👤 Gregory Foran

The accumulation and deposition of amyloid-beta (Aß) peptides is detrimental to neuronal networks and is driven by the cleavage of amyloid precursor protein (APP) by beta-secretase 1 (BACE1). The proteolytic processing of APP is tightly regulated by the opposing activities of BACE1 and ADAM10, with the latter producing a truncated, non-amyloidogenic fragment. Maintaining this balance is critical for normal physiological function, as complete inhibition of BACE1 has proven detrimental owing to the important physiological roles of its many substrates. Brain-derived neurotrophic factor (BDNF), an important mediator of neuronal function and survival, has recently been shown to reduce BACE1 activity in neural tissue, but the mechanism for this remains unknown. Previous research suggests that BACE1 cleavage of APP is favoured at acidic intracellular compartments, whereas non-amyloidogenic processing preferentially occurs at the plasma membrane. Hence, we hypothesized that BDNF alters the subcellular distribution of BACE1, reducing ß-cleavage of APP. Here, we show that acute BDNF treatment of differentiated neural cells (SH-SY5Y) reduced levels of sAPPß, a product of BACE1 cleavage of APP. Using confocal microscopy and quantitative image analysis, we found that this reduction in sAPPß levels is coincident with increased BACE1 localization to the plasma membrane, and a concomitant reduction of BACE1 localization to early endosomes. This effect appears to be independent of clathrin-mediated endocytosis (CME), as inhibition of CME by PitStop2 treatment increased a-cleavage of APP but did not reduce ß-cleavage independent of BDNF treatment. Hence, BDNF may reduce production of Aß by altering BACE1 distribution and decreasing upstream ß-cleavage. Show less

Lp(a) (lipoprotein[a]) is associated with cardiovascular disease, but neither the causal nature nor the underlying mechanisms are fully documented. This study investigated whether Lp(a) triggers atherogenesis by dysregulating vascular redox-sensitive inflammatory state. Plasma Lp(a) was measured in 1027 patients with advanced coronary artery disease undergoing cardiac surgery. These patients were genotyped, and a modified Increased plasma Lp(a) ( This study demonstrates for the first time that a genetically determined increase in plasma Lp(a) results in dysregulated vascular redox/nitrosative signaling in patients with atherosclerosis. Show less

T-cell acute lymphoblastic leukemia/lymphoma (T-ALL/LBL) is usually diagnosed based on the presence of immature lymphoid marker terminal deoxynucleotidyl transferase (TdT), and T-cell specific markers, specifically CD3, by immunohistochemistry (IHC) staining on bone marrow and/or extramedullary tissue. We present a novel, TdT and CD3 negative, aggressive early T-cell precursor LBL (ETP-LBL) initially misdiagnosed as a high grade B-cell lymphoma due to expression of CD79a and the erroneous detection of BCL2/IGH fusion. The patient was eventually evaluated using molecular diagnostic techniques, including fluorescence in situ hybridization (FISH) and next generation sequencing (NGS) assays that demonstrated PICALM-MLLT10 fusion and a NOTCH1 mutation in the absence of BCL2/IGH fusion. The use of NGS, specifically mate-pair sequencing (MPseq), subsequently confirmed an in-frame PICALM-MLLT10 fusion. Our retrospective analysis showed that PICALM-MLLT10 fusion has no association with CD3/TdT negativity, as 6/49 T-ALL/LBL cases from Mayo Clinic database (01/1998-09/2018), including this case, were noted to have PICALM-MLLT10 fusion; however, none of the other cases were associated with CD3/TdT negativity. We emphasize the importance of a comprehensive hematopathologic evaluation including multiple molecular studies for the appropriate interrogation and classification of a difficult acute leukemia diagnosis, and to prevent potential diagnostic errors of clinical significance. Show less