict TKI efficacy and survival in EGFR⁺ NSCLC irrespective of other currently available parameters ("ENS"). Together, they constitute a practical and reproducible approach for risk stratification of newly diagnosed metastatic EGFR⁺ NSCLC.

TP53 mutations in EGFR mt+ NSCLC IV as a predictive factor for ORR, PFS, and OS irrespective of T790M

e20679

Background: The impact of TP53 mutations in EGFR mt+ pts on PFS and OS is controversial, and different classifications of TP53 mt+ with respect to functional and potential predictive impact have been published. Therefore, we retrospectively analyzed the impact of TP53 aberrations on ORR, PFS and OS in a cohort of EGFR mt+ NSCLC IV pts (UICC 7) using different classifications of TP53 mutations. Methods: 75 EGFR mt+ NSCLC IV pts were analyzed for TP53 co-mutations. TP53 mt+ were classified according to Poeta et al. into (1) disruptive vs. non-disruptive, according to structural prediction and biophysical characteristics into (2) pathogenic vs. non-pathogenic and finally into (3) exon 8 vs. non-exon 8 mutations according to Crino et al.. The endpoints ORR according to Recist 1.1, PFS and OS were calculated by Kaplan Meier. Results: 69 of the 75 EGFR mt+ pts (92%) had a common mutation in EGFR E19/21. In 59/75 pts (79%) material was sufficient for successful TP53 analysis. TP53 mt+ were found in 29/59 pts (49%), 16/59 (27%) had a TP53 disruptive mt+, 13/59 (22%) a TP53 non-disruptive mt+ and 30/59 a TP53 WT configuration. Using the structural/biophysical classification, 7/59 (12%) had a TP53 non-pathogenic and 22/59 (37%) a TP53 pathogenic mt+. Of the 29 mutated pts, 6 had a TP53 Exon 8 mt+. Median PFS on 1st line TKI was 12 vs. 18 months for non-disruptive/disruptive mt+ vs. WT (p < 0.004), 11 vs. 17 months for pathogenic vs. non-pathogenic/WT (p < 0.0001), and 7 vs. 12 vs. 18 months for exon 8 vs. non-exon 8 vs. WT (p < 0.006). Median OS was 24 vs. 42 months in non-disruptive/disruptive mt+ vs. WT (p < 0.0009), 23 vs. 42 months in pathogenic vs. non-pathogenic/WT (p < 0.001) and 12 vs. 28 months for TP53 exon 8 vs. non-exon 8 mt+ (p < 0.024). Additionally ORR was significantly impacted by TP53 mt+. In rebiopsy samples on acquired resistance, no new TP53 mutations were observed and there were no correlations of TP53 mutations with clinical factors and the EGFR mt+ type including T790M. Conclusions: TP53 seems to be a frequent co-mutation in EGFR mt+ NSCLC and has a strong impact on all clinical endpoints on TKI therapy. These data might have an impact on the management and follow up of pts with TP53 mt+. Furthermore, there is an urgent need for further therapeutic approaches in this patient group.

Impact on OS of 2nd and 3rd generation TKI in EGFR mt+ and ALK+ patients: Results of the NOWEL network

e20560

Background: Available clinical research data shows that early mutation testing for patients with NSCLC stage IV could lead to an effective choice of therapy for patients with proven mutations. Targeted therapies achieve a higher ORR, PFS, OS and a better quality of life than chemotherapy in mt+ patients. With the advent of 2nd and 3rd generation TKI´s effective in 1st generation TKI resistant tumors, we wanted to study the impact of these drugs on the outcome of patients in a real life setting in 3 lung cancer centers. Methods: 1383 patients from the three cancer centers diagnosed with NSCLC stage IV (UICC 7) were examined. Methods for the detection of mutations included Sanger Sequencing, hybridization based COBAS testing as well as hybrid cage next generation sequencing. Results: 880/1383 (64%) consecutive patients with non-squamous cell NSCLC from the cancer centers were studied for the presence of tumor mutations, especially for EGFR and ALK mutations. The EGFR mutation rate was 16.6% (141/880), and the ALK-translocation rate 3.8% (24/635). Median OS in EGFR mt+ patients was 31 (n = 78) vs. 32 (n = 38) vs. 16 (n = 14) months respectively (center 1 vs. center 2 vs. center 3). Median OS in ALK mt+ patients was 25 (n = 17) months in center 1 and 11 (n = 5) months in center 2 (p < 0.05). Use of 3rd generation TKI Osimertinib (n = 17) lead to a significantly higher OS (n = 17, median OS 67 mo) than the use of only 1st and 2nd generation TKI (n = 113, median OS 24 mo, p < 0.000). Similarly, use of 2nd and 3rd generation ALKi impacted significantly on median OS: Crizotinib alone n = 7, 17 months, Crizotinib followed by Ceritinib and/or Brigatinib (n = 9) median OS not reached, p < 0.001. Conclusions: Smalldifferences in OS were observed, depending on the treatment centers, but the use of multiple EGFR and ALK-I impacted highly significantly on the outcome of patients with EGFR and ALK-alterations in a real life setting.

ATP-sensitive potassium channels in dopaminergic neurons: transducers of mitochondrial dysfunction

ATP-sensitive potassium (K(ATP)) channels directly couple the metabolic state of a cell to its electrical activity. Dopaminergic midbrain neurons express alternative types of K(ATP) channels mediating their differential response to mitochondrial complex I inhibition. Because reduced complex I activity is present in Parkinson's Disease, differential K(ATP) channel expression suggests a novel candidate mechanism for selective dopaminergic degeneration.

Differential expression of the small-conductance, calcium-activated potassium channel SK3 is critical for pacemaker control in dopaminergic midbrain neurons

The physiological activity of dopaminergic midbrain (DA) neurons is important for movement, cognition, and reward. Altered activity of DA neurons is a key finding in schizophrenia, but the cellular mechanisms have not been identified. Recently, KCNN3, a gene that encodes a member (SK3) of the small-conductance, calcium-activated potassium (SK) channels, has been proposed as a candidate gene for schizophrenia. However, the functional role of SK3 channels in DA neurons is unclear. We combined patch-clamp recordings with single-cell RT-PCR and confocal immunohistochemistry in mouse midbrain slices to study the function of molecularly defined SK channels in DA neurons. Biophysical and pharmacological analysis, single-cell mRNA, and protein expression profiling strongly suggest that SK3 channels mediate the calcium-dependent afterhyperpolarization in DA neurons. Perforated patch recordings of DA neurons in the substantia nigra (SN) demonstrated that SK3 channels dynamically control the frequency of spontaneous firing. In addition, SK3 channel activity was essential to maintain the high precision of the intrinsic pacemaker of DA SN neurons. In contrast, in the ventral tegmental area, DA neurons displayed significantly smaller SK currents and lower SK3 protein expression. In these DA neurons, SK3 channels were not involved in pacemaker control. Accordingly, they discharged in a more irregular manner compared with DA SN neurons. Thus, our study shows that differential SK3 channel expression is a critical molecular mechanism in DA neurons to control neuronal activity. This provides a cellular framework to understand the functional consequences of altered SK3 expression, a candidate disease mechanism for schizophrenia.

ATP-sensitive K+ channels in the hypothalamus are essential for the maintenance of glucose homeostasis

Glucose-responsive (GR) neurons in the hypothalamus are thought to be critical in glucose homeostasis, but it is not known how they function in this context. Kir6.2 is the pore-forming subunit of K(ATP) channels in many cell types, including pancreatic beta-cells and heart. Here we show the complete absence of both functional ATP-sensitive K+ (K(ATP)) channels and glucose responsiveness in the neurons of the ventromedial hypothalamus (VMH) in Kir6.2-/- mice. Although pancreatic alpha-cells were functional in Kir6.2-/-, the mice exhibited a severe defect in glucagon secretion in response to systemic hypoglycemia. In addition, they showed a complete loss of glucagon secretion, together with reduced food intake in response to neuroglycopenia. Thus, our results demonstrate that KATP channels are important in glucose sensing in VMH GR neurons, and are essential for the maintenance of glucose homeostasis.

Molecular physiology of neuronal K-ATP channels (review)

ATP sensitive potassium (K-ATP) channels are widely expressed in many cell types including neurons. K-ATP channels are heteromeric membrane proteins that consist of two very different subunits: the pore-forming, two-transmembrane spanning potassium channel subunit (Kir6) and the regulatory, 17 transmembrane spanning sulphonylurea receptor (SUR). This ensemble--joined together in a 4:4 stoichiometry--endows this channel with a unique combination of functional properties. The open probability of K-ATP channels directly depends on the intracellular ATP/ADP levels allowing the channels to directly couple the metabolic state of a cell to its electrical activity. Here, recent progress on the molecular composition and functional diversity of neuronal K-ATP channels is reviewed. One is particular concerned with single-cell mRNA expression studies that give insight to the coexpression patterns of Kir6 and SUR isoforms in identified neurons. In addition, the physiological roles of neuronal K-ATP channels in glucose sensing and adapting neuronal activity to metabolic demands are discussed, as well as their emerging pathophysiological functions in acute brain ischemia and chronic neurodegenerative diseases.

Single-cell mRNA expression of HCN1 correlates with a fast gating phenotype of hyperpolarization-activated cyclic nucleotide-gated ion channels (Ih) in central neurons

Hyperpolarization-activated currents (Ih) are key players in shaping rhythmic neuronal activity. Although candidate genes for Ih channels have been cloned (HCN1-HCN4), the subunit composition of different native Ih channels is unknown. We used a combined patch-clamp and qualitative single-cell reverse transcription multiplex polymerase chain reaction (RT-mPCR) approach to analyse HCN1-4 coexpression profiles in four neuronal populations in mouse CNS. Coexpression of HCN2, HCN3 and HCN4 mRNA was detected in single neurons of all four neuronal cell types analysed. In contrast, HCN1 mRNA was detected in neocortical and hippocampal pyramidal neurons but not in dopaminergic midbrain and thalamocortical neurons. HCN1 expression was correlated with significantly faster activation kinetics on the level of individual neurons. Semiquantitative single-cell RT-mPCR analysis demonstrated that HCN1 mRNA expression is at least eightfold higher in cortical neurons than subcortical neurons. We show that single neurons possess complex coexpression patterns of Ih candidate genes. Alternative expression of HCN1 is likely to be an important molecular determinant to generate the different neuronal Ih channel species adapted to tune either subcortical or cortical network activity.

Activity-dependent formation of perforated synapses in cultured hippocampal neurons

The study investigated the formation of perforated synapses in rat hippocampal cell cultures. Perforated synapses are defined by their discontinuous postsynaptic densities (PSDs) and are believed to occur in parallel with changes in synaptic activity and possibly also synaptic efficacy. Several in vivo studies have demonstrated an increase in the frequency of perforated synapses induced by development and environmental stimulation as well as long-term potentiation (LTP). Also in in vitro brain slices, LTP was associated with an elevated number of perforated spine synapses. Our study demonstrated for the first time that the formation of perforated synapses can be induced by a short-term increase in spontaneous neural activity in a hippocampal cell culture model. Stimulation with the GABAA-antagonist picrotoxin (PTX) induced a significant increase in the percentage of perforated synapses. This strong increase was blocked when APV was added together with PTX, indicating that the formation of perforated synapses depended on the activation of NMDA receptors. We also showed that inhibition of the tissue type plasminogen activator (tPA-stop/PAI-1) significantly interfered with the activity-induced increase in perforated synapses. This implies that the proteolytic activities of tPA might be involved in steps which are downstream from the NMDA receptor-mediated synaptic plasticity leading to structural changes at synaptic contacts. In contrast, even long-term inhibition of electrical network activity by tetrodotoxin had no effect on the number of perforated synapses, but almost completely abolished the formation of spine synapses. These results indicate that a short-term increase in neural activity via NMDA receptors and a proteolytic cascade involving tPA lead to the formation of perforated synapses.

The weaver mouse gain-of-function phenotype of dopaminergic midbrain neurons is determined by coactivation of wvGirk2 and K-ATP channels

The phenotype of substantia nigra (SN) neurons in homozygous weaver (wv/wv) mice was studied by combining patch-clamp and single-cell RT-multiplex PCR techniques in midbrain slices of 14-d-old mice. In contrast to GABAergic SN neurons, which were unaffected in homozygous weaver mice (wv/wv), dopaminergic SN neurons possessed a dramatically altered phenotype with a depolarized membrane potential and complete loss of spontaneous pacemaker activity. The gain-of-function phenotype was mediated by a large, nonselective membrane conductance exclusively present in (wv/wv) dopaminergic SN neurons. This constitutively activated conductance displayed a sensitivity to external QX-314 (IC(50) = 10.6 microM) very similar to that of heterologously expressed wvGirk2 channels and was not further activated by G-protein stimulation. Single-cell Girk1-4 expression profiling suggested that homomeric Girk2 channels were present in most dopaminergic SN neurons, whereas Girk2 was always coexpressed with other Girk family members in GABAergic SN neurons. Surprisingly, acute QX-314 inhibition of wvGirk2 channels did not induce wild-type-like pacemaker activity but instead caused membrane hyperpolarization. Additional application of a blocker of ATP-sensitive potassium channels (100 microM tolbutamide) induced wild-type-like pacemaker activity. We conclude that the gain-of-function weaver phenotype of dopaminergic substantia nigra neurons is mediated by coactivation of wvGirk2 and SUR1/Kir6. 2-mediated ATP-sensitive K(+) channels. We also show that in contrast to wild-type neurons, all (wv/wv) dopaminergic SN neurons expressed calbindin, a calcium-binding protein that marks dopaminergic SN neurons resistant to neurodegeneration. The identification of two ion channels that in concert determine the weaver phenotype of surviving calbindin-positive dopaminergic SN neurons will help to understand the molecular mechanisms of selective neurodegeneration of dopaminergic SN neurons in the weaver mouse and might be important in Parkinson's disease.

Functional and molecular aspects of voltage-gated K+ channel beta subunits

Voltage-gated potassium channels (Kv) of the Shaker-related superfamily are assembled from membrane-integrated alpha subunits and auxiliary beta subunits. The beta subunits may increase Kv channel surface expression and/or confer A-type behavior to noninactivating Kv channels in heterologous expression systems. The interaction of Kv alpha and Kv beta subunits depends on the presence or absence of several domains including the amino-terminal N-type inactivating and NIP domains and the Kv alpha and Kv beta binding domains. Loss of function of Kv beta 1.1 subunits leads to a reduction of A-type Kv channel activity in hippocampal and striatal neurons of knock-out mice. This reduction may be correlated with altered cognition and motor control in the knock-out mice.