CSTA Gene

The CSTA gene (CSTA stands for cystatin A) is a protein-coding gene located on chromosome 3q21.1. The CSTA gene encodes Stefin , a protein that functions as a cysteine protease inhibitor and forms tight complexes with papain and cathepsins B, H, and L. The protein is one of the precursor proteins of keratin. The protein is one of the precursor proteins of the keratin cell envelope in keratinocytes and plays a role in epidermal development and maintenance.

The superfamily of cystatins comprises proteins that contain multiple cystatin-like sequences. Some of the members are active cysteine protease inhibitors, while others do not (no longer) possess this inhibitory activity. There are three inhibitor families in the superfamily:

• the type-1 cystatins (stefins)
• the type-2 cystatins and
• the kininogens.

Diseases associated with CSTA include:

• peeling skin syndrome 4 and
• peeling skin syndrome 2 (Sarika GM et al. 2021).

Wang Y et al (2021) demonstrated that in primary oral squamous cell carcinoma (OSCC) tissue, CSTA expression is significantly downregulated. Low CSTA expression significantly correlated with poorer overall survival. CSTA appears to be a promising biomarker and potentially a therapeutic target with prognostic implications in patients with OSCC.

1. Muttardi K et al (2016) Acral peeling skin syndrome associated with a novel CSTA gene mutation. Clin Exp Dermatol 41:394-398