Faculty Bibliography

Liver fibrosis and fibrosis-associated hepatocarcinogenesis are driven by chronic inflammation and are leading causes of morbidity and death worldwide. SYK signaling regulates critical processes in innate and adaptive immunity, as well as parenchymal cells. We discovered high SYK expression in the parenchymal hepatocyte, hepatic stellate cell (HSC), and the inflammatory compartments in the fibrotic liver. We postulated that targeting SYK would mitigate hepatic fibrosis and oncogenic progression. We found that inhibition of SYK with the selective small molecule inhibitors Piceatannol and PRT062607 markedly protected against toxin-induced hepatic fibrosis, associated hepatocellular injury and intra-hepatic inflammation, and hepatocarcinogenesis. SYK inhibition resulted in increased intra-tumoral expression of the p16 and p53 but decreased expression of Bcl-xL and SMAD4. Further, hepatic expression of genes regulating angiogenesis, apoptosis, cell cycle regulation, and cellular senescence were affected by targeting SYK. We found that SYK inhibition mitigated both HSC trans-differentiation and acquisition of an inflammatory phenotype in T cells, B cells, and myeloid cells. However, in vivo experiments employing selective targeted deletion of SYK indicated that only SYK deletion in the myeloid compartment was sufficient to confer protection against fibrogenic progression. Targeting SYK promoted myeloid cell differentiation into hepato-protective TNFα^low CD206^hi phenotype downregulating mTOR, IL-8 signaling and oxidative phosphorylation. Collectively, these data suggest that SYK is an attractive target for experimental therapeutics in treating hepatic fibrosis and oncogenesis.

The emergence of neuronal diversity during development of the nervous system relies on dynamic changes in the epigenetic landscape of neural stem cells and their progeny. Targeted DamID (TaDa) is proving invaluable in identifying the genome-wide binding sites of chromatin-associated proteins in vivo, without fixation, cell isolation, or immunoprecipitation. The simplicity and efficiency of the technique have led to an ever-expanding TaDa toolbox. These tools enable profiling of gene expression and chromatin accessibility, as well as the identification of the genome-wide binding sites of chromatin complexes, transcription factors and RNAs. Here, we review these new developments, with particular emphasis on the use of TaDa in studying neuronal specification.

INTRODUCTION:Aberrant wound healing is a significant healthcare problem, posing a substantial burden on patients, their families, and the healthcare system. Existing treatment options remain only moderately effective and often fail to promote the closure of non-healing wounds in susceptible populations, such as aging and diabetic patients. Stem cell therapy has emerged as a promising treatment modality, with the potential to restore tissue to its pre-injured state. Of particular interest are mesenchymal stromal cells, which have been shown to accelerate wound healing by modulating the immune response and promoting angiogenesis. AREAS COVERED:This review provides an overview of wound healing and current methods for the management of chronic wounds, as well as the current state and considerations for optimizing stem cell therapy. Considerations include stem cell types, tissue source, donor selection, cell heterogeneity, delivery methods, and genetic engineering. EXPERT OPINION:A growing body of evidence has shown that delivery of stem cells, particularly mesenchymal stromal cells, has the potential to effectively improve the rate and quality of wound healing. However, significant additional basic and clinical research must be performed to optimize cell therapy, such as further elucidation of the therapeutic mechanisms of stem cells and standardization of clinical trial guidelines.

INTRODUCTION/BACKGROUND:Rapid diagnosis of drug resistant tuberculosis is required for better patient management and treatment outcome. Whole-genome sequencing (WGS) can detect single nucleotide polymorphisms (SNPs) and deletions/insertions which are responsible for mostMycobacterium tuberculosis drug resistance. WGS is being performed at scale in high-income countries but there are still limited reports of its use in India. METHOD/METHODS:In this study, 33 clinicalM. tuberculosis isolates were taken from Mycobacterial repository in Chandigarh and were whole-genome sequenced. Phenotypic drug susceptibility testing was performed according to WHO recommendations. Four were considered culture contaminated. RESULTS:Among the other 29 isolates, 21(72.4%) were multi-drug resistance (MDR-TB) and one was extensively-drug resistant (XDR-TB). The most common mutations observed for isoniazid, rifampicin, ofloxacin and kanamycin werekatG_S315 T, rpoB_S450 L, gyrA_A90 V and rrs_A1401 G respectively. The isolates belonged to lineage 2 and 3, with most MDR-TB among lineage 2 isolates. CONCLUSION/CONCLUSIONS:Whole-Genome Sequencing ofMycobacterium tuberculosis offers the detection of drug resistance to all drugs in a single test and also provides insight into the evolution and drug-resistant tuberculosis.

Chromatin remodeling accompanies differentiation, however, its role in self-renewal is less well understood. We report that in Drosophila, the chromatin remodeler Kismet/CHD7/CHD8 limits intestinal stem cell (ISC) number and proliferation without affecting differentiation. Stem-cell-specific whole-genome profiling of Kismet revealed its enrichment at transcriptionally active regions bound by RNA polymerase II and Brahma, its recruitment to the transcription start site of activated genes and developmental enhancers and its depletion from regions bound by Polycomb, Histone H1, and heterochromatin Protein 1. We demonstrate that the Trithorax-related/MLL3/4 chromatin modifier regulates ISC proliferation, colocalizes extensively with Kismet throughout the ISC genome, and co-regulates genes in ISCs, including Cbl, a negative regulator of Epidermal Growth Factor Receptor (EGFR). Loss of kismet or trr leads to elevated levels of EGFR protein and signaling, thereby promoting ISC self-renewal. We propose that Kismet with Trr establishes a chromatin state that limits EGFR proliferative signaling, preventing tumor-like stem cell overgrowths.

Megalin (gp330, LRP-2) is a protein structurally related to low-density lipoprotein receptor family, that displays a large luminal domain with multi-ligand binding properties. Megalin localizes to the apical surface of multiple epithelia, where it participates in endocytosis of a variety of ligands performing roles important for development or homeostasis. We recently described the apical recycling pathway of megalin in MDCK cells and found that it is a long lived, fast recycling receptor with a recycling turnover of 15 minutes and a half-life of 4.8 h. Previous work implicated clathrin and clathrin adaptors in the polarized trafficking of fast recycling basolateral receptors. Hence, here we study the role of clathrin and clathrin adaptors in megalin's apical localization and trafficking. Targeted silencing of clathrin or the γ1 subunit of clathrin adaptor AP-1 by RNAi in MDCK cells disrupted apical localization of megalin causing its redistribution to the basolateral membrane. In contrast, silencing of the γ2 subunit of AP-1 had no effect on megalin polarity. Trafficking assays we developed using FM4-HA-mini Megalin-GFP, a reversible conditional ER-retained chimera, revealed that clathrin and AP-1 silencing disrupted apical sorting of megalin in both biosynthetic and recycling routes. Our experiments demonstrate that clathrin and AP-1 control the sorting of an apical transmembrane protein.

BACKGROUND:While progress in the prevention of cardiovascular disease (CVD) has been noted over the past several decades, there are still those who develop CVD earlier in life than others. OBJECTIVE:We investigated traditional and lifestyle CVD risk factors in young to middle-aged patients compared to older ones with obstructive coronary artery disease (CAD). METHODS:A retrospective analysis of patients with a new diagnosis of obstructive CAD undergoing coronary intervention was performed. Young to middle-aged patients were defined as those in the youngest quartile (n = 281, mean age 50 ± 6 years, 81% male) compared to the other three older quartiles combined (n = 799, mean age 69 ± 7.5 years, 71% male). Obstructive CAD was determined by angiography. RESULTS:Young to middle-aged patients compared to older ones were more likely to be male (p < 0.01), smokers (21 vs. 9%, p < 0.001), and have a higher body mass index (31 ± 6 vs. 29 ± 6 kg/m2, p < 0.001). Younger patients were less likely to eat fruits, vegetables, and fish and had fewer controlled CVD risk factors (2.7 ± 1.2 vs. 3.0 ± 1.0, p < 0.001). Compared to older patients, higher levels of psychological stress (aOR 1.6, 95% CI 1.1-2.4), financial stress (aOR 1.8, 95% CI 1.3-2.5), and low functional capacity (aOR 3.3, 95% CI 2.4-4.5) were noted in the young to middle-aged population as well. CONCLUSION/CONCLUSIONS:Lifestyle in addition to traditional CVD risk factors should be taken into account when evaluating risk for development of CVD in a younger population.

Cardiovascular disease, with atherosclerosis as the major underlying factor, remains the leading cause of death worldwide. It is well established that cholesterol ester-enriched foam cells are the hallmark of atherosclerotic plaques. Multiple lines of evidence support that enhancing foam cell cholesterol efflux by HDL (high-density lipoprotein) particles, the first step of reverse cholesterol transport (RCT), is a promising antiatherogenic strategy. Yet, excitement towards the therapeutic potential of manipulating RCT for the treatment of cardiovascular disease has faded because of the lack of the association between cardiovascular disease risk and what was typically measured in intervention trials, namely HDL cholesterol, which has an inconsistent relationship to HDL function and RCT. In this review, we will summarize some of the potential reasons for this inconsistency, update the mechanisms of RCT, and highlight conditions in which impaired HDL function or RCT contributes to vascular disease. On balance, the evidence still argues for further research to better understand how HDL functionality contributes to RCT to develop prevention and treatment strategies to reduce the risk of cardiovascular disease.