R - Copy negative sign from one to another column

I have a dataframe (df_ann) as shown here:

Cha	Seg_value	Seg_value2
AXL2	-0.654	2.965
PTT1	1.957	1.84
AXL2	2.654	0.989
PTT1	-1.038	0.85

I want to add the negative sign in the Seg_value2 column if it is present in the Seg_value column.

Output should be:

Cha	Seg_value	Seg_value2
AXL2	-0.654	-2.965
PTT1	1.957	1.84
AXL2	2.654	0.989
PTT1	-1.038	-0.85

I have searched for the solution to the problem but did not find the answer. Anything would be helpful.

Thanks in advance!