title: Mitotic spindle destabilization and genomic instability in Shwachman-Diamond syndrome.
abstract: Deficiencies in the SBDS gene result in Shwachman-Diamond syndrome (SDS), an inherited bone marrow failure syndrome associated with leukemia predisposition. SBDS encodes a highly conserved protein previously implicated in ribosome biogenesis. Using human primary bone marrow stromal cells (BMSCs), lymphoblasts, and skin fibroblasts, we show that SBDS stabilized the mitotic spindle to prevent genomic instability. SBDS colocalized with the mitotic spindle in control primary BMSCs, lymphoblasts, and skin fibroblasts and bound to purified microtubules. Recombinant SBDS protein stabilized microtubules in vitro. We observed that primary BMSCs and lymphoblasts from SDS patients exhibited an increased incidence of abnormal mitoses. Similarly, depletion of SBDS by siRNA in human skin fibroblasts resulted in increased mitotic abnormalities and aneuploidy that accumulated over time. Treatment of primary BMSCs and lymphoblasts from SDS patients with nocodazole, a microtubule destabilizing agent, led to increased mitotic arrest and apoptosis, consistent with spindle destabilization. Conversely, SDS patient cells were resistant to taxol, a microtubule stabilizing agent. These findings suggest that spindle instability in SDS contributes to bone marrow failure and leukemogenesis.
authors.affiliation: Department of Pediatric Hematology, Children's Hospital Boston, Boston, Massachusetts, USA.
authors.forename: Karyn M
authors.initials: KM
authors.lastname: Austin
authors.forename: Mohan L
authors.initials: ML
authors.lastname: Gupta
authors.forename: Scott A
authors.initials: SA
authors.lastname: Coats
authors.forename: Asmin
authors.initials: A
authors.lastname: Tulpule
authors.forename: Gustavo
authors.initials: G
authors.lastname: Mostoslavsky
authors.forename: Alejandro B
authors.initials: AB
authors.lastname: Balazs
authors.forename: Richard C
authors.initials: RC
authors.lastname: Mulligan
authors.forename: George
authors.initials: G
authors.lastname: Daley
authors.forename: David
authors.initials: D
authors.lastname: Pellman
authors.forename: Akiko
authors.initials: A
authors.lastname: Shimamura
mesh_terms: D001855:Bone Marrow Diseases / Q000235:genetics* / Q000378:metabolism / Q000473:pathology*; D002460:Cell Line; D042822:Genomic Instability / Q000235:genetics*; D006801:Humans; D008870:Microtubules / Q000378:metabolism; D011485:Protein Binding; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D008941:Spindle Apparatus / Q000378:metabolism*; D013577:Syndrome
chemical_list: D011506:Proteins; D034741:RNA, Small Interfering; C470521:SBDS protein, human