Loss of intracisternal A-type retroviral particles in BL6 melanoma cells transfected with MHC class I genes

Abstract

Electron microscopy of B16 melanoma and its sublines revealed that these cells produce numerous intracisternal A-type retroviral particles (lAPs). To identify and sequence the melanoma-associated lAPs of C57BL/6 mice, a cDNA library was constructed from lAP-producing BL6-8 cell RNA and screened using MIA14 lAP DNA as a probe. A 6.8 kb mRNA was identified that represents the full-length message for a new subfamily of lAP, termed MelAP. The melanoma-derived lAP cDNA showed high similarity to MIA14 with major differences in the LTR. A nine base motif of the R region showed that this lAP differs from other previously sequenced lAPs. Analysis of the individual clones from BL6 melanoma revealed that lAPs were produced only in the clones that failed to express H-2K b molecules. No lAPs were found in the melanoma clones that expressed endogenous H-2K b. To analyse further the association between MHC class I genes and lAP production, the H-2Kb-negative clones of BL6 melanoma were transfected with various H-2 genes. Transfection of the H-2K b or H-2K d, but not H-2D d or H-2L d genes resulted in the elimination of lAPs.Northern blot analysis revealed that loss of lAPs in the H-2K gene-transfected BL6 melanoma cells was due to lack of lAP transcripts. Elimination of lAPs in the H-2Kb-positive BL6 melanoma cells was also accompanied by alterations in expression of various cellular genes and changes of their phenotypic properties.

Evidence for expression of endogenous retroviral sequences on primate reproductive tissues and detection of cross-reactive ERVS antigens in the baboon ovary: a review

“…possible involvement of steroid hormones in regulating the functions of ERVs (24,25). The detection of these ERV-related antigens in the baboon ovary as reported in the current study also supports the possible role of steroid hormones in regulating the expression of ERV in the ovarian endocrine micro-environment.…”

Endogenous retroviruses

“…Indeed, mostly younger and recently integrated MT [176] and MusD [131] LTR retrotransposons are expressed in permissive cells, suggesting this trend may persist when ERVs are re-activated. Additionally, expression and demethylation of only select IAP types was detected in tumor cell lines [177,178]. The only solution for determining if multiple or only a few select elements are transcribed is sequencing of RT-PCR products.…”

Identification of a Novel Posttranscriptional Regulatory Element by Using a rev- and RRE-Mutated Human Immunodeficiency Virus Type 1 DNA Proviral Clone as a Molecular Trap

“…IAP proviral elements can act as endogenous mutagens by transposition to new locations in the genome, both at the somatic cell (8,20,24,40,43) and germ line levels (7). Transposition of IAP elements is occasionally associated with cellular transformation because they can activate the genes located near the transposition site (2,3,8,11,38,71).…”