Telomerase activity, apoptosis and cell cycle progression in ataxia telangiectasia lymphocytes expressing TCL1.

Individuals affected by ataxia telangiectasia (AT) have a marked susceptibility to cancer. Ataxia telangiectasia cells, in addition to defects in cell cycle checkpoints, show dysfunction of apoptosis and of telomeres, which are both thought to have a role in the progression of malignancy. In 1-5% of patients with AT, clonal expansion of T lymphocytes carrying t(14;14) chromosomal translocation, deregulating TCL1 gene(s), has been described.

Telomeric associations and chromosome instability in ataxia telangiectasia T cells characterized by TCL1 expression.

T-cell tumors in ataxia telangiectasia (AT), such as T-PLL/T-CLL, are first preceded by the development of a large clone of T-lymphocytes, characterized by chromosomal rearrangements, which usually involve specific regions such as the 14q11 region. Malignancy develops years later, after additional chromosomal changes resulting from the genomic instability consequent to ATM disruption and to the activation of the TCL1 oncogene. Here we report the results of a cytogenetic follow-up of an AT patient (AT94-1), still without signs of hematological abnormalities, bearing a T-lymphocyte clone characterized by the t(14;14)(q11;q32) rearrangement and having TCL1 expression.

Chromosomal alterations and male infertility.

Reduced male fertility can be caused by genetic factors affecting gamete formation or function; in particular, chromosome abnormalities are a possible cause of male subfertility as shown by their higher frequency in infertile men than in the general male population. Meiotic studies in a number of these males have shown spermatogenesis breakdown, often related to alterations in the process of chromosome synapsis. Indeed, any condition that can interfere with X-Y bivalent formation and X-chromosome inactivation is critical to the meiotic process; furthermore, asynapsed regions may themselves represent a signal for the meiotic checkpoint that eliminates spermatocytes with synaptic errors.

Effects of poly(ADP-ribose) polymerase inhibition on cell death and chromosome damage induced by VP16 and bleomycin.

Poly(ADP-ribose) polymerase (PARP) is a DNA-binding protein involved in cellular response to various genotoxic agents. To understand the role of PARP in the mechanisms which lead from specific DNA damage to cell death, we studied the effects of PARP inhibition in human lymphoblasts damaged with bleomycin (BLM) and VP16. These agents can induce DNA breakage but through different mechanisms, enabling the study of the different effects of PARP in inducing apoptosis in damaged cells.