Laminin subunit beta-3 (LAMB3) (LAMB3)

Laminin-332 (formerly known as laminin-5) is a heterotrimeric extracellular matrix protein composed of alpha-3, beta-3, and gamma-2 subunits that plays a fundamental role in mediating cell adhesion and maintaining the structural integrity of the dermal-epidermal junction [1, 3]. The beta-3 chain (LAMB3) is a critical component of this complex, providing a specific binding interface for the non-collagenous 1 (NC1) domain of Collagen VII, particularly through its fibronectin type III-like repeats [3, 5]. This molecular interaction is the cornerstone of anchoring fibril assembly, which tethers the basement membrane of the epidermis to the underlying papillary dermis [2, 4]. Disruptions in this interaction, whether through genetic mutations in LAMB3 or COL7A1, lead to severe skin-fragility disorders such as Junctional and Dystrophic Epidermolysis Bullosa [4, 6]. In the context of therapeutic development, this interaction is a primary target for gene and protein replacement therapies aimed at restoring skin stability in patients with Epidermolysis Bullosa [7, 8]. For instance, gene therapy approaches have successfully utilized viral vectors to deliver functional LAMB3 or COL7A1 genes to patient-derived cells, effectively regenerating stable skin surfaces [7]. Additionally, small molecules like gentamicin are being explored to induce read-through of nonsense mutations in these genes to restore protein function [9]. Monitoring the restoration of this specific Laminin-332/Collagen VII linkage serves as a critical biomarker for therapeutic efficacy in clinical trials [8]. Sources: [1] UniProt P35908 (LAMB3_HUMAN). [2] UniProt Q02388 (CO7A1_HUMAN). [3] Chen M, et al. (1999). "The NC1 Domain of Type VII Collagen Binds to the Beta 3 Chain of Laminin 5." J Biol Chem. [4] Nakano A, et al. (2002). "Epidermolysis bullosa: mutations in the genes for type VII collagen and laminin 5." J Dermatol Sci. [5] Rousselle P, et al. (1997). "Laminin 5 binds the NC1 domain of type VII collagen." J Cell Biol. [6] Fine JD, et al. (2014). "Inherited epidermolysis bullosa: updated recommendations on diagnosis and classification." J Am Acad Dermatol. [7] Hassan HG, et al. (2017). "Regeneration of the entire human epidermis using transgenic stem cells." Nature. [8] Guide SV, et al. (2022). "A Phase 1/2 Trial of Beremagene Geperpavec Gene Therapy for Dystrophic Epidermolysis Bullosa." Nature Medicine. [9] Woodley DT, et al. (2017). "Gentamicin-induced readthrough of stop codons in animal models of dystrophic epidermolysis bullosa." Journal of Investigative Dermatology.

Other names

Laminin-5 beta chainNicein beta chainLAMNB3Laminin-332 beta-3 chainKalinin B1 chain

Restoration of the dermal-epidermal junction stability by providing functional Laminin-332 or Collagen VII to facilitate anchoring fibril formation.