Envelope proteins and their potential roles in EDMD physiopathology (Homo sapiens)

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Schematic model of the nuclear envelope proteins and their potential roles in Emery-Dreyfuss muscular dystrophy (EDMD) physiopathology.

Nuclear lamins form a meshwork. It interacts with proteins of the nuclear envelope, i.e., EMD, LBR, TMPO, SUN, and MAN1, and with several transcription factors. Through nesprin proteins, lamins interact with actin microfilaments, microtubules, and cytoplasmic intermediate filaments, connecting the nuclear lamina to the extracellular matrix.

MKL1 translocates into the nucleus and together with SRF induces gene expression. In addition, EMD facilitates polymerization of nuclear actin, reducing the nuclear export of MKL1 to the cytoplasm. In EDMD cells, emerin mislocalizes and is unable to modulate nuclear actin polymerization. G-actin binds to MKL1 and it is exported from the nucleus, impairing gene expression. YAP and TAZ are key transcription factors for cell proliferation. YAP/TAZ activation causes their nuclear accumulation, promoting cell proliferation, and inhibiting differentiation. Nuclear localization of YAP/TAZ is increased in patient myoblasts with LMNA mutations.