Passing value between usercontrols

To elaborate on Abhinav's answer, you need to create a Property in your form with the DataGridView that holds your node value. In the Setter for the property you could call a method that filters your results and rebinds the DataGridView. Something like this :

private string nodeValue;

   public string NodeValue
   {
       get
       {
           return nodeValue;
       }
       set
       {
           if (nodeValue != value)
           {
               nodeValue = value;
               NodeValueChanged(value);
           }
       }
   }

   public frmDataGridView(string nodeValue)
   {
       this.NodeValue = nodeValue;
   }

   void NodeValueChanged(string newNodeValue)
   {
       //get new results with newNodeValue as filter
   }

Then in your form with the TreView you need to create a private variable that references your GridView form, then whenever the treeview selection changes, in the treeview selection changed event you just need to change the property like this:

private frmDataGridView gridView;

   public frmTreeView()
   {
       gridView = new frmDataGridView();
       gridView.NodeValue = "DefaultValue";
   }

   void TreeViewChanged(object sender, TreeViewChangedEventArgs e)
   {
       gridView.NodeValue = "Selected TreeView Value";
   }

Hope this helps.
Disclaimer. This code has not been checked, the TreeViewChanged event I have used is fictitious, so you need to use the proper TreeView changed event.

Hope this[^] might help you.