S100A9 Protein - Calgranulin B

S100A9 Protein - Calgranulin B

Introduction

<table class="infobox infobox-protein">
<tr>
<th class="infobox-header" colspan="2">S100A9 Protein - Calgranulin B</th>
</tr>
<tr>
<td class="label">Approach</td>
<td>Status</td>
</tr>
<tr>
<td class="label">Anti-S100A9 antibodies</td>
<td>Preclinical</td>
</tr>
<tr>
<td class="label">TLR4 inhibitors</td>
<td>Preclinical</td>
</tr>
<tr>
<td class="label">[RAGE](/entities/rage-receptor) antagonists</td>
<td>Preclinical</td>
</tr>
<tr>
<td class="label">S100A9 knockout</td>
<td>Research</td>
</tr>
</table>

S100A9 Protein Calgranulin B is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.

S100A9 Protein - Calgranulin B

Introduction

<table class="infobox infobox-protein">
<tr>
<th class="infobox-header" colspan="2">S100A9 Protein - Calgranulin B</th>
</tr>
<tr>
<td class="label">Approach</td>
<td>Status</td>
</tr>
<tr>
<td class="label">Anti-S100A9 antibodies</td>
<td>Preclinical</td>
</tr>
<tr>
<td class="label">TLR4 inhibitors</td>
<td>Preclinical</td>
</tr>
<tr>
<td class="label">[RAGE](/entities/rage-receptor) antagonists</td>
<td>Preclinical</td>
</tr>
<tr>
<td class="label">S100A9 knockout</td>
<td>Research</td>
</tr>
</table>

S100A9 Protein Calgranulin B is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.

<div style="background:#f8f9fa;border:1px solid #ddd;padding:15px;border-radius:5px;margin:10px 0;"> [@calgranulin]
<h3 style="margin-top:0;">S100A9 Protein - Calgranulin B</h3> [@therapeutic]
<table style="width:100%;font-size:14px;"> [@biomarker]
<tr><td style="padding:5px;font-weight:bold;">Symbol</td><td style="padding:5px;">S100A9</td></tr> [@microglial]
<tr><td style="padding:5px;font-weight:bold;">Full Name</td><td style="padding:5px;">S100 Calcium Binding Protein A9</td></tr> [@parkinsons]
<tr><td style="padding:5px;font-weight:bold;">Aliases</td><td style="padding:5px;">Calgranulin B, MRP14, Myeloid-related protein 14</td></tr> [@calprotectin]
<tr><td style="padding:5px;font-weight:bold;">Molecular Weight</td><td>13.2 kDa</td></tr> [@neurofibrillary]
<tr><td style="padding:5px;font-weight:bold;">Protein Family</td><td>S100 EF-hand calcium-binding proteins</td></tr>
<tr><td style="padding:5px;font-weight:bold;">Associated Diseases</td><td>AD, PD, ALS, MS, Rheumatoid Arthritis, Inflammatory Bowel Disease</td></tr>
</table>
</div>

Overview

S100A9 (S100 Calcium Binding Protein A9), also known as Calgranulin B or Myeloid-Related Protein 14 (MRP14), is a member of the S100 family of EF-hand calcium-binding proteins. Like its partner S100A8, S100A9 forms a heterodimer (calprotectin) that functions as a Damage-Associated Molecular Pattern (DAMP) molecule. This complex is a major player in neuroinflammation and is implicated in the pathogenesis of Alzheimer's disease, Parkinson's disease, ALS, and multiple sclerosis.

Molecular Structure

S100A9 is a 13.2 kDa protein containing two EF-hand calcium-binding motifs. The C-terminal EF-hand is the high-affinity calcium-binding site. S100A9 can form both homodimers and heterodimers with S100A8. The S100A8/A9 heterodimer (calprotectin) is the biologically active form involved in immune signaling.

Molecular Function

Calcium Binding and Dimerization

• Forms heterodimer with S100A8 (calprotectin)
• Calcium binding induces conformational changes
• Heterodimer required for [TLR4](/entities/tlr4) and [RAGE](/genes/rage) activation
• Can also form S100A9 homodimers

DAMP and Pro-inflammatory Signaling

• Acts as Damage-Associated Molecular Pattern (DAMP)
• Binds to TLR4 and [RAGE](/genes/rage) receptors
• Activates [NF-κB](/entities/nf-kb) and MAPK signaling cascades
• Promotes production of pro-inflammatory cytokines (IL-1β, IL-6, TNF-α)
• Enhances neutrophil recruitment and activation

Antimicrobial Activity

• Calprotectin sequesters manganese and zinc
• Exhibits antimicrobial properties
• Involved in host defense against pathogens

Expression Pattern

CNS Expression

• Highly expressed in activated [microglia](/entities/microglia)
• Astrocytic expression in disease states
• Perivascular macrophage presence
• Low baseline expression in healthy brain

Peripheral Expression

• High in neutrophils, monocytes
• Elevated in inflammatory conditions
• Detectable in serum, plasma, CSF

Role in Disease

Alzheimer's Disease

Parkinson's Disease

Amyotrophic Lateral Sclerosis

Multiple Sclerosis

Therapeutic Targeting

Animal Models

• S100A9 knockout mice: Reduced inflammatory responses
• Transgenic S100A9 mice: Enhanced neuroinflammation
• Calprotectin administration: Pro-inflammatory effects

Background

The study of S100A9 Protein Calgranulin B has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.

Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.

See Also

• [Neuroinflammation Pathway](/mechanisms/neuroinflammation-pathway)
• [Oxidative Stress Pathway](/mechanisms/oxidative-stress)
• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Parkinson's Disease](/diseases/parkinsons-disease)
• [S100A8 Protein](/proteins/s100a8-protein)
• [Microglia](/cell-types/microglia)

External Links

• [UniProt: S100A9](https://www.uniprot.org/uniprot/P06702)
• [NCBI Protein: S100A9](https://www.ncbi.nlm.nih.gov/protein/NP_001243235)
• [GeneCards: S100A9](https://www.genecards.org/cgi-bin/carddisp.pl?gene=S100A9)
• [OMIM: S100A9](https://www.omim.org/entry/123856)

References