il\VOLVEMENT OF RETII\OIC ACID II{ - MSpace at the University of ...

and development of heart blocks. The changes in the conductivity were attributed to the
down-regulation and redistribution of gap junction protein Cx40 and the disruption of the
expression of intercalated discs proteins- p-catenin and N-cadherin (van Veen et al.
2002).
Thus, a number of studies indicate the existence of multitude of regulatory
function executed by retinoic acid on the heart tissue. However, current research has just
touched the tip of the iceberg and retinoic acid function may prove to be essential in the
multitude of physiological and pathological processes not only during fetal development,
but also during the adult life.
IV.e.Retinoic acid and apoptosis
As previously mentioned, retinoic acid is involved in the regulation of the
expression of a number of genes. Some of the genes are involved in the prevention or
execution of apoptosis. However, the exact role of retinoic acid in apoptosis is still
controversial. Furthermore, it is dependent on the cell type, cell maturity, specificity of
retinoic acid isomers and presence or the absence of other stimuli (Nugy et al. 1998)
(Ashwell 1998). In fact, it is reported that the retinoic acid regulates the expression of
programmed cells death, inducing the apoptosis in certain cell types (Martin et al. 1990),
while inhibiting it in the others (Yang et al. 1993), Apoptosis regulating characteristics of
retinoic acid are utilized in therapy of high-proliferative, pre malignant and malignant
diseases such as acute promyelocytic leukemia (APL) (Jimenez-Lara et al. 2004), T-cell
l1'rnphoma (Zhang and Duvic 2003), Kaposi's sarcoma (Aboulafia et al. 2003) and
variety of skin cancers (Niles 2002). The ongoing studies indicate the potential usage of
retinoic acid in the treatment of squamous cell carcinoma, ovarian carcinoma,
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