Das, Amitava

Mechanisms that mediate migration, homing and integration of blood outgrowth endothelial cells (BOEC) to sites of vascular injury are incompletely understood, although matrix metalloproteinases (MMPs) have been implicated in this process. Farnesoid X receptor (FXR) signaling pathway has recently been recognized to regulate vascular wall signaling. The aim of this study was to characterize the expression of FXR in human BOEC and examine signaling pathways relevant to BOEC migration. FXR mRNA and protein levels were detected by reverse‐transcriptase PCR and Western blot. Microarray analysis using a focused human endothelial cell biology array (Superarray) suggested that natural (Chenodeoxycholic acid (CDCA), 0.1–100μM) and synthetic (6‐ethylchenodeoxycholic acid (6‐ECDCA) 0.01–10μM) FXR ligands significantly increased MMP9 transcription which was confirmed by real time PCR and gelatin zymography. SiRNA based silencing of FXR prevented CDCA induced increases in MMP9 mRNA, while retroviral over‐expression of FXR in BOEC enhanced MMP9 mRNA levels. CDCA induced expression of Small Heterodimeric Partner (SHP), a downstream target of FXR. Retroviral over‐expression of SHP increased, whereas siRNA silencing of SHP inhibited CDCA induced MMP9 mRNA levels. Migration analysis using Boyden assay demonstrated that CDCA stimulated migration of BOEC which was blocked by transfection with FXR or MMP9 siRNA (p<0.05; n=5). These studies identify a novel signaling pathway by which a key protein important in cell homing and migration, MMP9, is regulated through a previously unrecognized FXR‐SHP pathway in BOEC. Funded by NIH Grant # DK59615

Acetylcholinesterase in CSF has been observed to be post‐translationally modified by abnormal glycosylation in Alzheimer’s disease. Present study was conducted to study the glycosylation profile of acetylcholinesterase (AChE) in different brain regions namely frontal and cerebral cortex and hippocampus in a rat model of dementia. The C/W ratio was calculated as percentage of AChE that did not bound to Con A (C) divided by percentage of AChE activity that did not bound to WGA (W). A retrograde dementia was induced by administering scopolamine (i.p.) 5 min prior to the first trial in passive avoidance test. No significant increase in transfer latency time on second trial after 24 h as compared to first trial indicated dementia. Tacrine, an AChE inhibitor, was studied for its effect on scopolamine dementia and AChE glycosylation pattern. C/W ratio exhibited specific alterations in the AChE glycosylation in cortex and hippocampus. In dementic rats among other brain regions there was significant increase in C/W ratio in cerebral cortex and hippocampus as compared to the control. The C/W ratio in Tacrine treated dementic rats was significantly decreased in cerebral cortex as compared to the control. Partially purified G4 and G1 molecular isoforms of AChE in rat brain revealed a differential binding pattern to lectins. The C/W ratio of G4 isoform was significantly increased in dementia as compared to control group while, G1 isoform remained unchanged. Tacrine treatment significantly increased and decreased the C/W ratio of G4 and G1 isoform, respectively as compared to the control group. Results obtained thus suggest that glycosylation of AChE was affected by alteration in learning and memory process – deficit (Scopolamine) and enhancement (Tacrine treatment).