title: HMGA2 regulates the in vitro aging and proliferation of human umbilical cord blood-derived stromal cells through the mTOR/p70S6K signaling pathway.
abstract: The human high-mobility group protein A2 (HMGA2) protein is an architectural transcription factor that transforms chromatin structure by binding to DNA. Recently, it has been reported that HMGA2 is highly expressed in fetal neural stem cells and has the capacity to promote stemness. However, there is currently no information available on the functional significance and molecular mechanisms of the cellular in vitro aging and proliferation of human umbilical cord blood-derived stromal cells (hUCBSCs). In the present study, we evaluated the direct effects of HMGA2 on the cellular aging and proliferation of hUCBSCs and investigated potential regulatory mechanisms responsible for the corresponding functions. We found that the overexpression of HMGA2 enhanced proliferation and reduced or even reversed the in vitro aging process of hUCBSCs. This effect was accompanied by the increased expression of cyclin E and CDC25A and the significantly decreased expression of cyclin-dependent kinase inhibitors. Furthermore, HMGA2 inhibition compromised cell proliferation and adipogenic differentiation in early-stage hUCBSCs. From the molecular/cellular functional analysis of microarray data, we found that HMGA2 overexpression induced a PI3K/Akt/mTOR/p70S6K cascade, which in turn suppressed the expression of p16(INK4A) and p21(CIP1/WAF1) in hUCBSCs. These results provide novel insights into the mechanism by which HMGA2 regulates the in vitro aging and proliferation of hUCBSCs.
authors.affiliation: Adult Stem Cell Research Center, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea.
authors.forename: Kyung-Rok
authors.initials: KR
authors.lastname: Yu
authors.forename: Sang-Bum
authors.initials: SB
authors.lastname: Park
authors.forename: Ji-Won
authors.initials: JW
authors.lastname: Jung
authors.forename: Min-Soo
authors.initials: MS
authors.lastname: Seo
authors.forename: In-Sun
authors.initials: IS
authors.lastname: Hong
authors.forename: Hyung-Sik
authors.initials: HS
authors.lastname: Kim
authors.forename: Yoojin
authors.initials: Y
authors.lastname: Seo
authors.forename: Tae-Wook
authors.initials: TW
authors.lastname: Kang
authors.forename: Jin Young
authors.initials: JY
authors.lastname: Lee
authors.forename: Andreas
authors.initials: A
authors.lastname: Kurtz
authors.forename: Kyung-Sun
authors.initials: KS
authors.lastname: Kang
mesh_terms: D050156:Adipogenesis / Q000235:genetics; D000328:Adult; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D049109:Cell Proliferation; D016922:Cellular Senescence / Q000235:genetics; D015536:Down-Regulation / Q000235:genetics; D004789:Enzyme Activation; D005260:Female; D005312:Fetal Blood / Q000166:cytology*; D005786:Gene Expression Regulation; D025743:HMGA2 Protein / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006801:Humans; D008954:Models, Biological; D020411:Oligonucleotide Array Sequence Analysis; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics; D017154:Stromal Cells / Q000166:cytology / Q000201:enzymology; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*; D055815:Young Adult; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; D025743:HMGA2 Protein; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D058570:TOR Serine-Threonine Kinases; D001616:beta-Galactosidase; C546842:MTOR protein, human