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The ERBB4/HER4 receptor tyrosine kinase regulates gene expression by functioning as a STAT5A nuclear chaperone.

Williams CC, Allison JG, Vidal GA, Burow ME, Beckman BS, Marrero L, Jones FE - J. Cell Biol. (2004)

Bottom Line: We have identified an intrinsic ERBB4 NLS (residues 676-684) within the ERBB4 intracellular domain (4ICD) that is essential for nuclear accumulation of 4ICD.Together, our results establish a novel molecular mechanism of transmembrane receptor signal transduction involving nuclear cotranslocation of the receptor intracellular domain and associated transcription factor.Subsequent binding of the two proteins at transcription factor target promoters results in activation of gene expression.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry, Tulane University Health Sciences Center, Tulane Cancer Center, New Orleans, LA 70112, USA.

ABSTRACT
In the lactating breast, ERBB4 localizes to the nuclei of secretory epithelium while regulating activities of the signal transducer and activator of transcription (STAT) 5A transcription factor essential for milk-gene expression. We have identified an intrinsic ERBB4 NLS (residues 676-684) within the ERBB4 intracellular domain (4ICD) that is essential for nuclear accumulation of 4ICD. To determine the functional significance of 4ICD nuclear translocation in a physiologically relevant system, we have demonstrated that cotransfection of ERBB4 and STAT5A in a human breast cancer cell line stimulates beta-casein promoter activity. Significantly, nuclear localization of STAT5A and subsequent stimulation of the beta-casein promoter requires nuclear translocation of 4ICD. Moreover, 4ICD and STAT5A colocalize within nuclei of heregulin beta 1 (HRG)-stimulated cells and both proteins bind to the endogenous beta-casein promoter in T47D breast cancer cells. Together, our results establish a novel molecular mechanism of transmembrane receptor signal transduction involving nuclear cotranslocation of the receptor intracellular domain and associated transcription factor. Subsequent binding of the two proteins at transcription factor target promoters results in activation of gene expression.

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A model for ERBB4 regulation of STAT5A-stimulated gene expression. Growth factor–stimulated ERBB4 undergoes sequential proteolytic processing at the cell membrane by TACE and presenilin-dependent γ-secretase to release 4ICD. 4ICD accumulates in the perinuclear region where a perinuclear/nuclear equilibrium is established favoring perinuclear over nuclear 4ICD. Cytosolic STAT5A associates with activated ERBB4/4ICD in an SH2 domain–dependent manner and STAT5A is phosphorylated at multiple residues including the regulatory Y694 (Jones et al., 1999, 2003). Nuclear cotranslocation of 4ICD and STAT5A requires an intact ERBB4 NLS. The two nuclear proteins bind to STAT5A target promoters containing GAS thereby stimulating expression of STAT5A regulated milk-genes including β-casein and whey acidic protein (Long et al., 2003). STAT5A mediates nuclear retention of 4ICD resulting in a dramatic shift from perinuclear and nuclear accumulation of 4ICD. Interestingly, 4ICD harbors transactivation activity (TA) which may directly augment STAT5A target gene expression.
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fig7: A model for ERBB4 regulation of STAT5A-stimulated gene expression. Growth factor–stimulated ERBB4 undergoes sequential proteolytic processing at the cell membrane by TACE and presenilin-dependent γ-secretase to release 4ICD. 4ICD accumulates in the perinuclear region where a perinuclear/nuclear equilibrium is established favoring perinuclear over nuclear 4ICD. Cytosolic STAT5A associates with activated ERBB4/4ICD in an SH2 domain–dependent manner and STAT5A is phosphorylated at multiple residues including the regulatory Y694 (Jones et al., 1999, 2003). Nuclear cotranslocation of 4ICD and STAT5A requires an intact ERBB4 NLS. The two nuclear proteins bind to STAT5A target promoters containing GAS thereby stimulating expression of STAT5A regulated milk-genes including β-casein and whey acidic protein (Long et al., 2003). STAT5A mediates nuclear retention of 4ICD resulting in a dramatic shift from perinuclear and nuclear accumulation of 4ICD. Interestingly, 4ICD harbors transactivation activity (TA) which may directly augment STAT5A target gene expression.

Mentions: We have identified a novel signal transduction pathway in which the ERBB4 transmembrane receptor regulates gene expression by functioning as a nuclear chaperone for the STAT5A transcription factor. After nuclear cotranslocation of the 4ICD and STAT5A both proteins associated in a complex at the β-casein promoter. Based on our observations, we propose a unique mechanism for ERBB4 regulation of STAT5A-stimulated gene activation (Fig. 7). Recent evidence indicates that HRG stimulation and subsequent proteolytic processing of ERBB4 at the cell surface results in release of 4ICD from the cell membrane (Rio et al., 2000; Ni et al., 2001; Lee et al., 2002). Here, we propose that 4ICD first accumulates in the perinuclear region. Then in a process requiring an intact NLS (residues 676–684) a 4ICD perinuclear/nuclear equilibrium is established. An efficient nuclear export mechanism, which is inhibited by LMB, maintains the equilibrium toward perinuclear 4ICD. When coexpressed, activated ERBB4 associates with the STAT5A transcription factor in a STAT5A SH2-dependent manner (Jones et al., 1999). STAT5A remains associated with 4ICD and the two proteins colocalize in the perinuclear region. Nuclear translocation and subsequent nuclear colocalization of both proteins requires an intact ERBB4 NLS. Interestingly, we also observe pronounced nuclear retention of 4ICD when coexpressed with STAT5A, indicating that STAT5A impairs 4ICD nuclear export, thereby dramatically shifting the 4ICD perinuclear/nuclear equilibrium in favor of nuclear accumulation. Finally, activation of the ERBB4/STAT5A signal transduction pathway and subsequent nuclear cotranslocation of 4ICD and STAT5A results in binding of the two proteins at STAT5A target gene promoters culminating in a robust stimulation of STAT5A target genes possibly potentiated by transactivation activity harbored within 4ICD. Together, our results suggest a novel molecular mechanism to explain our in vivo observations demonstrating ERBB4/STAT5A cooperative activation of essential milk-genes during lactation (Jones et al., 2003; Long et al., 2003).


The ERBB4/HER4 receptor tyrosine kinase regulates gene expression by functioning as a STAT5A nuclear chaperone.

Williams CC, Allison JG, Vidal GA, Burow ME, Beckman BS, Marrero L, Jones FE - J. Cell Biol. (2004)

A model for ERBB4 regulation of STAT5A-stimulated gene expression. Growth factor–stimulated ERBB4 undergoes sequential proteolytic processing at the cell membrane by TACE and presenilin-dependent γ-secretase to release 4ICD. 4ICD accumulates in the perinuclear region where a perinuclear/nuclear equilibrium is established favoring perinuclear over nuclear 4ICD. Cytosolic STAT5A associates with activated ERBB4/4ICD in an SH2 domain–dependent manner and STAT5A is phosphorylated at multiple residues including the regulatory Y694 (Jones et al., 1999, 2003). Nuclear cotranslocation of 4ICD and STAT5A requires an intact ERBB4 NLS. The two nuclear proteins bind to STAT5A target promoters containing GAS thereby stimulating expression of STAT5A regulated milk-genes including β-casein and whey acidic protein (Long et al., 2003). STAT5A mediates nuclear retention of 4ICD resulting in a dramatic shift from perinuclear and nuclear accumulation of 4ICD. Interestingly, 4ICD harbors transactivation activity (TA) which may directly augment STAT5A target gene expression.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2172499&req=5

fig7: A model for ERBB4 regulation of STAT5A-stimulated gene expression. Growth factor–stimulated ERBB4 undergoes sequential proteolytic processing at the cell membrane by TACE and presenilin-dependent γ-secretase to release 4ICD. 4ICD accumulates in the perinuclear region where a perinuclear/nuclear equilibrium is established favoring perinuclear over nuclear 4ICD. Cytosolic STAT5A associates with activated ERBB4/4ICD in an SH2 domain–dependent manner and STAT5A is phosphorylated at multiple residues including the regulatory Y694 (Jones et al., 1999, 2003). Nuclear cotranslocation of 4ICD and STAT5A requires an intact ERBB4 NLS. The two nuclear proteins bind to STAT5A target promoters containing GAS thereby stimulating expression of STAT5A regulated milk-genes including β-casein and whey acidic protein (Long et al., 2003). STAT5A mediates nuclear retention of 4ICD resulting in a dramatic shift from perinuclear and nuclear accumulation of 4ICD. Interestingly, 4ICD harbors transactivation activity (TA) which may directly augment STAT5A target gene expression.
Mentions: We have identified a novel signal transduction pathway in which the ERBB4 transmembrane receptor regulates gene expression by functioning as a nuclear chaperone for the STAT5A transcription factor. After nuclear cotranslocation of the 4ICD and STAT5A both proteins associated in a complex at the β-casein promoter. Based on our observations, we propose a unique mechanism for ERBB4 regulation of STAT5A-stimulated gene activation (Fig. 7). Recent evidence indicates that HRG stimulation and subsequent proteolytic processing of ERBB4 at the cell surface results in release of 4ICD from the cell membrane (Rio et al., 2000; Ni et al., 2001; Lee et al., 2002). Here, we propose that 4ICD first accumulates in the perinuclear region. Then in a process requiring an intact NLS (residues 676–684) a 4ICD perinuclear/nuclear equilibrium is established. An efficient nuclear export mechanism, which is inhibited by LMB, maintains the equilibrium toward perinuclear 4ICD. When coexpressed, activated ERBB4 associates with the STAT5A transcription factor in a STAT5A SH2-dependent manner (Jones et al., 1999). STAT5A remains associated with 4ICD and the two proteins colocalize in the perinuclear region. Nuclear translocation and subsequent nuclear colocalization of both proteins requires an intact ERBB4 NLS. Interestingly, we also observe pronounced nuclear retention of 4ICD when coexpressed with STAT5A, indicating that STAT5A impairs 4ICD nuclear export, thereby dramatically shifting the 4ICD perinuclear/nuclear equilibrium in favor of nuclear accumulation. Finally, activation of the ERBB4/STAT5A signal transduction pathway and subsequent nuclear cotranslocation of 4ICD and STAT5A results in binding of the two proteins at STAT5A target gene promoters culminating in a robust stimulation of STAT5A target genes possibly potentiated by transactivation activity harbored within 4ICD. Together, our results suggest a novel molecular mechanism to explain our in vivo observations demonstrating ERBB4/STAT5A cooperative activation of essential milk-genes during lactation (Jones et al., 2003; Long et al., 2003).

Bottom Line: We have identified an intrinsic ERBB4 NLS (residues 676-684) within the ERBB4 intracellular domain (4ICD) that is essential for nuclear accumulation of 4ICD.Together, our results establish a novel molecular mechanism of transmembrane receptor signal transduction involving nuclear cotranslocation of the receptor intracellular domain and associated transcription factor.Subsequent binding of the two proteins at transcription factor target promoters results in activation of gene expression.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry, Tulane University Health Sciences Center, Tulane Cancer Center, New Orleans, LA 70112, USA.

ABSTRACT
In the lactating breast, ERBB4 localizes to the nuclei of secretory epithelium while regulating activities of the signal transducer and activator of transcription (STAT) 5A transcription factor essential for milk-gene expression. We have identified an intrinsic ERBB4 NLS (residues 676-684) within the ERBB4 intracellular domain (4ICD) that is essential for nuclear accumulation of 4ICD. To determine the functional significance of 4ICD nuclear translocation in a physiologically relevant system, we have demonstrated that cotransfection of ERBB4 and STAT5A in a human breast cancer cell line stimulates beta-casein promoter activity. Significantly, nuclear localization of STAT5A and subsequent stimulation of the beta-casein promoter requires nuclear translocation of 4ICD. Moreover, 4ICD and STAT5A colocalize within nuclei of heregulin beta 1 (HRG)-stimulated cells and both proteins bind to the endogenous beta-casein promoter in T47D breast cancer cells. Together, our results establish a novel molecular mechanism of transmembrane receptor signal transduction involving nuclear cotranslocation of the receptor intracellular domain and associated transcription factor. Subsequent binding of the two proteins at transcription factor target promoters results in activation of gene expression.

Show MeSH
Related in: MedlinePlus