The TRPC family consists of multiple important cationic channels in mammals that participate in a variety of physiological and pathological processes. Our previous studies have shown that transforming growth factor-β1 (TGF-β1) increases the expression of TRPC6 in podocytes, but the roles of other members of the TRPC family in podocytes require further investigation. In this study, we investigated the effect of TGF-β1 on the expression of the TRPC family and the role of the TRPC family in the changes of the intracellular Ca²⁺ concentration ([Ca²⁺]_i) in podocytes induced by TGF-β1. The model of podocyte injury was established by treatment with TGF-β1 in immortalized glomerular podocytes (MPC5) in vitro. qRT-PCR and Western blot were used to detect the effect of TGF-β1 on the mRNA and protein expression of each TRPC family member. After the expression of each TRPC family member was knocked down by a siRNA-based approach and blocked by SKF96365, respectively, free cytosolic Ca²⁺ was measured using the fluorescent Ca²⁺ indicator Fluo-3/AM, and the dynamic change of [Ca²⁺]_i in podocytes was detected by a dynamic high-speed calcium imaging system. The results showed that TGF-β1 increased the protein expression of TRPC1/3/6 in podocytes, but had no effects on the protein expression of TRPC4. The protein expression levels of TRPC5/7 were only affected by 4 ng/mL and 8 ng/mL TGF-β1, respectively. TGF-β1 increased TRPC1/3/6 mRNA levels in podocytes, however had no effects on TRPC4/5/7 mRNA. TGF-β1 significantly increased [Ca²⁺]_i in podocytes. Knockdown of TRPC1/4/5/7 in podocytes had no significant effect on the [Ca²⁺]_i induced by TGF-β1, but TRPC3/6 knockdown significantly decreased the [Ca²⁺]_i. There was no significant difference in the [Ca²⁺]_i between the TRPC6 siRNA-treated group and SKF96365-treated group, but the [Ca²⁺]_i of the TRPC3 siRNA-treated group was significantly higher than that of SKF96365-treated group. These results demonstrate that TGF-β1 increases the expression of the TRPC1/3/6 in podocytes. TGF-β1 increases [Ca²⁺]_i in podocytes, which is dependent on the TRPC3/6 expression. Our results also suggest that the effect of TRPC6 on [Ca²⁺]_i in podocytes may be greater than that of TRPC3.
Animals ; TRPC6 Cation Channel/metabolism* ; Calcium/metabolism* ; TRPC Cation Channels/metabolism* ; Podocytes/metabolism* ; Transforming Growth Factor beta1/metabolism* ; RNA, Small Interfering/metabolism* ; RNA, Messenger/metabolism* ; Mammals/metabolism*

OBJECTIVETo investigate the essential role and mechanism of TRPC6 gene in the development of gastric cancer.

METHODSThe expression of TRPC6 protein was assessed in gastric cancer tissues and normal tissues adjacent to the cancer from 30 patients with gastric cancer. The inhibiting effect of TRPC6 activity on cell growth, cell cycle of a human gastric cancer cell line AGS cells, tumor progression and development of xenografted human gastric cancer in a mouse model was tested using dominant-negative mutant TRPC6 (DNC6). The survival of mice bearing xenografted tumors in the GFP and DNC6 was compared using Kaplan-Meier analysis. All statistical tests were two-sided.

RESULTSThe TRPC6 protein in the tumor tissues and para-tumor tissues was (21.60 ± 8.32)% versus (7.14 ± 2.24)%. After transfection of DNC6 virus for 24 hours, 48 hours, 72 hours and 96 hours, the growth inhibition rates of gastric cancer cells were (36.90 ± 1.13)%, (44.06 ± 2.17)%, (52.12 ± 2.76)% and (50.89 ± 1.97)%, respectively. The clone formation rates of control group and DNC6 group were (14.70 ± 3.00)% versus (43.80 ± 7.00)%. After transfection with DNC6 virus for 0, 24, 36 and 48 hours, the G(2)/M phase arrest was (20.34 ± 1.98)%, (24.31 ± 2.37)%, (27.70 ± 2.36)%, (35.10 ± 3.0)% in the DNC6 group and (18.40 ± 2.01)%, (18.0% ± 1.72)%, (17.50 ± 1.74)%, (16.80 ± 1.71)% in the control group, respectively. Inhibition of TRPC6 activity also reduced the subcutaneous tumor volume in the mouse models with xenografted human tumors (P < 0.05).

CONCLUSIONIn the preclinical models tested, TRPC6 channels are essential for gastric cancer development via regulation of G(2)/M phase transition.

Adenoviridae ; genetics ; Animals ; CDC2 Protein Kinase ; Cell Cycle ; Cell Line, Tumor ; Cell Proliferation ; Cyclin B ; metabolism ; Cyclin-Dependent Kinases ; Humans ; Male ; Mice ; Mice, Inbred BALB C ; Mice, Nude ; Neoplasm Transplantation ; Recombinant Proteins ; metabolism ; Stomach Neoplasms ; genetics ; metabolism ; pathology ; TRPC Cation Channels ; metabolism ; TRPC6 Cation Channel ; Transfection ; Tumor Burden

Steroid-resistant nephrotic syndrome poses a significant clinical challenge. Its pathogenesis has not been fully elucidated. In recent years, numerous studies have shown that podocyte-specific gene mutations may play important roles in the development of steroid-resistant nephrotic syndrome. Among the identified genes mutated in podocytes include NPHS2, NPHS1, WT1, TRPC6, MDR1, PLCE1, LMX1B, and LAMB2. This review aims to summarize the characteristics of these mutated genes in podocytes. The putative role for these podocyte-specific mutated genes in the pathogenesis, diagnosis, treatment and prognosis of steroid-resistant nephrotic syndrome is also discussed.
ATP Binding Cassette Transporter, Sub-Family B ; ATP-Binding Cassette, Sub-Family B, Member 1 ; genetics ; Genes, Wilms Tumor ; Humans ; Intracellular Signaling Peptides and Proteins ; genetics ; LIM-Homeodomain Proteins ; genetics ; Membrane Proteins ; genetics ; Mutation ; Nephrotic Syndrome ; congenital ; genetics ; Podocytes ; metabolism ; TRPC Cation Channels ; genetics ; TRPC6 Cation Channel ; Transcription Factors ; genetics