Identification and analysis of the human hyaluronan synthase 1 gene promoter reveals Smad3-and Sp3-mediated transcriptional induction

The ubiquitous mammalian extracellular matrix glycosaminoglycan hyaluronan (HA) plays a pivotal role in the regulation of cell phenotype in fibrosis and scarring. Transforming growth factor-beta 1 (TGF-beta 1) and interleukin-1 beta (IL-1 beta) up-regulate hyaluronan synthase (HAS) 1 and HAS2 in dermal fibroblasts and renal proximal tubular epithelial cells, and subsequent HA synthesis regulates cell phenotype. In the present study, we investigated the mechanism of HAS1 transcriptional up-regulation in response to these cytokines. We used 5'-rapid amplification of cDNA ends analysis to identify the 5' end of HAS1 transcripts, resulting in an increase of 26 nucleotides to the HAS1 exon 1 sequence of reference sequence NM_001523. Constitutive luciferase activity of upstream DNA sequences was shown in luciferase reporter assays, but our reporter vector signals were refractory to the addition of TGF-beta 1 and IL-1 beta. Using siRNAs to knockdown transcription factor mRNAs, we showed that TGF-beta 1 up-regulation of HAS1 transcription was mediated via Smad3 but not Smad2, while HAS1 induction by IL-1 beta was Sp3, not Sp1, dependent. (c) 2012 Elsevier B.V. All rights reserved.