In Vitro Reconstitutive Base Excision Repair (BER) Assay.

The mammalian cell genome is continuously exposed to endogenous and exogenous insults that modify its DNA. These modifications can be single-base lesions, bulky DNA adducts, base dimers, base alkylation, cytosine deamination, nitrosation, or other types of base alteration which interfere with DNA replication. Mammalian cells have evolved with a robust defense mechanism to repair these base modifications (damages) to preserve genomic stability.

EEPD1 promotes repair of oxidatively-stressed replication forks.

Unrepaired oxidatively-stressed replication forks can lead to chromosomal instability and neoplastic transformation or cell death. To meet these challenges cells have evolved a robust mechanism to repair oxidative genomic DNA damage through the base excision repair (BER) pathway, but less is known about repair of oxidative damage at replication forks. We found that depletion or genetic deletion of EEPD1 decreases clonogenic cell survival after oxidative DNA damage.

BRCA1 mediates protein homeostasis through the ubiquitination of PERK and IRE1.

Tumors with mutations have poor prognoses due to genomic instability. Yet this genomic instability has risks and BRCA1-deficient (def) cancer cells must develop pathways to mitigate these risks. One such risk is the accumulation of unfolded proteins in BRCA1-def cancers from increased mutations due to their loss of genomic integrity.

Targeting pheochromocytoma/paraganglioma with polyamine inhibitors.

Background: Pheochromocytomas (PCCs) and paragangliomas (PGLs) are neuroendocrine tumors that are mostly benign. Metastatic disease does occur in about 10% of cases of PCC and up to 25% of PGL, and for these patients no effective therapies are available. Patients with mutations in the succinate dehydrogenase subunit B (SDHB) gene tend to have metastatic disease.

The splicing component ISY1 regulates APE1 in base excision repair.

The integrity of cellular genome is continuously challenged by endogenous and exogenous DNA damaging agents. If DNA damage is not removed in a timely fashion the replisome may stall at DNA lesions, causing fork collapse and genetic instability. Base excision DNA repair (BER) is the most important pathway for the removal of oxidized or mono-alkylated DNA.

MiR223-3p promotes synthetic lethality in BRCA1-deficient cancers.

Defects in DNA repair give rise to genomic instability, leading to neoplasia. Cancer cells defective in one DNA repair pathway can become reliant on remaining repair pathways for survival and proliferation. This attribute of cancer cells can be exploited therapeutically, by inhibiting the remaining repair pathway, a process termed synthetic lethality.

The endonuclease EEPD1 mediates synthetic lethality in RAD52-depleted BRCA1 mutant breast cancer cells.

Background: Proper repair and restart of stressed replication forks requires intact homologous recombination (HR). HR at stressed replication forks can be initiated by the 5' endonuclease EEPD1, which cleaves the stalled replication fork. Inherited or acquired defects in HR, such as mutations in breast cancer susceptibility protein-1 (BRCA1) or BRCA2, predispose to cancer, including breast and ovarian cancers.

Pyrintegrin Induces Soft Tissue Formation by Transplanted or Endogenous Cells.

Focal adipose deficiency, such as lipoatrophy, lumpectomy or facial trauma, is a formidable challenge in reconstructive medicine, and yet scarcely investigated in experimental studies. Here, we report that Pyrintegrin (Ptn), a 2,4-disubstituted pyrimidine known to promote embryonic stem cells survival, is robustly adipogenic and induces postnatal adipose tissue formation in vivo of transplanted adipose stem/progenitor cells (ASCs) and recruited endogenous cells. In vitro, Ptn stimulated human adipose tissue derived ASCs to differentiate into lipid-laden adipocytes by upregulating peroxisome proliferator-activated receptor (PPARγ) and CCAAT/enhancer-binding protein-α (C/EBPα), with differentiated cells increasingly secreting adiponectin, leptin, glycerol and total triglycerides.

Endonuclease EEPD1 Is a Gatekeeper for Repair of Stressed Replication Forks.

Replication is not as continuous as once thought, with DNA damage frequently stalling replication forks. Aberrant repair of stressed replication forks can result in cell death or genome instability and resulting transformation to malignancy. Stressed replication forks are most commonly repaired via homologous recombination (HR), which begins with 5' end resection, mediated by exonuclease complexes, one of which contains Exo1.

Oral Mucosa Harbors a High Frequency of Endothelial Cells: A Novel Postnatal Cell Source for Angiogenic Regeneration.

Endothelial progenitor cells/endothelial cells (EPCs/ECs) have great potential to treat pathological conditions such as cardiac infarction, muscle ischemia, and bone fractures, but isolation of EPC/ECs from existing cell sources is challenging due to their low EC frequency. We have isolated endothelial progenitor (EP)-like cells from rat oral mucosa and characterized their yield, immunophenotype, growth, and in vivo angiogenic potential. The frequency of EP-like cells derived from oral mucosa is thousands of folds higher than EPCs derived from donor-match bone marrow samples.

EEPD1 Rescues Stressed Replication Forks and Maintains Genome Stability by Promoting End Resection and Homologous Recombination Repair.

Replication fork stalling and collapse is a major source of genome instability leading to neoplastic transformation or cell death. Such stressed replication forks can be conservatively repaired and restarted using homologous recombination (HR) or non-conservatively repaired using micro-homology mediated end joining (MMEJ). HR repair of stressed forks is initiated by 5' end resection near the fork junction, which permits 3' single strand invasion of a homologous template for fork restart.

Postnatal epithelium and mesenchyme stem/progenitor cells in bioengineered amelogenesis and dentinogenesis.

Rodent incisors provide a classic model for studying epithelial-mesenchymal interactions in development. However, postnatal stem/progenitor cells in rodent incisors have not been exploited for tooth regeneration. Here, we characterized postnatal rat incisor epithelium and mesenchyme stem/progenitor cells and found that they formed enamel- and dentin-like tissues in vivo.

Competitive stem cell recruitment by multiple cytotactic cues.

A multitude of cytotactic cues direct cell migration in development, cancer metastasis and wound healing. However, our understanding of cell motility remains fragmented partially because current migration devices only allow the study of independent factors. We developed a cell motility assay that allows competitive recruitment of a given cell population simultaneously by gradients of multiple cytotactic cues, observable under real-time imaging.

Musculoskeletal tissue engineering by endogenous stem/progenitor cells.

From its inception, tissue engineering has had three tenets: cells, biomaterial scaffolds and signaling molecules. Among the triad, cells are the center piece, because cells are the building blocks of tissues. For decades, cell therapies have focused on the procurement, manipulation and delivery of healthy cells for the treatment of diseases or trauma.

MIR-23A microRNA cluster inhibits B-cell development.

Objective: The transcription factor PU.1 (encoded by Sfpi1) promotes myeloid differentiation, but it is unclear what downstream genes are involved. Micro RNAs (miRNAs) are a class of small RNAs that regulate many cellular pathways, including proliferation, survival, and differentiation.

Expression of Scl in mesoderm rescues hematopoiesis in the absence of Oct-4.

In embryonic stem cells, Oct-4 concentration is critical in determining the development of endoderm, mesoderm, and trophectoderm. Although Oct-4 expression is essential for mesoderm development, it is unclear whether it has a role in the development of specific mesodermal tissues. In this study, we have examined the importance of Oct-4 in the generation of hematopoietic cells using an inducible Oct-4 ESC line.

Leucine 135 of tropomodulin-1 regulates its association with tropomyosin, its cellular localization, and the integrity of sarcomeres.

Tropomodulin-1 (Tmod-1) is a well defined actin-capping protein that interacts with tropomyosin (TM) at the pointed end of actin filaments. Previous studies by others have mapped its TM-binding domain to the amino terminus from amino acid 39 to 138. In this study, we have identified several amino acid residues on Tmod-1 that are important for its interaction with TM5 (a nonmuscle TM isoform).

Human umbilical cord blood cells differentiate into muscle in sjl muscular dystrophy mice.

Limb girdle muscular dystrophy type 2B form (LGMD-2B) and Miyoshi myopathy (MM) are both caused by mutations in the dysferlin (dysf) gene. In this study, we used dysferlin-deficient sjl mice as a mouse model to study cell therapy for LGMD-2B and MM. A single-blind study evaluated the therapeutic potential of human umbilical cord blood (HUCB) as a source of myogenic progenitor stem cells.

New cellular and molecular approaches for the treatment of cardiac disease.

Similar to the kidney in uremia, end-stage cardiac failure is an outcome common to many disparate disease processes including hypertension, various inflammatory pathologies, as well as ischemic loss of tissue. In regard to the heart, cellular and molecular mechanisms responsible for heart failure have been investigated with renewed intensity over the past several years with newer techniques of molecular genetics, genomic analysis, and cell biology. Although this article reviews some recent advances made in our understanding of molecular and cellular events in the heart leading to heart failure and explores possible new targets for therapeutics, the main point is to stress the importance of investigative interactions between organ physiologists and molecular and cellular biologists.

Cytoplasmic nuclear transfer of the actin-capping protein tropomodulin.

Tropomodulin (Tmod) is a cytoskeletal actin-capping protein that interacts with tropomyosin at the pointed end of actin filaments. E-Tmod is an isoform that expresses predominantly in cardiac cells and slow skeletal muscle fibers. We unexpectedly discovered significant levels of Tmod in nuclei and then defined peptide domains in Tmod responsible for nuclear import and export.