Issues associated with assessing nuclear localization of N-terminally unphosphorylated β-catenin with monoclonal antibody 8E7

Abstract Background β-catenin is a dual function adhesion/transcriptional co-activator protein, and both functions are critical for normal tissue homeostasis. Since the transcriptional functions of β-catenin are more often implicated in various disease processes, there is much interest in the development and use of reagents to interrogate spatial and temporal evidence of β-catenin nuclear signaling in cells and tissues. An important study demonstrated that the signaling form of β-catenin is specifically unphosphorylated at residues S37 and T41, and suggested that this form exhibits a propensity for cytosolic/nuclear accumulation relative to the total pool of β-catenin. Results We show that monoclonal antibody, 8E7, which recognizes the signaling form of β-catenin specifically unphosphorylated at S37 and T41 (Active B-Catenin, ABC), also cross-reacts with a widely expressed, variably accessible nuclear antigen that is not β-catenin. In cell types commonly used to study Wnt activation, this non-specific nuclear staining can be robust, obscuring the ABC signal. Definitive detection of nuclear localized ABC can be confirmed through an ability of classical cadherins to sequester ABC to cell junctions. In tissues, milder antigen retrieval methods can reduce the accessibility of mAb 8E7 to this cross-reacting nuclear antigen. Conclusion These findings reveal that interpretation of nuclear, signaling active β-catenin using monoclonal antibody 8E7 should be considered judiciously, and in conjunction with independent methods. Reviewers This article was reviewed by Frank J. T. Staal (nominated by Rachel Gerstein), Jyoti M. Sen (nominated by Avinash Bhandoola) and Manabu Sugai.</p

Trends in Spontaneous Cerebrospinal Fluid Leak Repairs in the United States, 2009-2018

Background: Rates of spontaneous cerebrospinal fluid leak (sCSF) repairs have increased in recent decades in line with increases in obesity rates. Objectives: To determine if the national rate of sCSF leak has continued to rise in recent years and to identify associated risk factors utilizing a comprehensive national database comprising most academic medical centers. Methods: A retrospective review from 2009 to 2018 was performed using the Vizient Clinical Database (CDB) of 105 leading academic medical centers in the United States. Patients who underwent CSF leak repair in the CDB database using ICD-9 and ICD-10 diagnostic and procedure codes. Patients with epidural hematomas over the same time frame were used as a control. National rates of craniotomy for sCSF leak repair each quarter were assessed and sCSF leak patient characteristics (age, gender, obesity, hypertension, diabetes) were calculated. Results: The rate of craniotomy for all sCSF leak repairs increased by 10.2% annually from 2009 to 2015 (P < 0.0001). There was no statistically significant change in the rate of epidural hematomas over the same period. The rate of lateral sCSF leak repair increased on average by 10.4% annually from 2009 (218 cases/year) to 2018 (457 cases/year) (P < 0.0001). A statistically significant increase was observed across all regions of the United States (P ≤ 0.005). sCSF leak patients had an average (standard deviation) age of 55.0 (13.2) years and 67.2% were female. Obesity was the only demographic factors that increased significantly over time. Likely due to comorbid factors, Black patients comprise a disproportionately large percentage of lateral sCSF leak repair patients. Conclusions: The rate of craniotomy for spontaneous CSF leaks continues to rise by approximately 10% annually