title: PUMILIO-2 is involved in the positive regulation of cellular proliferation in human adipose-derived stem cells.
abstract: Stem cells can either differentiate into more specialized cells or undergo self-renewal. Several lines of evidence from different organisms suggest that these processes depend on the post-transcriptional regulation of gene expression. The presence of the PUF [Pumilio/FBF (fem-3 binding factor)] domain defines a conserved family of RNA binding proteins involved in repressing gene expression. It has been suggested that a conserved function of PUF proteins is to repress differentiation and sustain the mitotic proliferation of stem cells. In humans, Pumilio-2 (PUM2) is expressed in embryonic stem cells and adult germ cells. Here we show that PUM2 is expressed in a subpopulation of adipose-derived stem cell (ASC) cultures, with a granular pattern of staining in the cytoplasm. Protein levels of PUM2 showed no changes during the differentiation of ASCs into adipocytes. Moreover, RNAi knockdown of pum2 did not alter the rate of adipogenic differentiation compared with wild-type control cells. A ribonomic approach was used to identify PUM2-associated mRNAs. Microarray analysis showed that PUM2-bound mRNAs are part of gene networks involved in cell proliferation and gene expression control. We studied pum2 expression in cell cultures with low or very high levels of proliferation and found that changes in pum2 production were dependent on the proliferation status of the cell. Transient knockdown of pum2 expression by RNAi impaired proliferation of ASCs in vitro. Our results suggest that PUM2 does not repress differentiation of ASCs but rather is involved in the positive control of ASCs division and proliferation.
authors.affiliation: Laboratório de Biologia Básica de Células-Tronco, Instituto Carlos Chagas, Curitiba, Brazil.
authors.forename: Patrícia
authors.initials: P
authors.lastname: Shigunov
authors.forename: Jose
authors.initials: J
authors.lastname: Sotelo-Silveira
authors.forename: Crisciele
authors.initials: C
authors.lastname: Kuligovski
authors.forename: Alessandra Melo
authors.initials: AM
authors.lastname: de Aguiar
authors.forename: Carmen K
authors.initials: CK
authors.lastname: Rebelatto
authors.forename: José A
authors.initials: JA
authors.lastname: Moutinho
authors.forename: Paulo S
authors.initials: PS
authors.lastname: Brofman
authors.forename: Marco A
authors.initials: MA
authors.lastname: Krieger
authors.forename: Samuel
authors.initials: S
authors.lastname: Goldenberg
authors.forename: David
authors.initials: D
authors.lastname: Munroe
authors.forename: Alejandro
authors.initials: A
authors.lastname: Correa
authors.forename: Bruno
authors.initials: B
authors.lastname: Dallagiovanna
mesh_terms: D017667:Adipocytes / Q000166:cytology / Q000378:metabolism*; D002454:Cell Differentiation; D049109:Cell Proliferation; D002478:Cells, Cultured; D005786:Gene Expression Regulation; D055785:Gene Knockdown Techniques; D020868:Gene Silencing; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000378:metabolism*; D008938:Mitosis / Q000235:genetics*; D020411:Oligonucleotide Array Sequence Analysis; D012333:RNA, Messenger / Q000235:genetics*; D034741:RNA, Small Interfering / Q000235:genetics; D016601:RNA-Binding Proteins / Q000235:genetics*
chemical_list: C471243:PUM2 protein, human; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins