Mitochondrial deoxyribonucleic acid (mtDNA) plays a key role in the regulation of cell growth and survival. It has been demonstrated that mutations in mtDNA have an impact on survival for cancer patients, and studying these alterations may therefore provide valuable insight into cancer progression and tumorigenesis.  In this project, three mtDNA genes, MT-COX3, MT-CYB and MT-ATP6 have been knockout out from Human Embryonic Kidney 293T (HEK293T) cell models to investigate their role in tumorigenesis and cancer progression. Knockout cell models developed for MT-COX3 and MTATP6 was successful obtained, however no satisfactory knockout cell model for MT-CYB was obtained, limiting the investigation to MT-ATP6 and MT-COX3. The function of these two genes were investigated using numerous techniques including measuring cell growth, cell metabolism, and mitochondrial function. The results suggests that the knockout of the genes reduces the proliferation and viability of the cells. It also causes the cells to shift their metabolism and reduces mitochondrial function in general. This suggests that both MT-ATP6 and MT-COX3 are important for proper function of the investigated cells. Based on the findings, it can be concluded that mitochondria play an important role for the fitness of the investigated cells and that mtDNA may be a potential target for cancer treatment.

Disorders of ATP synthase, the key enzyme of mitochondrial energy provision belong to the most severe metabolic diseases presenting mostly as early-onset mitochondrial encephalo-cardio-myopathies. Mutations in four nuclear genes can result in isolated deficiency of ATP synthase, all sharing a similar biochemical phenotype - pronounced decrease in the content of fully assembled and functional ATP synthase complex. The thesis summarises studies on two distinct causes of ATP synthase deficiency. First is TMEM70 protein, a novel ancillary factor of ATP synthase, which represents most frequent determinant of severe inborn deficiency of ATP synthase. TMEM70 is a 21 kDa protein of the inner mitochondrial membrane, facilitating the biogenesis of mitochondrial ATP synthase, possibly through TMEM70 protein region exposed to the mitochondrial matrix, but the proper regulatory mechanism remains to be elucidated. In TMEM70-lacking patient fibroblasts the low content of ATP synthase induces compensatory adaptive upregulation of mitochondrial respiratory chain complexes III and IV, interestingly by a posttranscriptional mechanisms. The second type of ATP synthase deficiency studied was mtDNA m.9205delTA mutation affecting maturation of MT-ATP8/MT-ATP6/MT-CO3 mRNA and thus biosynthesis of Atp6 (subunit a) and Cox3...

Disorders of ATP synthase, the key enzyme of mitochondrial energy provision belong to the most severe metabolic diseases presenting mostly as early-onset mitochondrial encephalo-cardio-myopathies. Mutations in four nuclear genes can result in isolated deficiency of ATP synthase, all sharing a similar biochemical phenotype - pronounced decrease in the content of fully assembled and functional ATP synthase complex. The thesis summarises studies on two distinct causes of ATP synthase deficiency. First is TMEM70 protein, a novel ancillary factor of ATP synthase, which represents most frequent determinant of severe inborn deficiency of ATP synthase. TMEM70 is a 21 kDa protein of the inner mitochondrial membrane, facilitating the biogenesis of mitochondrial ATP synthase, possibly through TMEM70 protein region exposed to the mitochondrial matrix, but the proper regulatory mechanism remains to be elucidated. In TMEM70-lacking patient fibroblasts the low content of ATP synthase induces compensatory adaptive upregulation of mitochondrial respiratory chain complexes III and IV, interestingly by a posttranscriptional mechanisms. The second type of ATP synthase deficiency studied was mtDNA m.9205delTA mutation affecting maturation of MT-ATP8/MT-ATP6/MT-CO3 mRNA and thus biosynthesis of Atp6 (subunit a) and Cox3...