Differential gene-expression of metallothionein 1M and 1G in response to zinc in sertoli TM4 cells

Zinc (Zn) as an important trace element is essential for testicular development and
spermatogenesis. Molecular mechanism of Zn action in the reproductive system may be related to metal
binding low-molecular weight proteins, metallothioneins (MT). Our objective was to determine the effect of
Zn on two important isoforms of MT, MT1M and MT1G genes expression on testicular sertoli cells.
Methods: Cultured sertoli TM4 cells were exposed to different concentrations of Zn at different time points.
Cellular uptake of Zn was tested using flame atomic absorption spectrometry. The cellular viability and gene
expression were assessed by MTT and real-time PCR methods, respectively. Results: The treated cells
resulted in higher Zn concentration and cellular viability. The expression of MT1M and MT1G genes in the
treated cells were greater than those of the untreated cells (P<0.05). In the high dosage treated group (100 and
500 μM), Zn concentration and expression of MT1M and MT1G genes increased three h after treatment;
MT1G gene expression increased more at sixth h. At 18th h of treatment, the expression of both genes
especially MT1G, increased dramatically while Zn concentration decreased. Conclusion: Since the increase
of MT1G mRNA was coincident with cellular Zn level, it seems that MT1G has a more prominent role than
MT1M in the homeostasis of Zn. In addition, Zn at dosage of 50 μM (pharmacologic concentration) may
protect cells by increasing the expression of MT genes at longer periods