Laboratory of Molecular Biology

About: Laboratory of Molecular Biology is a facility organization based out in Cambridge, Cambridgeshire, United Kingdom. It is known for research contribution in the topics: Gene & RNA. The organization has 19395 authors who have published 24236 publications receiving 2101480 citations.

Opposing effects of Ets and Id proteins on p16INK4a expression during cellular senescence.

Abstract: The p16INK4a cyclin-dependent kinase inhibitor is implicated in replicative senescence, the state of permanent growth arrest provoked by cumulative cell divisions or as a response to constitutive Ras-Raf-MEK signalling in somatic cells Some contribution to senescence presumably underlies the importance of p16INK4a as a tumour suppressor but the mechanisms regulating its expression in these different contexts remain unknown Here we demonstrate a role for the Ets1 and Ets2 transcription factors based on their ability to activate the p16INK4a promoter through an ETS-binding site and their patterns of expression during the lifespan of human diploid fibroblasts The induction of p16INK4a by Ets2, which is abundant in young human diploid fibroblasts, is potentiated by signalling through the Ras-Raf-MEK kinase cascade and inhibited by a direct interaction with the helix-loop-helix protein Id1 (ref 11) In senescent cells, where the Ets2 levels and MEK signalling decline, the marked increase in p16INK4a expression is consistent with the reciprocal reduction of Id1 and accumulation of Ets1

Brain homogenates from human tauopathies induce tau inclusions in mouse brain.

Abstract: Filamentous inclusions made of hyperphosphorylated tau are characteristic of numerous human neurodegenerative diseases, including Alzheimer’s disease, tangle-only dementia, Pick disease, argyrophilic grain disease (AGD), progressive supranuclear palsy, and corticobasal degeneration. In Alzheimer’s disease and AGD, it has been shown that filamentous tau appears to spread in a stereotypic manner as the disease progresses. We previously demonstrated that the injection of brain extracts from human mutant P301S tau-expressing transgenic mice into the brains of mice transgenic for wild-type human tau (line ALZ17) resulted in the assembly of wild-type human tau into filaments and the spreading of tau inclusions from the injection sites to anatomically connected brain regions. Here we injected brain extracts from humans who had died with various tauopathies into the hippocampus and cerebral cortex of ALZ17 mice. Argyrophilic tau inclusions formed in all cases and following the injection of the corresponding brain extracts, we recapitulated the hallmark lesions of AGD, PSP and CBD. Similar inclusions also formed after intracerebral injection of brain homogenates from human tauopathies into nontransgenic mice. Moreover, the induced formation of tau aggregates could be propagated between mouse brains. These findings suggest that once tau aggregates have formed in discrete brain areas, they become self-propagating and spread in a prion-like manner.

XRCC1 Polypeptide Interacts with DNA Polymerase β and Possibly Poly (ADP-Ribose) Polymerase, and DNA Ligase III Is a Novel Molecular ‘Nick-Sensor’ In Vitro

Abstract: The DNA repair proteins XRCC1 and DNA ligase III are physically associated in human cells and directly interact in vitro and in vivo. Here, we demonstrate that XRCC1 is additionally associated with DNA polymerase-beta in human cells and that these polypeptides also directly interact. We also present data suggesting that poly (ADP-ribose) polymerase can interact with XRCC1. Finally, we demonstrate that DNA ligase III shares with poly (ADP-ribose) polymerase the novel function of a molecular DNA nick-sensor, and that the DNA ligase can inhibit activity of the latter polypeptide in vitro. Taken together, these data suggest that the activity of the four polypeptides described above may be co-ordinated in human cells within a single multiprotein complex.

Abundant Tau Filaments and Nonapoptotic Neurodegeneration in Transgenic Mice Expressing Human P301S Tau Protein

Abstract: The identification of mutations in the Tau gene in frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17) has made it possible to express human tau protein with pathogenic mutations in transgenic animals Here we report on the production and characterization of a line of mice transgenic for the 383 aa isoform of human tau with the P301S mutation At 5-6 months of age, homozygous animals from this line developed a neurological phenotype dominated by a severe paraparesis According to light microscopy, many nerve cells in brain and spinal cord were strongly immunoreactive for hyperphosphorylated tau According to electron microscopy, abundant filaments made of hyperphosphorylated tau protein were present The majority of filaments resembled the half-twisted ribbons described previously in cases of FTDP-17, with a minority of filaments resembling the paired helical filaments of Alzheimer's disease Sarkosyl-insoluble tau from brains and spinal cords of transgenic mice ran as a hyperphosphorylated 64 kDa band, the same apparent molecular mass as that of the 383 aa tau isoform in the human tauopathies Perchloric acid-soluble tau was also phosphorylated at many sites, with the notable exception of serine 214 In the spinal cord, neurodegeneration was present, as indicated by a 49% reduction in the number of motor neurons No evidence for apoptosis was obtained, despite the extensive colocalization of hyperphosphorylated tau protein with activated MAP kinase family members The latter may be involved in the hyperphosphorylation of tau