You just pass the derived classes

public class UserPropertiesBaseViewModel
{
    public string Description { get; set; }
    public string Gender { get; set; }
}

public class CreateUserViewModel : UserPropertiesViewModel
{
    [DisplayName("User Name")]
    [Remote("ValidateUserName", "UserMgr", ErrorMessage = "The user name is already existing.")]
    [RegularExpression(Verifier.REG_EXP_USER_NAME, ErrorMessage = Verifier.ERRMSG_REG_EXP_USER_NAME)]
    public string UserName { get; set; }
}

public class EditUserViewModel : UserPropertiesViewModel
{
    [DisplayName("User Name")]
    [Required(ErrorMessage = Verifier.ERRMSG_REQUIRED)]
    [RegularExpression(Verifier.REG_EXP_USER_NAME, ErrorMessage = Verifier.ERRMSG_REG_EXP_USER_NAME)]
    public string UserName { get; set; }
}

// in views
Create.cshtml
@model SystemDemo.Models.CreateUserViewModel


Edit.cshtml
@model SystemDemo.Models.EditUserViewModel