Related Experiment Video
Updated: Jul 18, 2026
10:29
Quantitative Structure-Activity Relationship, Activity Prediction, and Molecular Dynamics of Non-nucleotide Reverse Transcriptase Inhibitors
Published on: May 9, 2025
Modulation of osteoclastogenesis induced by nucleoside reverse transcriptase inhibitors
George Pan1, Michael Kilby, Jay M McDonald
1Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA.
AIDS Research and Human Retroviruses
|December 7, 2006
Summary
Highly Active Antiretroviral Therapy (HAART) drugs like zidovudine (AZT) stimulate bone breakdown, leading to osteopenia. This study confirms NRTI drug-induced osteoclastogenesis is RANKL-dependent and suggests an assay for assessing bone loss risk in patients.
Area of Science:
- Bone Biology
- Pharmacology
- Immunology
Background:
- Osteopenia is a frequent complication of Highly Active Antiretroviral Therapy (HAART).
- The precise mechanisms by which HAART impacts bone metabolism remain largely unelucidated.
- Previous research indicated zidovudine (AZT) stimulates osteoclastogenesis and causes osteopenia in mice.
Purpose of the Study:
- To investigate the effects of nucleoside reverse transcriptase inhibitors (NRTIs) on osteoclastogenesis and bone metabolism.
- To determine the role of Receptor Activator of Nuclear Factor kappa-B Ligand (RANKL) in NRTI-induced osteoclastogenesis.
- To evaluate the potential of an in vitro assay for predicting bone turnover in patients on HAART.
Main Methods:
- In vitro osteoclastogenesis assays using murine and human osteoclast precursors.
- Administration of NRTI drugs (AZT, ddl, 3TC) to mice to induce osteopenia.
- Blocking experiments using osteoprotegerin (OPG) and testing of alendronate and tumor necrosis factor-alpha (TNF-α).
- Assessment of osteoblast and osteoclast parameters in vivo.
Main Results:
- AZT, ddl, and 3TC stimulated osteoclastogenesis in vitro and induced osteopenia in mice.
- NRTI-induced osteoclastogenesis was dependent on RANKL and could be blocked by OPG.
- Alendronate and TNF-α did not inhibit AZT-induced osteoclastogenesis in vitro.
- Osteopenia was associated with increased osteoclast activity, not osteoblast activity.
- AZT-induced osteoclastogenesis in human cells was RANKL-dependent.
Conclusions:
- NRTIs commonly used in HAART can directly stimulate osteoclastogenesis, contributing to osteopenia.
- The RANKL pathway is critical for NRTI-induced bone resorption.
- An in vitro assay using human peripheral blood mononuclear cells may serve as a valuable tool for assessing bone turnover and osteopenia risk in HIV patients undergoing HAART.
Related Concept Videos
01:22Antiviral Nucleoside Inhibitors
Antiviral Nucleoside InhibitorsAntiviral nucleoside inhibitors are structural analogs of natural nucleosides that interfere with viral DNA or RNA synthesis. These compounds selectively target viral polymerases due to their resemblance to host nucleosides, thereby disrupting viral genome replication.Mechanism of Acyclovir ActionAcyclovir is a guanosine analog with a three-carbon acyclic side chain. It selectively targets herpes simplex virus type 1 (HSV-1), herpes simplex virus type 2 (HSV-2),...
01:30Inhibitors of Viral Protein Synthesis
Protein synthesis is indispensable for viral replication, as viruses lack the cellular machinery required for this process and must hijack the host's translational apparatus. In response, host cells deploy a critical innate immune defense involving interferons, specialized cytokines that play a central role in inhibiting viral propagation.Upon viral detection, infected cells release interferons that bind to receptors on adjacent uninfected cells, activating the JAK-STAT signaling pathway and...
01:31Osteoclasts in Bone Remodeling
Osteoclasts are cells responsible for bone resorption and remodeling. They originate from hematopoietic progenitor cells present in the bone marrow. Numerous progenitor cells fuse to form multinucleated cells, each with 10-20 nuclei. A single osteoclast has a diameter of 150 to 200 µM. These cells have ruffled borders that break down the underlying bone tissue and release minerals such as calcium into the blood in bone resorption. Osteoclasts cling to bones with their ruffled edges during bone...
01:19Inhibitors of Virion Maturation and Assembly
As part of their replication cycle, certain viruses synthesize long precursor proteins called polyproteins within infected host cells. In human immunodeficiency virus (HIV), two major polyproteins are produced: Gag and Gag-Pol. The Gag polyprotein supplies the structural components of the virus, while Gag-Pol includes essential viral enzymes such as reverse transcriptase, integrase, and protease. After synthesis, these polyproteins move to the host cell membrane, where they assemble into an...
01:51Mechanisms of Retrovirus-induced Cancers
Retroviruses are RNA viruses that have been shown to cause cancers in diverse species, including chickens, mice, cats, and monkeys. The RNA genomes of these viruses are first reverse-transcribed into single and then double-stranded DNA (dsDNA) copies. This dsDNA called proviral DNA then integrates into the host genome. Subsequently, the host cell transcribes the proviral DNA in concert with the chromosomal DNA. This leads to the production of viral RNA and proteins that assemble at the host...
01:51Mechanisms of Retrovirus-induced Cancers
Retroviruses are RNA viruses that have been shown to cause cancers in diverse species, including chickens, mice, cats, and monkeys. The RNA genomes of these viruses are first reverse-transcribed into single and then double-stranded DNA (dsDNA) copies. This dsDNA called proviral DNA then integrates into the host genome. Subsequently, the host cell transcribes the proviral DNA in concert with the chromosomal DNA. This leads to the production of viral RNA and proteins that assemble at the host...