Cholesterol Sulfate Activates Transcription of Transglutaminase 1 Gene in Normal Human Keratinocytes

Abstract

Cholesterol sulfate and transglutaminase 1 are essential for the process of keratinization. Cholesterol sulfate is formed during keratinization and activates the eta isoform of protein kinase C. Transglutaminase 1 is a key enzyme for formation of the cornified envelope in terminally differentiated keratinocytes. In this study, we demonstrated that cholesterol sulfate acts as a transcriptional activator of the transglutaminase 1 gene in normal human keratinocytes. Growth of normal human keratinocytes was inhibited by cholesterol sulfate, but not by its parental cholesterol. Treatment of normal human keratinocytes with cholesterol sulfate induced activity of transglutaminase 1 in a dose- and time-dependent manner. Activation of transcription of transglutaminase 1 by cholesterol sulfate was demonstrated by northern blotting analysis, whereas that by cholesterol was not. In order to identify a cholesterol sulfate responsive region in the transglutaminase 1 gene, plasmids were constructed containing a luciferase reporter gene ligated to deletion fragments of the 5' upstream region of the tranglutaminase 1 gene and were transfected into normal human keratinocytes. Transfected cells were treated with cholesterol sulfate, the phorbol ester 12-O-tetradecanoylphorbol-13-acetate and a high concentration of Ca2+. Our results indicate that the responsive element(s) for cholesterol sulfate and phorbol ester is located upstream of the human transglutaminase 1 gene at a position(s) between -819 and -549, whereas the responsive element for Ca2+ is located at a position between -79 and -49.

LXR and PPAR activators stimulate cholesterol sulfotransferase type 2 isoform 1b in human keratinocytes

“…In patients with X-linked ichthyosis, mutations in the steroid sulfatase gene, the enzyme responsible for the catabolism of CS in the SC, lead to an increase in CS levels (‫-01ف‬fold increase) in the SC, in parallel with a reduction in rates of corneocyte desquamation (1,(41)(42)(43). The apparent mechanism that accounts for the CS-induced inhibition of corneocyte desquamation is likely an inhibition of serine protease activity in the SC (44,45), a general characteristic of CS. In addition to its key role in regulating corneocyte desquamation, CS also has been shown to stimulate keratinocyte differentiation (4), to play a role in antimicrobial defense (46), and to regulate cholesterol synthesis in keratinocytes (6,46).…”

Thematic review series: Skin Lipids. The role of epidermal lipids in cutaneous permeability barrier homeostasis

“…Steroid sulfatase deficiency results in recessive X-linked ichthyosis, which will be discussed in detail in the review by Peter Elias and colleagues (12,13,32). Additionally, cholesterol sulfate stimulates keratinocyte differentiation, adversely affects permeability barrier function, and inhibits cholesterol synthesis and HMG-CoA reductase activity in keratinocytes (44)(45)(46)(47)(48).…”

Cholesterol 3-Sulfate Interferes with Cornified Envelope Assembly by Diverting Transglutaminase 1 Activity from the Formation of Cross-links and Esters to the Hydrolysis of Glutamine

“…The strong charge of its sulfate moiety conferring mild detergent properties to CSO 4 was shown to interfere with spontaneous sheet-formation of epidermal lipids in vivo and thus theorized to affect epidermal barrier function by deranging skin lipid layers, repressing cholesterol synthesis, and replacing cholesterol in the lipid sheets (16). More recently, it was demonstrated that CSO 4 can induce TGase 1 expression in cultured keratinocytes (19), but the connection between excess TGase expression and disease etiology remains unclear. Our present data offer an alternative biochemical explanation as to how accumulation of CSO 4 may cause XI disease.…”

“…In another study, it was proposed that since CSO 4 has trypsin and chymotrypsin inhibitory properties in vitro, it might thereby affect breakdown of desmosomes, thus causing retention hyperkeratosis and abnormal scaling (18). Finally, more recently, it was demonstrated that CSO 4 can induce TGase 1 expression in cultured keratinocytes (19), but the connection between excess TGase expression and disease etiology remains unclear. CSO 4 in keratinocyte membranes was shown to activate the protein kinase C isoforms ⑀, , and , presumably by direct allosteric effects on their tertiary structures.…”

“…CSO 4 in keratinocyte membranes was shown to activate the protein kinase C isoforms ⑀, , and , presumably by direct allosteric effects on their tertiary structures. As these membrane-bound enzymes are involved in the signaling pathways of keratinocyte differentiation (20,21), CSO 4 could induce TGase 1 expression in this way (19).…”