Question: What is the role of the TSC1 and TSC2 genes in regulating the mTOR signaling pathway and cell growth?

Context:
The genetic basis of this disease has been attributed to mutations in one of two unlinked genes, TSC1 and TSC2.
The functions of the TSC1 and TSC2 gene products, hamartin and tuberin, respectively, have remained ill defined until recently
Genetic, biochemical, and biologic analyses have highlighted their role as negative regulators of the mTOR signaling pathway. Tuberin, serving as a substrate of AKT and AMPK, mediates mTOR activity by coordinating inputs from growth factors and energy availability in the control of cell growth, proliferation, and survival. Emerging evidence also suggests that the TSC 1/2 complex may play a role in modulating the activity of beta-catenin and TGFbeta. These findings provide novel functional links between the TSC genes and other tumor suppressors
Ten years ago, a mutation in the TSC2 gene was identified in the Eker rat at Fox Chase Cancer Center by Yeung and Knudson, and in Tokyo by Kobayashi and Hino.
Here, we will review the clinical association of RCC in TSC, consider the factors that have led to its under-emphasis within the RCC field, address the cellular and biochemical mechanisms that may contribute to RCC in cells with TSC1 or TSC2 mutations, and finally discuss the ways in which the TSC signaling pathways may be linked to sporadic RCC in the general population.
Either of two genes, TSC1 or TSC2, can be mutated, resulting in the tuberous sclerosis complex phenotype.
The protein products of the tuberous sclerosis complex genes, hamartin (TSC1) and tuberin (TSC2), have been discovered to play important roles in several cell-signaling pathways
Knowledge regarding the function of the tuberin-hamartin complex has led to therapeutic intervention trials. 
TSC2 mutations were identified in all cyst-positive patients who were tested (n = 8), whereas both TSC1 and TSC2 mutations were found in patients with nodular disease.
We previously found TSC2 loss of heterozygosity in 7 of 13 (54%) of angiomyolipomas from sporadic LAM patients, suggesting that LAM and TSC could have a common genetic basis.
Mutations in the tuberous sclerosis complex gene TSC2 are a cause of sporadic pulmonary lymphangioleiomyomatosis
The disease can be caused by mutations in either of two genes, TSC2, identified in 1993, and TSC1, only recently identified.
Molecular genetic basis of renal carcinogenesis in the Eker rat model of tuberous sclerosis (Tsc2)
We have recently identified on rat chromosome 10q a germline mutation in the tuberous sclerosis gene (Tsc2), the gene predisposing to renal carcinoma (RC) in the Eker rat
Tuberous sclerosis complex is a genetic disorder caused by mutations in either the TSC1 or TSC2 gene that can result in the growth of hamartomas in multiple organ systems
Striking improvements in the understanding of the genetic basis of this autosomal dominant genetic disease are coupled to the understanding of the mechanisms that link the loss of TSC1 (9q34) or TSC2 (16p13.3) genes with the regulation of the Rheb/m-TOR/p70S6K pathway. 
In all these lesions, genetic alterations related to the tuberous sclerosis complex (TSC) have been demonstrated. Striking improvements in the understanding of the genetic basis of this autosomal dominant genetic disease are coupled to the understanding of the mechanisms that link the loss of TSC1 (9q34) or TSC2 (16p13.3) genes with the regulation of the Rheb/m-TOR/p70S6K pathway.
In all these lesions, genetic alterations related to the tuberous sclerosis complex (TSC) have been demonstrated. Striking improvements in the understanding of the genetic basis of this autosomal dominant genetic disease are coupled to the understanding of the mechanisms that link the loss of TSC1 (9q34) or TSC2 (16p13.

Answer: The TSC1 and TSC2 genes act as negative regulators of the mTOR signaling pathway. Tuberin, a product of the TSC2 gene, coordinates inputs from growth factors and energy availability to control cell growth, proliferation, and survival. The TSC 1/2 complex may also modulate the activity of beta-catenin and TGFbeta, providing functional links between the TSC genes and other tumor suppressors.