  We study D-branes on Calabi-Yau threefolds, which are realized through the
blowing up the singularity of orbifold. This D-branes are represented as
sheaves, which can be stable or unstable, what is connected with the transition
in the Teichm$\ddot{u}$ller space. Using the derived category of McKay quiver
representations, which describe D-branes as quivers and open superstrings
between them by Ext groups, we can represent Higgs multiplets by the moduli
space of an open superstring, connecting two McKay quivers. Through the
equivalence between the derived category of coherent sheaves and triangulated
category of distinguished triangles over the abelian category of McKay quivers
we can associate D-branes with quivers or with sheaves, defined on Calabi-Yau.
After the dimensional reduction of the ten-dimensional space-time we can
receive matter content of the four-dimensional space-time. Thus, a
higher-dimensional breaking mechanism is associated with four-dimensional GUT
Higgs multiplets and symmetry breaking higgs mechanism.
