HDAC1 overexpression enhances beta-cell proliferation by down-regulating Cdkn1b/p27
BIOCHEMICAL JOURNAL
Authors: Draney, Carrie; Austin, Matthew C.; Leifer, Aaron H.; Smith, Courtney J.; Kener, Kyle B.; Aitken, Talon J.; Hess, Kavan H.; Haines, Amanda C.; Lett, Lanair A.; Hernandez-Carretero, Angelina; Fueger, Patrick T.; Arlotto, Michelle; Tessem, Jeffery S.
Abstract
The homeobox transcription factor Nkx6.1 is sufficient to increase functional beta-cell mass, where functional beta-cell mass refers to the combination of beta-cell proliferation, glucose-stimulated insulin secretion (GSIS) and beta-cell survival. Here, we demonstrate that the histone deacetylase 1 (HDAC1), which is an early target of Nkx6.1, is sufficient to increase functional beta-cell mass. We show that HDAC activity is necessary for Nkx6.1-mediated proliferation, and that HDAC1 is sufficient to increase beta-cell proliferation in primary rat islets and the INS-1 832/13 beta-cell line. The increase in HDAC1-mediated proliferation occurs while maintaining GSIS and increasing beta-cell survival in response to apoptotic stimuli. We demonstrate that HDAC1 overexpression results in decreased expression of the cell cycle inhibitor Cdkn1b/p27 which is essential for inhibiting the G1 to S phase transition of the cell cycle. This corresponds with increased expression of key cell cycle activators, such as Cyclin A2, Cyclin B1 and E2F1, which are activated by activation of the Cdk4/Cdk6/Cyclin D holoenzymes due to down-regulation of Cdkn1b/p27. Finally, we demonstrate that overexpression of Cdkn1b/p27 inhibits HDAC1-mediated beta-cell proliferation. Our data suggest that HDAC1 is critical for the Nkx6.1-mediated pathway that enhances functional beta-cell mass.
Transcriptional Regulatory Network Analysis to Reveal the Key Genes Involved in Skeletal Muscle Injury
JOURNAL OF COMPUTATIONAL BIOLOGY
Authors: Li, Qi; Luo, Zhengqiang
Abstract
Skeletal muscle is among the three major muscle types, and skeletal muscle injury (SMI) can elevate the risk of dependency and falls. This study is designed to explore the key genes involved in SMI and skeletal muscle regeneration. Microarray data set GSE81096, which included 11 injured skeletal muscle stem cell samples and 12 noninjured skeletal muscle stem cell samples, was from Gene Expression Omnibus. The differentially expressed genes (DEGs) between injured and noninjured samples were screened by R package limma, and then were performed with enrichment analysis based on the Database for Annotation, Visualization, and Integrated Discovery. Followed by protein-protein interaction (PPI), transcriptional regulatory analyses were conducted using Cytoscape software. A total of 1018 DEGs were screened from the injured samples, among which four upregulated genes and nine downregulated genes were predicted as transcription factors. Besides, four modules were identified from the PPI network. In the transcriptional regulatory network, E2F1, E2F4, JUNB, FOS, and MEF2C had higher degrees. Moreover, E2F4 and FOS might function in SMI separately through targeting E2F1 and JUNB. E2F1, E2F4, JUNB, FOS, and MEF2C might be involved in SMI and skeletal muscle regeneration.