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A J Franklin

Publications and source records attributed to A J Franklin.

12 recordsLinked to original sources
PubMed1994

BZP, a novel serum-responsive zinc finger protein that inhibits gene transcription.

We report the fortuitous isolation of cDNA clones encoding a novel zinc finger DNA-binding protein termed BZP. The protein encoded is 114 kDa and contains eight zinc finger motifs, seven of which are present in two clusters at opposite ends of the molecule. Both finger clusters bound to the 9-bp sequence AAAGGTGCA with apparent Kds of approximately 2.5 nM. Two of the finger motifs within the amino- and carboxy-terminal finger clusters share 63% amino acid identity. BZP inhibited transcription of the herpes simplex virus thymidine kinase promoter when copies of the 9-bp target motif were linked in cis, suggesting that it functions as a transcriptional repressor. BZP mRNA and immunoreactivity were detected in several established cell lines but were most abundant in hamster insulinoma (HIT) cells, the parental source of the cDNAs. In mouse tissues, BZP mRNA and immunoreactivity were identified in cells of the endocrine pancreas, anterior pituitary, and central nervous system. Interestingly, in HIT cells proliferating in culture, BZP immunoreactivity was predominately nuclear in location, whereas it was usually located in the cytoplasm in most neural and neuroendocrine tissues. Serum deprivation of HIT cells caused BZP immunoreactivity to become predominantly cytoplasmic in location and attenuated its inhibitory effect on transcription, thereby suggesting that the both the subcellular location and the function of this protein are modulated by factors in serum.

Amino Acid Sequence↗
PubMed1992

Multiple elements in the upstream glucokinase promoter contribute to transcription in insulinoma cells.

beta-cell type-specific expression of the upstream glucokinase promoter was studied by transfection of fusion genes and analysis of DNA-protein interactions. A construct containing 1,000 bp of 5'-flanking DNA was efficiently expressed in HIT M2.2.2 cells, a beta-cell-derived line that makes both insulin and glucokinase, but not in NIH 3T3 cells, a heterologous cell line. In a series of 5' deletion mutations between bases -1000 and -100 (relative to a base previously designated +1), efficient expression in HIT cells was maintained until -280 bp, after which transcription decreased in a stepwise manner. The sequences between -180 and -1 bp contributing to transcriptional activity in HIT cells were identified by studying 28 block transversion mutants that spanned this region in 10-bp steps. Two mutations reduced transcription 10-fold or more, while six reduced transcription between 3- and 10-fold. Three mutationally sensitive regions of this promoter were found to bind to a factor that was expressed preferentially in pancreatic islet beta cells. The binding sites, designated upstream promoter elements (UPEs), shared a consensus sequence of CAT(T/C)A(C/G). Methylation of adenine and guanine residues within this sequence prevented binding of the beta-cell factor, as did mutations at positions 2, 3, and 5. Analysis of nuclear extracts from different cell lines identified UPE-binding activity in HIT M2.2.2 and beta-TC-3 cells but not in AtT-20, NIH 3T3, or HeLa cells; the possibility of a greatly reduced amount in alpha-TC-6 cells could not be excluded. UV laser cross-linking experiments supported the beta-cell type expression of this factor and showed it to be approximately 50 kDa in size. Gel mobility shift competition experiments showed that this beta-cell factor is the same that binds to similar elements, termed CT boxes, in the insulin promoter. Thus, a role for these elements (UPEs or CT boxes), and the beta-cell factor that binds to them, in determining the expression of genes in the beta cells of pancreatic islets is suggested.

3T3 Cells↗
PubMed1984

Diet and behaviour.

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Attention Deficit Disorder with Hyperactivity↗
PubMed1975

Acute lymphoblastic leukaemia: cyclical chemotherapy with three combinations of four drugs (COAP-POMP-CART regimen).

Forty-two adults and children with previously untreated acute lymphoblastic leukaemia (ALL) were entered into a programme of chemotherapy in which three combinations, each of four drugs were administered in a predetermined cyclical rotation together with cranial irradiation and intrathecal injections of methotrexate. Forty-one patients (98%) entered remission and no patient developed neuroleukaemia. Relapse of ALL occurred in 10 patients, and three patients died during remission, while eight patients stopped treatment after two and a half years and have remained in remission for two to 26 months. Comparison of remission and survival experience in this mixed group of children and adults with the experience of children treated at Memphis and in the Medical Research Council's UKALL-I trial showed no significant differences. On the other hand, analysis by prognostic factors showed that neither age nor blast cell count at presentation had any adverse effect in patients treated in this study. No relapses occurred in nine patients with blast cell counts greater than 20 x 109/1 at presentation. This regimen is effective treatment for ALL and may be of special value in patients with poor prognoses. The regiment has not as yet proved superior for the treatment of children with ALL who do not have adverse prognostic features.

Adolescent↗