Biology subjects

Coulombe, P. A.

Publications and source records attributed to Coulombe, P. A..

3 recordsLinked to original sources

bioRxiv2019

A role for keratins in supporting mitochondrial organization and function in skin keratinocytes

Mitochondria fulfill essential roles in ATP production, metabolic regulation, calcium signaling, generation of reactive oxygen species (ROS) and additional determinants of cellular health. Recent studies have highlighted a role for mitochondria during cell differentiation, including in skin epidermis. The observation of oxidative stress in keratinocytes from Krt16 null mouse skin, a model for pachyonychia congenita (PC)-associated palmoplantar keratoderma, prompted us to examine the role of Keratin (K) 16 protein and its partner K6 in regulating the structure and function of mitochondria. Electron microscopy revealed major anomalies in mitochondrial ultrastructure in late stage, E18.5, Krt6a/Krt6b null embryonic mouse skin. Follow-up studies utilizing biochemical, metabolic, and live imaging readouts showed that, relative to controls, skin keratinocytes null for Krt6a/Krt6b or Krt16 exhibit elevated ROS, reduced mitochondrial respiration, intracellular distribution differences and altered movement of mitochondria within the cell. These findings highlight a novel role for K6 and K16 in regulating mitochondrial morphology, dynamics and function and shed new light on the causes of oxidative stress observed in PC and related keratin-based skin disorders.

cell biology↗

bioRxiv2019

Keratin 14-dependent disulfides regulate epidermal homeostasis and barrier function via 14-3-3sigma and YAP1

The type I intermediate filament (IF) keratin 14 (K14) provides vital structural support in basal keratinocytes of epidermis. Recent studies evidenced a role for K14-dependent disulfide bonding in the organization and dynamics of keratin IFs in skin keratinocytes. Here we report that knock-in mice harboring a cysteine-to-alanine substitution at codon 373 (C373A) in Krt14 exhibit alterations in disulfide-bonded K14 species and a barrier defect secondary to enhanced proliferation, faster transit time and altered differentiation in the epidermis. A proteomics screen identified 14-3-3 as major K14 interacting proteins. Follow-up studies showed that YAP1, a transcriptional effector of Hippo signaling regulated by 14-3-3sigma in skin keratinocytes, shows aberrant subcellular partitioning and function in differentiating Krt14C373A keratinocytes. Residue C373 in K14, which is conserved in several other type I IFs, is thus revealed as a novel regulator of keratin organization and YAP function in early differentiating keratinocytes, with an impact on cell mechanics, homeostasis and barrier function in the epidermis.

cell biology↗

bioRxiv2019

Structure-function analyses of a keratin heterotypic complex identify specific keratin regions involved in intermediate filament assembly

Intermediate filaments (IFs) provide vital mechanical support in a broad array of cell types. Interference with this role causes cell fragility and accounts for a large number of human diseases. Gaining an understanding IF structure is paramount to understanding their function and designing therapeutic agents for relevant diseases. Here, we report the 2.6 [A] resolution crystal structure of a complex of interacting 2B domains of keratin 5 (K5) and K14. K5 and K14 form a long-range, left-handle coiled coil, with participating -helices aligned in parallel and in register. Follow-up mutagenesis revealed that specific contacts between interacting 2B domains play a crucial role during 10-nm IF assembly, likely at the step of octamer-octamer association. The resulting structural model represents the first atomic-resolution visualization of 2B-2B interactions consistent with the A22 dimer alignment and provide insight into the defects introduced by mutations in IF genes associated with human skin diseases.

biochemistry↗