[Abstract unavailable

We have shown that a polypeptide of M(r) 60,000 (60K) that shares N-terminal homology with a calcium-binding protein, calreticulin, can bind to an amino-acid sequence motif, KXGFFKR, found in the cytoplasmic domains of all integrin alpha-subunits. The homologous amino-acid sequence, KXFFKR (where X is either G, A or V), is also present in the DNA-binding domain of all known members of the steroid hormone receptor family; amino acids in this sequence make direct contact with nucleotides in their DNA-responsive elements and are crucial for DNA binding. Here we show that both the 60K protein (p60), purified on a KLGFFKR-Sepharose affinity matrix, and recombinant calreticulin can inhibit the binding of androgen receptor to its hormone-responsive DNA element in a KXFFKR-sequence-specific manner. Calreticulin can also inhibit androgen receptor and retinoic acid receptor transcriptional activities in vivo, as well as retinoic acid-induced neuronal differentiation. Our results indicate that calreticulin can act as an important modulator of the regulation of gene transcription by nuclear hormone receptors.

The genes for the alpha and beta chains of a highly reactive anti-MART-1 T-cell receptor were isolated from T-lymphocytes that mediated in vivo regression of tumor in a patient with metastatic melanoma. These genes were cloned and inserted into MSCV-based retroviral vectors. After transduction, greater than 50% gene transfer efficiency was demonstrated in primary T-lymphocytes stimulated by an anti-CD3 antibody. The specificity and biologic activity of TCR gene-transduced T-cells was determined by cytokine production after coculture of T-cells with stimulator cells pulsed with MART-1 peptide. The production of interferon-gamma and granulocyte macrophage-colony stimulating factor (GM-CSF) was comparable to highly active MART-1 specific peripheral blood lymphocytes (PBL) in the amount of cytokine produced and transduced cells recognized peptide pulsed cells at dilutions similar to cytotoxic T lymphocyte (CTL) clones. Human leukocyte antigen (HLA) class I restricted recognition was demonstrated by mobilization of degranulation marker CD107a, by cell lysis, by cytokine production, and by proliferation in the presence of HLA-A2-positive but not HLA-A2-negative melanoma cell lines. Similar data was obtained when tumor-infiltrating lymphocytes (TIL) were transduced with the TCR genes, converting previously nonreactive cells to tumor reactive cells. TCR-transduced T-cells are thus attractive candidates for evaluation in cell transfer therapies of patients with cancer.

Here we describe the sustained expression of transgenes introduced into human embryonic stem (ES) cells using self-inactivating lentiviral vectors. At low multiplicity of infection, vesicular stomatitis virus-pseudotyped vectors containing a green fluorescent protein (GFP) transgene under the control of a human elongation factor 1α α promoter transduced human ES cells at high efficiency. The majority of the transduced ES cells, which harbored low numbers of integrated vectors, continued to express GFP after 60 days of culture. Incorporation of a scaffold attachment region (SAR) from the human interferon-β β gene into the lentiviral vector backbone increased the average level of GFP expression, and inclusion of the SAR together with a chromatin insulator from the 5′ ′ end of the chicken β β-globin locus reduced the variability in GFP expression. When the transduced ES cells were induced to differentiate into CD34 + hematopoietic precursors in vitro, GFP expression was maintained with minimal silencing. The ability to efficiently introduce active transgenes into human ES cells will facilitate gain-of-function studies of early developmental processes in the human system. These results also have important implications for the possible future use of gene-modified human ES cells in transplantation and tissue regeneration applications.