Search results for "Keratin"

Immunohistochemical expression of Cytokeratins in periapical lesions

2011

Objective. This study seeks to clarify the histological origin of apical lesions, through the expression of certain cytokeratins.Study design. In 3 years 30 patients were selected. After clinical and radiological exams were chosen patients who had severe apical lesions and tooth decay with exposure of the pulp chamber left untreated for very long periods (more the 12 months). Serial slides were prepared both for immunohistochemistry and Hematoxylin- Eosin. Material and methods. Twenty specimens coming from the 30 patients were used for our purpose. All periapical lesions were surgically extracted and fixed in Bouin mixture, and embedded in paraffin. Samples were processed immunohistochemica…

Cytokeratins identification in human Umbilical Cord at Term

2009

Expression of cytokeratins in human umbilical cord at term

2009

Background. Cytokeratins are the proteins that costitute intermediate filaments. In the cytoplasm, keratin filaments extend from the nucleus to the plasma membrane. This link is important for the structural organization of the cytoplasm and for many cellular processes such as mitosis, cell movement, cell differentiation and adhesion. The pattern of expression of cytokeratins is frequently organ or tissue specific and depends mainly on the type of epithelium, the level of differentiation and the stage of development. The expression of cytokeratins in umbilical cord has been investigated by many groups, but these previous studies gave only fragmentary informations: each single study focused o…

Enhancement of lysine acetylation accelerates wound repair

2013

In physiopathological conditions, such as diabetes, wound healing is significantly compromised and chronic complications, including ulcers, may occur. In a mouse model of skin repair, we recently reported that wound treatment with Sirtuin activators and class I HDAC inhibitors induced keratinocyte proliferation and enhanced healing via a nitric oxide (NO) dependent mechanism. We observed an increase in total protein acetylation in the wound area, as determined by acetylation of α-tubulin and histone H3 Lysine 9. We reasoned that this process activated cell function as well as regulated gene expression to foster tissue repair. We report here that the direct activation of P300/CBP-associated …

SiRNA-mediated selective inhibition of mutant keratin mRNAs responsible for the skin disorder pachyonychia congenita.

2006

RNA interference offers a novel approach for treating genetic disorders including the rare monogenic skin disorder pachyonychia congenita (PC). PC is caused by mutations in keratin 6a (K6a), K6b, K16, and K17 genes, including small deletions and single nucleotide changes. Transfection experiments of a fusion gene consisting of K6a and a yellow fluorescent reporter (YFP) resulted in normal keratin filament formation in transfected cells as assayed by fluorescence microscopy. Similar constructs containing a single nucleotide change (N171K) or a three-nucleotide deletion (N171del) showed keratin aggregate formation. Mutant-specific small inhibitory RNAs (siRNAs) effectively targeted these site…

Gingival and submandibular lymph node metastasis of sigmoid colon adenocarcinoma

2010

Introduction: Metastatic tumors of oral and maxillofacial region compromise 1% of all malignant oral neoplasms. Most commonly affect the jaw bone and less commonly intraoral soft tissues. They originate mainly from primary tumors of lung, breast, colon-rectum, prostate and kidney. Case report: a 77 years old man with history of sigmoid colon adenocarcinoma and liver metastasis. Two years later of being free of disease, he presented with submandi- bular lymphadenopathy and a gingival mass in right upper jaw. Fine needle aspiration of the node and biopsy of the gingival mass were performed. The cytological smears showed cohesive cell groups on a necrotic background. Biopsy examination showed …

Focal adhesions are hotspots for keratin filament precursor formation

2006

Recent studies showed that keratin filament (KF) formation originates primarily from sites close to the actin-rich cell cortex. To further characterize these sites, we performed multicolor fluorescence imaging of living cells and found drastically increased KF assembly in regions of elevated actin turnover, i.e., in lamellipodia. Abundant KF precursors (KFPs) appeared within these areas at the distal tips of actin stress fibers, moving alongside the stress fibers until their integration into the peripheral KF network. The earliest KFPs were detected next to actin-anchoring focal adhesions (FAs) and were only seen after the establishment of FAs in emerging lamellipodia. Tight spatiotemporal …

De novo formation of cytokeratin filament networks originates from the cell cortex in A-431 cells

2001

Of the three major cytoskeletal filament systems, the intermediate filaments are the least understood. Since they differ fundamentally from the actin- and microtubulebased networks by their lack of polarity, it has remained a mystery how and where these principally endless filaments are formed. Using a recently established epithelial cell system in which fluorescently labeled intermediate filaments of the cytokeratin type can be monitored in living cells, we address these issues. By multidimensional time-lapse fluorescence microscopy, we examine de novo intermediate filament network formation from non-filamentous material at the end of mitosis and show that it mirrors disassembly. It is dem…

Desmosomes: interconnected calcium-dependent structures of remarkable stability with significant integral membrane protein turnover

2002

Desmosomes are prominent cell adhesion structures that are major stabilizing elements, together with the attached cytoskeletal intermediate filament network, of the cytokeratin type in epithelial tissues. To examine desmosome dynamics in tightly coupled cells and in situations of decreased adhesion, fluorescent desmosomal cadherin desmocollin 2a (Dsc2a) chimeras were stably expressed in human hepatocellular carcinoma-derived PLC cells (clone PDc-13) and in Madin-Darby canine kidney cells (clone MDc-2) for the continuous monitoring of desmosomes in living cells. The hybrid polypeptides integrated specifically and without disturbance into normal-appearing desmosomes that occurred in associati…

Induction of rapid and reversible cytokeratin filament network remodeling by inhibition of tyrosine phosphatases

2002

The cytokeratin filament network is intrinsically dynamic, continuously exchanging subunits over its entire surface, while conferring structural stability on epithelial cells. However, it is not known how cytokeratin filaments are remodeled in situations where the network is temporarily and spatially restricted. Using the tyrosine phosphatase inhibitor orthovanadate we observed rapid and reversible restructuring in living cells, which may provide the basis for such dynamics. By examining cells stably expressing fluorescent cytokeratin chimeras, we found that cytokeratin filaments were broken down and then formed into granular aggregates within a few minutes of orthovanadate addition. After …