Characterization and localization of expression of an erythropoietin-induced gene, ERIC-1 /TACC3, identified in erythroid precursor cells

Gene expression profiles during erythropoietin (Epo)-induced differentiatio n of erythroid progenitor cells derived from the Friend virus anaemia (FVA) and phenylhydrazine (PHZ) murine models have been examined using different ial display polymerase chain reaction (PCR). Ten cDNA fragments upregulated by Epo were isolated. The ribonuclease protection assay confirmed differen tial expression between Epo-stimulated and Epo-deprived cells for one of th ese, provisionally named ERIC-1. Sequencing of the full-length cDNA predict ed a protein of 558 amino acids, 17 amino acids longer than mTACC3, the thi rd member of a novel family of proteins that contain a coiled-coil domain. The human homologue, cloned using rapid amplification of cDNA ends (RACE)-P CR, encodes a larger protein of 838 amino acids that is identical to hTACC3 . In addition to erythroid precursor cells, ERIC-1/TACC3 is expressed at hi gh levels in the testes, at moderate levels in the thymus and peripheral le ucocytes, and at lower levels in the spleen and intestinal tissue. Immunohi stochemical analysis using an antibody to a GST fusion product of the C-ter minus of hERIC-1/TACC3 revealed that it is localized to Sertoli cells in th e human testes. Confocal microscopy demonstrated hERIC1/TACC3 protein conce ntrated in the perinuclear vesicles of dermal microvascular endothelial cel ls. Although ERIC1/TACC3 is expressed in a wide range of tissues, its upreg ulation by Epo in erythroid progenitors implies that it has a role In termi nal erythropoiesis.