Connexin37 deficiency alters organic bone matrix, cortical bone geometry, and increases Wnt/β-catenin signaling

Rafael Pacheco-Costa, Jay R. Kadakia, Emily G. Atkinson, Joseph M. Wallace, Lilian Plotkin, Rejane D. Reginato

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Deletion of connexin (Cx) 37 in mice leads to increased cancellous bone mass due to defective osteoclast differentiation. Paradoxically; however, Cx37-deficient mice exhibit reduced cortical thickness accompanied by higher bone strength, suggesting a contribution of Cx37 to bone matrix composition. Thus, we investigated whether global deletion of Cx37 alters the composition of organic bone extracellular matrix. Five-month-old Cx37−/− mice exhibited increased marrow cavity area, and periosteal and endocortical bone surface resulting in higher total area in tibia compared to Cx37+/+ control mice. Deletion of Cx37 increased genes involved in collagen maturation (loxl3 and loxl4) and glycosaminoglycans- (chsy1, chpf and has3) proteoglycans- associated genes (biglycan and decorin). In addition, expression of type II collagen assessed by immunostaining was increased by 82% whereas collagen maturity by picrosirius-polarizarion tended to be reduced (p = 0.071). Expression of glycosaminoglycans by histochemistry was decreased, whereas immunostaining revealed that biglycan was unchanged and decorin was slightly increased in Cx37−/− bone sections. Consistent with these in vivo findings, MLO-Y4 osteocytic cells silenced for Cx37 gene exhibited increased mRNA levels for collagen synthesis (col1a1 and col3a1) and collagen maturation (lox, loxl1 and loxl2 genes). Furthermore, mechanistic studies showed Wnt/β-catenin activation in MLO-Y4 osteocytic cells, L5 vertebra, and authentic calvaria-derived osteocytes isolated by fluorescent-activated cell sorter. Our findings demonstrate that altered profile of the bone matrix components in Cx37-deficient mice acts in favor of higher resistance to fracture in long bones.

Original languageEnglish (US)
Pages (from-to)105-113
Number of pages9
JournalBone
Volume97
DOIs
StatePublished - Apr 1 2017

Fingerprint

Catenins
Bone Matrix
Collagen
Biglycan
Decorin
Bone and Bones
Glycosaminoglycans
Genes
Osteocytes
Collagen Type II
Osteoclasts
Proteoglycans
Tibia
Skull
Extracellular Matrix
Spine
Bone Marrow
Messenger RNA
Cortical Bone

Keywords

  • Bone
  • Collagen
  • Connexin 37
  • Glycosaminoglycans
  • Osteocytes
  • Wnt/β-catenin signaling

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Histology
  • Physiology

Cite this

Connexin37 deficiency alters organic bone matrix, cortical bone geometry, and increases Wnt/β-catenin signaling. / Pacheco-Costa, Rafael; Kadakia, Jay R.; Atkinson, Emily G.; Wallace, Joseph M.; Plotkin, Lilian; Reginato, Rejane D.

In: Bone, Vol. 97, 01.04.2017, p. 105-113.

Research output: Contribution to journalArticle

Pacheco-Costa, Rafael ; Kadakia, Jay R. ; Atkinson, Emily G. ; Wallace, Joseph M. ; Plotkin, Lilian ; Reginato, Rejane D. / Connexin37 deficiency alters organic bone matrix, cortical bone geometry, and increases Wnt/β-catenin signaling. In: Bone. 2017 ; Vol. 97. pp. 105-113.
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abstract = "Deletion of connexin (Cx) 37 in mice leads to increased cancellous bone mass due to defective osteoclast differentiation. Paradoxically; however, Cx37-deficient mice exhibit reduced cortical thickness accompanied by higher bone strength, suggesting a contribution of Cx37 to bone matrix composition. Thus, we investigated whether global deletion of Cx37 alters the composition of organic bone extracellular matrix. Five-month-old Cx37−/− mice exhibited increased marrow cavity area, and periosteal and endocortical bone surface resulting in higher total area in tibia compared to Cx37+/+ control mice. Deletion of Cx37 increased genes involved in collagen maturation (loxl3 and loxl4) and glycosaminoglycans- (chsy1, chpf and has3) proteoglycans- associated genes (biglycan and decorin). In addition, expression of type II collagen assessed by immunostaining was increased by 82{\%} whereas collagen maturity by picrosirius-polarizarion tended to be reduced (p = 0.071). Expression of glycosaminoglycans by histochemistry was decreased, whereas immunostaining revealed that biglycan was unchanged and decorin was slightly increased in Cx37−/− bone sections. Consistent with these in vivo findings, MLO-Y4 osteocytic cells silenced for Cx37 gene exhibited increased mRNA levels for collagen synthesis (col1a1 and col3a1) and collagen maturation (lox, loxl1 and loxl2 genes). Furthermore, mechanistic studies showed Wnt/β-catenin activation in MLO-Y4 osteocytic cells, L5 vertebra, and authentic calvaria-derived osteocytes isolated by fluorescent-activated cell sorter. Our findings demonstrate that altered profile of the bone matrix components in Cx37-deficient mice acts in favor of higher resistance to fracture in long bones.",
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AU - Kadakia, Jay R.

AU - Atkinson, Emily G.

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AU - Reginato, Rejane D.

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AB - Deletion of connexin (Cx) 37 in mice leads to increased cancellous bone mass due to defective osteoclast differentiation. Paradoxically; however, Cx37-deficient mice exhibit reduced cortical thickness accompanied by higher bone strength, suggesting a contribution of Cx37 to bone matrix composition. Thus, we investigated whether global deletion of Cx37 alters the composition of organic bone extracellular matrix. Five-month-old Cx37−/− mice exhibited increased marrow cavity area, and periosteal and endocortical bone surface resulting in higher total area in tibia compared to Cx37+/+ control mice. Deletion of Cx37 increased genes involved in collagen maturation (loxl3 and loxl4) and glycosaminoglycans- (chsy1, chpf and has3) proteoglycans- associated genes (biglycan and decorin). In addition, expression of type II collagen assessed by immunostaining was increased by 82% whereas collagen maturity by picrosirius-polarizarion tended to be reduced (p = 0.071). Expression of glycosaminoglycans by histochemistry was decreased, whereas immunostaining revealed that biglycan was unchanged and decorin was slightly increased in Cx37−/− bone sections. Consistent with these in vivo findings, MLO-Y4 osteocytic cells silenced for Cx37 gene exhibited increased mRNA levels for collagen synthesis (col1a1 and col3a1) and collagen maturation (lox, loxl1 and loxl2 genes). Furthermore, mechanistic studies showed Wnt/β-catenin activation in MLO-Y4 osteocytic cells, L5 vertebra, and authentic calvaria-derived osteocytes isolated by fluorescent-activated cell sorter. Our findings demonstrate that altered profile of the bone matrix components in Cx37-deficient mice acts in favor of higher resistance to fracture in long bones.

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