High impact information on USF2

• Transfections were done in the absence or presence of forskolin; the protein kinase A (PKA) inhibitor H-89; or an expression vector encoding USF1, USF2, the catalytic subunit of PKA (cPKA), or a PKA inhibitor protein (PKI) [1].
• Cotransfection studies with a USF2 mutant lacking N-terminal activation domains (U2Delta1-220) repressed forskolin-, cPKA-, and USF-dependent PGHS-2 promoter activities [1].
• Thus, high levels of amino-terminal truncated USF-2 and C/EBPbeta in bovine granulosa cells prior to hCG treatment could repress gene expression, and be involved in the delayed induction of PGHS-2 in species with a long ovulatory process [2].
• Interestingly, the presence of the amino-terminal truncated USF-2, which lacks the transcription activation domain, was detected in the 0-h extract, but not in extracts prepared post-hCG [2].
• The delayed activation of the prostaglandin G/H synthase-2 promoter in bovine granulosa cells is associated with down-regulation of truncated upstream stimulatory factor-2 [2].

Biological context of USF2

• Interestingly, transfections with U2Delta1-220 blocked the forskolin-dependent induction of PGHS-2 mRNA in granulosa cells, whereas transfections with full-length USF2 increased PGHS-2 transcript levels [3].
• By competition and supershift gel shift assays, we demonstrated that the basic helix-loop-helix transcription factors USF1 and USF2 specifically interacted with this R region E box motif [4].
• Thus, the ATPA gene is regulated by a multifunctional binding site through which the transcription factors, COUP-TFII/ARP-1 and USF2, bind and exert their antagonistic effects [5].

Physical interactions of USF2

• Upstream stimulatory factor (USF)-1 and USF-2 bound to the E-box of the Cox-2 gene, and binding was similar for nuclear extracts from fresh, cultured, or luteinized granulosa cells [6].

Regulatory relationships of USF2

• Overexpression of a USF2 truncated mutant lacking the first 220 residues (U2Delta1-220) acted as a dominant negative mutant and blocked endogenous and USF-stimulated PGHS-2 promoter activation [3].

Other interactions of USF2

• Results revealed that overexpression of USF1 or USF2 caused a marked and significant increase in basal and forskolin-inducible promoter activities (p<0.05), and these effects were dependent on the presence of a consensus E-box cis-element within the promoter fragment [3].

Analytical, diagnostic and therapeutic context of USF2

• Immunoprecipitation/Western blot analyses revealed an increase in the levels of phosphorylated USF1 and USF2 after forskolin treatment, whereas chromatin immunoprecipitation assays showed that binding of USF proteins to the endogenous PGHS-2 promoter was stimulated by forskolin [1].
• Antiserum directed against USF2 recognized factors present in HeLa nuclear extracts that interact with the ATPA promoter in mobility shift assays [7].

References