Angela N. Barrett

Plu-1 nuclear protein, which is upregulated in breast cancer, shows restricted expression in normal human adult tissues: A new cancer/testis antigen?

The PLU‐1 gene is expressed at the level of message in breast cancers and breast cancer cell lines and shows restricted expression in normal adult tissues with the exception of testis. The predicted protein sequence contains several domains, including the PLU domain, which is shared by other proteins involved in transcription and/or development. We have developed a polyclonal antiserum to a C‐terminal fragment of the PLU‐1 protein, which shows little homology to other family members. Immunohistochemic analysis with the antiserum α‐PLU‐1C confirmed the nuclear localisation of PLU‐1. α‐PLU‐1C also reacted with the mouse homologue of PLU‐1 (mPlu‐1) but not with the closest family member, RBP2. Using Western blot analysis, PLU‐1 was shown to be well expressed in breast cancers and breast cancer cell lines, while it was not detected in a range of normal adult tissues. Our results suggest that the PLU‐1 protein may belong to the class of testis/cancer antigens.

Digital PCR Analysis of Maternal Plasma for Noninvasive Detection of Sickle Cell Anemia

BACKGROUND Cell-free fetal DNA (cffDNA) constitutes approximately 10% of the cell-free DNA in maternal plasma and is a suitable source of fetal genetic material for noninvasive prenatal diagnosis (NIPD). The objective of this study was to determine the feasibility of using digital PCR for NIPD in pregnancies at risk of sickle cell anemia. METHODS Minor-groove binder (MGB) TaqMan probes were designed to discriminate between wild-type hemoglobin A and mutant (hemoglobin S) alleles encoded by the HBB (hemoglobin, beta) gene in cffDNA isolated from maternal plasma samples obtained from pregnancies at risk of sickle cell anemia. The fractional fetal DNA concentration was assessed in male-bearing pregnancies with a digital PCR assay for the Y chromosome-specific marker DYS14. In pregnancies with a female fetus, a panel of biallelic insertion/deletion polymorphism (indel) markers was developed for the quantification of the fetal DNA fraction. We used digital real-time PCR to analyze the dosage of the variant encoding hemoglobin S relative to that encoding wild-type hemoglobin A. RESULTS The sickle cell genotype was correctly determined in 82% (37 of 45) of male fetuses and 75% (15 of 20) of female fetuses. Mutation status was determined correctly in 100% of the cases (25 samples) with fractional fetal DNA concentrations >7%. The panel of indels was informative in 65% of the female-bearing pregnancies. CONCLUSIONS Digital PCR can be used to determine the genotype of fetuses at risk for sickle cell anemia. Optimization of the fractional fetal DNA concentration is essential. More-informative indel markers are needed for this assays comprehensive use in cases of a female fetus.

Great vessel development requires biallelic expression of Chd7 and Tbx1 in pharyngeal ectoderm in mice

Aortic arch artery patterning defects account for approximately 20% of congenital cardiovascular malformations and are observed frequently in velocardiofacial syndrome (VCFS). In the current study, we screened for chromosome rearrangements in patients suspected of VCFS, but who lacked a 22q11 deletion or TBX1 mutation. One individual displayed hemizygous CHD7, which encodes a chromodomain protein. CHD7 haploinsufficiency is the major cause of coloboma, heart defect, atresia choanae, retarded growth and development, genital hypoplasia, and ear anomalies/deafness (CHARGE) syndrome, but this patient lacked the major diagnostic features of coloboma and choanal atresia. Because a subset of CHARGE cases also display 22q11 deletions, we explored the embryological relationship between CHARGE and VCSF using mouse models. The hallmark of Tbx1 haploinsufficiency is hypo/aplasia of the fourth pharyngeal arch artery (PAA) at E10.5. Identical malformations were observed in Chd7 heterozygotes, with resulting aortic arch interruption at later stages. Other than Tbx1, Chd7 is the only gene reported to affect fourth PAA development by haploinsufficiency. Moreover, Tbx1+/-;Chd7+/- double heterozygotes demonstrated a synergistic interaction during fourth PAA, thymus, and ear morphogenesis. We could not rescue PAA morphogenesis by restoring neural crest Chd7 expression. Rather, biallelic expression of Chd7 and Tbx1 in the pharyngeal ectoderm was required for normal PAA development.

The clinical implementation of non-invasive prenatal diagnosis for single-gene disorders: challenges and progress made.

Recently, we have witnessed the rapid translation into clinical practice of non‐invasive prenatal testing for the common aneuploidies, most notably within the United States and China. This represents a lucrative market with testing being driven by companies developing and offering their services. These tests are currently aimed at women with high/medium‐risk pregnancies identified by serum screening and/or ultrasound scanning. Uptake has been impressive, albeit limited to the commercial sector. However, non‐invasive prenatal diagnosis (NIPD) for single‐gene disorders has attracted less interest, no doubt because this represents a much smaller market opportunity and in the majority of cases has to be provided on a bespoke, patient or disease‐specific basis. The methods and workflows are labour‐intensive and not readily scalable. Nonetheless, there exists a significant need for NIPD of single‐gene disorders, and the continuing advances in technology and data analysis should facilitate the expansion of the NIPD test repertoire. Here, we review the progress that has been made to date, the different methods and platform technologies, the technical challenges, and assess how new developments may be applied to extend testing to a wider range of genetic disorders.

New aids for the non‐invasive prenatal diagnosis of achondroplasia: dysmorphic features, charts of fetal size and molecular confirmation using cell‐free fetal DNA in maternal plasma

To improve the prenatal diagnosis of achondroplasia by constructing charts of fetal size, defining frequency of sonographic features and exploring the role of non‐invasive molecular diagnosis based on cell‐free fetal deoxyribonucleic acid (DNA) in maternal plasma.

Implementing Prenatal Diagnosis Based on Cell-Free Fetal DNA: Accurate Identification of Factors Affecting Fetal DNA Yield

Objective Cell-free fetal DNA is a source of fetal genetic material that can be used for non-invasive prenatal diagnosis. Usually constituting less than 10% of the total cell free DNA in maternal plasma, the majority is maternal in origin. Optimizing conditions for maximizing yield of cell-free fetal DNA will be crucial for effective implementation of testing. We explore factors influencing yield of fetal DNA from maternal blood samples, including assessment of collection tubes containing cell-stabilizing agents, storage temperature, interval to sample processing and DNA extraction method used. Methods Microfluidic digital PCR was performed to precisely quantify male (fetal) DNA, total DNA and long DNA fragments (indicative of maternal cellular DNA). Real-time qPCR was used to assay for the presence of male SRY signal in samples. Results Total cell-free DNA quantity increased significantly with time in samples stored in K3EDTA tubes, but only minimally in cell stabilizing tubes. This increase was solely due to the presence of additional long fragment DNA, with no change in quantity of fetal or short DNA, resulting in a significant decrease in proportion of cell-free fetal DNA over time. Storage at 4°C did not prevent these changes. Conclusion When samples can be processed within eight hours of blood draw, K3EDTA tubes can be used. Prolonged transfer times in K3EDTA tubes should be avoided as the proportion of fetal DNA present decreases significantly; in these situations the use of cell stabilising tubes is preferable. The DNA extraction kit used may influence success rate of diagnostic tests.

Breast cancer associated transcriptional repressor PLU-1/JARID1B interacts directly with histone deacetylases

The PLU‐1/JARID1B nuclear protein, which is expressed in a high proportion of breast cancers, but shows restricted expression elsewhere, belongs to the ARID family of proteins, known to play important roles in development, differentiation, transcriptional regulation and chromatin remodeling. PLU‐1/JARID1B is a strong transcriptional repressor, and here we show that the protein localizes in MAD bodies when cotransfected with class IIa histone deacetylases (HDACs) or N‐CoR. Direct binding to class I and class IIa HDACs is demonstrated, while the interaction with N‐CoR appears to be indirect. The domains involved in the HDAC4‐PLU‐1/JARID1B interaction were investigated in detail, and the data show that 2 PHD domains in PLU‐1/JARID1B, which are involved in transcriptional repression, are also crucial for binding to a domain in the 5′ region of HDAC4, overlapping the MEF‐2 binding region. Physiological relevance of this interaction in the mammary gland is suggested from the observation that HDAC4 and PLU‐1/JARID1B are coexpressed in the pregnant and involuting mouse mammary gland and are both silenced at lactation. Significantly, the expression of both proteins is seen in breast cancers.

Non-invasive prenatal diagnosis of achondroplasia and thanatophoric dysplasia: next-generation sequencing allows for a safer, more accurate, and comprehensive approach

Accurate prenatal diagnosis of genetic conditions can be challenging and usually requires invasive testing. Here, we demonstrate the potential of next‐generation sequencing (NGS) for the analysis of cell‐free DNA in maternal blood to transform prenatal diagnosis of monogenic disorders.

Safe, accurate, prenatal diagnosis of thanatophoric dysplasia using ultrasound and free fetal DNA

To improve the prenatal diagnosis of thanatophoric dysplasia by defining the change in fetal size across gestation and the frequency of sonographic features, and developing non‐invasive molecular genetic diagnosis based on cell‐free fetal DNA (cffDNA) in maternal plasma.

p130Cas: A key signalling node in health and disease

p130Cas/breast cancer anti-oestrogen resistance 1 (BCAR1) is a member of the Cas (Crk-associated substrate) family of adaptor proteins, which have emerged as key signalling nodes capable of interactions with multiple proteins, with important regulatory roles in normal and pathological cell function. The Cas family of proteins is characterised by the presence of multiple conserved motifs for protein-protein interactions, and by extensive tyrosine and serine phosphorylations. Recent studies show that p130Cas contributes to migration, cell cycle control and apoptosis. p130Cas is essential during early embryogenesis, with a critical role in cardiovascular development. Furthermore, p130Cas has been reported to be involved in the development and progression of several human cancers. p130Cas is able to perform roles in multiple processes due to its capacity to regulate a diverse array of signalling pathways, transducing signals from growth factor receptor tyrosine kinases, non-receptor tyrosine kinases, and integrins. In this review we summarise the current understanding of the structure, function, and regulation of p130Cas, and discuss the importance of p130Cas in both physiological and pathophysiological settings, with a focus on the cardiovascular system and cancer.