[HTML][HTML] Loss of the Arp2/3 complex component ARPC1B causes platelet abnormalities and predisposes to inflammatory disease

WHA Kahr, FG Pluthero, A Elkadri, N Warner… - Nature …, 2017 - nature.com
WHA Kahr, FG Pluthero, A Elkadri, N Warner, M Drobac, CH Chen, RW Lo, L Li, R Li, Q Li…
Nature communications, 2017nature.com
Abstract Human actin-related protein 2/3 complex (Arp2/3), required for actin filament
branching, has two ARPC1 component isoforms, with ARPC1B prominently expressed in
blood cells. Here we show in a child with microthrombocytopenia, eosinophilia and
inflammatory disease, a homozygous frameshift mutation in ARPC1B (p. Val91Trpfs* 30).
Platelet lysates reveal no ARPC1B protein and greatly reduced Arp2/3 complex. Missense
ARPC1B mutations are identified in an unrelated patient with similar symptoms and …
Abstract
Human actin-related protein 2/3 complex (Arp2/3), required for actin filament branching, has two ARPC1 component isoforms, with ARPC1B prominently expressed in blood cells. Here we show in a child with microthrombocytopenia, eosinophilia and inflammatory disease, a homozygous frameshift mutation in ARPC1B (p.Val91Trpfs*30). Platelet lysates reveal no ARPC1B protein and greatly reduced Arp2/3 complex. Missense ARPC1B mutations are identified in an unrelated patient with similar symptoms and ARPC1B deficiency. ARPC1B-deficient platelets are microthrombocytes similar to those seen in Wiskott–Aldrich syndrome that show aberrant spreading consistent with loss of Arp2/3 function. Knockout of ARPC1B in megakaryocytic cells results in decreased proplatelet formation, and as observed in platelets from patients, increased ARPC1A expression. Thus loss of ARPC1B produces a unique set of platelet abnormalities, and is associated with haematopoietic/immune symptoms affecting cell lineages where this isoform predominates. In agreement with recent experimental studies, our findings suggest that ARPC1 isoforms are not functionally interchangeable.
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