The nuclear lamina represents a multifunctional platform involved in such diverse yet interconnected processes as spatial organization of the genome, maintenance of mechanical stability of the nucleus, regulation of transcription and replication. Most of lamina activities are exerted through tethering of lamina-associated chromatin domains (LADs) to the nuclear periphery. Yet, the lamina is a dynamic structure demonstrating considerable expansion during the cell cycle to accommodate increased number of LADs formed during DNA replication. We analyzed dynamics of nuclear growth during interphase and changes in lamina structure as a function of cell cycle progression. The nuclear lamina demonstrates steady growth from G1 till G2, while quantitative analysis of lamina meshwork by super-resolution microscopy revealed that microdomain organization of the lamina is maintained, with lamin A and lamin B microdomain periodicity and interdomain gap sizes unchanged. FRAP analysis, in contrast, demonstrated differences in lamin A and B1 exchange rates; the latter showing higher recovery rate in S-phase cells. In order to further analyze the mechanism of lamina growth in interphase, we generated a lamina-free nuclear envelope in living interphase cells by reversible hypotonic shock. The nuclear envelope in nuclear buds formed after such a treatment initially lacked lamins, and analysis of lamina formation revealed striking difference in lamin A and B1 assembly: lamin A reassembled within 30 min post-treatment, whereas lamin B1 did not incorporate into the newly formed lamina at all. We suggest that in somatic cells lamin B1 meshwork growth is coordinated with replication of LADs, and lamin A meshwork assembly seems to be chromatin-independent process.
- Keywords
- Cell cycle, DNA replication, Interphase, Microdomains, Nuclear lamina, Nucleus,
- MeSH
- Cricetulus MeSH
- Interphase * MeSH
- Nuclear Lamina chemistry metabolism MeSH
- Cells, Cultured MeSH
- Humans MeSH
- Mice MeSH
- Swine MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Mice MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
The nuclear lamina supports many functions, including maintaining nuclear structure and gene expression control, and correct spatio-temporal assembly is vital to meet these activities. Recently, multiple lamina systems have been described that, despite independent evolutionary origins, share analogous functions. In trypanosomatids the two known lamina proteins, NUP-1 and NUP-2, have molecular masses of 450 and 170 kDa, respectively, which demands a distinct architecture from the ∼60 kDa lamin-based system of metazoa and other lineages. To uncover organizational principles for the trypanosome lamina we generated NUP-1 deletion mutants to identify domains and their arrangements responsible for oligomerization. We found that both the N- and C-termini act as interaction hubs, and that perturbation of these interactions impacts additional components of the lamina and nuclear envelope. Furthermore, the assembly of NUP-1 terminal domains suggests intrinsic organizational capacity. Remarkably, there is little impact on silencing of telomeric variant surface glycoprotein genes. We suggest that both terminal domains of NUP-1 have roles in assembling the trypanosome lamina and propose a novel architecture based on a hub-and-spoke configuration.
- Keywords
- Heterochromatin, Lamina, Macromolecular assembly, Nuclear organization, Trypanosomatid,
- MeSH
- Cell Nucleus MeSH
- Nuclear Lamina * genetics MeSH
- Nuclear Envelope MeSH
- Lamins genetics MeSH
- Telomere MeSH
- Trypanosoma * MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- Lamins MeSH
The organization of the nuclear periphery is crucial for many nuclear functions. Nuclear lamins form dense network at the nuclear periphery and play a substantial role in chromatin organization, transcription regulation and in organization of nuclear pore complexes (NPCs). Here, we show that TPR, the protein located preferentially within the nuclear baskets of NPCs, associates with lamin B1. The depletion of TPR affects the organization of lamin B1 but not lamin A/C within the nuclear lamina as shown by stimulated emission depletion microscopy. Finally, reduction of TPR affects the distribution of NPCs within the nuclear envelope and the effect can be reversed by simultaneous knock-down of lamin A/C or the overexpression of lamin B1. Our work suggests a novel role for the TPR at the nuclear periphery: the TPR contributes to the organization of the nuclear lamina and in cooperation with lamins guards the interphase assembly of nuclear pore complexes.
- Keywords
- Image analysis, Lamina, Lamins, Nuclear pore complex, Nucleus, Super-resolution imaging, TPR, Translocated promoter region,
- MeSH
- HeLa Cells MeSH
- Nuclear Lamina metabolism ultrastructure MeSH
- Nuclear Envelope metabolism ultrastructure MeSH
- Nuclear Pore Complex Proteins antagonists & inhibitors genetics metabolism MeSH
- Lamin Type A antagonists & inhibitors genetics metabolism MeSH
- Lamin Type B genetics metabolism MeSH
- Humans MeSH
- RNA, Small Interfering genetics metabolism MeSH
- Molecular Imaging MeSH
- Proto-Oncogene Proteins antagonists & inhibitors genetics metabolism MeSH
- Gene Expression Regulation MeSH
- Signal Transduction MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Names of Substances
- Nuclear Pore Complex Proteins MeSH
- Lamin Type A MeSH
- Lamin Type B MeSH
- LMNA protein, human MeSH Browser
- RNA, Small Interfering MeSH
- Proto-Oncogene Proteins MeSH
- TPR protein, human MeSH Browser
There are reports that in patients with aSAH (aneurysmal subarachnoid hemorrhage), LTF (lamina terminalis fenestration) reduces the rate of shunt-needed hydrocephalus via facilitation of CSF (cerebrospinal fluid) dynamic, diminished leptomeningeal inflammation, and decreased subarachnoid fibrosis. Regarding the conflicting results, this study was conducted to evaluate the effects of LTF on decreased shunt-needed hydrocephalus in patients with aSAH. A cross-sectional retrospective study was carried out to survey all patients with confirmed aSAH operated from March 2011 to September 2016 in an academic vascular center (Rasool Akram Hospital in Tehran, Iran). Of a total of 151 patients, 72 patients were male and 79 were female. The mean age of the participants was 51 years. A transiently CSF diversion (EVD - external ventricular drainage) was performed (the acute hydrocephalus rate) on 21 patients (13.9%). In 36 patients (23.8%), aneurysm occlusion with LTF and in 115 patients (76.2%) only aneurysm occlusion surgery was performed. In hydrocephalus follow-up after surgery, 13 (12%) patients needed shunt insertion (the rate of shunt-needed hydrocephalus). The statistical analysis demonstrated no significant relation between LTF and shunt-needed hydrocephalus. Confirmation of the hypothesis that LTF may decrease the rate of shunt-needed hydrocephalus can significantly decrease morbidity, mortality, and treatment costs of shunting (that is a simple, but a potentially dangerous procedure). So, it is advised to plan and perform an RCT (randomized controlled trial) that can remove the confounding factors, match the groups, and illustrate the exact effect of LTF on shunt-needed hydrocephalus.
- Keywords
- Acute hydrocephalus, Aneurysmal subarachnoid hemorrhage, Lamina terminalis fenestration, Shunt-needed hydrocephalus, Ventriculostomy,
- MeSH
- Hydrocephalus * etiology surgery MeSH
- Hypothalamus surgery MeSH
- Middle Aged MeSH
- Humans MeSH
- Cross-Sectional Studies MeSH
- Retrospective Studies MeSH
- Subarachnoid Hemorrhage * complications surgery MeSH
- Ventriculostomy * MeSH
- Check Tag
- Middle Aged MeSH
- Humans MeSH
- Male MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
- Geographicals
- Iran MeSH
The vestibular lamina (VL) forms the oral vestibule, creating a gap between the teeth, lips and cheeks. In a number of ciliopathies, formation of the vestibule is defective, leading to the creation of multiple frenula. In contrast to the neighbouring dental lamina, which forms the teeth, little is known about the genes that pattern the VL. Here, we establish a molecular signature for the usually non-odontogenic VL in mice and highlight several genes and signalling pathways that may play a role in its development. For one of these, the Sonic hedgehog (Shh) pathway, we show that co-receptors Gas1, Cdon and Boc are highly expressed in the VL and act to enhance the Shh signal from the forming incisor region. In Gas1 mutant mice, expression of Gli1 was disrupted and the VL epithelium failed to extend due to a loss of proliferation. This defect was exacerbated in Boc/Gas1 double mutants and could be phenocopied using cyclopamine in culture. Signals from the forming teeth, therefore, control development of the VL, coordinating the development of the dentition and the oral cavity.
- Keywords
- Ciliopathies, Dental lamina, Gas1, Mouse, Oral cavity, Sonic hedgehog, Vestibular lamina,
- MeSH
- Mice MeSH
- Hedgehog Proteins * metabolism MeSH
- Incisor metabolism MeSH
- Signal Transduction * genetics MeSH
- Mouth MeSH
- Animals MeSH
- Check Tag
- Mice MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- Hedgehog Proteins * MeSH
The bodies of primary sensory neurons and their satellite glial cells (SGCs) are limited by the basal laminae from extracellular matrix of the dorsal root ganglia (DRG). The basal laminae displayed uniform immunofluorescence staining for laminin-1 in the sections of rat intact (naive) DRG. A proximal or distal ligature of the spinal nerves resulted in a heterogeneous immunostaining for laminin-1 around neuron-SGC units in the sections of the corresponding DRG. The pattern of irregular laminin-1 immunofluorescence was more extensive in the ipsilateral than the contralateral DRG of the operated rats. The immunofluorescence for laminin-1 exactly coincided with binding of Concanavalin-A as well as immunostaining for type IV collagen in both naive DRG and DRG affected by nerve ligature. Nidogen immunostaining decreased or fully disappeared at the surface of the SGCs consistently with immunofluorescence staining for laminin-1, but retained or increased in the endothelial cells and ED-1 positive cells invaded the DRG affected by nerve ligature. The results indicate an alteration of the content of basal laminae surrounding the bodies of primary sensory neurons and their SGSs following nerve constriction injury. A modulation of the basal laminae may be related with other cellular and molecular alterations related with peripheral neuropathic pain, for example, expansion of sympathetic sprouts.
- MeSH
- Staining and Labeling methods MeSH
- Basement Membrane chemistry MeSH
- Ectodysplasins analysis MeSH
- Fluorescent Antibody Technique methods MeSH
- Collagen Type IV analysis MeSH
- Concanavalin A analysis MeSH
- Rats MeSH
- Laminin analysis MeSH
- Membrane Glycoproteins analysis MeSH
- Neuroglia chemistry pathology MeSH
- Rats, Wistar MeSH
- Ganglia, Spinal chemistry injuries pathology MeSH
- Constriction, Pathologic MeSH
- Animals MeSH
- Check Tag
- Rats MeSH
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- Ectodysplasins MeSH
- Collagen Type IV MeSH
- Concanavalin A MeSH
- laminin 1 MeSH Browser
- Laminin MeSH
- Membrane Glycoproteins MeSH
- nidogen MeSH Browser
The successional dental lamina (SDL) plays an essential role in the development of replacement teeth in diphyodont and polyphyodont animals. A morphologically similar structure, the rudimental successional dental lamina (RSDL), has been described in monophyodont (only one tooth generation) lizards on the lingual side of the developing functional tooth. This rudimentary lamina regresses, which has been proposed to play a role in preventing the formation of future generations of teeth. A similar rudimentary lingual structure has been reported associated with the first molar in the monophyodont mouse, and we show that this structure is common to all murine molars. Intriguingly, a lingual lamina is also observed on the non-replacing molars of other diphyodont mammals (pig and hedgehog), initially appearing very similar to the successional dental lamina on the replacing teeth. We have analyzed the morphological as well as ultrastructural changes that occur during the development and loss of this molar lamina in the mouse, from its initiation at late embryonic stages to its disappearance at postnatal stages. We show that loss appears to be driven by a reduction in cell proliferation, down-regulation of the progenitor marker Sox2, with only a small number of cells undergoing programmed cell death. The lingual lamina was associated with the dental stalk, a short epithelial connection between the tooth germ and the oral epithelium. The dental stalk remained in contact with the oral epithelium throughout tooth development up to eruption when connective tissue and numerous capillaries progressively invaded the dental stalk. The buccal side of the dental stalk underwent keratinisation and became part of the gingival epithelium, while most of the lingual cells underwent programmed cell death and the tissue directly above the erupting tooth was shed into the oral cavity.
- MeSH
- Apoptosis physiology MeSH
- Embryo, Mammalian embryology MeSH
- Hedgehogs MeSH
- Molar embryology MeSH
- Mice MeSH
- Swine MeSH
- SOXB1 Transcription Factors metabolism MeSH
- Mouth Mucosa embryology MeSH
- Animals MeSH
- Check Tag
- Mice MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- Sox2 protein, mouse MeSH Browser
- SOXB1 Transcription Factors MeSH
Frizzled 6 (FZD6) belongs to a family of proteins that serve as receptors in the WNT signaling pathway. FZD6 plays an important role in the establishment of planar cell polarity in many embryonic processes such as convergent extension during gastrulation, neural tube closure, or hair patterning. Based on its role during hair development, we hypothesized that FZD6 may have similar expression pattern and function in the dental lamina, which is also a distinct epithelial protrusion growing characteristically angled into the mesenchyme. Diphyodont minipig was selected as a model species because its dentition closely resemble human ones with successional generation of teeth initiated from the dental lamina. We revealed asymmetrical expression of FZD6 in the dental lamina of early as well as late stages during its regression with stronger expression located on the labial side of the dental lamina. During lamina regression, FZD6-positive cells were found in its superficial part and the signal coincided with the upregulation of molecules involved in epithelial-mesenchymal transition and increased migratory potential of epithelial cells. FZD6-expression was also turned on during differentiation of cells producing hard tissues, in which mature odontoblasts, ameloblasts, or surrounding osteoblasts were FZD6-positive. On the other hand, the tip of successional lamina and its lingual part, in which progenitor cells are located, exhibited FZD6-negativity. In conclusion, asymmetrical expression of FZD6 correlates with the growth directionality and side-specific morphological differences in the dental lamina of diphyodont species. Based on observed expression pattern, we propose that the dental lamina is other epithelial tissue, where planar cell polarity signaling is involved during its asymmetrical growth.
- Keywords
- FZD6, WNT signaling, ameloblast, epithelial remnants, odontoblast, osteoblast, planar cell polarity (PCP), successional dental lamina,
- Publication type
- Journal Article MeSH
Functional tooth germs in mammals, reptiles, and chondrichthyans are initiated from a dental lamina. The longevity of the lamina plays a role in governing the number of tooth generations. Monophyodont species have no replacement dental lamina, while polyphyodont species have a permanent continuous lamina. In diphyodont species, the dental lamina fragments and regresses after initiation of the second tooth generation. Regression of the lamina seems to be an important mechanism in preventing the further development of replacement teeth. Defects in the complete removal of the lamina lead to cyst formation and has been linked to ameloblastomas. Here, we show the previously unknown mechanisms behind the disappearance of the dental lamina, involving a combination of cell migration, cell-fate transformation, and apoptosis. Lamina regression starts with the loss of the basement membrane, allowing the epithelial cells to break away from the lamina and migrate into the surrounding mesenchyme. Cells deactivate epithelial markers (E-cadherin, cytokeratin), up-regulate Slug and MMP2, and activate mesenchymal markers (vimentin), while residual lamina cells are removed by apoptosis. The uncovering of the processes behind lamina degradation allows us to clarify the evolution of diphyodonty, and provides a mechanism for future manipulation of the number of tooth generations.
- MeSH
- Apoptosis MeSH
- Dentition, Permanent * MeSH
- Epithelial-Mesenchymal Transition MeSH
- Epithelial Cells cytology MeSH
- Cadherins metabolism MeSH
- Keratins metabolism MeSH
- Matrix Metalloproteinase 2 metabolism MeSH
- Swine, Miniature MeSH
- Odontogenesis physiology MeSH
- Cell Movement MeSH
- Swine MeSH
- Proto-Oncogene Proteins c-myb metabolism MeSH
- Snail Family Transcription Factors MeSH
- Transcription Factors metabolism MeSH
- Vimentin metabolism MeSH
- Tooth Germ cytology embryology MeSH
- Tooth, Deciduous * MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- Cadherins MeSH
- Keratins MeSH
- Matrix Metalloproteinase 2 MeSH
- Proto-Oncogene Proteins c-myb MeSH
- Snail Family Transcription Factors MeSH
- Transcription Factors MeSH
- Vimentin MeSH
