Faculty Bibliography
Searched for:
school:SOM
Department/Unit:Cell Biology
Total Results:
14183
Rap1 regulates TIP60 function during fate transition between two-cell-like and pluripotent states
In mammals, the conserved telomere binding protein Rap1 serves a diverse set of nontelomeric functions, including activation of the NF-kB signaling pathway, maintenance of metabolic function in vivo, and transcriptional regulation. Here, we uncover the mechanism by which Rap1 modulates gene expression. Using a separation-of-function allele, we show that Rap1 transcriptional regulation is largely independent of TRF2-mediated binding to telomeres and does not involve direct binding to genomic loci. Instead, Rap1 interacts with the TIP60/p400 complex and modulates its histone acetyltransferase activity. Notably, we show that deletion of Rap1 in mouse embryonic stem cells increases the fraction of two-cell-like cells. Specifically, Rap1 enhances the repressive activity of Tip60/p400 across a subset of two-cell-stage genes, including Zscan4 and the endogenous retrovirus MERVL. Preferential up-regulation of genes proximal to MERVL elements in Rap1-deficient settings implicates these endogenous retroviral elements in the derepression of proximal genes. Altogether, our study reveals an unprecedented link between Rap1 and the TIP60/p400 complex in the regulation of pluripotency.
PMID: 35210222
ISSN: 1549-5477
CID: 5172412
Multiple eruptive dermatofibromas in an adolescent with a history of pityriasis lichenoides et varioliformis acuta [Case Report]
PMCID:8816644
PMID: 35141383
ISSN: 2352-5126
CID: 5176102
The ups and downs of elevator-type di-/tricarboxylate membrane transporters
The divalent anion sodium symporter (DASS) family contains both sodium-driven anion cotransporters and anion/anion exchangers. The family belongs to a broader ion transporter superfamily (ITS), which comprises 24 families of transporters, including those of AbgT antibiotic efflux transporters. The human proteins in the DASS family play major physiological roles and are drug targets. We recently determined multiple structures of the human sodium-dependent citrate transporter (NaCT) and the succinate/dicarboxylate transporter from Lactobacillus acidophilus (LaINDY). Structures of both proteins show high degrees of structural similarity to the previously determined VcINDY fold. Conservation between these DASS protein structures and those from the AbgT family indicates that the VcINDY fold represents the overall protein structure for the entire ITS. The new structures of NaCT and LaINDY are captured in the inward- or outward-facing conformations, respectively. The domain arrangements in these structures agree with a rigid body elevator-type transport mechanism for substrate translocation across the membrane. Two separate NaCT structures in complex with a substrate or an inhibitor allowed us to explain the inhibition mechanism and propose a detailed classification scheme for grouping disease-causing mutations in the human protein. Structural understanding of multiple kinetic states of DASS proteins is a first step toward the detailed characterization of their entire transport cycle.
PMID: 34403567
ISSN: 1742-4658
CID: 5066842
Genome-wide association analyses identify new Brugada syndrome risk loci and highlight a new mechanism of sodium channel regulation in disease susceptibility
Brugada syndrome (BrS) is a cardiac arrhythmia disorder associated with sudden death in young adults. With the exception of SCN5A, encoding the cardiac sodium channel NaV1.5, susceptibility genes remain largely unknown. Here we performed a genome-wide association meta-analysis comprising 2,820 unrelated cases with BrS and 10,001 controls, and identified 21 association signals at 12 loci (10 new). Single nucleotide polymorphism (SNP)-heritability estimates indicate a strong polygenic influence. Polygenic risk score analyses based on the 21 susceptibility variants demonstrate varying cumulative contribution of common risk alleles among different patient subgroups, as well as genetic associations with cardiac electrical traits and disorders in the general population. The predominance of cardiac transcription factor loci indicates that transcriptional regulation is a key feature of BrS pathogenesis. Furthermore, functional studies conducted on MAPRE2, encoding the microtubule plus-end binding protein EB2, point to microtubule-related trafficking effects on NaV1.5 expression as a new underlying molecular mechanism. Taken together, these findings broaden our understanding of the genetic architecture of BrS and provide new insights into its molecular underpinnings.
PMID: 35210625
ISSN: 1546-1718
CID: 5172442
Community-based Parent Education for Caregivers of Children Newly Diagnosed with Autism Spectrum Disorder
Parents of children with autism spectrum disorder (ASD) frequently report high levels of stress related to the process of receiving an ASD diagnosis and navigating the intervention landscape. Parent education programs offer one approach to providing families with support, information, and resources following a child's diagnosis. Given the heterogeneity of such programs, there have been calls within the literature for increased characterization and systematic evaluation of this type of parent-focused intervention. The present study describes the structure and content of a community-based, group-format parent education program for families of children newly diagnosed with ASD. Following program participation, parents reported reductions in parenting stress, increases in knowledge and empowerment, and high levels of satisfaction. Implications and future research directions are discussed.
PMID: 33893937
ISSN: 1573-3432
CID: 5480062
Treatment of Segmental Bone Defects Biology and Treatment Options
Segmental bone defects (SBD) are difficult to treat, requiring a comprehensive understanding of the bone and soft tissue injury. Defect size, fracture characteristics, and local and systemic biology all help dictate treatment options. Bone grafting with autograft or allograft, Masquelet technique, and bone transport with external or internal fixation can all be used successfully in the correct patient. When deciding on the best treatment option and addressing any complications throughout the process, it is important to always keep in mind the three principles of bone healing: sterility, stability, and biology. The goal of this review is to present the history of treatment for critical SBD, including the indications and challenges that have been addressed and current and emerging treatment options.
PMID: 35234587
ISSN: 2328-5273
CID: 5190222
PKM2 is essential for bladder cancer growth and maintenance
Pyruvate kinase M2 (PKM2) has been shown to promote tumorigenesis by facilitating the Warburg effect and enhancing the activities of oncoproteins. However, this paradigm has recently been challenged by studies in which the absence of PKM2 failed to inhibit and instead accelerated tumorigenesis in mouse models. These results seem inconsistent with the fact that most human tumors overexpress PKM2. To further elucidate the role of PKM2 in tumorigenesis, we investigated the effect of PKM2 knockout in oncogenic HRAS-driven urothelial carcinoma. While PKM2 ablation in mouse urothelial cells did not affect tumor initiation, it impaired the growth and maintenance of HRAS-driven tumors. Chemical inhibition of PKM2 recapitulated these effects. Both conditions substantially reduced complex formation of PKM2 with STAT3, their nuclear translocation, and HIF1α- and VEGF-related angiogenesis. The reduction in nuclear STAT3 in the absence of PKM2 also correlated with decreased autophagy and increased apoptosis. Time-controlled, inducible PKM2 overexpression in simple urothelial hyperplasia did not trigger tumorigenesis, while overexpression of PKM2, but not PKM1, in nodular urothelial hyperplasia with angiogenesis strongly accelerated tumorigenesis. Finally, in human patients, PKM2 was overexpressed in low-grade non-muscle invasive and high-grade muscle-invasive bladder cancer. Based on these data, PKM2 is not required for tumor initiation but is essential for tumor growth and maintenance by enhancing angiogenesis and metabolic addiction. The PKM2-STAT3-HIF1α/VEGF signaling axis may play a critical role in bladder cancer and may serve as an actionable therapeutic target.
PMID: 34903602
ISSN: 1538-7445
CID: 5109682
Artificial intelligence and deep learning to map immune cell types in inflamed human tissue
Biopsies of inflammatory tissue contain a complex network of interacting cells, orchestrating the immune or autoimmune response. While standard histological examination can identify relationships, it is clear that a great amount of data on each slide is not quantitated or categorized in standard microscopic examinations. To deal with the huge amount of data present in biopsy tissue in an unbiased and comprehensive way, we have developed a deep learning algorithm to identify immune cells in biopsies of inflammatory lesions. We focused on T follicular helper (Tfh) cell subsets and B cells in dermatomyositis biopsy images. We achieved strong performance on detection and classification of cells, including the rare Tfh cell subsets present in the tissue. This algorithm could be used to perform distance mapping between cell types in tissue, and could be easily adapted to other disease states.
PMID: 35131237
ISSN: 1872-7905
CID: 5175982
LPGAT1 controls the stearate/palmitate ratio of phosphatidylethanolamine and phosphatidylcholine in sn-1 specific remodeling
Most mammalian phospholipids contain a saturated fatty acid at the sn-1 carbon atom and an unsaturated fatty acid at the sn-2 carbon atom of the glycerol backbone group. While the sn-2 linked chains undergo extensive remodeling by deacylation and reacylation (Lands cycle), it is not known how the composition of saturated fatty acids is controlled at the sn-1 position. Here, we demonstrate that lysophosphatidylglycerol acyltransferase 1 (LPGAT1) is an sn-1 specific acyltransferase that controls the stearate/palmitate ratio of phosphatidylethanolamine (PE) and phosphatidylcholine. Bacterially expressed murine LPGAT1 transferred saturated acyl-CoAs specifically into the sn-1 position of lysophosphatidylethanolamine (LPE) rather than lysophosphatidylglycerol and preferred stearoyl-CoA over palmitoyl-CoA as the substrate. In addition, genetic ablation of LPGAT1 in mice abolished 1-LPE:stearoyl-CoA acyltransferase activity and caused a shift from stearate to palmitate species in PE, dimethyl-PE, and phosphatidylcholine. Lysophosphatidylglycerol acyltransferase 1 KO mice were leaner and had a shorter life span than their littermate controls. Finally, we show that total lipid synthesis was reduced in isolated hepatocytes of LPGAT1 knockout mice. Thus, we conclude that LPGAT1 is an sn-1 specific LPE acyltransferase that controls the stearate/palmitate homeostasis of PE and the metabolites of the PE methylation pathway and that LPGAT1 plays a central role in the regulation of lipid biosynthesis with implications for body fat content and longevity.
PMID: 35131264
ISSN: 1083-351x
CID: 5175992
Emerging Concepts of Vascular Cell Clonal Expansion in Atherosclerosis
Clonal expansion is a process that can drive pathogenesis in human diseases, with atherosclerosis being a prominent example. Despite advances in understanding the etiology of atherosclerosis, clonality studies of vascular cells remain in an early stage. Recently, several paradigm-shifting preclinical studies have identified clonal expansion of progenitor cells in the vasculature in response to atherosclerosis. This review provides an overview of cell clonality in atherosclerotic progression, focusing particularly on smooth muscle cells and macrophages. We discuss key findings from the latest research that give insight into the mechanisms by which clonal expansion of vascular cells contributes to disease pathology. The further probing of these mechanisms will provide innovative directions for future progress in the understanding and therapy of atherosclerosis and its associated cardiovascular diseases.
PMID: 35109671
ISSN: 1524-4636
CID: 5153622
