Centrosome and ciliary abnormalities in fetal akinesia deformation sequence human fibroblasts

Abstract

Ciliopathies are clinical disorders of the primary cilium with widely recognised phenotypic and genetic heterogeneity. Here, we found impaired ciliogenesis in fibroblasts derived from individuals with fetal akinesia deformation sequence (FADS), a broad spectrum of neuromuscular disorders arising from compromised foetal movement. We show that cells derived from FADS individuals have shorter and less primary cilia (PC), in association with alterations in post-translational modifications in α-tubulin. Similarly, siRNA-mediated depletion of two known FADS proteins, the scaffold protein rapsyn and the nucleoporin NUP88, resulted in defective PC formation. Consistent with a role in ciliogenesis, rapsyn and NUP88 localised to centrosomes and PC. Furthermore, proximity-ligation assays confirm the respective vicinity of rapsyn and NUP88 to γ-tubulin. Proximity-ligation assays moreover show that rapsyn and NUP88 are adjacent to each other and that the rapsyn-NUP88 interface is perturbed in the examined FADS cells. We suggest that the perturbed rapsyn-NUP88 interface leads to defects in PC formation and that defective ciliogenesis contributes to the pleiotropic defects seen in FADS.

From the sideline: Tissue‐specific nucleoporin function in health and disease, an update

“…Ciliopathies comprise a set of more than 30 clinically distinct syndromes with overlapping phenotypes, including organ failures, such as of the heart, gonads, brain, eye, kidney, or the skeleton [157], similar to nucleoporin‐related disorders (Table 3). A link between nucleoporins and the nuclear transport machinery as well as cilia pore formation and cilia transport has been known for some time [69,147,158–163], although mechanistic details still remain mysterious. At least for NUP93 some insight emerges: the founder mutations in NUP93 p.G591V and p.Y629C (Fig.…”

“…On the nuclear side of the NPC, NUP88 interacts with the nuclear intermediate filament protein lamin A [43], and this interaction is also largely unaffected by FADS mutations [141]. Consistent with the pleiotropic developmental defects that coincide with FADS, loss of NUP88 function impairs the microtubule network and ciliogenesis in human fibroblasts [147]. Moreover, NUP88 interacts with the focal adhesion protein paxillin and together with other FADS proteins regulates actin‐myosin organisation [148].…”

TTC30A and TTC30B Redundancy Protects IFT Complex B Integrity and Its Pivotal Role in Ciliogenesis

“…However, in the study presented here, no effect on rootlet structures was seen ( Supplemental Figure S6 ), but transport speed or transition zone integrity were not analyzed. NUP88, which did not pass the significance test in TTC30A samples but was detected with both paralogues, and FBXO3 are two candidates which are described to be involved in cilia function and might help to understand the mild effect seen in single-KO cells as well [ 43 , 44 ].…”

Bi-allelic loss-of-function variants inKIF21Acause severe fetal akinesia with arthrogryposis multiplex

“…These include ion channels or pumps, receptors or modulators, inborn errors of metabolism, factors involved in transcription and translation, cell cycle, cell signalling/secretion as well as motor proteins or protein trafficking. 6 From an organelle perspective, a postulated mechanism underlying FA is impaired ciliogenesis, 33 which is interesting, as KIFs are known to fulfil an essential role in ciliogenesis and cilia function. 23 In addition, primary cilia-driven signalling regulates growth cone dynamics and axonal tract development, 34 and several genes linked to arthrogryposis, such as AUTS2, CBL, DNM2, IGHMBP2, KIF5C, SETX, SNAP25 and TOR1A function in growth cone regulation.…”