Faculty Bibliography

The H2A.Z histone variant, a genome-wide hallmark of permissive chromatin, is enriched near transcription start sites in all eukaryotes. H2A.Z is deposited by the SWR1 chromatin remodeler and evicted by unclear mechanisms. We tracked H2A.Z in living yeast at single-molecule resolution, and found that H2A.Z eviction is dependent on RNA Polymerase II (Pol II) and the Kin28/Cdk7 kinase, which phosphorylates Serine 5 of heptapeptide repeats on the carboxy-terminal domain of the largest Pol II subunit Rpb1. These findings link H2A.Z eviction to transcription initiation, promoter escape and early elongation activities of Pol II. Because passage of Pol II through +1 nucleosomes genome-wide would obligate H2A.Z turnover, we propose that global transcription at yeast promoters is responsible for eviction of H2A.Z. Such usage of yeast Pol II suggests a general mechanism coupling eukaryotic transcription to erasure of the H2A.Z epigenetic signal.

Objective: The anatomical calcaneal external fixator was designed by measuring and calculating the morphological data of the heel.
Method(s): A total of 100 normal people were randomly selected to obtain 200 hind foot data, including 45 males and 55 females, with an average age of 43.9 years (range, 19-67 years). According to the principles of human engineering and local anatomy, the morphological data of the heel in the weight-bearing standing position and supine position were measured with the direct measurement mode. The heel length, heel width, heel height, medial ankle height, lateral ankle height, and calcaneal pitch angle (CPA) were measured by vernier calipers and ulnar markers in weight-bearing standing position, and the gender groups and left and right foot groups were compared; the shape of the hind foot in the supine position was measured by three-dimensional (3D) dot matrix inverse model method. According to the stereoscopic data of the comprehensive anatomical morphology of the heel, the anatomical calcaneal external fixator was designed with AutoCAD 2019 and other 3D industrial design softwares.
Result(s): The measurements of shoe size, heel length, heel width, heel height, medial ankle height, lateral ankle height, and CPA in male were significantly higher than those in female ( P<0.05). There was no significant difference between the left and right feet in the other indexes except that the height of the medial malleolus of the left foot was significantly lower than that of the right foot ( t=-2.827, P=0.005). The measurement of 3D dot matrix inverse model in supine position showed that the heel part was non-circular arc edge, and many groups of arc edges fluctuate in a limited range. Based on the above data, an anatomical calcaneal external fixator was designed, which could fit the anatomic radian in theory, so as to be flexible in configuration. On this basis, the ordinary configuration, compression configuration, and orthodontic configuration were designed to meet the treatment needs of calcaneal fractures in different degrees. The ordinary configuration was suitable for patients with Sanders I, IIA, and IIB calcaneal fractures with no or slight displacement of intra-articular fractures; the ordinary configuration was mainly used for simple fixing. The compression configuration was suitable for patients with Sanders IIC, IIIA, and IIIB, tongue fractures, and avulsion fractures with severe displacement of intra-articular fractures; the compression configuration used obliquely drawn console wires to fix the displaced bones. The orthodontic configuration was suitable for patients with Sanders IIIC and IV calcaneal fractures with severe displacement of intra-articular fractures or severe calcaneal bone defects; the orthodontic configuration was a multi-module design, which took into account the stable fixation of the fracture and the arbitrary adjustment of the joint fixation angle.
Conclusion(s): The hind foot is special for morphology, so the external fixator designed based on the vernier caliper measurement method and 3D dot matrix measuring plate measurement method is an anatomical type and its configuration can theoretically meet stable and flexible clinical needs

Mammalian cells have evolved multiple pathways to repair DNA double strand breaks (DSBs) and ensure genome stability. In addition to non-homologous end-joining (NHEJ) and homologous recombination (HR), cells evolved an error-prone repair pathway termed microhomology-mediated end joining (MMEJ). The mutagenic outcome of MMEJ derives from the activity of DNA polymerase theta (Polθ) - a multidomain enzyme that is minimally expressed in normal tissue but overexpressed in tumors. Polθ expression is particularly crucial for the proliferation of HR deficient cancer cells. As a result, this mutagenic repair emerged as an attractive target for cancer therapy, and inhibitors are currently in pre-clinical development. Here, we review the multifunctionality of this enigmatic polymerase, focusing on its role during DSB repair in mammalian cells and its impact on cancer genomes.

Rationale: Barth syndrome (BTHS) is an X-linked cardiac and skeletal myopathy caused by mutation of the gene Tafazzin (TAZ). Currently there is no targeted treatment for BTHS. Lack of a proper genetic animal model that recapitulates the features of BTHS has hindered understanding of disease pathogenesis and therapeutic development. Objective: We characterized murine germline (TAZ-KO) and cardiac specific (TAZ-CKO) Taz knockout models and tested the efficacy of AAV-mediated TAZ gene replacement therapy. Methods and Results: TAZ-KO caused embryonic and neonatal lethality, impaired growth, dilated cardiomyopathy, and skeletal myopathy. TAZ-KO mice that survived the neonatal period developed progressive, severe cardiac dysfunction and fibrosis. Cardiomyocyte specific inactivation of floxed Taz in CMs using Myh6-Cre caused progressive dilated cardiomyopathy without fetal or perinatal loss. Using both constitutive and conditional knockout models, we tested the efficacy and durability of Taz replacement by AAV gene therapy. Neonatal AAV-TAZ rescued neonatal death, cardiac dysfunction, and fibrosis in TAZ-KO mice, and both prevented and reversed established cardiac dysfunction in TAZ-KO and TAZ-CKO models. However, both neonatal and adult therapies required high CM transduction (~70%) for durable efficacy. Conclusions: TAZ-KO and TAZ-CKO mice recapitulate many of the key clinical features of BTHS. AAV-mediated gene replacement is efficacious when a sufficient fraction of CMs are transduced.

Neutrophil extracellular traps (NETs) promote inflammation and atherosclerosis progression. NETs are increased in diabetes and impair the resolution of inflammation during wound healing. Atherosclerosis resolution, a process resembling wound healing, is also impaired in diabetes. Thus, we hypothesized that NETs impede atherosclerosis resolution in diabetes by increasing plaque inflammation. Indeed, transcriptomic profiling of plaque macrophages from NET positive and negative areas in low-density lipoprotein receptor-deficient (Ldlr-/-) mice revealed inflammasome and glycolysis pathway upregulation, indicating a heightened inflammatory phenotype. We found that NETs decline during atherosclerosis resolution, which was induced by reducing hyperlipidemia in non-diabetic mice, but they persist in diabetes, exacerbating macrophage inflammation and impairing resolution. In diabetic mice deoxyribonuclease 1 (DNase1) treatment reduced plaque NETs content and macrophage inflammation, promoting atherosclerosis resolution after lipid-lowering. Given that humans with diabetes also exhibit impaired atherosclerosis resolution with lipid-lowering, these data suggest that NETs contribute to the increased cardiovascular disease risk in this population and are a potential therapeutic target.

Lysosomal dysfunction is considered pathogenic in Alzheimer disease (AD). Loss of presenilin-1 (PSEN1) function causing AD impedes acidification via defective vacuolar ATPase (vATPase) V0a1 subunit delivery to lysosomes. We report that isoproterenol (ISO) and related β2-adrenergic agonists reacidify lysosomes in PSEN1 Knock out (KO) cells and fibroblasts from PSEN1 familial AD patients, which restores lysosomal proteolysis, calcium homeostasis, and normal autophagy flux. We identify a novel rescue mechanism involving Portein Kinase A (PKA)-mediated facilitation of chloride channel-7 (ClC-7) delivery to lysosomes which reverses markedly lowered chloride (Cl^-) content in PSEN1 KO lysosomes. Notably, PSEN1 loss of function impedes Endoplasmic Reticulum (ER)-to-lysosome delivery of ClC-7. Transcriptomics of PSEN1-deficient cells reveals strongly downregulated ER-to-lysosome transport pathways and reversibility by ISO, thus accounting for lysosomal Cl^- deficits that compound pH elevation due to deficient vATPase and its rescue by β2-adrenergic agonists. Our findings uncover a broadened PSEN1 role in lysosomal ion homeostasis and novel pH modulation of lysosomes through β2-adrenergic regulation of ClC-7, which can potentially be modulated therapeutically.

The etiology of aortic aneurysms is poorly understood, but it is associated with atherosclerosis, hypercholesterolemia, and abnormal transforming growth factor β (TGF-β) signaling in smooth muscle. Here, we investigated the interactions between these different factors in aortic aneurysm development and identified a key role for smooth muscle cell (SMC) reprogramming into a mesenchymal stem cell (MSC)-like state. SMC-specific ablation of TGF-β signaling in Apoe^-/- mice on a hypercholesterolemic diet led to development of aortic aneurysms exhibiting all the features of human disease, which was associated with transdifferentiation of a subset of contractile SMCs into an MSC-like intermediate state that generated osteoblasts, chondrocytes, adipocytes, and macrophages. This combination of medial SMC loss with marked increases in non-SMC aortic cell mass induced exuberant growth and dilation of the aorta, calcification and ossification of the aortic wall, and inflammation, resulting in aneurysm development.

In the original publication of the paper, the in-text citation for reference 33 was published in the incorrect place. The citation currently appears in the following sentence: "Based on a detailed empirical analysis of Kleinberg [33] and her coauthors "¦." However, the correct position of the citation should be as follows: "We refer the interested reader to [33] and citations within." In addition to this, the use of the story of the Sneetches as an analogy to help illustrate causal discrimination was originally sourced from Blank RM, Dabady M, Citro CF. Measuring racial discrimination. Natl Academy Pr; 2004. A reference to the book by Blank et al. (2004) was included in the text, but it should have been included in multiple instances in Section 1.2.