Analysis of Kif5b expression during mouse kidney development

Mitochondrial dysfunction in the pathophysiology of renal diseases

Mitochondria are essential organelles in the human body, serving as the metabolic factory of the whole organism. When mitochondria are dysfunctional, it can affect all organs of the body. The kidney is rich in mitochondria, and its function is closely related to the development of kidney diseases. Studying the relationship between mitochondria and kidney disease progression is of great interest. In the past decade, scientists have made inspiring progress in investigating the role of mitochondria in the pathophysiology of renal diseases. This article discusses various mechanisms for maintaining mitochondrial quality, including mitochondrial energetics, mitochondrial biogenesis, mitochondrial dynamics, mitochondrial DNA repair, mitochondrial proteolysis and the unfolded protein response, mitochondrial autophagy, mitochondria-derived vesicles, and mitocytosis. The article also highlights the cross talk between mitochondria and other organelles, with a focus on kidney diseases. Finally, the article concludes with an overview of mitochondria-related clinical research.

In Search of Imprints Left by the Impairment of Nephrogenesis

Clinical aspects dealing with the impairment of nephrogenesis in preterm and low birth weight babies were intensely researched. In this context it was shown that quite different noxae can harm nephron formation, and that the morphological damage in the fetal kidney is rather complex. Some pathological findings show that the impairment leads to changes in developing glomeruli that are restricted to the maturation zone of the outer cortex in the fetal human kidney. Other data show also imprints on the stages of nephron anlage including the niche, the pretubular aggregate, the renal vesicle, and comma- and S-shaped bodies located in the overlying nephrogenic zone of the rodent and human kidneys. During our investigations it was noticed that the stages of nephron anlage in the fetal human kidney during the phase of late gestation have not been described in detail. To contribute, these stages were recorded along with corresponding images. The initial nephron formation in the rodent kidney served as a reference. Finally, the known imprints left by the impairment in both specimens were listed and discussed. In sum, the relatively paucity of data on nephron formation in the fetal human kidney during the late phase of gestation is a call to start with intense research so that concepts for a therapeutic prolongation of nephrogenesis can be designed.

A role for kinesin-1 subunits KIF5B/KLC1 in regulating epithelial mesenchymal plasticity in breast tumorigenesis

Background

Epithelial mesenchymal plasticity (EMP) is deemed vital in breast cancer progression, metastasis, stemness and resistance to therapy. Therefore, characterizing molecular mechanisms contributing to EMP are in need enabling the development of more advanced therapeutics against breast cancer. While kinesin superfamily proteins (KIFs) are well known for their role in intracellular cargo movement, our knowledge of their function in breast tumorigenesis is still limited.

Methods

Various breast cancer cell lines representing different molecular subtypes were used to determine the role of kinesine-1 subunits KIF5B/KLC1 in regulation of EMP.

Findings

In breast cancer, we show that kinesin family member 5B (KIF5B) and its partner protein kinesin light chain 1 (KLC1), subunits of kinesin-1, to play differential roles in regulating EMP and tumorigenesis. Indeed, we found KIF5B to be expressed in triple negative (TN)-basal-like/claudin low breast cancer subtype and to be an inducer of epithelial-mesenchymal transition (EMT), stemness, invasiveness, tumor formation and metastatic colonization. Whereas, we found KLC1 to be expressed in epithelial/luminal breast cancer subtypes and to be a suppressor of EMT, invasion, metastasis and stem cell markers expression as well as to be an inducer of epithelial/luminal phenotype. Interestingly, in TN-basal-like/claudin low cells we found a novel nuclear accumulation of KIF5B and its interaction with the EMT transcriptional regulator Snail1 independent of KLC1. In addition, TGF-β mediated pro-invasive activity was found to be dependent on KIF5B expression. In contrast, the epithelial differentiation factor and EMT suppressor prolactin (PRL) was found to repress KIF5B gene expression and KIF5B-Snail1 nuclear accumulation, but enhanced KLC1 gene expression and KIF5B-KLC1 interaction.

Interpretation

Together, these results highlight a new paradigm for kinesin-1 function in breast tumorigenesis by regulating EMP programing and aggressiveness.

Fund

This work was supported by the Canadian Institutes of Health Research (operating grants #233437 and 233438) granted to Suhad Ali.

Adipose-specific deletion of Kif5b exacerbates obesity and insulin resistance in a mouse model of diet-induced obesity

Recent studies have shown that KIF5B (conventional kinesin heavy chain) mediates glucose transporter type 4 translocation and adiponectin secretion in 3T3-L1 adipocytes, suggesting an involvement of KIF5B in the homeostasis of metabolism. However, the in vivo physiologic function of KIF5B in adipose tissue remains to be determined. In this study, adipose-specific Kif5b knockout (F-K5bKO) mice were generated using the Cre-LoxP strategy. F-K5bKO mice had similar body weights to controls fed on a standard chow diet. However, F-K5bKO mice had hyperlipidemia and significant glucose intolerance and insulin resistance. Deletion of Kif5b aggravated the deleterious impact of a high-fat diet (HFD) on body weight gain, hepatosteatosis, glucose tolerance, and systematic insulin sensitivity. These changes were accompanied by impaired insulin signaling, decreased secretion of adiponectin, and increased serum levels of leptin and proinflammatory adipokines. F-K5bKO mice fed on an HFD exhibited lower energy expenditure and thermogenic dysfunction as a result of whitening of brown adipose due to decreased mitochondria biogenesis and down-regulation of key thermogenic gene expression. In conclusion, selective deletion of Kif5b in adipose tissue exacerbates HFD-induced obesity and its associated metabolic disorders, partly through a decrease in energy expenditure, dysregulation of adipokine secretion, and insulin signaling.-Cui, J., Pang, J., Lin, Y.-J., Gong, H., Wang, Z.-H., Li, Y.-X., Li, J., Wang, Z., Jiang, P., Dai, D.-P., Li, J., Cai, J.-P., Huang, J.-D., Zhang, T.-M. Adipose-specific deletion of Kif5b exacerbates obesity and insulin resistance in a mouse model of diet-induced obesity.

Stable knockdown of Kif5b in MDCK cells leads to epithelial-mesenchymal transition

Polarization of epithelial cells requires vectorial sorting and transport of polarity proteins to apical or basolateral domains. Kif5b is the mouse homologue of the human ubiquitous Kinesin Heavy Chain (uKHC). To investigate the function of Kif5b in epithelial cells, we examined the phenotypes of Kif5b-deficient MDCK cells. Stable knockdown of Kif5b in MDCK cells resulted in reduced cell proliferation rate, profound changes in cell morphology, loss of epithelial cell marker, and gain of mesenchymal marker, as well as increased cell migration, invasion, and tumorigenesis abilities. E-cadherin and NMMIIA could interact with Kif5b in polarized MDCK cells, and their expression levels were decreased in Kif5b-deficient MDCK cells. Overexpression of E-cadherin and NMMIIA in Kif5b depleted MDCK cells could decrease mesenchymal marker expression and cell migration ability. These results indicate that stable knockdown of Kif5b in MDCK cells can lead to epithelial-mesenchymal transition, which is mediated by defective E-cadherin and NMMIIA expression.