Epigenetic profiling of growth plate chondrocytes sheds insight into regulatory genetic variation influencing height

GWAS have identified hundreds of height-associated loci. However, determining causal mechanisms is challenging, especially since height-relevant tissues (e.g. growth plates) are difficult to study. To uncover mechanisms by which height GWAS variants function, we performed epigenetic profiling of murine femoral growth plates. The profiled open chromatin regions recapitulate known chondrocyte and skeletal biology, are enriched at height GWAS loci, particularly near differentially expressed growth plate genes, and enriched for binding motifs of transcription factors with roles in chondrocyte biology. At specific loci, our analyses identified compelling mechanisms for GWAS variants. For example, at CHSY1, we identified a candidate causal variant (rs9920291) overlapping an open chromatin region. Reporter assays demonstrated that rs9920291 shows allelic regulatory activity, and CRISPR/Cas9 targeting of human chondrocytes demonstrates that the region regulates CHSY1 expression. Thus, integrating biologically relevant epigenetic information (here, from growth plates) with genetic association results can identify biological mechanisms important for human growth.

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Investigation of RARg Signaling in Human Growth-Plate Chondrocytes

10.1542/peds.147.3_meetingabstract.790 ◽

2021 ◽

Author(s):

Joshua M. Abzug ◽

Hongying Tian ◽

Masatake Matsuoka ◽

Danielle A. Hogarth ◽

Casey M. Codd ◽

...

Keyword(s):

Growth Plate ◽

Human Growth ◽

Growth Plate Chondrocytes

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Catch-Up Growth after Hypothyroidism Is Caused by Delayed Growth Plate Senescence

Endocrinology ◽

10.1210/en.2007-0993 ◽

2008 ◽

Vol 149 (4) ◽

pp. 1820-1828 ◽

Cited By ~ 32

Author(s):

Rose Marino ◽

Anita Hegde ◽

Kevin M. Barnes ◽

Lenneke Schrier ◽

Joyce A. Emons ◽

...

Keyword(s):

Growth Rate ◽

Growth Inhibition ◽

Growth Plate ◽

Bone Growth ◽

Structural Characteristics ◽

Linear Growth Rate ◽

Growth Plate Chondrocytes ◽

Growth Plates ◽

Catch Up ◽

Growth Inhibiting

Catch-up growth is defined as a linear growth rate greater than expected for age after a period of growth inhibition. We hypothesized that catch-up growth occurs because growth-inhibiting conditions conserve the limited proliferative capacity of growth plate chondrocytes, thus slowing the normal process of growth plate senescence. When the growth-inhibiting condition resolves, the growth plates are less senescent and therefore grow more rapidly than normal for age. To test this hypothesis, we administered propylthiouracil to newborn rats for 8 wk to induce hypothyroidism and then stopped the propylthiouracil to allow catch-up growth. In untreated controls, the growth plates underwent progressive, senescent changes in multiple functional and structural characteristics. We also identified genes that showed large changes in mRNA expression in growth plate and used these changes as molecular markers of senescence. In treated animals, after stopping propylthiouracil, these functional, structural, and molecular senescent changes were delayed, compared with controls. This delayed senescence included a delayed decline in longitudinal growth rate, resulting in catch-up growth. The findings demonstrate that growth inhibition due to hypothyroidism slows the developmental program of growth plate senescence, including the normal decline in the rate of longitudinal bone growth, thus accounting for catch-up growth.

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Cellular reactions to biodegradable magnesium alloys on human growth plate chondrocytes and osteoblasts

International Orthopaedics ◽

10.1007/s00264-013-2163-3 ◽

2013 ◽

Vol 38 (4) ◽

pp. 881-889 ◽

Cited By ~ 35

Author(s):

Karin Pichler ◽

Tanja Kraus ◽

Elisabeth Martinelli ◽

Patrick Sadoghi ◽

Giuseppe Musumeci ◽

...

Keyword(s):

Growth Plate ◽

Magnesium Alloys ◽

Human Growth ◽

Growth Plate Chondrocytes ◽

Biodegradable Magnesium

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The synthesis of type X collagen by bovine and human growth-plate chondrocytes

Journal of Cell Science ◽

10.1242/jcs.99.3.641 ◽

1991 ◽

Vol 99 (3) ◽

pp. 641-649 ◽

Cited By ~ 3

Author(s):

A. Marriott ◽

S. Ayad ◽

M.E. Grant

Keyword(s):

Growth Plate ◽

Type I Collagen ◽

Polyacrylamide Gel Electrophoresis ◽

Human Growth ◽

Type I ◽

Collagen Gels ◽

Type X Collagen ◽

Growth Plate Chondrocytes ◽

Growth Plate Cartilage ◽

Disulphide Bonds

Chondrocytes were isolated from bovine growth-plate cartilage and cultured within type I collagen gels. A major collagen with chains of Mr 59,000, decreasing to 47,000 on pepsinization, was synthesized and identified as type X collagen. This collagen was cleaved at two sites by mammalian collagenase, resulting in a major triple-helical fragment with chains of Mr 32,000. The species of Mr 59,000, 47,000 and 32,000 were not detected by SDS-polyacrylamide gel electrophoresis before reduction, indicating the presence of disulphide bonds within the triple helix. In contrast, similar biosynthetic studies with human growth-plate cartilage in organ culture, indicated that human type X collagen does not contain disulphide bonds. A polyclonal antiserum was raised to bovine type X collagen and used in immunolocalization studies to provide direct evidence for the association of type X collagen with the hypertrophic chondrocytes in both bovine and human growth plates during development.

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Monoclonal Antibody Enhanced Stimulation of Human Growth Hormone ActionIn VitroUsing Ovine Costal Cartilage Growth Plate Chondrocytes

Hormone and Metabolic Research ◽

10.1055/s-2007-978943 ◽

1998 ◽

Vol 30 (10) ◽

pp. 610-613 ◽

Cited By ~ 2

Author(s):

J. Mockridge ◽

C. Carter ◽

A. Holder

Keyword(s):

Monoclonal Antibody ◽

Growth Hormone ◽

Growth Plate ◽

Human Growth Hormone ◽

Costal Cartilage ◽

Human Growth ◽

Cartilage Growth ◽

Growth Plate Chondrocytes ◽

Cartilage Growth Plate ◽

Stimulation Of

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Imaging IGF-I uptake in growth plate cartilage using in vivo multiphoton microscopy

Journal of Applied Physiology ◽

10.1152/japplphysiol.00645.2017 ◽

2017 ◽

Vol 123 (5) ◽

pp. 1101-1109 ◽

Cited By ~ 3

Author(s):

Maria A. Serrat ◽

Gabriela Ion

Keyword(s):

Real Time ◽

Growth Plate ◽

Multiphoton Microscopy ◽

Biologically Active ◽

Growth Plate Chondrocytes ◽

Growth Plates ◽

Metatarsal Bones ◽

Wide Range ◽

Igf I

Bones elongate through endochondral ossification in cartilaginous growth plates located at ends of primary long bones. Linear growth ensues from a cascade of biochemical signals initiated by actions of systemic and local regulators on growth plate chondrocytes. Although cellular processes are well defined, there is a fundamental gap in understanding how growth regulators are physically transported from surrounding blood vessels into and through dense, avascular cartilage matrix. Intravital imaging using in vivo multiphoton microscopy is one promising strategy to overcome this barrier by quantitatively tracking molecular delivery to cartilage from the vasculature in real time. We previously used in vivo multiphoton imaging to show that hindlimb heating increases vascular access of large molecules to growth plates using 10-, 40-, and 70-kDa dextran tracers. To comparatively evaluate transport of similarly sized physiological regulators, we developed and validated methods for measuring uptake of biologically active IGF-I into proximal tibial growth plates of live 5-wk-old mice. We demonstrate that fluorescently labeled IGF-I (8.2 kDa) is readily taken up in the growth plate and localizes to chondrocytes. Bioactivity tests performed on cultured metatarsal bones confirmed that the labeled protein is functional, assessed by phosphorylation of its signaling kinase, Akt. This methodology, which can be broadly applied to many different proteins and tissues, is relevant for understanding factors that affect delivery of biologically relevant molecules to the skeleton in real time. Results may lead to the development of drug-targeting strategies to treat a wide range of bone and cartilage pathologies. NEW & NOTEWORTHY This paper describes and validates a novel method for imaging transport of biologically active, fluorescently labeled IGF-I into skeletal growth plates of live mice using multiphoton microscopy. Cellular patterns of fluorescence in the growth plate were completely distinct from our prior publications using biologically inert probes, demonstrating for the first time in vivo localization of IGF-I in chondrocytes and perichondrium. These results form important groundwork for future studies aimed at targeting therapeutics into growth plates.

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