Ψ KLK8 - Physeter catodon

Reference Gene:
Job_ID:
Curator:
GlossID Species Gene Loss Mechanism Loss Type Lineage Specific Evidence Accession Nr.
GL_HCRWZZ Physeter catodon LOF (frameshift, premature stop, ss) Full Yes Multiple individual SRA XM_055079221.1

Statements

Type Excerpt DOI
Functional "First, in the skin of terrestrial mammals, KLK8 activates antimicrobial proteolytic cascades in sweat (Eissa et al. 2011). As neither cetaceans nor manatees have sweat glands (Berta et al. 2015; Mouton and Botha 2012; Rodrigues et al. 2014), in contrast to the semi-aquatic pinnipeds and terrestrial mammals that have an intact KLK8 gene, the antimicrobial of functions of KLK8 are likely no longer useful for aquatic mammals. Furthermore, the epidermis of KLK8 knockout mouse exhibits delayed recovery from the UVB-induced inflammation (Kirihara et al. 2003). UVB-induced inflammation might be less important for fully-aquatic mammals that live in an environment where UVB light penetration substantially decreases after a few meters of depths (Tedetti and Sempere 2006).Finally, KLK8 also plays a role in keratinocyte proliferation and desquamation (Kishibe et al. 2007). In dolphins, it is known that the desquamation rate of the outer most epidermal cell layers is 8.5 times faster than in humans, which is likely an adaptation that maintains a smooth surface and limits microbe colonization in the aquatic environment (Hicks et al. 1985), and may have further contributed to KLK8 loss in dolphin." 10.1093/gbe/evx239
Mutation Description "Although we could not identify inactivating mutations in the sperm whale, RNA-seq data from sperm whale skin (Warren et al. 2017) showed that KLK8 is not expressed anymore in this tissue (supplementary table 10, Supplementary Material online). Furthermore, we found the sperm whale KLK8 gene to be under relaxed selection (P-value<10^-4) using RELAX analysis (Wertheim et al. 2015)." 10.1093/gbe/evx239
Other "It should be noted that whereas kallikreins comprise a gene family, the protein and nucleotide sequence of the different members are sufficiently diverged from each other. In particular, KLK8 has at most 51% nucleotide identity to other KLK genes (Prassas et al. 2015)." 10.1093/gbe/evx239

Curator Observations

KLK8 is not completely lost in the sperm whale; rather, it evolves neutrally in this species. The study found that while KLK8 has an intact reading frame in the sperm whale, it is under relaxed selection, indicating that it may accumulate inactivating mutations over time. Thus, KLK8 is present but not functionally significant in the sperm whale.

Related Glosses

GL_ID Symbol Species Order Gene Loss Mechanism Loss Type Lineage Specific Citation
GL_0YBEXU KLK8 Physeter catodon Artiodactyla LOF (frameshift, premature stop, ss) Full No 10.1093/gbe/evx187