Expression of Sec61alpha in F9 and P19 teratocarcinoma cells after retinoic acid treatment

Abstract

Nascent procollagen peptides and other secretory proteins are transported across the endoplasmic reticulum (RE) membrane through a protein-conducting channel called the translocon. Sec61 alpha, 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 Sec61 alpha is ubiquitously expressed in collagen producing teratocarcinoma cells. Furthermore, the production, expression, and utilization of Sec61 alpha 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 Sec61 alpha was determined by reverse trancriptase polimerase chain reaction (RT-PCR). In untreated conditions, F9 cells expressed undetected Sec61 alpha amounts. It was also demonstrated that Sec61 alpha expression is stimulated in F9 cells after retinoic acid treatment for 72 hours. No changes were found in Sec61 alpha expression in P19 cells after retinoic acid treatment. These data indicate that the expression of Sec61 alpha is enhanced with retinoic acid induced differentiation of F9 teratocarcinoma cells.

Hsp47 a novel collagen binding serpin chaperone, autoantigen and therapeutic target

“…This potential role in protein translocation is analogous to that described for BiP, which seems to involve multiple BiP/substrate binding as well as release measures and BiP transactions with Sec63, a membrane component of the translocation machinery (67). Interestingly, Sec61 alpha, a multispanning membrane translocon protein that has been implicated as essential for translocation of polypeptides chains into the cisterns of the ER, has been recovered in a protein complex with collagen and Hsp47 in F9 cells treated with retinoic acid for 72 hours (68,69). However, additional functional studies will be essential to substantiate a role of Hsp47 in collagen translocation.…”