Jillian Nicholl

Identification and characterization of a new member of the TNF family that induces apoptosis

A novel tumor necrosis factor (TNF) family member has been cloned and characterized. This protein, designated TNF-related apoptosis-inducing ligand (TRAIL), consists of 281 and 291 aa in the human and murine forms, respectively, which share 65% aa identity. TRAIL is a type II membrane protein, whose C-terminal extracellular domain shows clear homology to other TNF family members. TRAIL transcripts are detected in a variety of human tissues, most predominantly in spleen, lung, and prostate. The TRAIL gene is located on chromosome 3 at position 3q26, which is not close to any other known TNF ligand family members. Both full-length cell surface expressed TRAIL and picomolar concentrations of soluble TRAIL rapidly induce apoptosis in a wide variety of transformed cell lines of diverse origin.

DNAM-1, A Novel Adhesion Molecule Involved in the Cytolytic Function of T Lymphocytes

Intercellular adhesion molecules play an important role in the generation of T lymphocyte-mediated immune responses. Here, we describe a novel accessory molecule, DNAX accessory molecule-1 (DNAM-1), that is constitutively expressed on the majority of peripheral blood T lymphocytes. DNAM-1 is a 65 kDa transmembrane glycoprotein consisting of 318 aa including two immunoglobulin-like domains. Anti-DNAM-1 monoclonal antibody (MAb) inhibits T and NK cell-mediated cytotoxicity against a variety of tumor cell targets and blocks cytokine production by alloantigen-specific T cells. In addition, DNAM-1 is a tyrosine-phosphorylated signal-transducing molecule that participates in primary adhesion during cytotoxic T lymphocyte (CTL)-mediated cytotoxicity.

Further Characterization of Proteins Associated with Elastic Fiber Microfibrils Including the Molecular Cloning of MAGP-2 (MP25)

Together with the 31-kDa microfibril-associated glycoprotein (MAGP), four polypeptides designated MP340 (340 kDa), MP78 (78 kDa), MP70 (70 kDa), and MP25 (25 kDa) have previously been identified in tissue extracts designed specifically to solubilize the microfibrillar component of elastic fibers. In the present study, both MP78 and MP70 were shown to be forms of a protein which is closely related to the human protein βig-h3, and MP340 was confirmed to be the bovine form of fibrillin-1. Peptide sequences from MP25 proved to be unique, and affinity-purified anti-MP25 antibodies were shown, by immunofluorescence and immunoelectron microscopy, to localize specifically to the elastin-associated microfibrils. This confirmed that MP25 was a distinct component of these structures. Expression screening of nuchal ligament cDNA libraries yielded a cDNA, cM10A (770 base pairs) which encodes amino acid sequences matching those of the MP25 peptides. Further library screening with cM10A identified cDNAs which encode the complete primary structures of bovine and human MP25. Bovine and human MP25 were found to be around 80% homologous and contain 170 and 173 amino acids, respectively. Data base searches revealed that MP25 had significant similarity of structure only with MAGP, indicating that the two proteins form a new family of microfibrillar proteins. In acknowledgment, MP25 has been formally renamed MAGP-2, and MAGP is referred to as MAGP-1. The close similarity between the two proteins (57%) is confined to a central region of 60 amino acids where there is precise alignment of 7 cysteine residues. Elsewhere the MAGP-2 molecule is rich in serine and threonine residues and contains an RGD motif. MAGP-2 lacks the proline-, glutamine-, and tyrosine-rich sequences and a hydrophobic carboxyl terminus, characteristic of MAGP-1. These structural differences suggest that MAGP-2 has some functions which are distinct from those of MAGP-1. The locus of the human MAGP-2 gene was identified on chromosome 12 in the region of 12p12.3-12p13.1.

AMP-activated protein kinase isoenzyme family: subunit structure and chromosomal location.

The AMP‐activated protein kinase (AMPK) consists of catalytic α and non‐catalytic, β and γ (38 kDa) subunits and is responsible for acting as a metabolic sensor for AMP levels. There are multiple genes for each subunit and we find that rat liver AMPK‐α2 isoform catalytic subunit is associated with β1 and γ1 and not with β2 or γ2 subunit isoforms. The β1 and γ1 isoforms are also subunits of the α1 isoform. The sequence of cloned human AMPK‐β1 is 95% identical in amino acid sequence with rat β1. Human chromosomal localizations were determined for AMPK‐α1 (5p11‐p14), AMPK‐β1 (12q24.1‐24.3) and AMPK‐γ1 (12q12‐q14), respectively.

Isolation and identification of homeobox genes from the human placenta including a novel member of the Distal-less family, DLX4

We have carried out a DNA binding site screen of a 32-week human placental cDNA library using a consensus homeodomain binding site as a probe. This study represents the first library screen carried out to isolate homeobox genes from the human placenta. We have shown that three homeobox genes known to be expressed in the embryo, HB24, GAX and MSX2 are also expressed in the placenta. We have also identified a novel homeobox gene, DLX4, that shows 85% sequence identity with the homeodomain encoded by the Drosophila Distal-less (Dll) gene. DLX4 therefore represents a new member of the Distal-less family of homeobox genes. This is the first evidence that members of the Distal-less family of homeobox genes are expressed in the placenta. Using fluorescence in situ hybridisation (FISH), DLX4 has been assigned to human chromosome 17q21-q22. This places DLX4 in the same region of chromosome 17 as another member of the Distal-less family, DLX3 (Scherer et al., 1995), and the HOX-B homeobox gene cluster (Acampora et al., 1989: Boncinelli et al., 1991). Members of the Distal-less family (DLX1 and DLX2; DLX5 and DLX6) are found as closely linked pairs on human chromosomes (Simeone et al., 1994). We predict that DLX3 and DLX4 are closely linked and have arisen through gene duplication and divergence from a common ancestral precursor.

Rare copy number variation in cerebral palsy

Recent studies have established the role of rare copy number variants (CNVs) in several neurological disorders but the contribution of rare CNVs to cerebral palsy (CP) is not known. Fifty Caucasian families having children with CP were studied using two microarray designs. Potentially pathogenic, rare (<1% population frequency) CNVs were identified, and their frequency determined, by comparing the CNVs found in cases with 8329 adult controls with no known neurological disorders. Ten of the 50 cases (20%) had rare CNVs of potential relevance to CP; there were a total of 14 CNVs, which were observed in <0.1% (<8/8329) of the control population. Eight inherited from an unaffected mother: a 751-kb deletion including FSCB, a 1.5-Mb duplication of 7q21.13, a 534-kb duplication of 15q11.2, a 446-kb duplication including CTNND2, a 219-kb duplication including MCPH1, a 169-kb duplication of 22q13.33, a 64-kb duplication of MC2R, and a 135-bp exonic deletion of SLC06A1. Three inherited from an unaffected father: a 386-kb deletion of 12p12.2-p12.1, a 234-kb duplication of 10q26.13, and a 4-kb exonic deletion of COPS3. The inheritance was unknown for three CNVs: a 157-bp exonic deletion of ACOX1, a 693-kb duplication of 17q25.3, and a 265-kb duplication of DAAM1. This is the first systematic study of CNVs in CP, and although it did not identify de novo mutations, has shown inherited, rare CNVs involving potentially pathogenic genes and pathways requiring further investigation.

The closely linked genes encoding the myeloid nuclear differentiation antigen (MNDA) and IFI16 exhibit contrasting haemopoietic expression.

Recently, a novel family of highly homologous interferon (IFN)-inducible nuclear proteins have been described in both humans and in the mouse, whose expression is associated with myeloid differentiation. IFI16 and the myeloid nuclear differentiation antigen (MNDA) are the two known human members of this family, characterized by their interferon inducibility, and structurally by the presence of at least one copy of a conserved 200 amino acid motif. IFI16 has been shown to be constitutively expressed in lymphoid cell lines, but is inducible with IFN-{alpha} and -{gamma}, and chemical agents eliciting differentiation in myeloid cell lines such as HL-60. By contrast, MNDA is specifically expressed in myeloid cells from the promyelocytic stage onwards, and is inducible only with IFN-{alpha}. Both proteins are localized to the nucleus, and have been shown to bind to DNA, properties which allude to a putative function as transcription factors. 20 refs., 3 figs.

De novo intragenic deletion of the autism susceptibility candidate 2 (AUTS2) gene in a patient with developmental delay: a case report and literature review.

Alexandra Jolley, Mark Corbett, Lesley McGregor, Wendy Waters, Susan Brown, Jillian Nicholl, and Sui Yu

Choreoathetosis, congenital hypothyroidism and neonatal respiratory distress syndrome with intact NKX2‐1

Mutations in the NK2 homeobox 1 gene (NKX2‐1) cause a rare syndrome known as choreoathetosis, congenital hypothyroidism, and neonatal respiratory distress syndrome (OMIM 610978). Here we present the first reported patient with this condition caused by a 14q13.3 deletion which is adjacent to but does not interrupt NKX2‐1, and review the literature on this condition. The infant presented at 23 months with a history of developmental delay, hyperkinesia, recurrent respiratory infections, neonatal respiratory distress, and hypothyroidism. Choreiform movements and delayed motor milestones were first noted at 6–8 months of age. TSH levels had been consistently elevated from 8 months of age. The clinical presentation was suggestive of an NKX2‐1 mutation. Sequencing of all exons and splice site junctions of NKX2‐1 was performed but was normal. Array CGH was then performed and a 3.29 Mb interstitial deletion at 14q13.1–q13.3 was detected. The distal region of loss of the deletion disrupted the surfactant associated 3 (SFTA3) gene but did disrupt NKX2‐1. Findings were confirmed on high resolution SNP array and multiplex semiquanitative PCR. NKX2‐1 encodes transcriptional factors involved in the developmental pathways for thyroid, lung, and brain. We hypothesize that the region centromeric to NKX2‐1 is important for the normal functioning of this gene and when interrupted produces a phenotype that is typical of the choreoathetosis, congenital hypothyroidism, and neonatal respiratory distress syndrome, as seen in our patient. We conclude that deletions at 14q13.3 adjacent to but not involving NKX2‐1 can cause choreoathetosis, congenital hypothyroidism, and neonatal respiratory distress syndrome.

Epilepsy with cognitive deficit and autism spectrum disorders: Prospective diagnosis by array CGH†‡§

The clinical significance of chromosomal microdeletions and microduplications was predicted based on their gene content, de novo or familial inheritance and accumulated knowledge recorded on public databases. A patient group comprised of 247 cases with epilepsy and its common co‐morbidities of developmental delay, intellectual disability, autism spectrum disorders, and congenital abnormalities was reviewed prospectively in a diagnostic setting using a standardized oligo‐array CGH platform. Seventy‐three (29.6%) had copy number variations (CNVs) and of these 73 cases, 27 (37.0%) had CNVs that were likely causative. These 27 cases comprised 10.9% of the 247 cases reviewed. The range of pathogenic CNVs associated with seizures was consistent with the existence of many genetic determinants for epilepsy.