Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

The protein kinase MLTK Is a key regulator for chondrogenesis.

ABSTRACT: Sox9 acts together with Sox5 or Sox6 as a master regulator for chondrocyte differentiation; however, how these transcription factors functionally interact and collaborate to regulate chondrogenesis remains unclear. Here we show that the protein kinase MLTK plays an essential role in the onset of chondrogenesis through triggering the induction of Sox6 by Sox9. Knockdown of MLTK in Xenopus embryos results in drastic loss of craniofacial cartilages without defects in neural crest formation. We also find that Sox6 is specifically induced during craniofacial chondrogenesis and this induction is inhibited by MLTK knockdown. Remarkably, Sox6-knockdown embryos display essentially the same phenotype as the MLTK-knockdown embryos; the drastic loss of cartilages and the marked down-regulation of genes involved in chondrogenesis. Microarray analysis reveals a remarkable similarity between Sox6-depleted and MLTK-depleted embryos in their gene expression pattern. Moreover, we find that ectopic expression of MLTK can induce Sox6 expression in a Sox9-dependent manner. These results identify a novel, key regulator for chondrogenesis. We used microarrays to describe the genome-wide gene expression profiles of xMLTK-depleted and xSox6-depleted embryos. CoMO, xMLTK-MO, or xSox6-MO was injected into the animal pole of all blastomeres (10 ng/cell) at the four-cell stage. The heads of embryos were cut out and harvested at 72 hours after fertilization (corresponding to about stage 41). Total RNA was extracted using TRIsol reagent, treated with DNase (TURBO DNase, Ambion), and then purified using RNeasy Mini Kit (QIAGEN) according to the manufacturerM-bM-^@M-^Ys instruction. The quality of total RNA was assessed using the Agilent 2100 BioAnalyzer. Reverse transcription to synthesize first-strand cDNA, second-strand cDNA synthesis, in vitro transcription to synthesize Biotin-modified aRNA, aRNA purification and fragmentation of the labeled aRNA were performed using the GeneChip 3M-bM-^@M-^Y IVT Express Kit and hybridization to the Affymetrix GeneChip Xenopus laevis Genome 2.0 Array was performed using the GeneChip Hybridization Wash and Stain Kit according to the manufacturerM-bM-^@M-^Ys instruction. Hybridized arrays were scanned using an Affymetrix GeneChip Scanner. Scanned Chip images were analyzed with GeneChip operating Software v.1.4 (GCOS) and GeneSpring GX 11.0.2. (Agilent technologies).

ORGANISM(S): Xenopus laevis

SUBMITTER: Eisuke Nishida

PROVIDER: E-GEOD-33767 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

The protein kinase MLTK regulates chondrogenesis by inducing the transcription factor Sox6.

Suzuki Toshiyasu T Kusakabe Morioh M Nakayama Kei K Nishida Eisuke E

Development (Cambridge, England) 20120704 16

Sox9 acts together with Sox5 or Sox6 as a master regulator for chondrogenesis; however, the inter-relationship among these transcription factors remains unclear. Here, we show that the protein kinase MLTK plays an essential role in the onset of chondrogenesis through triggering the induction of Sox6 expression by Sox9. We find that knockdown of MLTK in Xenopus embryos results in drastic loss of craniofacial cartilages without defects in neural crest development. We also find that Sox6 is specifi ...[more]

PMID: 22764049

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Project description:Vascular calcification and increased extracellular matrix (ECM) stiffness are hallmarks of vascular ageing. Sox9 (SRY-Box Transcription Factor 9) is a master regulator of chondrogenesis, also expressed in the vasculature, that has been implicated in vascular smooth muscle cell (VSMC) osteo-chondrogenic conversion. Here, we investigated the relationship between vascular ageing, calcification and Sox9-driven ECM regulation in VSMCs. Immunohistochemistry in human aortic samples showed that Sox9 was not spatially associated with vascular calcification but correlated with the senescence marker p16. Analysis of Sox9 expression in vitro showed it was mechanosensitive with increased expression and nuclear translocation in senescent cells and on stiff matrices. Manipulation of Sox9 via overexpression and depletion, combined with atomic force microscopy (AFM) and proteomics, revealed that Sox9 regulates ECM stiffness and organisation by orchestrating changes in collagen expression and reducing VSMC contractility, leading to the formation of an ECM that mirrored that of senescent cells. These ECM changes promoted phenotypic modulation of VSMCs whereby senescent cells plated onto ECM synthesized from cells depleted of Sox9 returned to a proliferative state, while proliferating cells on a matrix produced by Sox9 expressing cells showed reduced proliferation and increased DNA damage, reiterating features of senescent cells. Procollagen-lysine, 2-oxoglutarate 5-dioxygenase 3 (LH3) was identified as a Sox9 target, and key regulator of ECM stiffness. LH3 is packaged into extracellular vesicles (EVs) and Sox9 promoted EV secretion, leading to increased LH3 deposition within the ECM. These findings identify cellular senescence and Sox9 as a key regulators of ECM stiffness during VSMC ageing and highlight a crucial role for ECM structure and composition in regulating VSMC phenotype. We identify a positive feedback cycle whereby cellular senescence and increased ECM stiffening promote Sox9 expression which drives further ECM modifications that act to accelerate vascular stiffening and cellular senescence.

Dataset Information

The protein kinase MLTK Is a key regulator for chondrogenesis.

Publications

The protein kinase MLTK regulates chondrogenesis by inducing the transcription factor Sox6.

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