bluuebunny/crossref_metadata_2025_split huggingface dataset:
Altered Intracellular Trafficking of Mutant Thyroid Hormone Receptors in Resistance to Thyroid Hormone Syndrome
Authors: Tofil Hannah P , Allison Lizabeth Ann 
Published: May 2021

Abstract
Resistance to Thyroid Hormone α (RTHα), a reduced sensitivity to thyroid hormone (T3) in peripheral tissues, is caused by mutations in thyroid hormone receptor α (TRα), a nuclear receptor that mediates T3-responsive gene expression. All mutations characterized in RTHα, to date, are in the ligand binding domain (LBD), resulting in reduced affinity for T3. In addition, some mutations result in truncated proteins lacking all or part of helix 12. Previously, we have used fluorescence recovery after photobleaching (FRAP) to examine the effects of select RTHα mutations on the intracellular trafficking of TRα. After transfecting HeLa cells with expression plasmids for green fluorescent protein (GFP)-tagged wild-type TRα and each of the mutants, we first assessed their intracellular distribution and initial intranuclear mobility. Although wild-type TRα is known to shuttle between the nucleus and cytoplasm, it is primarily localized to the nucleus at a steady state. We showed that TR-E403X, Ala382ProfsX7, and F397fs406X are also primarily localized to the nucleus, and FRAP revealed that wild-type TRα and the RTHα mutants are highly dynamic within the nucleus, indicating that the receptors rapidly dissociate and reassociate with DNA binding sites and/or other nuclear binding sites, independent of T3 (1). Some studies have shown that Nuclear Receptor Corepressor 1 (NCoR1), which interacts with the hinge region of TRα (the region between the DNA-binding domain and LBD) has a higher affinity for RTHα mutants compared to wild-type TRα, supporting the hypothesis that helix 12 of the LBD also functions to disassociate NCoR1 from TRα when it is bound to T3 (2). We proposed that this increased affinity for NCoR1 alters the mobility of TRα in the nucleus, impacting its function. Here, we show that NCoR1 has slower FRAP recovery kinetics compared with TRα, and we evaluate the intranuclear dynamics of RTH TRα1 mutants ΤR-E403X, Ala382ProfsX7, and F397fs406X in response to increased levels of NCoR1. Investigation of the effects of overexpression of NCoR1 will provide further insight into the impact of altered binding affinity for NCoR1 on the intranuclear dynamics of RTHα mutants. References: (1) Femia et al., Journal of Cellular Biochemistry, 2020 2020 Apr; 121(4), 2909-2926.(2) Bochukova et al., New England Journal of Medicine, 2012 Jan. 19; 366(3), 243–249.
Nuclear Receptor Corepressors NCoR1 and SMRT Plays Unique Roles in Central Nervous System
Authors: Amano Izuki , Ninomiya Ayane , Ritter Megan , Vella Kristen R , Hollenberg Anthony Neil , Koibuchi Noriyuki 
Published: May 2021

Abstract
The nuclear corepressor 1 (NCoR1) and the silencing mediator of retinoid and thyroid hormone receptors (SMRT) are critical coregulators of the thyroid hormone receptor (TR), mediating transcriptional repression via histone deacetylation. Thyroid hormone (TH) plays an essential role in many physiological processes via the TR. How the corepressors regulate TR signaling is not fully understood, especially in central nervous system (CNS). To determine the role of NCoR1 and SMRT in the CNS, we used mice with conditional NCoR1 (NCoR1lox/lox) and SMRT (SMRTlox/lox) alleles in combination with mice that express Cre recombinase in a neuronal specific fashion (Snap25-Cre). Global deletion of NCoR1 or SMRT during embryogenesis results in lethality. We also showed that NCoR1/SMRT double knock-out mice die within two weeks after induction of Cre activity in adult mice. Now, we found that neuronal specific NCoR1 or SMRT KO mice survive without obvious impairment of neuronal development. However, NCoR1/SMRT double knock-out mice die within postnatal 1-2 weeks and have impaired body growth. Thus, both NCoR1 and SMRT have important roles in maintaining normal neuronal function. Recently, cased of mutations in NCoR1 and SMRT in humans have been reported. These cases report phenotypes including Autism Spectrum Disorder (ASD) and intellectual disability. The cerebellum has been thought to contribute to motor control and learning. Surprisingly, it has also been shown to be a key brain structure involved in social cognition and its dysfunction may play a role in ASD. The Purkinje cell is the main neuron in the cerebellum. Thus, we generated cerebellar Purkinje cell specific NCoR1/SMRT knock-out mice using L7/Pcp2-Cre mice. In contrast to neuronal specific KO mice, both NCoR1 or SMRT single or double knock-out mice survive until adulthood. SMRT Purkinje cell knock-out mice showed abnormalities in 3ch social interaction test indicating impaired social functioning, similar to some ASD symptoms. Electrophysiological testing showed current injection evoked more action potentials in SMRT KO mice. These results suggest Purkinje cell dysfunction caused by SMRT deletion may result in social disability. Our data demonstrate for the first time that NCoR1 and SMRT have separate functions in different areas of the brain but also have some redundant function when knocked out together in all neurons.
T3-Dependent Transcriptional Programming by TRβ in Thyroid Cells Requires SWI/SNF Chromatin Remodelers
Authors: Gillis Noelle , Tomczak Jennifer , Frietze Seth , Carr Frances E 
Published: May 2021

Abstract
Transcriptional regulation in response to thyroid hormone (T3) is a dynamic and cell-type specific process that maintains cellular homeostasis and identity. A bimodal switch model, where T3 binding alters the co-regulator profile of a constitutively DNA-bound thyroid hormone receptor (TR) to affect downstream gene expression, is widely used to describe the interaction between TRβ and chromatin. To test this model on a genome-wide scale, we used an integrated genomics approach to profile and characterize the cistrome of TRβ by CUT&RUN, map changes in chromatin accessibility by ATAC-seq, and capture the transcriptomic changes in response to T3 by RNA-seq in the normal thyroid cell line, Nthy-ORI. Our CUT&RUN data demonstrated that T3 binding causes significant shifts in TRβ genomic occupancy; these shifts are associated with differential chromatin accessibility. Most of the T3-induced differentially expressed genes have a TRβ binding site associated with the proximal protomer region within one kilobase of the transcriptional start site, suggesting that these are direct TRβ regulatory target genes. Remarkably, the majority of TRβ binding sites were found in transgenic regions and distal regulatory elements. In order to identify the co-regulatory proteins that are required for execution of a T3-dependent transcriptional program in our thyroid cells, we used a TRβ-miniTurboID fusion construct to perform a proximity ligation assay followed by mass spectrometry. We identified 1,138 nuclear proteins that interact with TRβ. Of these proteins, 75 interact preferentially in the presence of T3 and 68 in the absence of T3. All of the core SWI/SNF complex subunits from both of the major subtypes (BAF and PBAF) were identified as TRβ. Interestingly, we found that the PBAF-specific subunit, PBRM1, was significantly enriched in the presence of T3. BAF complex-specific subunits, such as ARID1A, were also present in our dataset. To test whether TRβ could differentially recruit BAF and PBAF complexes to its binding sites, we performed CUT&RUN targeting BRG1, PBRM, and ARID1A to determine the degree of co-occupancy with TRβ. Based on our comprehensive genomic and proteomic analyses, we propose a new model for selective recruitment of BAF and PBAF SWI/SNF complexes to TRβ binding sites for differential functions in regulating chromatin accessibility.
ERa-Dependent Lethal Hyperactivation of the Anticipatory Unfolded Protein Response Induces Complete Regression Without Recurrence of Advanced Breast Cancer
Authors: Duraki Darjan , Boudreau Matthew , Wang Lawrence , Mao Chengjian , Tang Bingtao , Ma Liqian , Roy Edward , Fan Timothy , Park Ben Ho , Nelson Erik Russell , Hergenrother Paul , Shapiro David J 
Published: May 2021

Abstract
Metastatic estrogen receptor α (ERα) positive breast cancer is presently incurable and most patients die within 7 years. From a medicinal chemistry program, we identified a novel small molecule that acts through ERα to kill breast cancer cells and often induces complete regression without recurrence of large, therapy-resistant primary breast tumors and of lung, bone, and liver metastases. We exploited our finding that estrogen-ERα activates an extranuclear tumor-protective, signaling pathway, the anticipatory unfolded protein response (UPR). We repurposed this tumor protective pathway by targeting it with the small molecule, ErSO. ErSO kills cancer cells by acting non-competitively through ERα to induce lethal hyperactivation of the anticipatory UPR (a-UPR), triggering rapid necrotic cell death. Using luciferase to image primary tumors and metastases containing lethal ERαD538G and ERαY537S mutations seen in metastatic breast cancer, oral and injected ErSO exhibited unprecedented antitumor activity. In mouse xenografts bearing large breast tumors, oral and injected ErSO induced complete regression (&gt;115,000 fold mean regression) in about 45% of mice (18/39). Although durable response without treatment for 4-6 months was common, tumors that did recur remained fully sensitive to ErSO re-treatment. Consistent with the essential nature of the a-UPR pathway targeted by ErSO, in more than 100 tumor-bearing mice, we have never seen an ErSO-resistant tumor. In just 7 days, oral ErSO induced complete regression of most lung, bone, and liver metastases. ErSO is well-tolerated in mice and blood-brain-barrier penetrant. Injected ErSO induced profound regression of challenging brain tumors. On average, ErSO-treated tumors were &gt;180-fold smaller than vehicle-treated tumors. Moreover, use of ErSO is not limited to breast cancer. With its unique mechanism of action through the a-UPR, ErSO eradicated orthotoptic ERα positive ovarian tumors that do not require estrogen for growth. These xenograft studies used human cancer cells in immune compromised mice and therefore did not exploit the known ability of inducers of necrotic cell death to activate immune cells and induce immunogenic cell death. Notably, medium from breast cancer cells killed by ErSO contained high levels of the established immune cell activators, HMGB1 and ATP, robustly activated mouse and human macrophages and increased macrophage migration. ErSO’s potent activity against advanced primary and metastatic ERα-positive breast cancers represents a paradigm shift in leveraging ERα for anticancer efficacy.
Pro-Tumorigenic Role of Neutrophil Elastase in Lymphangioleiomyomatosis (LAM)
Authors: Gibbons Erin , Taya Manisha , Minor Briaunna , Seger Christina , Hammes Stephen R 
Published: May 2021

Abstract
Lymphangioleiomyomatosis (LAM) is an estrogen-sensitive lung disease found almost exclusively in women. LAM is characterized by the hyperproliferation of smooth muscle cells creating small tumors throughout the lungs, resulting in the formation of large cysts that replace normal alveolar space. Growth of these tumors and progression of the cyst development leads to loss of pulmonary function, and sometimes subsequent lung transplantation. LAM tumor cells contain mutations in one of the tuberous sclerosis genes (TSC1 or TSC2), leading to activation of the mTORC1 pathway. In fact, mTOR inhibitors are commonly used to treat LAM; however, these drugs are not always effective and have significant side effects, suggesting the need for new therapeutic targets. Additionally, tumors recur even after lung transplantation and LAM cells are found in circulating body fluids, suggesting a metastatic nature of LAM, and a question of the origin of the LAM cell. Due to LAM’s estrogen sensitivity, female specificity, and metastatic nature, we previously proposed that LAM cells originate from the uterine myometrium. We therefore designed a uterine-specific TSC2-null mouse model where all the mice generate uterine tumors characteristic of LAM and half develop lung metastases. Using RNASeq analysis of uterine tissue from this mouse model, when focusing on genes regulated by estrogen and TSC2, we discovered significant upregulation of inflammatory proteases such as Neutrophil Elastase (NE). NE is secreted by myeloid cells such as polymorphonuclear cells (PMNs) and has been reported to promote invasion, migration, and proliferation in various cancers. We found this to be true in LAM as well, as depleting myeloid cells with an antibody directed against PMNs, or inhibiting NE with the NE inhibitor, sivelestat, markedly decreased TSC2-null uterine tumor growth. NE is released when PMNs undergo Neutrophil Extracellular Trap release, or NETosis. NETosis has been shown to have a pro-tumorigenic role in various cancers and we are investigating the effects of NETosis in LAM. We have also generated a novel uterine-specific TSC2-null mouse in the background of no NE to determine whether uterine tumor burden and lung metastases are reduced in NE-null mice and if these mice have PMNs capable of undergoing NETosis in the absence of NE. Overall, our results suggest that NE release from PMNs is critical for LAM tumor development and may be a novel target for its treatment.
A Rare Case of Adult Nesidioblastosis Causing Persistent Hypoglycemia in Patient With Atrial Fibrillation and Chronic Kidney Disease
Authors: Zarghamravanbakhsh Paria , Murthi Swetha , Liao Emilia Pauline 
Published: May 2021

Abstract
Nesidioblastosis is a very rare adult disorder in the absence of gastrointestinal surgery. Nesidioblastosis is a disorder of the endocrine pancreas causing hyperinsulinemic hypoglycemia. We describe a case of 83 year-old Caucasian male, with a 3-year history of severe refractory hypoglycemia with glucose level below 2.1 mmol/L. Confusion and sleepiness were reported as his neuroglycopenic symptoms. According to his family, his symptoms improved within 30 minutes of drinking orange juice. Hypoglycemia episodes mostly occurred while fasting and post exercise (after playing golf). His work up included low venous plasma glucose levels, high insulin and C-peptide levels that were consistent with an insulinoma. His history is remarkable for chronic kidney disease stage 3, penicillin allergy and atrial fibrillation with loop recorder for cardiac rhythm monitoring, which precluded him from undergoing CT with IV contrast or MRI studies. Abdominal computed tomography with oral contrast did not reveal any lesion. In an attempt to localize the suspected Insulinoma, he had celiac angiogram and portal vein sampling, which were inconclusive. He had a PET scan with dotatate that showed increased amount activity in the uncinate process of the pancreas. He was diagnosed with insulinoma and placed on monthly lanreotide injections, however continued to have severe hypoglycemia episodes. Due to persistent refractory hypoglycemia, patient underwent distal pancreatectomy and splenectomy and the histological findings were consistent with nesidioblastosis. Patient developed hyperglycemia in the post-operative course which was controlled with a carb consistent diet. This case demonstrates that differentiation between insulinoma and nesidioblastosis is very challenging, and in most cases, the diagnosis is made post operatively based on histologic findings.
A Unique Presentation of a Paraganglioma and Its Consequences
Authors: Shah Kunal , Mimms Remy , Anolik Jonathan Robert 
Published: May 2021

Abstract
Introduction: Paragangliomas (PGL) are extremely rare tumors arising from extra-adrenal neural crest cells with an incidence of 0.8 per 100,000 person-years. Sympathetic chain PGLs usually arise in the abdomen, with about 75% of them arising intra-abdominally [2]. On CT or MRI, PGLs are usually have homogenous enhancement or central areas of low attenuation. The consequences of PGLs are many, and one complication that is rarely noted is glycemic disturbances with catecholamine excess. Here, we present a case of a radiographically unique appearing PGL that resulted in dramatic improvement of diabetes after resection.
Case: 41 year old male with a past medical history of diabetes, CKD and developmental delay presented with hyperglycemia. Patient’s home regimen of Glargine 15 units qHS and Humalog 5 units TID AC had run out a few days prior. Patient had Hemoglobin A1c of 11.8% mg/dL and a C-peptide of 0.4 ng/ml. Endocrine was initially consulted for glucose management. Hospital course was complicated by abdominal pain and CT imaging showed low attenuation splenic masses, retroperitoneal lymphadenopathy and a large, necrotic appearing mesenteric mass consistent with lymphoma. MRI reaffirmed mass with peripheral enhancement and central necrosis consistent with neoplasm.
Patient underwent biopsy of lymphadenopathy, which came back benign and then went for biopsy of mass. As the needle entered the mass, the patient became acutely hypertensive and tachycardic. He received phentolamine with good response and labs were drawn for catecholamine producing tumor. Plasma norepinephrine level was 6048 pg/ml and a chromogranin level of 4788 ng/ml. An MIBG scan revealed focal uptake at the lesion without evidence of metastasis. In the subsequent weeks, he was alpha- and then beta-blocked and underwent resection of mass that was complicated by transient hypotension and hypoglycemia. Eventually, patient’s blood pressure was controlled and insulin requirements dropped precipitously to just requiring 4 units of glargine by discharge.
Discussion: This patient had a mass on CT scan that appeared to be consistent with lymphoma as opposed to PGL that led to biopsy and subsequent catecholamine crisis. Fortunately, this was controlled and subsequent resection led to improvement in the patient’s glycemic control. It has been thought that glucose intolerance in PGL patients is due to impaired insulin release through desensitization of the beta-adrenergic receptor. Furthermore, Catecholamines, as counter-regulatory hormones, have been well documented to raise blood sugar on this basis as well. Fortunately for our patient, he survived an initial biopsy and post-operatively, was able to actually have an improvement in his glycemic control. It also is a reminder to always do a screen for PGL before doing a needle biopsy of a compatible abdominal mass.
An Atypical Presentation of a Patient With Postprandial Hypoglycemic Induced Seizures
Authors: Harmson Jeremy S , Sosa-Pagan Max 
Published: May 2021

Abstract
Background: Insulinomas are exceptionally uncommon pancreatic islet cell neuroendocrine tumors. Typically, insulinoma induced hypoglycemia occurs exclusively in the fasting state in 73 percent, reported in a retrospective analysis of 237 patients, whereas 6 percent reported only postprandial symptoms.
Clinical Case: A 53-year-old female with a history of rheumatoid arthritis, obesity, and prediabetes initially admitted for new onset seizures and recurrent spontaneous hypoglycemic episodes. She experienced recurrent, symptomatic, post-prandial, hypoglycemia daily for the past 8 years. Each episode was closely associated with a high carbohydrate meal, inducing a post-prandial hypoglycemia more consistently and more profoundly than intermittent fasting. Symptoms of lightheadedness, shakiness, and seizure were exacerbated by each carbohydrate meal. Initial labs revealed serum glucose of 35 mg/dl. After recovery with dextrose infusion, a brief fasting trial less than 24 hours was performed with no recurrence of hypoglycemia. However, a mixed meal study utilizing watermelon resulted in a postprandial serum hypoglycemia of 28 mg/dl, provoking a seizure within 30 minutes. During her hospitalization, recurrent hypoglycemia was found during the postprandial period rather than intermittent fasting periods requiring dextrose infusion and octreotide. A Hypoglycemia panel sent during the initial episode was consistent with endogenous hyperinsulinism (Serum glucose=35, Insulin level=24, Proinsulin=166, C-peptide=0.9, BHB=undetectable, Sulfonurea=negative). A subsequent CT of the abdomen/pelvis revealed a mass associated with the pancreatic tail, measuring 4.1 x 4.4 x 5.2 cm concerning for pancreatic malignancy. A fine needle aspiration followed by a distal pancreatectomy and splenectomy with histopathological and immuno-histochemical evaluation confirming a well differentiated (grade 1), 5.0 x 4.5 x 3.0 cm, neuroendocrine tumor (insulinoma). Her recovery, post-operatively, was complicated by an intraabdominal abscess, left pleural effusion, necessitating insulin therapy for hyperglycemia believed to be secondary to morbid obesity, weight gain, and insulin resistance. Hypoglycemic symptoms resolved, blood glucose normalized, and insulin therapy was weaned over the following 3 months and she remains on metformin to date with no evidence of recurrence.
Conclusion: Although rare, an insulinoma should be considered in the differential diagnosis of any individual with recurrent episodes of frequent symptomatic hypoglycemia. The classical clinical manifestation of an insulinoma is a fasting hypoglycemia, with distinct episodes of autonomic symptoms. However, postprandial symptoms have been reported with increasing frequency. Here we present a case of surgically confirmed insulinoma with predominantly post-prandial hypoglycemia.