Sex differences in metabolic pathways are regulated by Pfkfb3 and Pdk4 expression in rodent muscle

Skeletal muscles display sexually dimorphic features. Biochemically, glycolysis and fatty acid β-oxidation occur preferentially in the muscles of males and females, respectively. However, the mechanisms of the selective utilization of these fuels remains elusive. Here, we obtain transcriptomes from quadriceps type IIB fibers of untreated, gonadectomized, and sex steroid-treated mice of both sexes. Analyses of the transcriptomes unveil two genes, Pfkfb3 (phosphofructokinase-2) and Pdk4 (pyruvate dehydrogenase kinase 4), that may function as switches between the two sexually dimorphic metabolic pathways. Interestingly, Pfkfb3 and Pdk4 show male-enriched and estradiol-enhanced expression, respectively. Moreover, the contribution of these genes to sexually dimorphic metabolism is demonstrated by knockdown studies with cultured type IIB muscle fibers. Considering that skeletal muscles as a whole are the largest energy-consuming organs, our results provide insights into energy metabolism in the two sexes, during the estrus cycle in women, and under pathological conditions involving skeletal muscles.

LncRNA HCG11 promotes 5-FU resistance of colon cancer cells through reprogramming glucose metabolism by targeting the miR-144-3p-PDK4 axis

BACKGROUND: Colorectal cancer (CRC), one of the most common human malignancies, is a leading cause of the cancer-related mortality. 5-FU is a first-line chemotherapeutic agent against CRC. Although CRC patients responded to 5-FU therapy initially, a part of patients succumbed to CRC due to the acquired drug resistance. Thus, investigating molecular mechanisms underlying chemoresistance will contribute to developing novel strategies against colorectal cancer. OBJECTIVE: Accumulation evidence revealed pivotal roles of long non-coding RNAs (lncRNAs) in tumorigenesis and chemoresistance of CRC. However, the precise roles and molecular mechanisms of lncRNA-HCG11 in CRC remain unclear. This study aimed to investigate the biological roles and underlying mechanisms of HCG11 as well as its molecular targets in regulating the cellular metabolism processes, which facilitate the chemoresistance of CRC. METHODS AND RESULTS: This study uncovers that HCG11 was significantly upregulated in CRC tumors tissues and cell lines. Moreover, HCG11 was elevated in 5-FU resistant CRC tumors. Silencing HCG11 inhibited colon cancer cell proliferation, migration, invasion and glucose metabolism and sensitized CRC cells to 5-FU. In addition, we detected increased HCG11 expression level and glucose metabolism in the established 5-FU resistant CRC cell line (DLD-1 5-FU Res). Furthermore, microRNA-microArray, RNA pull-down and luciferase assays demonstrated that HCG11 inhibited miR-144-3p which displays suppressive roles in colon cancer via sponging it to form a ceRNA network. We identified pyruvate dehydrogenase kinase 4 (PDK4), which is a glucose metabolism key enzyme, was directly targeted by miR-144-3p in CRC cells. Rescue studies validated that the miR-144-3p-inhibited glucose metabolism and 5-FU sensitization were through targeting PDK4. Finally, restoration of miR-144-3p in HCG11-overexpressing DLD-1 5-FU resistant cells successfully overcame the HCG11-faciliated 5-FU resistance via targeting PDK4. CONCLUSION: In summary, this study reveals critical roles and molecular mechanisms of the HCG11-mediated 5-FU resistance through modulating the miR-144-3p-PDK4-glucose metabolism pathway in CRC.

Androgen regulated protein and pyruvate dehydrogenase kinase 4 in severe erectile dysfunction: A gene expression analysis, and computational study of protein structure

Erectile dysfunction (ED) is one of the most common sexual disorders in men. During the past 30 years, there has been no new drug development for ED. Thus, exploring the genetic basis of ED deserves further study, in hope of developing new pharmacological treatments for ED. In this study, Real-Time PCR analysis was used to assess the expression of androgen regulatory protein (Andpro) and pyruvate dehydrogenase kinase 4 (Pdk4) genes in ED. For this purpose, the experiment was performed on 20 men with severe ED and 20 potent men. IIEF-15 was used to determine the ED severity. The study was conducted in the Department of Sexual Medicine of the Kermanshah University of Medical Sciences, Kermanshah, Iran. The EDTA-Na vacuum blood tube was taken from ED patients and controls. Informed consent was obtained from all participants. After blood sampling, RNA was extracted from whole blood. Then cDNA was synthesized. The gene expression was analyzed through the qPCR method. The ß-actin was used as a reference gene. To further study these two proteins, their three-dimensional structures were predicted through I-TASSER. Compared with controls, in ED patients, the expression of the Andpro gene decreased, while the expression of the Pdk4 gene increased (p<0.01). Predicting the structure of the protein showed that Pyruvate Dehydrogenase Kinase 4 had a double subunit and androgen-regulated protein had a single subunit.

Differential expression of pyruvate dehydrogenase kinase 4 in cancers of the breast.

Breast cancer affects women at relatively high frequency (1). We mined published microarray datasets (2, 3) to determine in an unbiased fashion and at the systems level genes most differentially expressed in the primary tumors of patients with breast cancer. We report here significant differential expression of the gene encoding pyruvate dehydrogenase kinase 4, PDK4, when comparing primary tumors of the breast to the tissue of origin, the normal breast. PDK4 was also differentially expressed in the tumor cells of patients with triple negative breast cancer. PDK4 mRNA was present at significantly lower quantities in tumors of the breast as compared to normal breast tissue. Analysis of human survival data revealed that expression of PDK4 in primary tumors of the breast was correlated with overall survival in patients with luminal A subtype cancer, demonstrating a relationship between primary tumor expression of a differentially expressed gene and patient survival outcomes influenced by molecular subtype. PDK4 may be of relevance to initiation, maintenance or progression of cancers of the female breast.