Protein kinase A subunit expression is altered in Bloom syndrome fibroblasts and the BLM protein is increased in adrenocortical hyperplasias: inverse findings for BLM and PRKAR1A

Horm Metab Res. 2008 Jun;40(6):391-7. doi: 10.1055/s-2008-1058089. Epub 2008 Mar 6.

Abstract

Bloom syndrome is a genetic disorder associated with chromosomal instability and a predisposition to tumors that is caused by germline mutations of the BLM gene, a RecQ helicase. Benign adrenocortical tumors display a degree of chromosomal instability that is more significant than benign tumors of other tissues. Cortisol-producing hyperplasias, such as primary pigmented nodular adrenocortical disease (PPNAD), which has been associated with protein kinase A (PKA) abnormalities and/or PRKAR1A mutations, also show genomic instability. Another RecQ helicase, WRN, directly interacts with the PRKAR1B subunit of PKA. In this study, we have investigated the PRKAR1A expression in primary human Bloom syndrome cell lines with known BLM mutations and examined the BLM gene expression in PPNAD and other adrenal tumor tissues. PRKAR1A and other protein kinase A (PKA) subunits were expressed in Bloom syndrome cells and their level of expression differed by subunit and cell type. Overall, fibroblasts exhibited a significant decrease in protein expression of all PKA subunits except for PRKAR1A, a pattern that has been associated with neoplastic transformation in several cell types. The BLM protein was upregulated in PPNAD and other hyperplasias, compared to samples from normal adrenals and normal cortex, as well as samples from cortisol- and aldosterone-producing adenomas (in which BLM was largely absent). These data reveal an inverse relationship between BLM and PRKAR1A: BLM deficiency is associated with a relative excess of PRKAR1A in fibroblasts compared to other PKA subunits; and PRKAR1A deficiency is associated with increased BLM protein in adrenal hyperplasias.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adrenal Cortex Diseases / complications
  • Adrenal Cortex Diseases / genetics
  • Adrenal Cortex Diseases / metabolism*
  • Adrenal Cortex Diseases / pathology
  • Adrenal Cortex Neoplasms / genetics
  • Adrenal Cortex Neoplasms / metabolism
  • Adrenal Cortex Neoplasms / pathology
  • Adrenal Glands / metabolism
  • Adrenal Glands / pathology
  • Bloom Syndrome / genetics
  • Bloom Syndrome / metabolism*
  • Cell Line
  • Cyclic AMP-Dependent Protein Kinase RIalpha Subunit / genetics
  • Cyclic AMP-Dependent Protein Kinase RIalpha Subunit / metabolism*
  • DNA Helicases / genetics
  • DNA Helicases / metabolism*
  • Fibroblasts / metabolism*
  • Gene Expression Regulation
  • Humans
  • Hyperplasia
  • Immunohistochemistry
  • Pigmentation Disorders / complications
  • Pigmentation Disorders / genetics
  • Pigmentation Disorders / metabolism
  • Pigmentation Disorders / pathology
  • RNA, Messenger / analysis
  • RecQ Helicases

Substances

  • Cyclic AMP-Dependent Protein Kinase RIalpha Subunit
  • PRKAR1A protein, human
  • RNA, Messenger
  • Bloom syndrome protein
  • DNA Helicases
  • RecQ Helicases