Question

I need help with this question below. Researchers generated a transgenic strain of mice called DrpTg which overexpresses a protein called Drp1 under a muscle-specific promoter. DrpTg mice had poor postnatal weight gain, smaller muscle mass and lower muscle strength than WT mice of the same age and fed the same diet. The experiments shown in the left panel below showed that phosphorylation of the normal cellular protein labeled P-? was increased in DrpTG muscle compared to WT muscle tissue. The panel on the right shows that phosphorylation of another protein was also increased in DrpTg compared to WT muscle tissue. Based on mechanisms of post-transcriptional regulation and the data shown in the figure below, what normal cellular protein is the protein labeled ‘P-?’ below most likely to be? (This is as clear as the pictures get).

7. (4 pt) Researchers generated a transgenic strain of mice called Drp Tg which overexpresses a protein called Drp 1 under a muscle-specific promoter. DrpTg mice had poor postnatal weight gain, smaller muscle mass and lower muscle strength than WT mice of the same age and fed the same diet. The experiments shown in the left panel below showed that phosphorylation of the normal cellular protein labeled P-? was increased in DrpTG muscle compared to WT muscle tissue. The panel on the right shows that phosphorylation of another protein was also increased in DrpTg compared to WT muscle tissue. Based on mechanisms of post-transcriptional regulation and the data shown in the figure below, what normal cellular protein is the protein labeled 'P-?' below most likely to be? _ P100 P-? _ P7 P25 P-elF2 ---- - - elF2 - Actin -- - LLL Mouse Coomassie IM WT Drp/MC WT WT Figure legend. P7, P25, P100 denote muscle lysates obtained from mice at postnatal days 7, 25, and 100. Left panel: Postnatal day 7 (P7) muscle lysate from a WT mouse and a DrpTg mouse were immunoblotted using antibody that recognizes the phosphorylated form of protein '?' (P-?). Right panel: Muscle tissue from three wild type mice (WT) and 2-3 DrpTg mice was homogenized and the muscles lysed for Western blot analysis using antibodies to the indicated proteins. Leave this area blank and go to the next page for Question 9.

Answer 1

Answer:

In the process of identifying the protein pathways involved during the overexpression of dynamin-related protein (DrpTg) in mice leading to poor muscle mass, the authors performed the western blot analysis. For this, elF2 pathway was studied since it is a known crucial protein regulator of translation and its studies were previously linked to mitochondria stress. This mitochondrial stress-induced elF2 was linked to the RNA-activated protein kinase (PKR) pathway. Therefore, since skeletal muscle growth and mitochondrial stress are related, the present study was performed.

The protein in the left panel that is upregulated with overexpressed Drp in transgenic mice is the p-PKR protein. Thus, the Drp protein stimulates mitochondrial stress-related proteins PKR and elF2 as observed with the above-mentioned results.