RESUMEN
B lymphopoiesis arrests in rabbits by 4 months of age. To identify molecules that contribute to this arrest, cDNA-representational difference analysis on BM stromal cells from young and adult rabbits showed that expression of Postn that encodes for the extracellular matrix protein periostin dramatically reduced with age. Postn-small interfering RNA OP9 cells lost their capacity to support B-cell development from rabbit or murine BM cells, and reexpression of periostin restored this potential, indicating an in vitro requirement for periostin in B lymphopoiesis. In our system, we determined that periostin deficiency leads to increased cell death and decreased proliferation of B-lineage progenitors. Further, RGD peptide inhibition of periostin/α(v)ß(3) interaction resulted in a marked decrease in B lymphopoiesis in vitro. Microarray analysis of the Postn-small interfering RNA OP9 cells showed decreased expression of key B-lymphopoietic factors, including IL-7 and CXCL12. In vivo, unidentified molecule(s) probably compensate periostin loss because Postn(-/-) mice had normal numbers of B-cell progenitors in BM. We conclude that the decline in periostin expression in adult rabbit BM does not solely explain the arrest of B lymphopoiesis. However, the interaction of periostin with α(v)ß(3) on lymphoid progenitors probably provides both proliferative and survival signals for cells in the B-cell development pathway.
Asunto(s)
Linfocitos B/fisiología , Moléculas de Adhesión Celular/fisiología , Linfopoyesis/genética , Factores de Edad , Animales , Animales Recién Nacidos , Linfocitos B/efectos de los fármacos , Linfocitos B/metabolismo , Moléculas de Adhesión Celular/antagonistas & inhibidores , Moléculas de Adhesión Celular/genética , Moléculas de Adhesión Celular/metabolismo , Diferenciación Celular/efectos de los fármacos , Diferenciación Celular/genética , Diferenciación Celular/inmunología , Proliferación Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Supervivencia Celular/genética , Células Cultivadas , Linfopoyesis/efectos de los fármacos , Linfopoyesis/fisiología , Ratones , Ratones Noqueados , Células Precursoras de Linfocitos B/efectos de los fármacos , Células Precursoras de Linfocitos B/metabolismo , Células Precursoras de Linfocitos B/fisiología , ARN Interferente Pequeño/farmacología , ConejosRESUMEN
IL-7 is required for B cell development in mouse and is a key regulator of T cell development and peripheral T cell homeostasis in mouse and human. Recently, we found that IL-7 is expressed in rabbit bone marrow and in vitro, is required for differentiation of lymphoid progenitors to B and T lineage cells. Herein, we report the identification of a novel rabbit IL-7 isoform, IL-7II. Recombinant IL-7II (rIL-7II) binds lymphocytes via the IL-7R and induces phosphorylation of STAT5. Further, rIL-7II supports proliferation and differentiation of BM progenitor cells into B and T lineage cells. IL7-II is generated by alternative splicing, with an 11 amino acid insertion encoded by a separate exon, exon 2b. Exon 2b is conserved in other lagomorphs, in Perissodactyla, Artiodactyla, and Carnivora, but is absent in mouse and human.