Southern Illinois University School of Medicine

About: Southern Illinois University School of Medicine is a education organization based out in Springfield, Illinois, United States. It is known for research contribution in the topics: Population & Cancer. The organization has 3747 authors who have published 5977 publications receiving 209115 citations. The organization is also known as: SIU School of Medicine.

INO80 exchanges H2A.Z for H2A by translocating on DNA proximal to histone dimers

Abstract: ATP-dependent chromatin remodellers modulate nucleosome dynamics by mobilizing or disassembling nucleosomes, as well as altering nucleosome composition. These chromatin remodellers generally function by translocating along nucleosomal DNA at the H3-H4 interface of nucleosomes. Here we show that, unlike other remodellers, INO80 translocates along DNA at the H2A-H2B interface of nucleosomes and persistently displaces DNA from the surface of H2A-H2B. DNA translocation and DNA torsional strain created near the entry site of nucleosomes by INO80 promotes both the mobilization of nucleosomes and the selective exchange of H2A.Z-H2B dimers out of nucleosomes and replacement by H2A-H2B dimers without any additional histone chaperones. We find that INO80 translocates and mobilizes H2A.Z-containing nucleosomes more efficiently than those containing H2A, partially accounting for the preference of INO80 to replace H2A.Z with H2A. Our data suggest that INO80 has a mechanism for dimer exchange that is distinct from other chromatin remodellers including its paralogue SWR1.

Growth hormone action predicts age-related white adipose tissue dysfunction and senescent cell burden in mice.

Abstract: The aging process is associated with the development of several chronic diseases. White adipose tissue (WAT) may play a central role in age-related disease onset and progression due to declines in adipogenesis with advancing age. Recent reports indicate that the accumulation of senescent progenitor cells may be involved in age-related WAT dysfunction. Growth hormone (GH) action has profound effects on adiposity and metabolism and is known to influence lifespan. In the present study we tested the hypothesis that GH activity would predict age-related WAT dysfunction and accumulation of senescent cells. We found that long-lived GH-deficient and -resistant mice have reduced age-related lipid redistribution. Primary preadipocytes from GH-resistant mice also were found to have greater differentiation capacity at 20 months of age when compared to controls. GH activity was also found to be positively associated with senescent cell accumulation in WAT. Our results demonstrate an association between GH activity, age-related WAT dysfunction, and WAT senescent cell accumulation in mice. Further studies are needed to determine if GH is directly inducing cellular senescence in WAT or if GH actions on other target organs or alternative downstream alterations in insulin-like growth factor-1, insulin or glucose levels are responsible.

Ultrastructural Observations of Spermatogenesis Following Transplantation of Rat Testis Cells Into Mouse Seminiferous Tubules

Abstract: The testes of busulfan-treated immunodeficient mice receiving seminiferous tubule injections of testis cells from rats were examined by light and electron microscopy. The presence of active rat spermatogenesis was verified by criteria that are known to characterize spermatogenic cells of this species. In addition, spermatogenesis from the mouse was identified as taking place in some seminiferous tubules as the result of reinitiation of spermatogenesis after busulfan treatment. Rat spermatogenesis in mouse seminiferous tubules showed the generally recognized associations of cells known to characterize stages of spermatogenesis of the rat. The Sertoli cells associated with rat spermatogenesis were identified ultrastructurally as being of mouse origin. Thus, rat spermatogenesis, which has a cycle length that is 50% longer than mouse spermatogenesis, can proceed among mouse Sertoli cells, which supposedly exert much shorter cyclic influences in concert with mouse germ cell development. Studies are needed to determine if the timing of rat spermatogenesis is controlled by the germ cells or the Sertoli cells. These observations are considered preliminary since a thorough study of somatic-germ cell relationships was not undertaken. It is concluded that a mouse Sertoli cell in the environment provided by the mouse testis can produce both mouse and rat gametes.