Primary microcephaly 3 (MCPH3): Revisiting two critical mutations

Park, John S.Y.; Lee, Marie-Katrina; Rosales, Jesusa L.; Lee, Ki-Young

doi:10.4161/cc.10.8.15358

Cited by 4 publications

(5 citation statements)

References 9 publications

(13 reference statements)

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“…Premature BJ cell senescence due to CDK5RAP2 loss was verified by an increase in number of SAHF positive cells, upregulation of the senescence-associated genes, p21 CIP1 and p16 INK4a [ 41 ], and increased SA-β-gal staining. These senescent phenotypes observed in CDK5RAP2-depleted BJ cells are recapitulated in ex vivo MEFs isolated from Cdk5rap2 an/an embryos, and consistent with a previous report that MEFs isolated from mice carrying a frameshift loss-of-function mutation (R1334SfsX5) [ 6 , 42 ] in Cdk5rap2 show growth arrest between passages 8 and 10 and stop growing to confluence after then [ 43 ]. However, the latter finding was not further investigated.…”

Section: Discussionsupporting

confidence: 90%

CDK5RAP2 loss-of-function causes premature cell senescence via the GSK3β/β-catenin-WIP1 pathway

Wang

Sipila

et al. 2021

Cell Death Dis

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Developmental disorders characterized by small body size have been linked to CDK5RAP2 loss-of-function mutations, but the mechanisms underlying which remain obscure. Here, we demonstrate that knocking down CDK5RAP2 in human fibroblasts triggers premature cell senescence that is recapitulated in Cdk5rap2an/an mouse embryonic fibroblasts and embryos, which exhibit reduced body weight and size, and increased senescence-associated (SA)-β-gal staining compared to Cdk5rap2+/+ and Cdk5rap2+/an embryos. Interestingly, CDK5RAP2-knockdown human fibroblasts show increased p53 Ser15 phosphorylation that does not correlate with activation of p53 kinases, but rather correlates with decreased level of the p53 phosphatase, WIP1. Ectopic WIP1 expression reverses the senescent phenotype in CDK5RAP2-knockdown cells, indicating that senescence in these cells is linked to WIP1 downregulation. CDK5RAP2 interacts with GSK3β, causing increased inhibitory GSK3β Ser9 phosphorylation and inhibiting the activity of GSK3β, which phosphorylates β-catenin, tagging β-catenin for degradation. Thus, loss of CDK5RAP2 decreases GSK3β Ser9 phosphorylation and increases GSK3β activity, reducing nuclear β-catenin, which affects the expression of NF-κB target genes such as WIP1. Consequently, loss of CDK5RAP2 or β-catenin causes WIP1 downregulation. Inhibition of GSK3β activity restores β-catenin and WIP1 levels in CDK5RAP2-knockdown cells, reducing p53 Ser15 phosphorylation and preventing senescence in these cells. Conversely, inhibition of WIP1 activity increases p53 Ser15 phosphorylation and senescence in CDK5RAP2-depleted cells lacking GSK3β activity. These findings indicate that loss of CDK5RAP2 promotes premature cell senescence through GSK3β/β-catenin downregulation of WIP1. Premature cell senescence may contribute to reduced body size associated with CDK5RAP2 loss-of-function.

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Section: Discussionsupporting

confidence: 90%

CDK5RAP2 loss-of-function causes premature cell senescence via the GSK3β/β-catenin-WIP1 pathway

Wang

Sipila

et al. 2021

Cell Death Dis

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“…It was used for generation of truncated versions and point mutations which were introduced by site-directed mutagenesis. The following mutant versions encoding shortened polypeptides were generated: CDK5RAP2-C corresponding to nonsense mutation c.246T > A, p.Y82* (residues 1–82) (Park et al 2011), CDK5RAP2-C1 (residues 1–580) encompasses the γTuRC and SMC domains, CDK5RAP2-C2 (residues 1–1271) and CDK5RAP2-C3 (residues 1–1372) encompass the γTuRC, SMC and EB1 domain. GFP-MST1 and Flag-TAZ are described in Habbig et al (2011); Flag-hnRNPF was obtained from Dr. Ping Li.…”

Section: Methodsmentioning

confidence: 99%

CDK5RAP2 interaction with components of the Hippo signaling pathway may play a role in primary microcephaly

et al. 2016

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Autosomal recessive primary microcephaly (MCPH) is characterized by a substantial reduction in brain size but with normal architecture. It is often linked to mutations in genes coding for centrosomal proteins; however, their role in brain size regulation is not completely understood. By combining homozygosity mapping and whole-exome sequencing in an MCPH family from Pakistan, we identified a novel mutation (XM_011518861.1; c.4114C > T) in CDK5RAP2, the gene associated with primary microcephaly-3 (MCPH3), leading to a premature stop codon (p.Arg1372*). CDK5RAP2 is a component of the pericentriolar material important for the microtubule-organizing function of the centrosome. Patient-derived primary fibroblasts had strongly decreased CDK5RAP2 amounts, showed centrosomal and nuclear abnormalities and exhibited changes in cell size and migration. We further identified an interaction of CDK5RAP2 with the Hippo pathway components MST1 kinase and the transcriptional regulator TAZ. This finding potentially provides a mechanism through which the Hippo pathway with its roles in the regulation of centrosome number is linked to the centrosome. In the patient fibroblasts, we observed higher levels of TAZ and YAP. However, common target genes of the Hippo pathway were downregulated as compared to the control with the exception of BIRC5 (Survivin), which was significantly upregulated. We propose that the centrosomal deficiencies and the altered cellular properties in the patient fibroblasts can also result from the observed changes in the Hippo pathway components which could thus be relevant for MCPH and play a role in brain size regulation and development.Electronic supplementary materialThe online version of this article (doi:10.1007/s00438-016-1277-x) contains supplementary material, which is available to authorized users.

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“…One of the twelve MCPH genes [ 5 – 7 ] is MCPH3 which encodes cyclin-dependent kinase 5 (CDK5) [ 8 , 9 ] regulatory subunit-associated protein 2 (CDK5RAP2) [ 10 ] that was first described [ 11 ]. The human CDK5RAP2 gene ( hCDK5RAP2 ) consists of 38 exons, encoding a 1893 amino acid residue protein that is composed of a CM1 domain (residues 58–90)[ 12 ] that binds γ-tubulin complexes, two structural maintenance of chromosome (SMC) domains (one each in the N- and C- terminals, corresponding to residues 137–470 and 1399–1646, respectively)[ 1 ], EB1 binding region (residues 926–1208)[ 13 ], a p35 interacting domain (residues 1682–1827)[ 11 , 14 , 15 ], and a pericentrin binding CM2 domain (residues 1726–1893)[ 16 ].…”

Section: Introductionmentioning

confidence: 99%

“…For example, two in Pakistani families (n = 10), one in a Somali patient (n = 1), and one in two (n = 2) patients of European descent. In the northern Pakistani microcephaly pedigrees [ 15 , 17 ], the first pedigree mutation (246T→A, Y82X; n = 8) generates a truncated 81 amino acid peptide that lacks a portion of the SM1 binding motif, the two SMC motifs, the EB1 binding region, and the p35- and pericentrin-binding regions. The second pedigree mutation (IVS26-15A→G, R1334SfsX5, n = 2) in northern Pakistani microcephaly pedigrees [ 15 , 17 ], on the other hand, results in a truncated 1338 amino acid protein that lacks the EB1 binding region, the C-terminal SMC and the p35- and pericentrin-binding motifs.…”

Section: Introductionmentioning

confidence: 99%

“…In the northern Pakistani microcephaly pedigrees [ 15 , 17 ], the first pedigree mutation (246T→A, Y82X; n = 8) generates a truncated 81 amino acid peptide that lacks a portion of the SM1 binding motif, the two SMC motifs, the EB1 binding region, and the p35- and pericentrin-binding regions. The second pedigree mutation (IVS26-15A→G, R1334SfsX5, n = 2) in northern Pakistani microcephaly pedigrees [ 15 , 17 ], on the other hand, results in a truncated 1338 amino acid protein that lacks the EB1 binding region, the C-terminal SMC and the p35- and pericentrin-binding motifs. A third pedigree mutation (4441C→T) from two (n = 2) patients of European descent [ 17 ] results in a truncated 1481 amino acid protein that lacks part of C-terminal SMC and the p35- and pericentrin-binding regions motifs.…”

Section: Introductionmentioning

confidence: 99%

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Species-Specific Expression of Full-Length and Alternatively Spliced Variant Forms of CDK5RAP2

et al. 2015

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CDK5RAP2 is one of the primary microcephaly genes that are associated with reduced brain size and mental retardation. We have previously shown that human CDK5RAP2 exists as a full-length form (hCDK5RAP2) or an alternatively spliced variant form (hCDK5RAP2-V1) that is lacking exon 32. The equivalent of hCDK5RAP2-V1 has been reported in rat and mouse but the presence of full-length equivalent hCDK5RAP2 in rat and mouse has not been examined. Here, we demonstrate that rat expresses both a full length and an alternatively spliced variant form of CDK5RAP2 that are equivalent to our previously reported hCDK5RAP2 and hCDK5RAP2-V1, repectively. However, mouse expresses only one form of CDK5RAP2 that is equivalent to the human and rat alternatively spliced variant forms. Knowledge of this expression of different forms of CDK5RAP2 in human, rat and mouse is essential in selecting the appropriate model for studies of CDK5RAP2 and primary microcephaly but our findings further indicate the evolutionary divergence of mouse from the human and rat species.

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Primary microcephaly 3 (MCPH3): Revisiting two critical mutations

Cited by 4 publications

References 9 publications

CDK5RAP2 loss-of-function causes premature cell senescence via the GSK3β/β-catenin-WIP1 pathway

CDK5RAP2 loss-of-function causes premature cell senescence via the GSK3β/β-catenin-WIP1 pathway

CDK5RAP2 interaction with components of the Hippo signaling pathway may play a role in primary microcephaly

Species-Specific Expression of Full-Length and Alternatively Spliced Variant Forms of CDK5RAP2

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