P-TEFb kinase complex phosphorylates histone H1 to regulate expression of cellular and HIV-1 genes

J Biol Chem. 2010 Sep 24;285(39):29713-20. doi: 10.1074/jbc.M110.125997. Epub 2010 Jun 15.

Abstract

Transcription of HIV-1 genes depends on the RNA polymerase II kinase and elongation factor positive transcription elongation factor b (P-TEFb), the complex of cyclin T1 and CDK9. Recent evidence suggests that regulation of transcription by P-TEFb involves chromatin binding and modifying factors. To determine how P-TEFb may connect chromatin remodeling to transcription, we investigated the relationship between P-TEFb and histone H1. We identify histone H1 as a substrate for P-TEFb involved in cellular and HIV-1 transcription. We show that P-TEFb interacts with H1 and that P-TEFb inhibition by RNAi, flavopiridol, or dominant negative CDK9 expression correlates with loss of phosphorylation and mobility of H1 in vivo. Importantly, P-TEFb directs H1 phosphorylation in response to wild-type HIV-1 infection, but not Tat-mutant HIV-1 infection. Our results show that P-TEFb phosphorylates histone H1 at a specific C-terminal phosphorylation site. Expression of a mutant H1.1 that cannot be phosphorylated by P-TEFb also disrupts Tat transactivation in an HIV reporter cell line as well as transcription of the c-fos and hsp70 genes in HeLa cells. We identify histone H1 as a novel P-TEFb substrate, and our results suggest new roles for P-TEFb in both cellular and HIV-1 transcription.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Cyclin T / genetics
  • Cyclin T / metabolism*
  • Cyclin-Dependent Kinase 9 / genetics
  • Cyclin-Dependent Kinase 9 / metabolism
  • Flavonoids / pharmacology
  • Gene Expression Regulation, Viral / drug effects
  • Gene Expression Regulation, Viral / physiology*
  • Genes, Viral / physiology*
  • HIV Infections / genetics
  • HIV Infections / metabolism
  • HIV-1 / genetics
  • HIV-1 / metabolism*
  • HSP70 Heat-Shock Proteins / genetics
  • HSP70 Heat-Shock Proteins / metabolism
  • HeLa Cells
  • Histones / genetics
  • Histones / metabolism*
  • Humans
  • Multienzyme Complexes / genetics
  • Multienzyme Complexes / metabolism
  • Phosphorylation / drug effects
  • Phosphorylation / genetics
  • Piperidines / pharmacology
  • Positive Transcriptional Elongation Factor B / genetics
  • Positive Transcriptional Elongation Factor B / metabolism*
  • Protein Kinase Inhibitors / pharmacology
  • Proto-Oncogene Proteins c-fos / genetics
  • Proto-Oncogene Proteins c-fos / metabolism
  • tat Gene Products, Human Immunodeficiency Virus / genetics
  • tat Gene Products, Human Immunodeficiency Virus / metabolism

Substances

  • CCNT1 protein, human
  • Cyclin T
  • Flavonoids
  • HSP70 Heat-Shock Proteins
  • Histones
  • Multienzyme Complexes
  • Piperidines
  • Protein Kinase Inhibitors
  • Proto-Oncogene Proteins c-fos
  • tat Gene Products, Human Immunodeficiency Virus
  • alvocidib
  • Positive Transcriptional Elongation Factor B
  • CDK9 protein, human
  • Cyclin-Dependent Kinase 9