Progressive skeletal defects caused by Kindlin3 deficiency, a model of autosomal recessive osteopetrosis in humans

Area of Science:

• Skeletal Biology
• Hematology
• Molecular Genetics

Background:

• Bone development and homeostasis rely on complex cellular and molecular mechanisms.
• Mutations in Kindlin3 cause Leukocyte adhesion deficiencies (LAD), leading to skeletal complications like osteopetrosis.
• Mechanistic studies in LAD patients are limited due to rarity and lethality.

Purpose of the Study:

• To investigate the role of Kindlin3 in myeloid cells during skeletal development and homeostasis.
• To elucidate the specific skeletal abnormalities caused by Kindlin3 deficiency in the myeloid lineage.
• To establish a mouse model for studying autosomal recessive osteopetrosis (ARO) linked to Kindlin3.

Main Methods:

• Utilized inducible and constitutive tissue-specific Kindlin3 knockout (K3KO) mouse models.
• Performed micro-computed tomography (Micro-CT) analysis to assess skeletal morphology.
• Examined skeletal development and bone remodeling in mice with varying Kindlin3 expression in myeloid cells.

Main Results:

• Constitutive absence of embryonic Kindlin3 in myeloid cells resulted in growth retardation, edentulism, and skull deformities.
• Micro-CT revealed craniosynostosis, choanal stenosis, micrognathia, and osteopetrosis-like features.
• Progressive osteosclerosis and bone marrow cavity narrowing were observed in adult K3KO mice, while postnatal deficiency had less impact.

Conclusions:

• Myeloid Kindlin3 is essential for normal skeletal development and maintenance.
• Kindlin3 deficiency in myeloid cells leads to autosomal recessive osteopetrosis (ARO).
• This research aids in diagnosing and managing LAD-III and ARO patients.