Browsing by Author "Firulli, Anthony B."
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Item Corrigendum to "Structure-function studies of the bHLH phosphorylation domain of TWIST1 in prostate cancer cells" [Neoplasia 17 (2014) 85](Elsevier, 2024) Gajula, Rajendra P.; Chettiar, Sivarajan T.; Williams, Russell D.; Nugent, Katriana; Kato, Yoshinori; Wang, Hailun; Malek, Reem; Taparra, Kekoa; Cades, Jessica; Annadanam, Anvesh; Yoon, A-Rum; Fertig, Elana; Firulli, Beth A.; Mazzacurati, Lucia; Burns, Timothy F.; Firulli, Anthony B.; An, Steven S.; Tran, Phuoc T.; Pediatrics, School of MedicineThe authors regret an accidental duplication in one of the softagar clonogenic phase contrast photomicrographs for Myc-CaP + Vector cells that was brought to our attention in Fig. 4C. This was an accidental error, and the photomicrographs were removed as they were simply representative images and not used for the quantification displayed later in the figure. Furthermore, the accompanying figure legend has been corrected to reflect this change (changes indicated in bolded text). This error does not affect the interpretation of the data in the manuscript, but the authors would like to apologize for any inconvenience caused.Item Defective Hand1 phosphoregulation uncovers essential roles for Hand1 in limb morphogenesis(The Company of Biologists Ltd, 2017-07-01) Firulli, Beth A.; Milliar, Hannah; Toolan, Kevin P.; Harkin, Jade; Fuchs, Robyn K.; Robling, Alex G.; Firulli, Anthony B.; Anatomy and Cell Biology, School of MedicineThe morphogenesis of the vertebrate limbs is a complex process in which cell signaling and transcriptional regulation coordinate diverse structural adaptations in diverse species. In this study, we examine the consequences of altering Hand1 dimer choice regulation within developing vertebrate limbs. Although Hand1 deletion via the limb-specific Prrx1-Cre reveals a non-essential role for Hand1 in mouse limb morphogenesis, altering Hand1 phosphoregulation, and consequently Hand1 dimerization affinities, results in a severe truncation of proximal-anterior limb elements. Molecular analysis reveals a non-cell-autonomous mechanism that causes widespread cell death within the embryonic limb bud. In addition, we observe changes in proximal-anterior gene regulation, including a reduction in the expression of Irx3, Irx5, Gli3 and Alx4, all of which are upregulated in Hand2 limb conditional knockouts. A reduction of Hand2 and Shh gene dosage improves the integrity of anterior limb structures, validating the importance of the Twist-family bHLH dimer pool in limb morphogenesis., Summary: Altering Hand1 phosphoregulation, and consequently Hand1 dimerization affinities, results in a severe truncation of anterior-proximal limb elements in mice.Item Deletion of a Hand1 lncRNA-Containing Septum Transversum Enhancer Alters lncRNA Expression but Is Not Required for Hand1 Expression(MDPI, 2021-05-04) George, Rajani M.; Firulli, Anthony B.; Pediatrics, School of MedicineWe have previously identified a Hand1 transcriptional enhancer that drives expression within the septum transversum, the origin of the cells that contribute to the epicardium. This enhancer directly overlaps a common exon of a predicted family of long non-coding RNAs (lncRNA) that are specific to mice. To interrogate the necessity of this Hand1 enhancer, as well as the importance of these novel lncRNAs, we deleted the enhancer sequences, including the common exon shared by these lncRNAs, using genome editing. Resultant homozygous Hand1 enhancer mutants (Hand1ΔST/ΔST) present with no observable phenotype. Assessment of lncRNA expression reveals that Hand1ΔST/ΔST mutants effectively eliminate detectable lncRNA expression. Expression analysis within Hand1ΔST/ΔST mutant hearts indicates higher levels of Hand1 than in controls. The generation of Hand1 compound heterozygous mutants with the Hand1LacZ null allele (Hand1ΔST/LacZ) also did not reveal any observable phenotypes. Together these data indicate that deletion of this Hand1 enhancer and by consequence a family of murine-specific lncRNAs does not impact embryonic development in observable ways.Item Epigenetics and Heart Development(Frontiers Media, 2021-05-06) George, Rajani M.; Firulli, Anthony B.; Pediatrics, School of MedicineEpigenetic control of gene expression during cardiac development and disease has been a topic of intense research in recent years. Advances in experimental methods to study DNA accessibility, transcription factor occupancy, and chromatin conformation capture technologies have helped identify regions of chromatin structure that play a role in regulating access of transcription factors to the promoter elements of genes, thereby modulating expression. These chromatin structures facilitate enhancer contacts across large genomic distances and function to insulate genes from cis-regulatory elements that lie outside the boundaries for the gene of interest. Changes in transcription factor occupancy due to changes in chromatin accessibility have been implicated in congenital heart disease. However, the factors controlling this process and their role in changing gene expression during development or disease remain unclear. In this review, we focus on recent advances in the understanding of epigenetic factors controlling cardiac morphogenesis and their role in diseases.Item Exclusion of Dlx5/6 expression from the distal-most mandibular arches enables BMP-mediated specification of the distal cap(Proceedings of the National Academy of Sciences, 2016-07-05) Vincentz, Joshua W.; Casasnovas, Jose J.; Barnes, Ralston M.; Que, Jianwen; Clouthier, David E.; Wang, Jun; Firulli, Anthony B.; Department of Pediatrics, IU School of MedicineCranial neural crest cells (crNCCs) migrate from the neural tube to the pharyngeal arches (PAs) of the developing embryo and, subsequently, differentiate into bone and connective tissue to form the mandible. Within the PAs, crNCCs respond to local signaling cues to partition into the proximo-distally oriented subdomains that convey positional information to these developing tissues. Here, we show that the distal-most of these subdomains, the distal cap, is marked by expression of the transcription factor Hand1 (H1) and gives rise to the ectomesenchymal derivatives of the lower incisors. We uncover a H1 enhancer sufficient to drive reporter gene expression within the crNCCs of the distal cap. We show that bone morphogenic protein (BMP) signaling and the transcription factor HAND2 (H2) synergistically regulate H1 distal cap expression. Furthermore, the homeodomain proteins distal-less homeobox 5 (DLX5) and DLX6 reciprocally inhibit BMP/H2-mediated H1 enhancer regulation. These findings provide insights into how multiple signaling pathways direct transcriptional outcomes that pattern the developing jaw.Item GATA3 is essential for separating patterning domains during facial morphogenesis(The Company of Biologists, 2021) Abe, Makoto; Cox, Timothy C.; Firulli, Anthony B.; Kanai, Stanley M.; Dahlka, Jacob; Lim, Kim-Chew; Engel, James Douglas; Clouthier, David E.; Pediatrics, School of MedicineNeural crest cells (NCCs) within the mandibular and maxillary prominences of the first pharyngeal arch are initially competent to respond to signals from either region. However, mechanisms that are only partially understood establish developmental tissue boundaries to ensure spatially correct patterning. In the ‘hinge and caps’ model of facial development, signals from both ventral prominences (the caps) pattern the adjacent tissues whereas the intervening region, referred to as the maxillomandibular junction (the hinge), maintains separation of the mandibular and maxillary domains. One cap signal is GATA3, a member of the GATA family of zinc-finger transcription factors with a distinct expression pattern in the ventral-most part of the mandibular and maxillary portions of the first arch. Here, we show that disruption of Gata3 in mouse embryos leads to craniofacial microsomia and syngnathia (bony fusion of the upper and lower jaws) that results from changes in BMP4 and FGF8 gene regulatory networks within NCCs near the maxillomandibular junction. GATA3 is thus a crucial component in establishing the network of factors that functionally separate the upper and lower jaws during development.Item GENETIC CONTROL OF EYE AND CENTRAL NERVOUS SYSTEM DEVELOPMENT(2011-07-08) Carbe, Christian J.; Zhang, Xin; White, Kenneth E.; Firulli, Anthony B.; Thurmond, Debbie C.Aniridia, a congenital ocular disorder caused by haploinsufficiency of transcription factor PAX6, is characterized by complete or partial iris hypoplasia with associated foveal hypoplasia. Brain imaging performed in patients heterozygous for PAX6 mutations often reveal absence of the brain anterior or posterior commissure, absence of the pineal gland, and a present but reduced in size corpus callosum. Renal coloboma syndrome, another autosomal dominant inherited disease, is characterized by hypodysplastic kidneys and optic nerve defects, and is caused by haploinsufficiency of transcription factor PAX2. In the first part of this thesis we investigated the role of these Pax genes in neural development, by generating an allelic series of knock-in models at the Pax6 locus. We showed that Pax6(5a) and Pax2 could not replace Pax6 for its auto-regulation in lens induction or for neural differentiation in retina. In brain development, however, we demonstrated that cell proliferation in the cerebral cortex and dorsoventral patterning of the telencephalon and neural tube was partially rescued in either knock-in mutant. We believe our novel findings not only reveal Pax-protein functional specificity during neural development, but may also be utilized to understand the aberrant molecular mechanism that result in aniridia and/or renal coloboma syndrome. Aphakia (lack of lens) is a rare human congenital disorder with its genetic etiology largely unknown. In the second part of this thesis, we show that homozygous deletion of Nf1, the Ras GTPase gene underlying human neurofibromatosis type 1 syndrome, caused lens dysgenesis in mouse. While early lens specification proceeded normally in Nf1 mutants, lens induction was disrupted due to deficient cell proliferation. Further analysis showed that ERK signaling was initially elevated in invaginating lens placode, but by lens vesicle stage, Ras signaling antagonist Sprouty2 was up regulated, followed by rapid decrease in ERK phosphorylation. Only after intraperitoneal treatment of U0126, an inhibitor of ERK phosphorylation, was lens development restored in Nf1 mutants. Hyperactive RAS-MAPK signaling is known to cause neuro-cardiofacial-cutaneous (NCFC) syndromes in human. As a member of NCFC family genes, Nf1 represents the first example that attenuation of Ras-MAPK kinase signaling pathway is essential for normal lens development.Item A glimpse of Cre-mediated controversies in epicardial signalling(Oxford University Press, 2013-12-01) Zhang, Wenjun; Firulli, Anthony B.; Shou, Weinian; Pediatrics, School of MedicineItem Hand factor ablation causes defective left ventricular chamber development and compromised adult cardiac function(PLOS, 2017-07-21) Vincentz, Joshua W.; Toolan, Kevin P.; Zhang, Wenjun; Firulli, Anthony B.; Pediatrics, School of MedicineCoordinated cardiomyocyte growth, differentiation, and morphogenesis are essential for heart formation. We demonstrate that the bHLH transcription factors Hand1 and Hand2 play critical regulatory roles for left ventricle (LV) cardiomyocyte proliferation and morphogenesis. Using an LV-specific Cre allele (Hand1LV-Cre), we ablate Hand1-lineage cardiomyocytes, revealing that DTA-mediated cardiomyocyte death results in a hypoplastic LV by E10.5. Once Hand1-linage cells are removed from the LV, and Hand1 expression is switched off, embryonic hearts recover by E16.5. In contrast, conditional LV loss-of-function of both Hand1 and Hand2 results in aberrant trabeculation and thickened compact zone myocardium resulting from enhanced proliferation and a breakdown of compact zone/trabecular/ventricular septal identity. Surviving Hand1;Hand2 mutants display diminished cardiac function that is rescued by concurrent ablation of Hand-null cardiomyocytes. Collectively, we conclude that, within a mixed cardiomyocyte population, removal of defective myocardium and replacement with healthy endogenous cardiomyocytes may provide an effective strategy for cardiac repair., The left ventricle of the heart drives blood flow throughout the body. Impaired left ventricle function, associated either with heart failure or with certain, severe cardiac birth defects, constitutes a significant cause of mortality. Understanding how heart muscle grows is vital to developing improved treatments for these diseases. Unfortunately, genetic tools necessary to study the left ventricle have been lacking. Here we engineer the first mouse line to enable specific genetic study of the left ventricle. We show that, unlike in the adult heart, the embryonic left ventricle is remarkably tolerant of cell death, as remaining cells have the capacity to proliferate and to restore heart function. Conversely, disruption of two related genes, Hand1 and Hand2, within the left ventricle causes cells to assume the wrong identity, and to consequently overgrow and impair cardiac function. Ablation of these mutant cells rescues heart function. We conclude that selective removal of defective heart muscle and replacement with healthy cells may provide an effective therapy to treat heart failure.Item Hand Factors in Cardiac Development(Wiley, 2019-01) George, Rajani M.; Firulli, Anthony B.; Pediatrics, School of MedicineCongenital heart defects account for 1% of infant mortality and 10% of in utero deaths. As the vertebrate embryo develops, multiple tissue types develop in tandem to morphologically pattern the functional heart. Underlying cardiac development is a network of transcription factors known to tightly control these morphological events. Members of the Twist family of basic helix–loop–helix transcription factors, Hand1 and Hand2, are essential to this process. The expression patterns and functional role of Hand factors in neural crest cells, endocardium, myocardium, and epicardium is indicative of their importance during cardiogenesis; however, to date, an extensive understanding of the transcriptional targets of Hand proteins and their overall mechanism of action remain unclear. In this review, we summarize the recent findings that further outline the crucial functions of Hand factors during heart development and in post‐natal heart function.