RETINOIC ACID TREATMENT

(With 5 figures) Nascent procollagen peptides and other secretory proteins are transported across the endoplasmic reticulum (RE) membrane through a protein-conducting channel called the translocon. Sec61α, a multispanning membrane translocon protein, has been implicated as essential for translocation of polypeptides chains into the cisterns of the ER. However, it is not known whether Sec61α is ubiquitously expressed in collagen producing teratocarcinoma cells. Furthermore, the production, expression, and utilization of Sec61α may depend on the cell differentiation stage. Stem cells from many cultured teratocarcinoma cell lines such as F9 and P19 cells are capable of differentiation in response to low retinoic acid concentrations. This differentiation of the tumorigenic stem cells results in tumorigenicity loss. For this study, mouse F9 and P19 teratocarcinoma cells were grown in culture medium treated with or without retinoic acid. Expression of Sec61α was determined by reverse trancriptase polimerase chain reaction (RT-PCR). In untreated conditions, F9 cells expressed undetected Sec61α amounts. It was also demonstrated that Sec61α ex-pression is stimulated in F9 cells after retinoic acid treatment for 72 hours. No changes were found in Sec61α expression in P19 cells after retinoic acid treatment. These data indicate that the expression of Sec61α is enhanced with retinoic acid induced differentiation of F9 teratocarcinoma cells