FANCJ DNA helicase is recruited to the replisome by AND-1 to ensure genome stability.

FANCJ, a DNA helicase linked to Fanconi anemia and frequently mutated in cancers, counteracts replication stress by dismantling unconventional DNA secondary structures (such as G-quadruplexes) that occur at the DNA replication fork in certain sequence contexts. However, how FANCJ is recruited to the replisome is unknown. Here, we report that FANCJ directly binds to AND-1 (the vertebrate ortholog of budding yeast Ctf4), a homo-trimeric protein adaptor that connects the CDC45/MCM2-7/GINS replicative DNA helicase with DNA polymerase α and several other factors at DNA replication forks. The interaction between FANCJ and AND-1 requires the integrity of an evolutionarily conserved Ctf4-interacting protein (CIP) box located between the FANCJ helicase motifs IV and V. Disruption of the CIP box significantly reduces FANCJ association with the replisome, causing enhanced DNA damage, decreased replication fork recovery and fork asymmetry in cells unchallenged or treated with Pyridostatin, a G-quadruplex-binder, or Mitomycin C, a DNA inter-strand cross-linking agent. Cancer-relevant FANCJ CIP box variants display reduced AND-1-binding and enhanced DNA damage, a finding that suggests their potential role in cancer predisposition.

A dual-function SNF2 protein drives chromatid resolution and nascent transcripts removal in mitosis.

Mitotic chromatin is largely assumed incompatible with transcription due to changes in the transcription machinery and chromosome architecture. However, the mechanisms of mitotic transcriptional inactivation and their interplay with chromosome assembly remain largely unknown. By monitoring ongoing transcription in Drosophila early embryos, we reveal that eviction of nascent mRNAs from mitotic chromatin occurs after substantial chromosome compaction and is not promoted by condensin I. Instead, we show that the timely removal of transcripts from mitotic chromatin is driven by the SNF2 helicase-like protein Lodestar (Lds), identified here as a modulator of sister chromatid cohesion defects. In addition to the eviction of nascent transcripts, we uncover that Lds cooperates with Topoisomerase 2 to ensure efficient sister chromatid resolution and mitotic fidelity. We conclude that the removal of nascent transcripts upon mitotic entry is not a passive consequence of cell cycle progression and/or chromosome compaction but occurs via dedicated mechanisms with functional parallelisms to sister chromatid resolution.

Adenoid cystic carcinoma of the palpebral lobe of the lacrimal gland - case report and literature review.

Epithelial tumors of the lacrimal gland are rare and usually develop in the orbital lobe. We report the exceedingly rare occurrence of a primary adenoid cystic carcinoma in the palpebral lobe of the lacrimal gland. A 26-year-old female was referred for evaluation of a gradually enlarging mass in the lateral upper eyelid, previously diagnosed as a chalazion. Computed tomography revealed a heterogeneous round lesion anterior to the orbital rim. Excisional biopsy was compatible with an adenoid cystic carcinoma. After excluding distant metastasis, and as the patient refused adjuvant radiotherapy, a second surgical procedure, with wide local excision, was indicated. Follow-up showed no recurrence. This case highlights the importance of performing a thorough clinical examination when diagnosing any lateral upper eyelid mass. A high index of suspicion for malignant tumors of the lacrimal gland should always be maintained, and a complete excision with histological analysis should be preferred whenever possible.

The Genome Stability Maintenance DNA Helicase DDX11 and Its Role in Cancer.

DDX11/ChlR1 is a super-family two iron-sulfur cluster containing DNA helicase with roles in DNA replication and sister chromatid cohesion establishment, and general chromosome architecture. Bi-allelic mutations of the DDX11 gene cause a rare hereditary disease, named Warsaw breakage syndrome, characterized by a complex spectrum of clinical manifestations (pre- and post-natal growth defects, microcephaly, intellectual disability, heart anomalies and sister chromatid cohesion loss at cellular level) in accordance with the multifaceted, not yet fully understood, physiological functions of this DNA helicase. In the last few years, a possible role of DDX11 in the onset and progression of many cancers is emerging. Herein we summarize the results of recent studies, carried out either in tumoral cell lines or in xenograft cancer mouse models, suggesting that DDX11 may have an oncogenic role. The potential of DDX11 DNA helicase as a pharmacological target for novel anti-cancer therapeutic interventions, as inferred from these latest developments, is also discussed.

Functional Coupling between DNA Replication and Sister Chromatid Cohesion Establishment.

Several lines of evidence suggest the existence in the eukaryotic cells of a tight, yet largely unexplored, connection between DNA replication and sister chromatid cohesion. Tethering of newly duplicated chromatids is mediated by cohesin, an evolutionarily conserved hetero-tetrameric protein complex that has a ring-like structure and is believed to encircle DNA. Cohesin is loaded onto chromatin in telophase/G1 and converted into a cohesive state during the subsequent S phase, a process known as cohesion establishment. Many studies have revealed that down-regulation of a number of DNA replication factors gives rise to chromosomal cohesion defects, suggesting that they play critical roles in cohesion establishment. Conversely, loss of cohesin subunits (and/or regulators) has been found to alter DNA replication fork dynamics. A critical step of the cohesion establishment process consists in cohesin acetylation, a modification accomplished by dedicated acetyltransferases that operate at the replication forks. Defects in cohesion establishment give rise to chromosome mis-segregation and aneuploidy, phenotypes frequently observed in pre-cancerous and cancerous cells. Herein, we will review our present knowledge of the molecular mechanisms underlying the functional link between DNA replication and cohesion establishment, a phenomenon that is unique to the eukaryotic organisms.

Role of the DDX11 DNA Helicase in Warsaw Breakage Syndrome Etiology.

Warsaw breakage syndrome (WABS) is a genetic disorder characterized by sister chromatid cohesion defects, growth retardation, microcephaly, hearing loss and other variable clinical manifestations. WABS is due to biallelic mutations of the gene coding for the super-family 2 DNA helicase DDX11/ChlR1, orthologous to the yeast chromosome loss protein 1 (Chl1). WABS is classified in the group of "cohesinopathies", rare hereditary diseases that are caused by mutations in genes coding for subunits of the cohesin complex or protein factors having regulatory roles in the sister chromatid cohesion process. In fact, among the cohesion regulators, an important player is DDX11, which is believed to be important for the functional coupling of DNA synthesis and cohesion establishment at the replication forks. Here, we will review what is known about the molecular and cellular functions of human DDX11 and its role in WABS etiopathogenesis, even in light of recent findings on the role of cohesin and its regulator network in promoting chromatin loop formation and regulating chromatin spatial organization.

Bilateral metastases to the extraocular muscles from small cell lung carcinoma / Metástases bilaterais aos músculos extraoculares de um carcinoma de pequenas células do pulmão

ABSTRACT Bilateral orbital metastases restricted to the extraocular muscles (EOMs) are exceedingly rare. We report a case of bilateral extraocular muscle metastases from a small cell lung carcinoma and provide a review of the relevant literature. A 56-year-old smoker presented with proptosis, motility changes, and a relative afferent pupillary defect of the left eye, with a previous history of a small cell lung carcinoma. An orbital computerized tomography scan revealed a mass restricted to the left medial rectus. An incisional biopsy confirmed metastasis. Visual acuity of the left eye decreased rapidly, and right globe proptosis became evident. Orbital magnetic resonance imaging at two months follow-up showed marked left orbital mass enlargement and a new right lateral rectus mass. The patient was maintained on palliative care and died from metastatic disease-related complications.

RESUMO As metástases orbitárias bilaterais restritas aos mús­culos extraoculares são extremamente raras. Os autores apresentam um caso de metástases bilaterais, localizadas aos musculares extraoculares com base num carcinoma de pequenas células do pulmão e revisão da literatura relevante. Um homem, fumador, de 56 anos recorreu ao serviço de urgência por proptose, alterações de motilidade ocular extrínseca e um defeito pupilar aferente relativo do olho esquerdo, com história pessoal de carcinoma de pequenas células do pulmão. A tomografia computadorizada orbitária revelou uma massa restrita ao reto medial esquerdo. Uma biópsia incisional confirmou o diagnóstico de metástase. A acuidade visual do olho esquerdo diminuiu rapidamente e surgiu uma proptose do globo ocular direito. A ressonância magnética orbitária aos dois meses de seguimento revelou um aumento da massa orbitária esquerda e uma nova massa no reto lateral direito. O paciente foi mantido em cuidados paliativos e faleceu devido a complicações relacionadas com doença metastática.

Bilateral metastases to the extraocular muscles from small cell lung carcinoma.

Bilateral orbital metastases restricted to the extraocular muscles (EOMs) are exceedingly rare. We report a case of bilateral extraocular muscle metastases from a small cell lung carcinoma and provide a review of the relevant literature. A 56-year-old smoker presented with proptosis, motility changes, and a relative afferent pupillary defect of the left eye, with a previous history of a small cell lung carcinoma. An orbital computerized tomography scan revealed a mass restricted to the left medial rectus. An incisional biopsy confirmed metastasis. Visual acuity of the left eye decreased rapidly, and right globe proptosis became evident. Orbital magnetic resonance imaging at two months follow-up showed marked left orbital mass enlargement and a new right lateral rectus mass. The patient was maintained on palliative care and died from metastatic disease-related complications.

PowerPlex® fusion 6C system: internal validation study.

This work is aimed at describing the proceedings and parameters used to validate PowerPlex® Fusion 6C System, the polymerase chain reaction (PCR) amplification kit by Promega, for posterior implementation in the laboratorial routine of the Forensic Genetic Service. The PowerPlex® Fusion 6C System allows multiplex PCR, through simultaneous amplification and posterior detection by fluorescence of 27 loci. Characterization of the kit was made according to the laboratory's internal validation procedure based on validation guidelines from Scientific Working Group on DNA Analysis Methods. Some parameters were evaluated, such as specificity, analytical thresholds, sensitivity, precision, mixture studies, DNA control samples, a proficiency test and changes in the PCR-based procedures: final reaction volume and cycle number, changes in the reaction mixture for direct amplification. This kit proved to be very robust and the results are in concordance with previous developmental validation by the manufacturer. In some parameters, the results were better than expected.