dissolve polygons of GeoJSON with gdal/ogr

I have a GeoJSON with only polygons in it. I have to dissolve (merge) the polygons with the same “DN”-value. I found out that you can do it with shapefiles like this:

ogr2ogr outputfile.shp inputfile.shp -dialect sqlite -sql “SELECT dissolvefield,ST_Union(geometry) as geometry FROM inputfile GROUP BY dissolvefield”

but since I dont know shp nor SQL I don’t know how to apply that to GeoJSON and “DN”-value. I hope someone can help me out here.

{
    "type": "FeatureCollection",

    "features": [
    { "type": "Feature", "properties": { "DN": "0" }, "geometry": { "type": "Polygon", "coordinates": [ [ [ 1425, 0 ], [ 1425, 1 ], [ 1592, 0 ], [ 1425, 0 ] ] ] } },
    { "type": "Feature", "properties": { "DN": "1" }, "geometry": { "type": "Polygon", "coordinates": [ [ [ 4397, 88 ], [ 4397, 89 ], [ 4398, 88 ], [ 4397, 88 ] ] ] } },
    { "type": "Feature", "properties": { "DN": "2" }, "geometry": { "type": "Polygon", "coordinates": [ [ [ 369, 93 ], [ 369, 101 ], [ 371, 93 ], [ 369, 93 ] ] ] } },
    { "type": "Feature", "properties": { "DN": "2" }, "geometry": { "type": "Polygon", "coordinates": [ [ [ 368, 106 ], [ 368, 107 ], [ 369, 106 ], [ 368, 106 ] ] ] } }
    ]
}

EDIT:
I think I had a wrong Idea what “dissolve” is. So I want to explain what I want more detailed: I only want to MERGE two or more polygons with the SAME DN-Value AND which are neighbours. So that Polygons which were splitted due to tiles are unified again.