RESUMO
Pheochromocytomas are adrenal medullary tumors which arise from the transformation of neural crest-derived cells. In the course of studies of mice transgenic for an SV40 T-gene ectopically expressed in the adrenal medulla, we observed the occurrence of large, mainly bilateral tumors in a high proportion of transgenic animals. From these tumors we established immortalized cell lines which grow in vitro at 32 degrees C (the permissive temperature for the tsA58 T-protein encoded by the transgene), but not at 38 C. These cells demonstrate characteristics of both neuronal (160 kd neurofilament) and endocrine (chromogranins) cells. The expression of Mash-1 and ret supports their initial characterization as early bipotential neuro-endocrine progenitors.
Assuntos
Neoplasias das Glândulas Suprarrenais/genética , Neoplasias das Glândulas Suprarrenais/patologia , Antígenos Transformantes de Poliomavirus/genética , Camundongos Transgênicos/genética , Neoplasias das Glândulas Suprarrenais/mortalidade , Medula Suprarrenal/patologia , Animais , Northern Blotting , Divisão Celular/efeitos dos fármacos , Cromogranina A , Cromograninas/metabolismo , Citocinas/farmacologia , Proteínas de Ligação a DNA/genética , Fatores de Ligação de DNA Eritroide Específicos , Fatores de Crescimento de Fibroblastos/farmacologia , Regulação Neoplásica da Expressão Gênica , Camundongos , Mutação , Fatores de Crescimento Neural/farmacologia , Crista Neural/citologia , Crista Neural/patologia , Fatores de Transcrição/genética , Células Tumorais CultivadasRESUMO
The transcription factor GATA-1 is required for the normal development of erythroid cells. GATA-1 is also expressed in other hemopoietic cells, suggesting that it might be initially activated in a multipotent progenitor. To immortalize GATA-1-expressing progenitors, we generated mice transgenic for a thermosensitive SV40 T gene, driven by the GATA-1 promoter-enhancer. Immortalized marrow cells grow in culture at 32 degrees C but not at 38 degrees C, and are dependent on erythropoietin (Epo) or interleukin 3 (IL-3). Epo dependent cells express hemoglobin, high levels of GATA-1, GATA-2 and NF-E2 p45 mRNAs, and are positive for stem cell antigen 2 (Sca-2) and the early myeloid marker ER-MP12. IL-3 dependent cells can be derived from Epo dependent lines, and are hemoglobin-, Sca-2- and ER-MP12-negative, have low GATA-1 and NF-E2 p45 mRNA levels, and express myeloid markers Mac-1, F4/80 and Gr-1. Brief treatment of Epo dependent cells with myeloid growth factors (plus Epo) leads to the induction of Mac-1, F4/80 and Gr-1, concomitant with the disappearance from most cells of Sca-2, ER-MP12 and GATA-1 driven T antigen nuclear expression. Thus, the immortalized Epo dependent cells have the property of a progenitor capable of differentiation towards either the erythroid or myeloid lineages. These cells initiate transcription of a proportion of GATA-1 RNA molecules at an upstream promoter, previously known to be expressed only in testis cells.
Assuntos
Proteínas de Ligação a DNA/fisiologia , Substâncias de Crescimento/fisiologia , Células-Tronco Hematopoéticas/citologia , Vírus 40 dos Símios/genética , Fatores de Transcrição/fisiologia , Animais , Antígenos Transformantes de Poliomavirus/genética , Sequência de Bases , Diferenciação Celular/genética , Linhagem Celular Transformada , Transformação Celular Viral/genética , Fatores de Ligação de DNA Eritroide Específicos , Eritropoetina/fisiologia , Fator de Transcrição GATA1 , Camundongos , Camundongos Transgênicos , Dados de Sequência Molecular , Fator de Transcrição NF-E2 , Subunidade p45 do Fator de Transcrição NF-E2 , Regiões Promotoras Genéticas/fisiologia , TemperaturaRESUMO
In all vertebrate groups, the progenitors of the germ line, the primordial germ cells (PGCs) arise extragonadally and move to the developing gonad early in embryonic development. We have examined the behavior of isolated pregonadal and gonadal PGCs in vitro on feeder layers of an embryo-derived cell line. Histochemically and serologically identified pregonadal germ cells are found to be actively motile in vitro and, furthermore, show behavior characteristic of invasive cells. PGCs isolated from the developing gonad, however, show little locomotory activity and are not invasive on the same cellular substrate. These observations suggest that PGCs undergo a major change in phenotype at the time of their entry into the gonad anlagen.
