  Like early-type galaxies, also nearby galaxy clusters define a Fundamental
Plane, a luminosity-radius, and a luminosity-velocity dispersion relations,
whose physical origin is still unclear. By means of high resolution N--body
simulations of massive dark matter halos in a Lambda-CDM cosmology, we find
that scaling relations similar to those observed for galaxy clusters are
already defined by their dark matter hosts. The slopes however are not the
same, and among the various possibilities in principle able to bring the
simulated and the observed scaling relations in mutual agreement, we show that
the preferred solution is a luminosity dependent mass-to-light ratio (M/L ~
L^0.3), that well corresponds to what inferred observationally. We then show
that at galactic scales there is a conflict between the cosmological
predictions of structure formation, the observed trend of the mass-to-light
ratio in ellipticals, and the slope of their luminosity-velocity dispersion
relation (that significantly differs from the analogous one followed by
clusters). The conclusion is that the scaling laws of elliptical galaxies might
be the combined result of the cosmological collapse of density fluctuations at
the epoch when galactic scales became non-linear, plus important modifications
afterward due to early-time dissipative merging. Finally, we briefly discuss
the possible evolution of the cluster scaling relations with redshift.
