9.B.329. The Resistin-like Molecule (RELM) Family Vitamin A deficiency increases susceptibility to skin infection. Harris et al. 2019 showed that resistin-like molecule α (RELMα), a small secreted cysteine-rich protein, is expressed by epidermal keratinocytes and sebocytes and serves as an antimicrobial protein that is required for vitamin-A-dependent resistance to skin infection. RELMα is induced by microbiota colonization of the murine skin, is bactericidal in vitro, and protects against bacterial infection of the skin in vivo. RELMα expression requires dietary vitamin A and is induced by the therapeutic vitamin A analog isotretinoin, which protects against skin infection in a RELMα-dependent manner. The RELM family member Resistin was expressed in human skin, was induced by vitamin A analogs, and killed skin bacteria, indicating a conserved function for RELM proteins in skin innate immunity. These findings provide insight into how vitamin A promotes resistance to skin infection (Harris et al. 2019). This family may be distantly related to the Dermaseptin Family (1.C.52), and therefore part of the Cecropin Superfamily.
References:
Chumakov, A.M., T. Kubota, S. Walter, and H.P. Koeffler. (2004). Identification of murine and human XCP1 genes as C/EBP-ε-dependent members of FIZZ/Resistin gene family. Oncogene 23: 3414-3425.
Harris, T.A., S. Gattu, D.C. Propheter, Z. Kuang, S. Bel, K.A. Ruhn, A.L. Chara, M. Edwards, C. Zhang, J.H. Jo, P. Raj, C.C. Zouboulis, H.H. Kong, J.A. Segre, and L.V. Hooper. (2019). Resistin-like Molecule α Provides Vitamin-A-Dependent Antimicrobial Protection in the Skin. Cell Host Microbe 25: 777-788.e8.
Luo, J., H.P. Li, F. Xu, B.Q. Wu, and H.C. Lin. (2019). Early diagnosis of necrotizing enterocolitis by plasma RELMβ and thrombocytopenia in preterm infants: A pilot study. Pediatr Neonatol. [Epub: Ahead of Print]
Examples:
TC#	Name	Organismal Type	Example
9.B.329.1.1	Resistin-like α (RELMα, Retnia, Fizz1, Himf, Pmng1) of 111 aas and 1 N-terminal TMS. This antibacterial resistin-like molecule α (RELMα), a small secreted cysteine-rich protein, is expressed by epidermal keratinocytes and sebocytes and serves as an antimicrobial protein that is required for vitamin-A-dependent resistance to skin infections (Harris et al. 2019).		Resistin-like α of Mus musculus (Mouse)

9.B.329.1.2	ββ Resistin-like β (RETNLB CCRG, FIZZ2, HXCP2, RETNL2, UNQ408/PRO770 ) if 111 aas and 1 N-terminal TMS. Colon and small intestine-specific secreted cysteine-rich protein. RELMβ levels in necrotizing enterocolitis are higher than controls (Luo et al. 2019).		RELMβ of Homo sapiens

9.B.329.1.3	*Resistin-like gamma (Resistin-like γ, RELMγ, Retnig, Xcp1, of 117 aas and 1 N-terminal TMS. It promotes chemotaxis in myeloid cells (Chumakov et al.* 2004).**		RELMγ of Mus musculus

9.B.329.1.4	Uncharacterized secreted protein of 121 aas and 1 N-terminal TMS.		UP of Nematostella vectensis

9.B.329.1.5	Resistin of 98 aas and 1 TMS.		Resistin of Equus asinus

9.B.329.1.6	Resistin of 180 aas and 1 TMS.		Resistin of Ursus maritimus