PLEC Gene

The PLEC gene (PLEC is the acronym for plectin) is a protein-coding gene located on 8q24.3. Until 2010, this gene locus was named Plectin 1 (symbol PLEC1 in humans), and the gene product was referred to as "hemidesmosomal protein 1" or "Plectin 1, intermediate filament binding 500kDa". These designations have been replaced by plectin. The encoded protein, plectin, is a member of an important family of structurally and, to some extent, functionally related proteins called plakins, which are capable of linking various elements of the cytoskeleton. With their multi-domain structure and substantial size, plakins not only play a critical role in maintaining cell and tissue integrity and orchestrating dynamic changes in cytoarchitecture and cell shape, but also serve as scaffolding platforms for the assembly, positioning, and regulation of signaling complexes.

Plectin connects intermediate filaments to microtubules and microfilaments and anchors intermediate filaments to desmosomes or hemidesmosomes. PLectin is able to bind muscle proteins such as actin to membrane complexes in muscle. In doing so, the protein also appears to be involved in regulating their dynamics. Isoform 9 plays an important role in maintaining myofiber integrity.

Analysis of the human locus identified eight of the eleven alternative 5' exons also found in mouse and rat. Since the expression of specific plectin isoforms was found to depend on cell type (tissue) and developmental stage, it could be concluded that apparently each cell type (tissue) contains a unique set (proportion and composition) of plectin isoforms. It seems that a specific plectin isoform is tailor-made for the specific requirements of each cell.

At the same time, the individual isoforms were found to exert different and specific functions.

Plectin mutations: In 1996, several groups reported that patients suffering from epidermolysis bullosa simplex with muscular dystrophy (EBS-MD) lack plectin expression in skin and muscle tissues due to defects in the plectin gene. Mutations in PLEC have been identified in the following econditions:

• Epidermolysis bullosa simplex autosomal recessive with pyloric atresia (OMIM: 612138).
• Epidermolysisbullosa simplex with muscular dystrophy (OMIM: 226670)
• Epidermolysisbullosa simplex type Ogna (ORPHA: 79401; OMIM: 131950)
• Epidermolysis bullosa simplex, autosomal recessive with mutation in KRT14 (OMIM: 601001)

• Epidermolysis bullosa simplex, autosomal recessive with mutation in PLEC isoform 1a

• Epidermolysis bullosa simplex with congenital muscular dystrophy and myasthenia (Maselli RA et al. 2011)
• Congenital myasthenia syndrome

1. Chiavérini Cet al.(2010) Epidermolysis bullosa simplex with muscular dystrophy. Dermatol Clin 28:245-255.
2. Forrest K et al. (2010) Congenital muscular dystrophy, myasthenic symptoms and epidermolysis bullosa simplex (EBS) associated with mutations in the PLEC1 gene encoding plectin. Neuromuscul Disord 20:709-711.
3. Gonzalez Garcia A et al (2019) Novel PLEC gene variants causing congenital myasthenic syndrome. Muscle Nerve 60:E40-E43.
4. Has C et al.(2020) Consensus reclassification of inherited epidermolysis bullosa and other disorders with skin fragility. Brit. J. Derm. 183: 614-627.
5. Maselli RA et al. (2011) Congenital myasthenic syndrome associated with epidermolysis bullosa caused by homozygous mutations in PLEC1 and CHRNE. Clin Genet 80:444-451.
6. Selma Osmanagic-Myers S et al (2006) Plectin-controlled keratin cytoarchitecture affects MAP kinases involved in cellular stress response and migration. J Cell Biol 174: 557-568.
7. Villa CR et al (2015) Left ventricular non-compaction cardiomyopathy associated with epidermolysis bullosa simplex with muscular dystrophy and PLEC1 mutation. Neuromuscul Disord 25:165-168.