SPINK9 gene

SPINK is the acronym for "Serine Peptidase Inhibitor Kazal" and comprises a gene family placed on different chromosomes. The members of this gene family code for specific proteases, the SPINK protease inhibitor Kazal-type (SPINK) family. These are serine peptidase inhibitors. They contain at least one inhibitory Kazal domain. This domain binds to its target, the serine proteases, and inhibits their proteolytic functions. This regulatory inhibitory function and its fine-tuning is fundamental for many epithelia.

SPINK9 is a gene that, like SPINK 7, is located on chromosome 5q32. The protein encoded by this gene is a Kazal-type serine protease inhibitor that appears to act specifically on kallikrein-related peptidase 5 (KLK5) in the palmo-plantar epidermis. KLK5 is an important initiator of skin desquamation, so the encoded protease inhibitor may regulate skin differentiation in the palms and soles. This cationic protein has also been shown to promote keratinocyte migration through activation of the epidermal growth factor receptor (EGFR) (Brattsand M et al. 2009). Apparently, this serine protease exerts antimicrobial activities (Wu Z et al. 2019).

Diseases associated with SPINK9 include pompholyx and Netherton syndrome. An important paralog of this gene is SPINK7.

SPINK9 is also expressed in lichen simplex chronicus. It is also found in some actinic keratoses and squamous cell carcinomas (Redelfs L et al. 2016).

1. Redelfs L et al. (2016) The serine protease inhibitor of Kazal-type 9 (SPINK9) is expressed in lichen simplex chronicus, actinic keratosis and squamous cell carcinomas. Archives of Dermatological Research 308: 133-137
2. Brattsand M et al (2009) SPINK9: a selective, skin-specific Kazal-type serine protease inhibitor. J Invest Dermatol 129:1656-1665.
3. Wu Z et al (2019) Skin-derived SPINK9 kills Escherichia coli. J Invest Dermatol 139:1135-1142.